:root {
  /* surfaces + text */
  --bg: #ffffff;
  --panel2: #fafafa;
  --border: #e8e8e8;
  --text: #171717;
  --dim: #6b6b6b;              /* 5.1:1 on --panel2 (was #737373 = 4.12:1) */
  --acc: #171717;
  --link: #2563eb;
  --on-acc: #fff;
  --field: #fff;
  --card: #ffffff;
  --topbar: rgba(255,255,255,.85);
  --sel: rgba(37,99,235,.2);
  --hero-a: #2563eb;
  --hero-b: #7aa2ff;

  /* status: text colour, solid chip background, soft surface */
  --green: #15803d;
  --yellow: #a16207;
  --red: #dc2626;
  --green-solid: #15803d;
  --yellow-solid: #a16207;
  --magenta-solid: #7e22ce;
  --red-solid: #b91c1c;
  --neutral-solid: #52525b;
  --badge-fg: #fff;
  --ok-bg: #f2fbf5;    --ok-line: #bbe5c9;
  --warn-bg: #fffdf3;  --warn-line: #f0dfae;
  --err-bg: #fff5f4;   --err-line: #f5c6c2;

  /* statement notice banner */
  --notice-bg: #fff8e6; --notice-fg: #7a5b00; --notice-line: #f0dfae;

  /* leaderboard medals */
  --rank1-bg: #f6c945; --rank1-fg: #5c430a; --rank1-line: #d9a821;
  --rank2-bg: #e2e8f0; --rank2-fg: #3d4b5e; --rank2-line: #b6c2d2;
  --rank3-bg: #f0c8a0; --rank3-fg: #6b3d16; --rank3-line: #d69a63;

  /* Google button keeps Google's own colours, per theme */
  --google-bg: #fff; --google-fg: #1f1f1f; --google-line: #dadce0;
  --google-hover: #f8faff; --google-hover-line: #c6d7f5; --google-accent: #1a73e8;

  /* code highlighting */
  --tk-k: #7c3aed; --tk-s: #15803d; --tk-c: #8a8f98;
  --tk-n: #b45309; --tk-f: #1d4ed8; --tk-p: #dc2626;

  /* type scale — one token per size, no more one-off px */
  --fs-2xs: 11px; --fs-xs: 12px; --fs-sm: 13px; --fs-md: 14px;
  --fs-base: 15px; --fs-lg: 16px; --fs-xl: 18px; --fs-2xl: 22px;
  --fs-3xl: 24px; --fs-stat: 30px; --fs-display: 40px;
  --lh-body: 1.7;              /* Thai needs room for ascenders/descenders */
  --lh-tight: 1.35;

  /* spacing + radii */
  --sp-2: 8px; --sp-3: 12px; --sp-4: 16px; --sp-5: 24px; --sp-6: 32px;
  --r-sm: 8px; --r-md: 12px; --r-lg: 16px; --r-pill: 999px;

  /* interaction */
  --t-fast: .15s ease;
  --focus: 2px solid var(--link);

  --mono: "JetBrains Mono", "Prompt", ui-monospace, "SF Mono", "Cascadia Code", Menlo, Consolas, monospace;
  --sans: "Prompt", -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  --shadow-sm: 0 1px 2px rgba(0,0,0,.05);
  --shadow: 0 1px 2px rgba(0,0,0,.05), 0 4px 16px rgba(0,0,0,.05);
}

/* Dark mode only redefines what actually has to change: every token that is a
 * colour gets a counterpart, so nothing falls back to a light-theme literal. */
[data-theme="dark"] {
  --bg: #0a0a0a;
  --panel: #0a0a0a;
  --panel2: #161616;
  --border: #2a2a2a;
  --text: #ededed;
  --dim: #b3b3b3;
  --acc: #ededed;
  --on-acc: #0a0a0a;
  --link: #7aa2ff;
  --field: #111111;
  --card: #101010;
  --topbar: rgba(10,10,10,.85);
  --sel: rgba(122,162,255,.25);
  --hero-a: #7aa2ff;
  --hero-b: #2f6bd8;

