/* Rankwise — exam-desk visual language.
   Cool answer-sheet paper, ballpoint blue for every action, OMR-print red for small marks,
   highlighter yellow for the one number that matters. */

/* Lighter palette (29 Oct): near-white paper, soft section tints, one friendly blue for actions. */
:root {
  --paper: #fbfcfe;
  --paper-2: #f2f5fb;
  --card: #ffffff;
  --ink: #1f2740;
  --ink-2: #4b5470;
  --muted: #5f6880;
  --rule: #e8ecf4;
  --rule-strong: #d3d9e6;
  --blue: #3560e8;
  --blue-ink: #ffffff;
  --blue-soft: #eef2ff;
  --red: #c9413a;
  --green: #11744c;
  --green-soft: #e3f6ec;
  --amber-soft: #fff5d6;
  --hl: #fff09a;
  --shadow: 0 1px 2px rgba(31, 39, 64, .04), 0 8px 24px -14px rgba(58, 99, 240, .18);
  --radius: 14px;
  --display: "Archivo", "Arial Narrow", system-ui, sans-serif;
  --serif: var(--display);
  --sans: system-ui, -apple-system, "Segoe UI", Roboto, "Noto Sans", sans-serif;
  --mono: "IBM Plex Mono", ui-monospace, SFMono-Regular, Menlo, monospace;
  /* section tints: soft background + readable accent */
  --jee: #2563d6; --jee-soft: #e8f1ff;
  --neet: #c23a5b; --neet-soft: #fdecf0;
  --chemistry: #11744c; --chemistry-soft: #e4f6ee;
  --physics: #6045d6; --physics-soft: #efecff;
  --maths: #a65310; --maths-soft: #fff0e2;
  --study: #806200; --study-soft: #fdf5dc;
  --games: #0f7088; --games-soft: #e6f5fa;
  --sec: var(--blue); --sec-soft: var(--blue-soft);
  color-scheme: light;
}

/* Light only: Shubham asked for light tones (29 Oct), and his phone runs in dark mode. */

body[data-sec] { --sec: var(--jee); --sec-soft: var(--jee-soft); }
body[data-sec="neet"] { --sec: var(--neet); --sec-soft: var(--neet-soft); }
body[data-sec="chemistry"] { --sec: var(--chemistry); --sec-soft: var(--chemistry-soft); }
body[data-sec="physics"] { --sec: var(--physics); --sec-soft: var(--physics-soft); }
body[data-sec="maths"] { --sec: var(--maths); --sec-soft: var(--maths-soft); }
body[data-sec="study"] { --sec: var(--study); --sec-soft: var(--study-soft); }
body[data-sec="games"] { --sec: var(--games); --sec-soft: var(--games-soft); }
[data-s="jee"] { --t: var(--jee); --ts: var(--jee-soft); }
[data-s="neet"] { --t: var(--neet); --ts: var(--neet-soft); }
[data-s="chemistry"] { --t: var(--chemistry); --ts: var(--chemistry-soft); }
[data-s="physics"] { --t: var(--physics); --ts: var(--physics-soft); }
[data-s="maths"] { --t: var(--maths); --ts: var(--maths-soft); }
[data-s="study"] { --t: var(--study); --ts: var(--study-soft); }
[data-s="games"] { --t: var(--games); --ts: var(--games-soft); }

*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font: 17px/1.6 var(--sans);
  text-rendering: optimizeLegibility;
}
img, svg { max-width: 100%; display: block; }
a { color: var(--blue); text-underline-offset: 3px; text-decoration-thickness: 1px; }
a:hover { text-decoration-thickness: 2px; }
:focus-visible { outline: 3px solid var(--blue); outline-offset: 2px; border-radius: 4px; }

.wrap { max-width: 1080px; margin: 0 auto; padding: 0 20px; }
.narrow { max-width: 720px; }

/* ---------- header, menu, search ---------- */
.site-head { border-bottom: 1px solid var(--rule); background: color-mix(in srgb, var(--paper) 92%, transparent); backdrop-filter: saturate(1.4) blur(10px); -webkit-backdrop-filter: saturate(1.4) blur(10px); position: sticky; top: 0; z-index: 20; }
.site-head .wrap { display: flex; align-items: center; gap: 14px; height: 60px; }
.brand { display: flex; align-items: center; gap: 9px; font: 800 21px/1 var(--display); color: var(--ink); text-decoration: none; letter-spacing: -.02em; margin-right: auto; }
.brand-mark { width: 30px; height: 30px; flex: none; border-radius: 8px; }
.head-act { display: flex; gap: 8px; order: 3; }
.search-btn, .nav-toggle { display: inline-flex; align-items: center; gap: 7px; min-height: 40px; background: var(--card); border: 1px solid var(--rule-strong); color: var(--ink); border-radius: 999px; padding: 0 14px; font: 600 14px var(--sans); cursor: pointer; }
.search-btn { color: var(--ink-2); min-width: 150px; }
.search-btn:hover, .nav-toggle:hover { border-color: var(--blue); color: var(--ink); }
.nav-toggle { display: none; }
.bars { width: 16px; height: 10px; border-top: 2px solid currentColor; border-bottom: 2px solid currentColor; position: relative; }
.bars::after { content: ""; position: absolute; left: 0; right: 0; top: 2px; border-top: 2px solid currentColor; }
.nav { order: 2; }
.nav-grid { display: flex; gap: 2px; }
.nav-grid a { display: flex; align-items: center; gap: 7px; color: var(--ink-2); text-decoration: none; font-size: 15px; padding: 7px 10px; border-radius: 999px; }
.nav-grid a i { width: 8px; height: 8px; border-radius: 50%; background: var(--t); flex: none; }
.nav-grid a b { font-weight: 500; }
.nav-grid a span { display: none; }
.nav-grid a:hover { background: var(--ts); color: var(--ink); }
.nav-grid a[aria-current] { background: var(--ts); color: var(--ink); }
.nav-grid a[aria-current] b { font-weight: 650; }
.nav-quick { display: none; }
@media (max-width: 960px) {
  .search-btn { min-width: 0; padding: 0 12px; }
  .search-btn span { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0 0 0 0); }
  .nav-toggle { display: inline-flex; }
  .nav { position: absolute; top: 60px; left: 0; right: 0; background: var(--paper); border-bottom: 1px solid var(--rule); box-shadow: 0 18px 30px -20px rgba(31, 39, 64, .35); padding: 14px 16px 16px; display: none; max-height: calc(100vh - 60px); overflow-y: auto; }
  .nav.open { display: block; }
  .nav-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 8px; }
  .nav-grid a { display: grid; grid-template-columns: auto 1fr; align-items: start; gap: 2px 9px; padding: 12px; border-radius: 12px; background: var(--ts); color: var(--ink); }
  .nav-grid a i { margin-top: 7px; grid-row: span 2; }
  .nav-grid a b { font-weight: 650; font-size: 16px; }
  .nav-grid a span { display: block; font-size: 13px; line-height: 1.35; color: var(--ink-2); }
  .nav-grid a[aria-current] { box-shadow: inset 0 0 0 2px var(--t); }
  .nav-quick { display: flex; flex-wrap: wrap; gap: 8px; margin: 14px 0 0; }
  .nav-quick a { font-size: 14px; padding: 7px 12px; border: 1px solid var(--rule-strong); border-radius: 999px; text-decoration: none; color: var(--ink); background: var(--card); }
}
.sr-only { position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px; overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; border: 0; }