  /* the status colours were never redefined: 3.79-4.10:1 on dark */
  --green: #4ade80;
  --yellow: #fbbf24;
  --red: #f87171;
  --ok-bg: #0e1a12;    --ok-line: #1e4a2c;
  --warn-bg: #1c1808;  --warn-line: #4a3c12;
  --err-bg: #1d1111;   --err-line: #4a2020;

  --notice-bg: #231a05; --notice-fg: #f0d48a; --notice-line: #6b5518;

  --google-bg: #131314; --google-fg: #e3e3e3; --google-line: #8e918f;
  --google-hover: #1f2020; --google-hover-line: #bdc1c6;

  --tk-k: #c4b5fd; --tk-s: #86efac; --tk-c: #6b7280;
  --tk-n: #fbbf24; --tk-f: #93c5fd; --tk-p: #f87171;

  --shadow-sm: 0 1px 2px rgba(0,0,0,.35);
  --shadow: 0 1px 2px rgba(0,0,0,.4);
  color-scheme: dark;
}

* { box-sizing: border-box; }
/* buttons should use the page font, never the platform default */
button { font: inherit; }
::selection { background: var(--sel); }
button, a, input, select, textarea { transition: border-color var(--t-fast), background var(--t-fast), color var(--t-fast), opacity var(--t-fast); }
:focus-visible { outline: var(--focus); outline-offset: 2px; }
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { animation-duration: .001ms !important; animation-iteration-count: 1 !important; transition-duration: .001ms !important; }
}
.ic {
  width: 16px; height: 16px; stroke: currentColor; fill: none;
  stroke-width: 2; stroke-linecap: round; stroke-linejoin: round;
  vertical-align: -3px; flex: none;
}
.ic-lg { width: 28px; height: 28px; }
.nav-link, .btn-primary, .btn-ghost, .submit-btn, .backlink, .ghost-btn {
  display: inline-flex; align-items: center; gap: 7px;
}
.icon-btn {
  background: transparent; border: 1px solid var(--border); border-radius: 7px;
  padding: 5px 7px; cursor: pointer; color: var(--dim); line-height: 0;
}
.icon-btn:hover { color: var(--text); border-color: var(--text); }
/* score colors */
.s100 { color: var(--green); font-weight: 700; }
.smid { color: var(--yellow); font-weight: 700; }
.s0 { color: var(--dim); }
/* rank medals */
.rank {
  display: inline-flex; align-items: center; justify-content: center;
  width: 24px; height: 24px; border-radius: 50%;
  font-size: var(--fs-xs); font-weight: 700; font-family: var(--mono);
  background: var(--panel2); border: 1px solid var(--border); color: var(--dim);
}
.rank-1 { background: var(--rank1-bg); border-color: var(--rank1-line); color: var(--rank1-fg); }
.rank-2 { background: var(--rank2-bg); border-color: var(--rank2-line); color: var(--rank2-fg); }
.rank-3 { background: var(--rank3-bg); border-color: var(--rank3-line); color: var(--rank3-fg); }
body {
  margin: 0; background: var(--bg); color: var(--text);
  font-family: var(--sans);
  font-size: var(--fs-base); line-height: var(--lh-body);
  min-height: 100vh; display: flex; flex-direction: column;
  -webkit-font-smoothing: antialiased;
}

/* top nav */
.topbar {
  display: flex; align-items: center; gap: 28px;
  padding: 14px 28px; background: var(--topbar);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--border);
  position: sticky; top: 0; z-index: 10;
}
.brand { font-weight: 700; letter-spacing: 3px; font-size: var(--fs-md); color: var(--text); text-decoration: none; display: inline-flex; align-items: center; gap: 9px; }
.brand-logo { width: 28px; height: 28px; border-radius: 7px; background: var(--card); flex: none; }
.logo-dark { display: none; }
[data-theme="dark"] .logo-light { display: none; }
[data-theme="dark"] .logo-dark { display: inline-block; }
[data-theme="dark"] .brand-logo { background: transparent; }
.brand-acc { color: var(--dim); font-weight: 400; }
.nav { display: flex; gap: 2px; }
.nav-link {
  color: var(--dim); text-decoration: none; font-size: var(--fs-md);
  padding: 6px 12px; border-radius: 6px;
}
.nav-link:hover { color: var(--text); background: var(--panel2); }
.nav-link.active { color: var(--text); font-weight: 600; background: var(--panel2); }
.health { margin-left: auto; font-size: var(--fs-2xs); color: var(--dim); font-family: var(--mono); letter-spacing: .5px; }
.health.ok { color: var(--green); }
.auth { display: flex; gap: 8px; align-items: center; }
.signup-btn {
  background: var(--acc); color: var(--on-acc); border: 1px solid var(--acc);
  border-radius: var(--r-sm); padding: 7px 16px; font-size: var(--fs-sm); font-weight: 600; cursor: pointer;
}
.signup-btn:hover { opacity: .85; }
.google-btn {
  width: 100%; display: inline-flex; align-items: center; justify-content: center; gap: 10px;
  background: var(--google-bg); color: var(--google-fg); border: 1px solid var(--google-line);
  border-radius: var(--r-sm);
  padding: 10px 16px; font-size: var(--fs-md); font-weight: 500; cursor: pointer;
}
.google-btn:hover { background: var(--google-hover); border-color: var(--google-hover-line); box-shadow: var(--shadow); }
.google-btn .ic { color: var(--google-accent); }
.or-divider { display: flex; align-items: center; gap: 12px; color: var(--dim); font-size: var(--fs-xs); margin: 4px 0 12px; }
.or-divider::before, .or-divider::after { content: ""; flex: 1; border-top: 1px solid var(--border); }
#user-chip { font-size: var(--fs-sm); font-weight: 600; max-width: 160px; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.report-row { display: flex; gap: 8px; flex-wrap: wrap; margin-bottom: 8px; }
.report-row select {
  border: 1px solid var(--border); border-radius: var(--r-sm); padding: 8px 10px;
  font-size: var(--fs-sm); background: var(--field); color: var(--text);
}
.report-row input[type="text"] {
  flex: 1; min-width: 180px; border: 1px solid var(--border); border-radius: var(--r-sm);
  padding: 8px 12px; font-size: var(--fs-sm); background: var(--field); color: var(--text);
}
.report-row input[type="text"]:focus { outline: none; border-color: var(--text); }
.report-item { padding: 8px 0; border-bottom: 1px solid var(--border); font-size: var(--fs-sm); }
.report-item:last-child { border-bottom: none; }
/* clickable chips are real <button>s: without an explicit face they inherit the
 * user-agent button colour, which is light in one theme and dark in the other */
.tag-click {
  cursor: pointer; font: inherit;
  background: var(--panel2); border: 1px solid var(--border); color: var(--dim);
}
.tag-click:hover { border-color: var(--text); color: var(--text); }
/* tasks sidebar + cards */
.tasks-layout { display: grid; grid-template-columns: 190px 1fr; gap: 20px; align-items: start; }
.side-group { display: flex; flex-direction: column; gap: 2px; }
.side-btn {
  background: none; border: none; text-align: left; cursor: pointer;