.site-search { position: relative; }
.ss-field { position: relative; }
.ss-field svg { position: absolute; left: 14px; top: 50%; transform: translateY(-50%); color: var(--muted); pointer-events: none; }
.site-search input[type="search"] { padding-left: 42px; font: 500 17px var(--sans); background: var(--card); border-radius: 12px; }
.ss-res { list-style: none; margin: 8px 0 0; padding: 0; }
.ss-res:empty { display: none; }
.ss-res a { display: flex; align-items: center; gap: 10px; padding: 11px 12px; border-radius: 10px; text-decoration: none; color: var(--ink); }
.ss-res a b { font-weight: 550; flex: 1; min-width: 0; }
.ss-res a em { font-style: normal; font-size: 12.5px; font-weight: 600; color: var(--t, var(--muted)); background: var(--ts, var(--paper-2)); padding: 2px 8px; border-radius: 999px; white-space: nowrap; }
.ss-res a:hover, .ss-res a:focus { background: var(--paper-2); }
.ss-res a:focus-visible { outline-offset: -2px; }
.ss-res mark { background: var(--hl); padding: 0 1px; border-radius: 2px; }
.ss-res .ss-h { font-size: 12.5px; font-weight: 600; color: var(--muted); text-transform: uppercase; letter-spacing: .06em; padding: 6px 12px 2px; }
.site-search.inline { margin: 22px 0 8px; }
.site-search.inline .ss-res:not(:empty) { background: var(--card); border: 1px solid var(--rule); border-radius: 12px; padding: 6px; box-shadow: var(--shadow); }
.search-dlg { border: 0; padding: 0; background: transparent; width: min(640px, calc(100% - 24px)); max-height: calc(100vh - 40px); margin: 6vh auto auto; }
.search-dlg::backdrop { background: rgba(31, 39, 64, .35); backdrop-filter: blur(2px); }
.sd-box { background: var(--card); border-radius: 16px; padding: 14px; box-shadow: 0 30px 60px -20px rgba(31, 39, 64, .45); position: relative; }
.sd-box .ss-res { max-height: min(60vh, 520px); overflow-y: auto; }
.sd-box input[type="search"] { padding-right: 76px; }
.sd-box input::-webkit-search-cancel-button { display: none; }
.sd-close { position: absolute; right: 22px; top: 22px; min-height: 36px; padding: 0 12px; border-radius: 8px; border: 1px solid var(--rule-strong); background: var(--paper-2); color: var(--ink-2); font: 600 13px var(--sans); cursor: pointer; }
@media (max-width: 600px) { .search-dlg { margin-top: 10px; } }

/* section pages and tiles */
.sec-tiles { display: grid; grid-template-columns: repeat(auto-fill, minmax(220px, 1fr)); gap: 10px; margin: 8px 0 16px; }
.sec-tile { display: flex; flex-direction: column; gap: 3px; padding: 16px 16px 14px; border-radius: 14px; background: var(--ts); color: var(--ink); text-decoration: none; border: 1px solid transparent; }
.sec-tile:hover { border-color: var(--t); }
.sec-tile b { font: 750 20px/1.15 var(--display); letter-spacing: -.01em; }
.sec-tile span { font-size: 14px; color: var(--ink-2); }
.sec-tile em { font-style: normal; font-size: 14px; font-weight: 600; color: var(--t); margin-top: 6px; }
@media (max-width: 600px) { .sec-tiles { grid-template-columns: 1fr 1fr; } .sec-tile { padding: 13px; } .sec-tile b { font-size: 17px; } .sec-tile span { font-size: 13px; } }
body[data-sec] main { background: linear-gradient(var(--sec-soft), var(--paper) 340px); }
body[data-sec] .crumbs a { color: var(--sec); }
.sec-list { list-style: none; margin: 18px 0 0; padding: 0; display: grid; grid-template-columns: repeat(auto-fill, minmax(300px, 1fr)); gap: 10px; }
.sec-list a { display: flex; align-items: center; gap: 12px; padding: 15px 16px; background: var(--card); border: 1px solid var(--rule); border-radius: 12px; text-decoration: none; color: var(--ink); height: 100%; }
.sec-list a:hover { border-color: var(--sec); }
.sec-list div { flex: 1; }
.sec-list b { display: block; font-size: 16.5px; }
.sec-list span { font-size: 14px; color: var(--muted); }
.sec-list .go { color: var(--sec); font-size: 18px; }
.pop-links, .sec-other { display: flex; flex-wrap: wrap; gap: 8px; }
.pop-links a, .sec-other a { padding: 8px 13px; border-radius: 999px; background: var(--card); border: 1px solid var(--rule-strong); color: var(--ink); text-decoration: none; font-size: 15px; }
.pop-links a:hover { border-color: var(--sec); }
.sec-other a { background: var(--ts); border-color: transparent; }

/* ---------- type ---------- */
h1, h2, h3 { font-family: var(--display); line-height: 1.12; letter-spacing: -.02em; margin: 0 0 .5em; text-wrap: balance; font-stretch: 92%; }
h1 { font-size: clamp(32px, 5.4vw, 48px); font-weight: 800; }
h2 { font-size: clamp(23px, 3.2vw, 29px); font-weight: 750; margin-top: 1.8em; }
h3 { font-size: 20px; font-weight: 700; margin-top: 1.4em; }
p { margin: 0 0 1em; }
.lede { font-size: 19px; color: var(--ink-2); max-width: 62ch; }
.eyebrow { font: 600 13px/1 var(--sans); letter-spacing: .08em; text-transform: uppercase; color: var(--red); margin-bottom: 14px; display: block; }
.muted { color: var(--muted); }
.small { font-size: 14px; }
mark, .hl { background: linear-gradient(transparent 55%, var(--hl) 55%); color: inherit; padding: 0 2px; }
.num { font-family: var(--mono); font-variant-numeric: tabular-nums; }

/* ---------- breadcrumbs ---------- */
.crumbs { font-size: 14px; color: var(--muted); margin: 22px 0 18px; }
.crumbs a { color: var(--muted); }
.crumbs span[aria-hidden] { margin: 0 6px; }

/* ---------- page hero ---------- */
.page-top { padding: 4px 0 8px; }
.page-top h1 { max-width: 24ch; }
.peek { display: none; }
@media (max-width: 860px) {
  .peek:not(:empty) { display: block; margin: 10px 0 0; padding: 10px 12px; background: var(--blue-soft); border-radius: 8px; font: 600 17px var(--sans); }
  .peek a { font-weight: 500; font-size: 15px; margin-left: 6px; }
  .lede { font-size: 17px; }
  .page-top .updated > span:not(.lang-sw) { display: none; }
  .panel, .result { padding: 18px; }
  .result { padding-left: 30px; }
  .result::before { left: 15px; }
  .bubble span { padding: 8px 12px 8px 9px; font-size: 14.5px; }
}
.updated { font-size: 14px; color: var(--muted); display: flex; gap: 14px; flex-wrap: wrap; margin-top: -4px; }

/* ---------- tool layout ---------- */
.tool { display: grid; grid-template-columns: minmax(0, 1fr) minmax(0, 1.1fr); gap: 22px; margin: 22px 0 10px; align-items: start; }
@media (max-width: 860px) { .tool { grid-template-columns: 1fr; } }
.panel { background: var(--card); border: 1px solid var(--rule); border-radius: var(--radius); padding: 22px; box-shadow: var(--shadow); }
.panel h2 { font-size: 18px; margin: 0 0 14px; font-family: var(--sans); font-weight: 650; letter-spacing: 0; }

/* fields */
.field { margin-bottom: 18px; }
.field:last-child { margin-bottom: 0; }
.label { display: block; font-weight: 600; font-size: 15px; margin-bottom: 7px; }
.hint { font-size: 13.5px; color: var(--muted); margin-top: 6px; }
.input-row { display: flex; align-items: stretch; gap: 0; }
input[type="number"], input[type="text"], input[type="search"], input[type="date"], select {
  width: 100%; font: 500 20px/1.2 var(--mono); font-variant-numeric: tabular-nums;
  color: var(--ink); background: var(--paper); border: 1.5px solid var(--rule-strong);
  border-radius: 8px; padding: 12px 14px; min-height: 52px; appearance: none; -moz-appearance: textfield;
}
select { font: 500 16px var(--sans); background-image: linear-gradient(45deg, transparent 50%, var(--ink-2) 50%), linear-gradient(135deg, var(--ink-2) 50%, transparent 50%); background-position: calc(100% - 20px) 50%, calc(100% - 14px) 50%; background-size: 6px 6px; background-repeat: no-repeat; padding-right: 36px; }
input::-webkit-outer-spin-button, input::-webkit-inner-spin-button { -webkit-appearance: none; margin: 0; }
input::placeholder { font-family: var(--sans); font-size: 17px; color: var(--muted); opacity: .8; }
input:focus, select:focus { outline: none; border-color: var(--blue); box-shadow: 0 0 0 3px var(--blue-soft); }
.suffix { display: flex; align-items: center; padding: 0 14px; border: 1.5px solid var(--rule-strong); border-left: 0; border-radius: 0 8px 8px 0; color: var(--muted); font: 500 15px var(--mono); background: var(--paper-2); white-space: nowrap; }
.input-row input { border-radius: 8px 0 0 8px; }
input[type="range"] { width: 100%; accent-color: var(--blue); margin: 12px 0 0; height: 28px; }
.field-error { color: var(--red); font-size: 14px; margin-top: 6px; min-height: 0; }