  padding: 9px 12px; border-radius: var(--r-sm); font-size: var(--fs-md); color: var(--dim);
}
.side-btn:hover { color: var(--text); background: var(--panel2); }
.side-btn.active { background: var(--panel2); color: var(--text); font-weight: 700; }
.side-head { display: flex; align-items: baseline; justify-content: space-between; margin: 4px 0 6px; }
.side-head h3 { margin: 0; font-size: var(--fs-sm); }
.link-btn { background: none; border: none; cursor: pointer; font-size: var(--fs-xs); color: var(--dim); padding: 0; }
.link-btn:hover { color: var(--text); }
#tag-list { display: flex; flex-direction: column; gap: 1px; }
.tag-row {
  background: none; border: none; text-align: left; cursor: pointer;
  padding: 6px 12px; border-radius: 6px; font-size: var(--fs-md); color: var(--dim);
}
.tag-row:hover { color: var(--text); background: var(--panel2); }
.tag-row.on { color: var(--text); font-weight: 700; background: var(--panel2); }
.tag-more { color: var(--link); }
.task-card {
  display: flex; gap: 16px; align-items: center; justify-content: space-between;
  background: var(--card); border: 1px solid var(--border); border-radius: var(--r-md);
  padding: 16px 18px; margin-bottom: 12px; cursor: pointer; box-shadow: var(--shadow);
  color: inherit; text-decoration: none;   /* it is an <a>: keep the card look */
}
.task-card:hover { border-color: var(--dim); }
.tc-main { min-width: 0; }
.tc-title { font-size: var(--fs-lg); font-weight: 700; }
.tc-tags { margin-top: 6px; }
.tc-meta { margin-top: 6px; display: flex; gap: 10px; align-items: center; font-size: var(--fs-xs); }
.tc-side { flex: none; width: 210px; }
.score-wrap { display: flex; gap: 10px; align-items: center; justify-content: flex-end; }
.score-bar { flex: 1; min-width: 90px; max-width: 150px; height: 6px; border-radius: 3px; background: var(--panel2); border: 1px solid var(--border); overflow: hidden; }
.score-fill { height: 100%; background: var(--link); border-radius: 3px; }
@media (max-width: 900px) {
  .tasks-layout { grid-template-columns: 1fr; }
  .side-group { flex-direction: row; }
  #tag-list { flex-direction: row; flex-wrap: wrap; }
}
#archive-tags { display: flex; gap: 8px; flex-wrap: wrap; margin-bottom: 8px; }
.archive-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 12px; margin: 12px 0; }
.archive-card {
  background: var(--card); border: 1px solid var(--border); border-radius: var(--r-md);
  padding: 16px 18px; cursor: pointer; box-shadow: var(--shadow);
}
.archive-card:hover { border-color: var(--dim); }
.archive-card:focus-visible { outline: 2px solid var(--link); outline-offset: 2px; }
.arch-top { display: flex; align-items: center; justify-content: space-between; gap: 12px; }
.arch-title { display: flex; align-items: center; gap: 8px; font-size: var(--fs-lg); font-weight: 700; min-width: 0; }
.arch-bar { flex: 1; max-width: 150px; height: 6px; border-radius: 3px; background: var(--panel2); border: 1px solid var(--border); overflow: hidden; }
.arch-fill { height: 100%; background: var(--link); border-radius: 3px; }
.arch-sub { display: flex; align-items: center; justify-content: space-between; gap: 12px; margin-top: 8px; font-size: var(--fs-xs); color: var(--dim); }
@media (max-width: 900px) {
  .archive-grid { grid-template-columns: 1fr; }
}
.settings-row { margin: 14px 0; max-width: 420px; }
.settings-row label { display: block; font-size: var(--fs-sm); font-weight: 600; margin-bottom: 6px; }
.settings-row input, .settings-row select {
  width: 100%; border: 1px solid var(--border); border-radius: var(--r-sm);
  padding: 9px 12px; font-size: var(--fs-md); background: var(--field); color: var(--text);
}
.settings-row input:focus, .settings-row select:focus { outline: none; border-color: var(--text); }