/* OMR-bubble choice group */
.bubbles { display: flex; flex-wrap: wrap; gap: 8px; border: 0; padding: 0; margin: 0; }
.bubbles legend { padding: 0; }
.bubble { position: relative; }
.bubble input { position: absolute; opacity: 0; inset: 0; cursor: pointer; margin: 0; }
.bubble span { display: inline-flex; align-items: center; gap: 9px; padding: 9px 14px 9px 10px; border: 1.5px solid var(--rule-strong); border-radius: 999px; font-size: 15px; cursor: pointer; background: var(--paper); user-select: none; }
.bubble span::before { content: ""; width: 16px; height: 16px; border-radius: 50%; border: 1.5px solid var(--ink-2); flex: none; transition: background .12s, box-shadow .12s; }
.bubble input:checked + span { border-color: var(--blue); background: var(--blue-soft); font-weight: 600; }
.bubble input:checked + span::before { background: var(--blue); box-shadow: inset 0 0 0 2px var(--card); border-color: var(--blue); }
.bubble input:focus-visible + span { outline: 3px solid var(--blue); outline-offset: 2px; }

/* subject grid for score calculators */
.subj-grid { display: grid; grid-template-columns: 1fr repeat(2, minmax(70px, 96px)); gap: 8px 10px; align-items: center; }
.subj-grid .h { font-size: 13px; color: var(--muted); font-weight: 600; text-transform: uppercase; letter-spacing: .05em; }
.subj-grid .s { font-weight: 600; }
.subj-grid input { font-size: 18px; padding: 10px; min-height: 46px; text-align: center; }
.subj-total { display: flex; justify-content: space-between; border-top: 1px dashed var(--rule-strong); margin-top: 12px; padding-top: 10px; font-size: 14px; color: var(--muted); }

/* ---------- result card (notebook page) ---------- */
.result {
  position: relative; background: var(--card); border: 1px solid var(--rule); border-radius: var(--radius);
  padding: 22px 22px 20px 34px; box-shadow: var(--shadow); overflow: hidden;
}
.result::before { content: ""; position: absolute; left: 18px; top: 0; bottom: 0; width: 2px; background: var(--red); opacity: .7; }
.result-label { font-size: 14px; color: var(--muted); font-weight: 600; }
.result-big { font: 600 clamp(44px, 9vw, 64px)/1.05 var(--mono); font-variant-numeric: tabular-nums; letter-spacing: -.03em; margin: 4px 0 6px; color: var(--ink); }
.result-big small { font-size: .42em; letter-spacing: 0; color: var(--ink-2); margin-left: 4px; }
.result-range { font-size: 15px; color: var(--ink-2); margin-bottom: 14px; }
.result-say { font-size: 17px; margin: 0 0 16px; padding: 12px 0; border-top: 1px solid var(--rule); border-bottom: 1px solid var(--rule); }
.result-empty { color: var(--muted); padding: 30px 0; font-size: 16px; }
.stats { display: grid; grid-template-columns: repeat(auto-fit, minmax(130px, 1fr)); gap: 12px; margin: 0 0 16px; }
.stat { background: var(--paper); border: 1px solid var(--rule); border-radius: 8px; padding: 10px 12px; }
.stat b { display: block; font: 600 22px/1.2 var(--mono); font-variant-numeric: tabular-nums; }
.stat span { font-size: 13px; color: var(--muted); }

/* status chips */
.chips { display: flex; flex-direction: column; gap: 8px; margin: 0 0 14px; padding: 0; list-style: none; }
.chip { display: flex; gap: 10px; align-items: flex-start; font-size: 15px; padding: 9px 12px; border-radius: 8px; background: var(--paper); border: 1px solid var(--rule); }
.chip i { font-style: normal; font-weight: 700; flex: none; width: 20px; text-align: center; }
.chip.yes { background: var(--green-soft); border-color: transparent; }
.chip.yes i { color: var(--green); }
.chip.no { background: var(--amber-soft); border-color: transparent; }
.chip.no i { color: var(--red); }

/* scale bar */
.scale { margin: 6px 0 18px; }
.scale-track { position: relative; height: 10px; border-radius: 99px; background: var(--paper-2); box-shadow: inset 0 0 0 1px var(--rule); }
.scale-range { position: absolute; top: 0; bottom: 0; background: var(--hl); opacity: .9; border-radius: 99px; }
.scale-dot { position: absolute; top: 50%; width: 20px; height: 20px; margin: -10px 0 0 -10px; border-radius: 50%; background: var(--blue); border: 3px solid var(--card); box-shadow: 0 0 0 1.5px var(--blue); transition: left .25s ease; }
.scale-ticks { display: flex; justify-content: space-between; font: 12px var(--mono); color: var(--muted); margin-top: 6px; }

/* buttons */
.btn { display: inline-flex; align-items: center; justify-content: center; gap: 8px; font: 600 15px/1 var(--sans); padding: 12px 18px; border-radius: 8px; border: 1.5px solid var(--blue); background: var(--blue); color: var(--blue-ink); cursor: pointer; text-decoration: none; min-height: 46px; }
.btn:hover { filter: brightness(1.08); }
.btn.ghost { background: transparent; color: var(--ink); border-color: var(--rule-strong); }
.btn.ghost:hover { border-color: var(--ink); }
.btn-row { display: flex; gap: 10px; flex-wrap: wrap; }
.toast { position: fixed; left: 50%; bottom: 24px; transform: translateX(-50%) translateY(20px); background: var(--ink); color: var(--paper); padding: 10px 16px; border-radius: 8px; font-size: 15px; opacity: 0; transition: .2s; pointer-events: none; z-index: 50; }
.toast.show { opacity: 1; transform: translateX(-50%) translateY(0); }

/* ---------- content ---------- */
.content { margin: 30px 0 0; }
.content ul, .content ol { padding-left: 22px; margin: 0 0 1em; }
.content li { margin-bottom: .4em; }
.note { background: var(--amber-soft); border-radius: 8px; padding: 14px 16px; font-size: 15.5px; margin: 1.2em 0; }
.note strong { color: var(--ink); }
.formula { font: 500 16px/1.5 var(--mono); background: var(--paper-2); border-radius: 8px; padding: 14px 16px; overflow-x: auto; margin: 1em 0; }

table { border-collapse: collapse; width: 100%; font-size: 15px; margin: 1em 0 1.4em; }
.table-wrap { overflow-x: auto; -webkit-overflow-scrolling: touch; }
th, td { text-align: left; padding: 10px 12px; border-bottom: 1px solid var(--rule); }
th { font-size: 13px; text-transform: uppercase; letter-spacing: .05em; color: var(--muted); font-weight: 600; background: var(--paper-2); }
td.n, th.n { text-align: right; font-family: var(--mono); font-variant-numeric: tabular-nums; }
tr.is-you td { background: var(--blue-soft); font-weight: 600; }

details.faq { border-bottom: 1px solid var(--rule); padding: 4px 0; }
details.faq summary { cursor: pointer; list-style: none; font-weight: 600; padding: 12px 30px 12px 0; position: relative; font-size: 17px; }
details.faq summary::-webkit-details-marker { display: none; }
details.faq summary::after { content: "+"; position: absolute; right: 4px; top: 9px; font: 400 24px var(--mono); color: var(--muted); }
details.faq[open] summary::after { content: "–"; }
details.faq p { color: var(--ink-2); }

.related { display: grid; grid-template-columns: repeat(auto-fill, minmax(230px, 1fr)); gap: 12px; margin: 14px 0 0; }
.related a { display: block; padding: 14px 16px; border: 1px solid var(--rule); border-radius: 8px; text-decoration: none; color: var(--ink); background: var(--card); }
.related a:hover { border-color: var(--ink-2); }
.related b { display: block; font-size: 16px; }
.related span { font-size: 14px; color: var(--muted); }

/* ---------- home ---------- */
.hero { padding: 54px 0 28px; display: grid; grid-template-columns: 1.15fr .85fr; gap: 40px; align-items: center; }
@media (max-width: 860px) { .hero { grid-template-columns: 1fr; padding-top: 34px; gap: 24px; } }
.hero h1 { font-size: clamp(38px, 6.4vw, 62px); max-width: 13ch; letter-spacing: -.03em; }
.hero h1 em { font-style: normal; background: linear-gradient(transparent 58%, var(--hl) 58%); padding: 0 .06em; }
.quick { background: var(--card); border: 1px solid var(--rule); border-radius: var(--radius); padding: 20px; box-shadow: var(--shadow); }
.quick h2 { font: 650 16px var(--sans); margin: 0 0 12px; letter-spacing: 0; }
.quick-out { margin-top: 12px; font-size: 16px; color: var(--ink-2); min-height: 52px; }
.quick-out b { color: var(--ink); font: 600 22px var(--mono); }
.section-title { display: flex; justify-content: space-between; align-items: baseline; gap: 10px; border-bottom: 2px solid var(--blue); padding-bottom: 8px; margin: 46px 0 0; }
.section-title h2 { margin: 0; font-size: 24px; }
.section-title.neet { border-color: var(--green); }
.section-title.play { border-color: var(--red); }
.tool-list .idx { display: inline-grid; place-items: center; width: 30px; height: 30px; border-radius: 50%; border: 1.5px solid var(--rule-strong); }
.tool-list a:hover .idx { background: var(--blue); border-color: var(--blue); color: var(--blue-ink); }
.section-title span { font-size: 14px; color: var(--muted); }
.tool-list { list-style: none; margin: 0; padding: 0; }
.tool-list li { border-bottom: 1px solid var(--rule); }
.tool-list a { display: grid; grid-template-columns: 34px 1fr auto; gap: 14px; align-items: center; padding: 16px 4px; text-decoration: none; color: var(--ink); }
.tool-list a:hover { background: var(--card); }
.tool-list .idx { font: 500 14px var(--mono); color: var(--muted); }
.tool-list b { display: block; font-size: 18px; font-weight: 650; }
.tool-list span { display: block; color: var(--muted); font-size: 15px; }
.tool-list .go { color: var(--blue); font-weight: 600; font-size: 15px; white-space: nowrap; }
@media (max-width: 560px) { .tool-list .go { display: none; } .tool-list a { grid-template-columns: 28px 1fr; } }

.dates { display: grid; grid-template-columns: repeat(auto-fit, minmax(220px, 1fr)); gap: 12px; margin-top: 16px; }
.date-card { border: 1px solid var(--rule); border-radius: 8px; padding: 14px 16px; background: var(--card); }
.date-card b { display: block; font: 600 28px/1.1 var(--mono); }
.date-card span { color: var(--muted); font-size: 14px; }

/* ---------- countdown ---------- */
.count-big { display: flex; gap: 10px; flex-wrap: wrap; margin: 8px 0 12px; }
.count-unit { background: var(--paper); border: 1px solid var(--rule); border-radius: 8px; padding: 10px 14px 8px; min-width: 86px; text-align: center; }
.count-unit b { display: block; font: 600 36px/1 var(--mono); font-variant-numeric: tabular-nums; }
.count-unit span { font-size: 12.5px; color: var(--muted); text-transform: uppercase; letter-spacing: .06em; }
.timeline { list-style: none; padding: 0; margin: 0; }
.timeline li { display: grid; grid-template-columns: 110px 1fr; gap: 12px; padding: 10px 0; border-bottom: 1px dashed var(--rule); font-size: 15px; }
.timeline li time { font-family: var(--mono); font-size: 14px; color: var(--ink-2); }
.timeline li.past { color: var(--muted); text-decoration: line-through; text-decoration-color: var(--rule-strong); }
.timeline li.next { font-weight: 600; }
.timeline li.next time { color: var(--red); }

/* ---------- mock timer ---------- */
#mt-run, #mt-done { scroll-margin-top: 76px; }
.timer-face { text-align: center; padding: 10px 0 6px; }
.timer-clock { font: 600 clamp(58px, 15vw, 104px)/1 var(--mono); font-variant-numeric: tabular-nums; letter-spacing: -.04em; }
.timer-sub { color: var(--muted); font-size: 15px; margin-top: 8px; }
.pace { display: inline-block; margin-top: 12px; padding: 6px 12px; border-radius: 99px; font-size: 15px; font-weight: 600; background: var(--paper-2); }
.pace.ahead { background: var(--green-soft); color: var(--green); }
.pace.behind { background: var(--amber-soft); color: var(--red); }
.timer-controls { display: grid; grid-template-columns: 1fr 1fr; gap: 10px; margin-top: 18px; }
.timer-controls .btn { min-height: 56px; font-size: 16px; }
.timer-controls .btn.primary-wide { grid-column: 1 / -1; min-height: 72px; font-size: 19px; }
.qbar { display: flex; flex-wrap: wrap; gap: 3px; margin-top: 16px; }
.qbar i { width: 10px; height: 18px; border-radius: 2px; background: var(--rule); }
.qbar i.ok { background: var(--blue); opacity: .55; }
.qbar i.skip { background: transparent; box-shadow: inset 0 0 0 1.5px var(--ink-2); }
.qbar i.slow { background: var(--red); opacity: .8; }
.kbd { font: 12px var(--mono); border: 1px solid var(--rule-strong); border-bottom-width: 2px; border-radius: 4px; padding: 1px 5px; }
.subject-tabs { display: flex; gap: 6px; margin-top: 14px; justify-content: center; flex-wrap: wrap; }

/* ---------- formula sprint ---------- */
#fs-play, #fs-done { scroll-margin-top: 76px; }
.fs-top { display: flex; justify-content: space-between; align-items: baseline; gap: 10px; }
.fs-meta { font-size: 15px; color: var(--ink-2); }
.fs-meta b { font-size: 20px; color: var(--ink); }
.fs-track { height: 6px; background: var(--paper-2); border-radius: 99px; margin: 10px 0 18px; overflow: hidden; }
#fs-bar { height: 100%; background: var(--red); transform-origin: left; transition: transform .1s linear; }
.fs-q { font: 650 clamp(22px, 4.6vw, 28px)/1.3 var(--serif); margin: 0 0 18px; min-height: 2.6em; }
.fs-opts { display: grid; grid-template-columns: 1fr 1fr; gap: 10px; }
@media (max-width: 560px) { .fs-opts { grid-template-columns: 1fr; } }
.fs-opt { display: flex; align-items: center; gap: 12px; text-align: left; font: 500 17px/1.3 var(--sans); color: var(--ink); background: var(--paper); border: 1.5px solid var(--rule-strong); border-radius: 8px; padding: 14px; min-height: 58px; cursor: pointer; }
.fs-opt:hover { border-color: var(--ink); }
.fs-opt .kbd { color: var(--muted); }
.fs-opt.right { background: var(--green-soft); border-color: var(--green); }
.fs-opt.wrong { background: var(--amber-soft); border-color: var(--red); }
.fs-missed { list-style: none; padding: 0; margin: 0; }
.fs-missed li { display: flex; justify-content: space-between; gap: 12px; padding: 9px 0; border-bottom: 1px dashed var(--rule); font-size: 15px; }
.fs-missed b { text-align: right; white-space: nowrap; }