main { max-width: 1080px; width: 100%; margin: 0 auto; padding: 48px 24px 64px; flex: 1; }
.view { display: none; }
.view.active { display: block; animation: fade .25s ease; }
@keyframes fade { from { opacity: 0; transform: translateY(4px); } to { opacity: 1; } }

/* "pick up where you left off" card */
.resume {
  display: flex; align-items: center; justify-content: space-between; gap: var(--sp-4);
  background: var(--card); border: 1px solid var(--border); border-radius: var(--r-md);
  padding: 14px 18px; margin: 0 0 var(--sp-5); box-shadow: var(--shadow);
}
.resume-main { min-width: 0; }
.resume-title { font-weight: 700; margin-bottom: 2px; }

/* home */
.hero { text-align: left; padding: var(--sp-5) 0 40px; max-width: 680px; }
.hero::before {
  content: ""; display: block; width: 56px; height: 4px; border-radius: 2px;
  background: linear-gradient(90deg, var(--hero-a), var(--hero-b)); margin-bottom: 20px;
}
.hero h1 { margin: 0 0 14px; font-size: var(--fs-display); line-height: var(--lh-tight); font-weight: 700; letter-spacing: -1px; }
.hero .lede { color: var(--dim); font-size: var(--fs-xl); margin: 0 0 28px; line-height: 1.7; }
.hero-btns { display: flex; gap: 10px; margin-bottom: 40px; flex-wrap: wrap; }
.btn-primary {
  background: var(--acc); color: var(--on-acc); text-decoration: none; font-weight: 600;
  padding: 10px 22px; border-radius: var(--r-sm); font-size: var(--fs-md); border: 1px solid var(--acc);
}
.btn-primary:hover { opacity: .85; }
.btn-ghost {
  border: 1px solid var(--border); color: var(--text); text-decoration: none;
  padding: 9px 20px; border-radius: var(--r-sm); font-size: var(--fs-md); background: transparent; cursor: pointer;
}
.btn-ghost:hover { border-color: var(--text); }
.stat-strip { display: flex; gap: 32px; flex-wrap: wrap; }
.stat { min-width: 90px; }
.stat-num { font-size: var(--fs-stat); font-weight: 700; letter-spacing: -0.5px; }
.stat-label { font-size: var(--fs-xs); color: var(--dim); }
.features { display: grid; grid-template-columns: repeat(3, 1fr); gap: 0; border-top: 1px solid var(--border); margin-top: 8px; }
.feature { padding: 24px 24px 8px 0; }
.feature + .feature { padding-left: 24px; border-left: 1px solid var(--border); }
.feature h3 { margin: 0 0 6px; font-size: var(--fs-md); }
.feature p { margin: 0; color: var(--dim); font-size: var(--fs-sm); }

/* pages */
.page-head { display: flex; align-items: baseline; gap: 14px; margin: 0 0 20px; flex-wrap: wrap; }
.page-head h2 { margin: 0; font-size: var(--fs-3xl); font-weight: 700; letter-spacing: -0.5px; }
.dim { color: var(--dim); }
.meta { font-size: var(--fs-xs); color: var(--dim); font-family: var(--mono); }
.card { border-top: 1px solid var(--border); padding: 20px 0; min-width: 0; }
.table-card { background: var(--card); border: 1px solid var(--border); border-radius: var(--r-lg); padding: 0; overflow-x: auto; box-shadow: var(--shadow); }
.card-head { display: flex; align-items: center; justify-content: space-between; gap: 12px; flex-wrap: wrap; }
.card-head h2 { margin: 0; font-size: var(--fs-lg); font-weight: 600; }

/* filter */
.filterbar {
  display: flex; gap: 8px; align-items: center; margin-bottom: 16px; flex-wrap: wrap;
  background: var(--card); border: 1px solid var(--border); border-radius: var(--r-md);
  padding: 10px 12px; box-shadow: var(--shadow);
}
.filterbar input[type="search"] {
  flex: 1; min-width: 140px; border: 1px solid var(--border);
  border-radius: var(--r-sm); padding: 8px 12px; font-size: var(--fs-md); background: var(--field); color: var(--text);
}
.filterbar input[type="search"]:focus { outline: none; border-color: var(--text); }
.filterbar select, .history-tools select {
  border: 1px solid var(--border); border-radius: var(--r-sm); padding: 8px 10px;
  font-size: var(--fs-sm); background: var(--field); color: var(--text);
}