/* ---------- revision planner ---------- */
.pl-row { display: flex; align-items: center; justify-content: space-between; gap: 10px; padding: 8px 0; border-top: 1px dashed var(--rule); flex-wrap: wrap; }
.pl-name { font-weight: 600; min-width: 88px; }
.pl-b { gap: 5px; }
.pl-b .bubble span { padding: 6px 11px 6px 8px; font-size: 14px; gap: 6px; }
.pl-b .bubble span::before { width: 13px; height: 13px; }
.pl-table td:first-child { white-space: nowrap; }
.pl-ph { display: none; font-size: 12.5px; color: var(--blue); font-weight: 600; }
@media (max-width: 600px) { .pl-focus { display: none; } .pl-ph { display: block; } .pl-table th, .pl-table td { padding: 9px 7px; } .pl-table th { font-size: 11px; letter-spacing: .02em; } }

/* ---------- element hunt ---------- */
.eh-clues { list-style: none; padding: 0; margin: 14px 0; display: grid; gap: 8px; }
.eh-clues li { display: grid; grid-template-columns: 30px 1fr; gap: 10px; align-items: start; padding: 11px 12px; border-radius: 8px; font-size: 16px; }
.eh-clues li.on { background: var(--blue-soft); }
.eh-clues li.off { background: var(--paper-2); color: var(--muted); font-size: 14.5px; }
.eh-n { display: inline-grid; place-items: center; width: 26px; height: 26px; border-radius: 50%; border: 1.5px solid currentColor; font: 600 13px var(--mono); }
.eh-clues li.on .eh-n { background: var(--blue); border-color: var(--blue); color: var(--blue-ink); }
.eh-tried { display: flex; flex-wrap: wrap; gap: 6px; margin: 0 0 12px; }
.eh-g { font-size: 14px; padding: 4px 10px; border-radius: 99px; background: var(--amber-soft); text-decoration: line-through; text-decoration-color: var(--red); }
.eh-g.ok { background: var(--green-soft); text-decoration: none; font-weight: 600; }
.eh-done { display: flex; gap: 16px; align-items: center; }
.eh-tile { flex: none; width: 92px; height: 92px; border: 2px solid var(--ink); border-radius: 10px; display: grid; grid-template-rows: auto 1fr auto; padding: 6px 8px; background: var(--card); }
.eh-tile small { font: 600 13px var(--mono); }
.eh-tile b { font: 800 34px/1 var(--display); text-align: center; align-self: center; }
.eh-tile span { font-size: 12px; text-align: center; color: var(--ink-2); }

/* ---------- formula sheets ---------- */
.fjump { display: flex; gap: 6px; overflow-x: auto; padding: 4px 0 12px; scrollbar-width: thin; }
.fjump a { flex: none; font-size: 14px; padding: 6px 11px; border: 1px solid var(--rule-strong); border-radius: 99px; text-decoration: none; color: var(--ink-2); background: var(--card); }
.fjump a:hover { border-color: var(--blue); color: var(--blue); }
.fsheet { columns: 2 420px; column-gap: 22px; }
.fchap { break-inside: avoid; background: var(--card); border: 1px solid var(--rule); border-radius: var(--radius); padding: 16px 18px 8px; margin: 0 0 18px; scroll-margin-top: 80px; }
.fchap h2 { font-size: 19px; margin: 0 0 8px; color: var(--blue); }
.flist { margin: 0; }
.frow { display: grid; grid-template-columns: minmax(0, 1fr) minmax(0, 1.25fr); gap: 4px 14px; padding: 9px 0; border-top: 1px dashed var(--rule); }
.frow:first-child { border-top: 0; }
.frow dt { font-size: 14.5px; color: var(--ink-2); }
.frow dd { margin: 0; font: 600 16px/1.45 var(--sans); color: var(--ink); overflow-wrap: anywhere; }
@media (max-width: 480px) { .frow { grid-template-columns: 1fr; } }
@media print { .fjump, #ff-q, .field { display: none !important; } .fchap { border: 0; padding: 0; } }

/* ---------- inline charts ---------- */
.chart { margin: 1em 0 1.4em; }
.chart svg { width: 100%; height: auto; overflow: visible; }
.chart text { fill: var(--muted); font: 12px var(--mono); }
.chart text.v { fill: var(--ink); font-weight: 600; }
.chart .g { stroke: var(--rule); stroke-width: 1; }
.chart .l { fill: none; stroke: var(--blue); stroke-width: 2.5; stroke-linejoin: round; }
.chart .d { fill: var(--card); stroke: var(--blue); stroke-width: 2; }
.chart .end { fill: var(--blue); }
@media (max-width: 560px) { .chart text { font-size: 19px; } .chart text.v { font-size: 18px; } }
.result-big.range { font-size: clamp(36px, 8vw, 52px); white-space: nowrap; }
.chart figcaption { font-size: 13.5px; color: var(--muted); margin-top: 6px; }

/* ---------- ad slot (reserve space to avoid layout shift once AdSense is on) ---------- */
.ad-slot { display: none; }
.ads-on .ad-slot { display: block; min-height: 120px; margin: 26px 0; }

/* ---------- footer ---------- */
.site-foot { margin-top: 70px; border-top: 1px solid var(--rule); padding: 28px 0 40px; font-size: 14.5px; color: var(--muted); }
.foot-grid { display: grid; grid-template-columns: 1.4fr 1fr 1fr; gap: 24px; }
@media (max-width: 720px) { .foot-grid { grid-template-columns: 1fr 1fr; } .foot-grid > :first-child { grid-column: 1 / -1; } }
.site-foot h3, .site-foot .foot-h { font: 600 13px var(--sans); text-transform: uppercase; letter-spacing: .07em; color: var(--ink-2); margin: 0 0 10px; }
.site-foot ul { list-style: none; padding: 0; margin: 0; }
.site-foot li { margin-bottom: 6px; }
.site-foot a { color: var(--muted); }

@media print {
  .site-head, .site-foot, .btn-row, .related, .ad-slot { display: none !important; }
  body { background: #fff; }
}
@media (prefers-reduced-motion: reduce) { * { transition: none !important; } }

/* equation balancer */
.chip-row { display: flex; flex-wrap: wrap; gap: 8px; }
.chip-btn { font: 500 14.5px var(--sans); padding: 7px 11px; border-radius: 8px; border: 1px solid var(--rule-strong); background: var(--card); color: var(--ink); cursor: pointer; text-align: left; max-width: 100%; overflow-wrap: anywhere; }
.chip-btn:hover { border-color: var(--blue); color: var(--blue); }
.cb-out { font: 500 22px/1.5 var(--sans); margin: 4px 0 14px; overflow-wrap: anywhere; }
.cb-out .co, .bi-sp .co { color: var(--blue); font-weight: 800; margin-right: 1px; }
.cb-out .arr { color: var(--muted); margin: 0 4px; }
.cb-out:empty { display: none; }

/* Balance It */
.bi-bar { display: flex; justify-content: space-between; align-items: center; gap: 10px; font-size: 14px; color: var(--muted); margin: 10px 0 14px; }
.bi-dots { display: flex; gap: 6px; }
.bi-dots span { width: 10px; height: 10px; border-radius: 50%; border: 1.5px solid var(--rule-strong); }
.bi-dots .now { border-color: var(--blue); background: var(--blue-soft); }
.bi-dots .ok { background: var(--green); border-color: var(--green); }
.bi-dots .rev { background: var(--hl); border-color: #c9a800; }
.bi-eq { background: var(--paper); border-radius: 10px; padding: 14px; }
.bi-live { font: 500 20px/1.5 var(--sans); text-align: center; margin: 2px 0 14px; overflow-wrap: anywhere; }
.bi-live .co { color: var(--blue); font-weight: 800; margin-right: 1px; }
.bi-live .arr { color: var(--muted); margin: 0 4px; }
.bi-sides { display: grid; grid-template-columns: 1fr 1fr; gap: 14px; }
.bi-sides ul { list-style: none; margin: 0; padding: 0; display: grid; gap: 8px; }
.bi-h { margin: 0 0 6px; font-size: 12px; font-weight: 600; letter-spacing: .06em; text-transform: uppercase; color: var(--muted); }
.bi-sp { display: flex; align-items: center; justify-content: space-between; gap: 8px; background: var(--card); border: 1px solid var(--rule); border-radius: 10px; padding: 6px 6px 6px 12px; }
.bi-f { font: 600 18px var(--sans); white-space: nowrap; }
.bi-step { display: flex; align-items: center; gap: 4px; }
.bi-sp input.bi-c { width: 48px; flex: none; min-height: 44px; padding: 4px; text-align: center; font: 700 20px var(--sans); color: var(--blue); border: 1.5px solid var(--rule-strong); border-radius: 8px; background: var(--card); -moz-appearance: textfield; }
.bi-c::-webkit-inner-spin-button, .bi-c::-webkit-outer-spin-button { -webkit-appearance: none; margin: 0; }
.bi-sp input.bi-c:disabled { color: var(--green); border-color: transparent; background: var(--green-soft); opacity: 1; }
.bi-b { width: 44px; height: 44px; border-radius: 8px; border: 1px solid var(--rule-strong); background: var(--paper); color: var(--ink); font: 600 22px/1 var(--sans); cursor: pointer; touch-action: manipulation; }
.bi-b:hover:not(:disabled) { border-color: var(--blue); color: var(--blue); }
.bi-b:disabled { opacity: .35; cursor: default; }
@media (max-width: 640px) { .bi-sides { grid-template-columns: 1fr; } .bi-eq { padding: 12px 10px; } .bi-live { font-size: 18px; } }
.bi-tally { list-style: none; margin: 0; padding: 0; display: flex; flex-wrap: wrap; gap: 6px; }
.bi-tally li { display: grid; grid-template-columns: auto auto auto auto; gap: 6px; align-items: baseline; padding: 6px 10px; border-radius: 8px; background: var(--amber-soft); font: 500 15px var(--mono); }
.bi-tally li b { font-family: var(--sans); }
.bi-tally li i { font-style: normal; color: var(--red); font-weight: 700; }
.bi-tally li.ok { background: var(--green-soft); }
.bi-tally li.ok i { color: var(--green); }
.bi-msg { min-height: 24px; margin: 12px 0; font-size: 15.5px; }
.bi-squares { font-size: 26px; letter-spacing: 4px; margin: 6px 0 10px; }
[hidden] { display: none !important; }
.check { display: flex; gap: 10px; align-items: center; margin-top: 14px; font-size: 15px; cursor: pointer; }
.check input { width: 20px; height: 20px; min-height: 0; accent-color: var(--blue); flex: none; }
.sr-only { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; }
/* mock tracker */
.tk-two { display: grid; grid-template-columns: 1fr 1fr; gap: 0 12px; }
.tk-subj { display: grid; grid-template-columns: repeat(3, 1fr); gap: 10px; }
.tk-subj label { display: grid; gap: 4px; font-size: 13px; color: var(--muted); font-weight: 600; }
.tk-subj input { text-align: center; font: 600 18px var(--mono); }
.tk-subj input::placeholder { font: 500 14px var(--sans); }
.tk-table td, .tk-table th { white-space: nowrap; }
.tk-del { border: 1px solid var(--rule-strong); background: var(--card); color: var(--muted); border-radius: 6px; min-width: 32px; height: 30px; font-size: 14px; cursor: pointer; padding: 0 8px; }
.tk-del[data-armed] { color: var(--red); border-color: var(--red); }
#tk-chart .chart { margin-top: 22px; }
@media (max-width: 480px) { .tk-two { grid-template-columns: 1fr; } }
.tk-nm { display: block; font-size: 12.5px; color: var(--muted); max-width: 12ch; overflow: hidden; text-overflow: ellipsis; }
@media (max-width: 480px) { .tk-table td, .tk-table th { padding-left: 8px; padding-right: 8px; } }
/* study timer */
.st-face { text-align: center; }
.st-phase { display: flex; justify-content: space-between; font-weight: 700; font-size: 15px; text-transform: uppercase; letter-spacing: .06em; color: var(--blue); }
.st-break .st-phase { color: var(--green); }
.st-face .timer-clock { margin: 18px 0 14px; }
.st-bar, .st-goalbar { height: 8px; border-radius: 99px; background: var(--paper-2); overflow: hidden; }
.st-bar span, .st-goalbar span { display: block; height: 100%; width: 0; background: var(--blue); border-radius: 99px; transition: width .25s linear; }
.st-break .st-bar span { background: var(--green); }
.st-goalbar span { background: var(--hl); }
.st-today { margin-top: 18px; }
.st-head { display: flex; justify-content: space-between; align-items: baseline; margin-bottom: 10px; }
.st-head .num { font-size: 22px; font-weight: 700; }
.st-subs { list-style: none; margin: 0; padding: 0; display: grid; gap: 8px; }
.st-subs li { display: grid; grid-template-columns: 90px 1fr auto; gap: 10px; align-items: center; font-size: 15px; }
.st-sb { height: 8px; background: var(--paper-2); border-radius: 99px; overflow: hidden; }
.st-sb i { display: block; height: 100%; background: var(--blue); border-radius: 99px; }
/* home */
.dates-top { margin: 0 0 8px; grid-template-columns: repeat(4, 1fr); }
a.date-card { text-decoration: none; color: var(--ink); transition: border-color .15s; }
a.date-card:hover { border-color: var(--blue); }
@media (max-width: 720px) { .dates-top { grid-template-columns: 1fr 1fr; } .dates-top .date-card { padding: 10px 12px; } .dates-top b { font-size: 24px; } .dates-top span { font-size: 13px; } }
@media (min-width: 900px) { .tool-list.cols { display: grid; grid-template-columns: 1fr 1fr; column-gap: 36px; } }
.section-title a.small { font-weight: 600; text-decoration: none; }
.game-cards { display: grid; grid-template-columns: repeat(3, 1fr); gap: 14px; margin: 16px 0 8px; }
.game-card { display: grid; grid-template-rows: auto auto auto 1fr auto; gap: 4px; padding: 0 0 16px; border: 1px solid var(--rule); border-radius: var(--radius); background: var(--card); text-decoration: none; color: var(--ink); overflow: hidden; transition: border-color .15s, transform .15s; }
.game-card:hover { border-color: var(--blue); transform: translateY(-2px); }
.game-card > *:not(.gc-art) { padding: 0 16px; }
.gc-art { display: grid; place-items: center; height: 104px; margin-bottom: 10px; font: 800 40px/1 var(--display); letter-spacing: -.02em; background: var(--blue-soft); color: var(--blue); }
.g-eh .gc-art { background: var(--green-soft); color: var(--green); }
.g-bi .gc-art { background: var(--amber-soft); color: #8a5a00; }
.gc-tag { font-size: 12px; font-weight: 700; text-transform: uppercase; letter-spacing: .08em; color: var(--muted); }
.game-card b { font-size: 19px; font-weight: 700; }
.gc-d { color: var(--muted); font-size: 15px; }
.game-card .go { color: var(--blue); font-weight: 600; font-size: 15px; margin-top: 8px; }
@media (max-width: 720px) { .game-cards { grid-template-columns: 1fr; } .game-card { grid-template-columns: 84px 1fr; grid-template-rows: auto auto 1fr auto; padding: 0; column-gap: 0; } .gc-art { grid-row: 1 / -1; height: auto; margin: 0; font-size: 22px; } .game-card > *:not(.gc-art) { padding: 0 14px; } .gc-tag { padding-top: 12px !important; } .game-card .go { padding-bottom: 12px !important; margin-top: 4px; } }
tr.is-you td .muted { color: var(--ink-2); }
@media (max-width: 560px) { .hub-table th, .hub-table td { padding: 10px 6px; font-size: 14.5px; } .hub-table th { font-size: 11px; letter-spacing: .02em; white-space: normal; } }
.fsheet-text dt { font-weight: 700; color: var(--ink); font-size: 16px; }
.fsheet-text dd { font: 400 15.5px/1.5 var(--sans); color: var(--ink-2); }
.glance { grid-template-columns: repeat(3, 1fr); margin: 22px 0 6px; max-width: 760px; }
@media (max-width: 560px) { .glance { grid-template-columns: 1fr 1fr; } }
/* periodic table */
.c-alkali { --c: rgba(214, 69, 52, .16); } .c-alkaline { --c: rgba(230, 140, 30, .18); } .c-transition { --c: rgba(41, 80, 230, .13); }
.c-post { --c: rgba(110, 120, 150, .16); } .c-metalloid { --c: rgba(160, 130, 40, .2); } .c-nonmetal { --c: rgba(19, 160, 100, .16); }
.c-halogen { --c: rgba(20, 150, 170, .17); } .c-noble { --c: rgba(130, 80, 210, .16); } .c-lanthanoid { --c: rgba(210, 70, 140, .13); } .c-actinoid { --c: rgba(170, 60, 90, .15); }
.pt-top { display: grid; grid-template-columns: minmax(0, 1.2fr) minmax(0, 1fr); gap: 18px; align-items: start; }
.pt-card { display: flex; gap: 18px; padding: 18px; border-radius: var(--radius); border: 1px solid var(--rule); background: linear-gradient(var(--c), var(--c)), var(--card); min-height: 168px; }
.pt-big { flex: none; width: 96px; height: 96px; border: 2px solid var(--ink); border-radius: 10px; background: var(--card); display: grid; grid-template-rows: auto 1fr; padding: 6px 8px; }
.pt-big small { font: 600 14px var(--mono); }
.pt-big b { font: 800 40px/1 var(--display); text-align: center; align-self: center; }
.pt-info h2 { margin: 0; font-size: 24px; }
.pt-cat-name { margin: 2px 0 10px; color: var(--ink-2); font-size: 14.5px; }
.pt-info dl { margin: 0; display: grid; grid-template-columns: 1fr 1fr; gap: 8px 16px; }
.pt-info dt { font-size: 12px; text-transform: uppercase; letter-spacing: .05em; color: var(--muted); font-weight: 600; }
.pt-info dd { margin: 0; font: 600 15.5px var(--sans); }
.pt-info dd small { font-weight: 400; color: var(--muted); }
.pt-legend { display: flex; flex-wrap: wrap; gap: 6px; margin-top: 12px; }
.pt-cat { font: 500 13.5px var(--sans); padding: 6px 10px; border-radius: 99px; border: 1px solid var(--rule-strong); background: linear-gradient(var(--c), var(--c)), var(--card); color: var(--ink); cursor: pointer; min-height: 32px; }
.pt-cat[aria-pressed="true"] { border-color: var(--ink); box-shadow: inset 0 0 0 1px var(--ink); }
.pt-hint { display: none; margin: 14px 0 0; }
.pt-scroll { overflow-x: auto; margin-top: 16px; padding-bottom: 6px; }
.pt-grid { display: grid; grid-template-columns: repeat(18, minmax(40px, 1fr)); grid-template-rows: repeat(7, auto) 14px auto auto; gap: 3px; min-width: 740px; }
.pt-el { position: relative; aspect-ratio: 1 / 1.08; border: 0; border-radius: 5px; background: linear-gradient(var(--c), var(--c)), var(--card); color: var(--ink); cursor: pointer; padding: 2px; display: grid; grid-template-rows: auto 1fr; font-family: var(--sans); transition: opacity .15s, transform .1s; }
.pt-el small { font: 500 10px var(--mono); text-align: left; padding-left: 2px; color: var(--ink-2); }
.pt-el b { font: 700 16px/1 var(--sans); align-self: center; }
.pt-el:hover { transform: scale(1.06); z-index: 1; box-shadow: 0 0 0 1.5px var(--ink); }
.pt-el.on { box-shadow: 0 0 0 2px var(--ink); z-index: 2; }
.pt-el.dim { opacity: .18; }
.pt-row-label { align-self: center; justify-self: end; padding-right: 8px; font-size: 12.5px; color: var(--muted); font-weight: 600; }
@media (max-width: 760px) { .pt-top { grid-template-columns: 1fr; } .pt-hint { display: block; } .pt-card { min-height: 0; padding: 14px; gap: 14px; } .pt-big { width: 78px; height: 78px; } .pt-big b { font-size: 32px; } }

:lang(hi) .hub-table th, :lang(hi) th { letter-spacing: 0; text-transform: none; font-size: 13px; }

/* ---------- log / antilog / maths tables ---------- */
.logt { font-variant-numeric: tabular-nums; font-size: 14px; }
.logt th, .logt td { padding: 6px 7px; white-space: nowrap; }
.logt td.md, .logt th.md { background: var(--paper-2); color: var(--ink-2); font-size: 13px; }
.logt tbody th { position: sticky; left: 0; background: var(--card); z-index: 1; }
.logt .logt-sub th { font-family: var(--sans); font-size: 12px; font-weight: 600; color: var(--muted); text-align: center; border-bottom: 0; }
.logt tbody tr:nth-child(5n) td, .logt tbody tr:nth-child(5n) th { border-bottom: 2px solid var(--rule); }
.logt tr.lc-on td, .logt tr.lc-on th { background: var(--hl); color: var(--ink); }
.logt td.lc-hit { outline: 2px solid var(--blue); outline-offset: -2px; font-weight: 700; }
.logt tr[id] { scroll-margin-top: 90px; }
.lc-steps ol { margin: 10px 0 0; padding-left: 20px; }
.lc-steps li { margin: 6px 0; }
.bar { text-decoration: overline; }
.trig-t th small { font-weight: 500; color: var(--muted); }
.trig-t td, .trig-t th { white-space: nowrap; }
.trig-t th { text-transform: none; letter-spacing: 0; font-size: 14px; }
.trig-t tbody th { font-family: var(--mono); }
.sq-t { font-variant-numeric: tabular-nums; }

/* ---------- pH scale ---------- */
.ph-scale { position: relative; margin: 14px 0 6px; }
.ph-bar { height: 12px; border-radius: 6px; background: linear-gradient(90deg, #d7263d 0%, #f46036 18%, #f6c445 35%, #3fa34d 50%, #2e86ab 68%, #3d5a98 84%, #6a3d9a 100%); }
.ph-pin { position: absolute; top: -5px; width: 4px; height: 22px; margin-left: -2px; background: var(--ink); border-radius: 2px; box-shadow: 0 0 0 2px var(--card); }
.ph-ticks { display: flex; justify-content: space-between; font: 600 12px var(--mono); color: var(--muted); margin-top: 4px; }

.mm-t th, .mm-t td { padding-left: 6px; padding-right: 6px; white-space: nowrap; }
.mm-t abbr { text-decoration: none; }

/* ---------- physics calculators ---------- */
.pj-stats { margin: 12px 0 8px; grid-template-columns: repeat(3, 1fr); }
.pj-stats .stat b { font-size: 17px; }
.pj-svg { width: 100%; height: auto; display: block; margin: 6px 0 4px; background: var(--paper); border-radius: 8px; }
.pj-ground { stroke: var(--rule-strong); stroke-width: 2; }
.pj-path { fill: none; stroke: var(--blue); stroke-width: 2.5; stroke-linecap: round; }
.pj-h { stroke: var(--muted); stroke-width: 1; stroke-dasharray: 3 3; }
.pj-dot { fill: var(--red); }
.sf-digits { font: 600 30px/1.3 var(--mono); letter-spacing: .04em; margin: 4px 0 8px; word-break: break-all; }
.sf-y { color: var(--blue); }
.sf-n { color: var(--muted); opacity: .7; }
.sf-q { color: #b7791f; }
.sf-key { font-size: 14px; }
.sf-key .sf-y, .sf-key .sf-q { font-weight: 700; }

/* ---------- ray diagram ---------- */
.op-svg { width: 100%; height: auto; display: block; margin: 8px 0 4px; background: var(--paper); border-radius: 8px; }
.op-axis { stroke: var(--rule-strong); stroke-width: 1; }
.op-el { fill: none; stroke: var(--ink-2); stroke-width: 2.5; }
.op-lens { fill: var(--blue-soft); stroke-width: 1.5; }
.op-f { fill: var(--muted); }
.op-t { font: 600 10px var(--mono); fill: var(--muted); text-anchor: middle; }
.op-ray { stroke: #b7791f; stroke-width: 1.2; }
.op-virt { stroke-dasharray: 4 3; }
.op-obj { stroke: var(--blue); stroke-width: 3; }
.op-obj-tip { fill: var(--blue); }
.op-img { stroke: var(--red); stroke-width: 3; }
.op-img-tip, .op-img.op-virt-tip { fill: var(--red); }

.el-t td.cfg, td.cfg { font-family: var(--mono); font-size: 14px; white-space: nowrap; }
.el-t th[scope=row] { text-transform: none; letter-spacing: 0; font-size: 15px; font-weight: 600; color: var(--ink); white-space: nowrap; }
.el-t td, .el-t th { white-space: nowrap; }
.el-t .sym { display: inline-block; min-width: 2.2em; margin-left: 6px; padding: 1px 6px; border-radius: 5px; background: var(--card); border: 1px solid var(--rule); color: var(--blue); font: 700 13px var(--mono); text-align: center; }
.section-title[id] { scroll-margin-top: 80px; }

.sv-row { display: flex; justify-content: space-between; align-items: baseline; gap: 12px; padding: 10px 0; border-bottom: 1px solid var(--rule); }
.sv-row span { color: var(--ink-2); }
.sv-row b { font: 700 24px var(--mono); }
.unit-sel { width: auto; min-width: 84px; border-radius: 0 8px 8px 0; border-left: 0; font: 500 15px var(--mono); background-color: var(--paper-2); }
.input-row > input + .unit-sel { margin: 0; }
.bubbles + .field, .bubbles + div > .field:first-child, .bubbles + p + .field { margin-top: 14px; }

.tool-find { margin: 22px 0 0; max-width: 560px; }
.tool-find input { font: 500 17px var(--sans); padding-left: 42px; background: var(--card) url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='18' height='18' fill='none' stroke='%236b7390' stroke-width='2'%3E%3Ccircle cx='8' cy='8' r='6'/%3E%3Cpath d='m13 13 4 4'/%3E%3C/svg%3E") no-repeat 14px 50%; }
.tool-find p { margin: 10px 0 0; }
.tool-find { scroll-margin-top: 80px; }

.ox-out { display: flex; flex-wrap: wrap; gap: 10px; margin: 10px 0 6px; }
.ox-el { display: flex; flex-direction: column; align-items: center; min-width: 76px; padding: 10px 12px; border: 1.5px solid var(--rule); border-radius: 10px; background: var(--paper); }
.ox-el b { font: 700 20px var(--sans); }
.ox-el span { font: 700 26px var(--mono); color: var(--blue); }
.ox-el small { font-size: 12px; color: var(--muted); }
.ef-rows { display: grid; gap: 8px; margin-bottom: 8px; }
.ef-row { display: grid; grid-template-columns: 84px 1fr; gap: 8px; }
.ef-row .ef-el { font-family: var(--sans); text-align: center; }

.print-head { display: flex; justify-content: space-between; align-items: center; gap: 12px; flex-wrap: wrap; margin-top: 30px; }
.print-head h2 { margin: 0; }
.print-head .btn { min-height: 40px; padding: 8px 14px; font-size: 15px; }
@media print {
  .tool, .print-head .btn, .page-top .lede, .page-top .updated, .crumbs, .content, .tool-find { display: none !important; }
  .logt { font-size: 9.5pt; } .logt th, .logt td { padding: 1px 3px; } .logt tr.lc-on td, .logt tr.lc-on th { background: none; }
  .table-wrap { overflow: visible !important; }
}

/* hybridization and bond order */
.vs-stats { grid-template-columns: repeat(2, minmax(0, 1fr)); margin: 6px 0 10px; }
.vs-stats .stat b { font-size: 18px; font-family: var(--sans); font-weight: 700; }
.vs-fig { margin: 4px 0 8px; text-align: center; }
.vs-fig figcaption { margin-top: 2px; }
.vs-svg { width: 100%; max-width: 280px; height: auto; display: block; margin: 0 auto; }
.vs-svg .bond { stroke: var(--ink-2); stroke-width: 3.5; stroke-linecap: round; }
.vs-svg .bond.dash { stroke-dasharray: 4 4; stroke-width: 3; }
.vs-svg .wedge { fill: var(--ink-2); }
.vs-svg .at { fill: var(--card); stroke: var(--rule-strong); stroke-width: 2; }
.vs-svg .at.c { fill: var(--blue-soft); stroke: var(--blue); }
.vs-svg text { font: 700 13px var(--sans); fill: var(--ink); text-anchor: middle; }
.vs-svg .lp { fill: var(--amber-soft); stroke: #c79a00; stroke-width: 1.5; }
.vs-svg .lpd { fill: var(--ink); }
.vs-one { display: grid; gap: 14px; align-items: center; max-width: 760px; }
@media (min-width: 720px) { .vs-one { grid-template-columns: 1.2fr 1fr; } }
.mo-wrap { display: grid; gap: 14px; align-items: start; margin-top: 12px; }
@media (min-width: 560px) { .mo-wrap { grid-template-columns: auto 1fr; } }
.mo-diag { display: flex; flex-direction: column; gap: 6px; padding: 10px 12px; border: 1.5px solid var(--rule); border-radius: 10px; background: var(--paper); min-width: 190px; }
.mo-row { display: flex; align-items: center; justify-content: space-between; gap: 12px; }
.mo-name { font: 600 14px var(--mono); color: var(--green); min-width: 52px; }
.mo-row.anti .mo-name { color: var(--red); }
.mo-boxes { display: flex; gap: 6px; }
.mo-box { width: 40px; height: 28px; border: 1.5px solid var(--rule-strong); border-radius: 6px; display: grid; place-items: center; font: 700 15px var(--sans); background: var(--card); letter-spacing: -1px; }
.mo-conf { font: 500 14px/1.7 var(--mono); overflow-wrap: anywhere; }
.ob-row { display: flex; flex-wrap: wrap; gap: 10px 18px; padding: 12px; border: 1.5px solid var(--rule); border-radius: 10px; background: var(--paper); }
.ob { display: flex; align-items: center; gap: 8px; }
.ob .mo-name { min-width: 0; color: var(--blue); }
.ob .mo-box { width: 34px; }
.cfg-big { font: 600 17px/1.7 var(--mono); overflow-wrap: anywhere; }
.ion-t tbody th { text-transform: none; letter-spacing: 0; }
.ry-sw { display: inline-block; width: 1.1em; height: 1.1em; border-radius: 50%; vertical-align: -0.15em; border: 1px solid var(--rule-strong); }
.stat b { overflow-wrap: anywhere; }
.dim-stats .stat b { font-size: 17px; }
.calc-t td.cfg{font-family:var(--sans);font-size:16px;white-space:normal;overflow-wrap:anywhere}
.calc-t td:first-child{min-width:9em}
.cv-out{font:600 22px/1.4 var(--sans);margin:14px 0 6px}.cv-out b{font-family:var(--sans)}
.cv-v{white-space:nowrap}
.cv-u{min-width:9.5em}.cv-u b{white-space:nowrap}
.page-top h1 sub{font-size:.45em}
.bubble:has(input:disabled){opacity:.45;cursor:not-allowed}
.cf-chem{display:block;font-size:14px;color:var(--muted);margin-top:2px}.nw{white-space:nowrap}
.is-you .cf-chem{color:inherit}
.year-links{margin:10px 0 0;font-size:15px}