/* tables */
table.tests { width: 100%; border-collapse: collapse; font-size: var(--fs-base); }
table.tests th, table.tests td { padding: 13px 16px; text-align: left; border-bottom: 1px solid var(--border); }
table.tests th {
  color: var(--dim); font-weight: 600; font-size: var(--fs-xs);
  white-space: nowrap;
}
table.tests td:last-child, table.tests th:last-child { text-align: right; }
table.tests td:last-child { padding-right: 20px; font-variant-numeric: tabular-nums; }
table.tests tbody tr:last-child td { border-bottom: none; }
.diff-tag {
  display: inline-block; font-size: var(--fs-2xs); font-weight: 600; border-radius: var(--r-pill);
  padding: 2px 10px; margin-right: 6px;
  background: var(--panel2); color: var(--dim); border: 1px solid var(--border);
}
.diff-easy { color: var(--green); border-color: var(--ok-line); background: var(--ok-bg); }
.diff-medium { color: var(--yellow); border-color: var(--warn-line); background: var(--warn-bg); }
.diff-hard { color: var(--red); border-color: var(--err-line); background: var(--err-bg); }
.tag-chip {
  display: inline-block; font-size: var(--fs-2xs); border-radius: var(--r-pill); padding: 2px 10px;
  margin: 1px 4px 1px 0; color: var(--dim);
  font-family: var(--mono);
}
.tag-chip::before { content: "#"; }

.badge {
  display: inline-block; min-width: 40px; text-align: center;
  font-family: var(--mono); font-weight: 600; font-size: var(--fs-2xs);
  border-radius: var(--r-pill); padding: 2px 10px; color: var(--badge-fg);
}
.b-AC { background: var(--green-solid); }
.b-WA, .b-RE, .b-CE { background: var(--red-solid); }
.b-TLE, .b-OLE { background: var(--yellow-solid); }
.b-MLE { background: var(--magenta-solid); }
.b-SKIP { background: var(--neutral-solid); }

/* task detail */
.backlink { display: inline-flex; align-items: center; gap: 6px; margin-bottom: var(--sp-4); color: var(--link); text-decoration: none; font-size: var(--fs-md); font-weight: 500; }
.backlink:hover { text-decoration: underline; }
.task-head { display: flex; align-items: flex-start; justify-content: space-between; gap: var(--sp-4); margin-bottom: 14px; flex-wrap: wrap; }
.task-head h2 { margin: 0 0 4px; font-size: var(--fs-3xl); letter-spacing: -0.5px; }
.notice {
  margin-top: 10px; padding: 10px 14px; border-radius: var(--r-sm); font-size: var(--fs-sm);
  background: var(--notice-bg); border: 1px solid var(--notice-line); color: var(--notice-fg);
}
#pdf-frame { width: 100%; height: 88vh; min-height: 700px; border: 1px solid var(--border); border-radius: var(--r-sm); background: var(--field); }
/* Thai has no case: uppercase + letter-spacing only made headings harder to read */
.pane-h { margin: var(--sp-5) 0 var(--sp-2); font-size: var(--fs-sm); color: var(--dim); font-weight: 600; }
.pane-h:first-of-type { margin-top: 4px; }
.score-box {
  text-align: right; border: 1px solid var(--border); border-radius: var(--r-sm);
  padding: 6px var(--sp-4); background: var(--card); min-width: 130px; box-shadow: var(--shadow);
}
.score-box span { display: block; font-size: var(--fs-2xs); color: var(--dim); }
.score-box strong { font-size: var(--fs-2xl); }
.tabbar { display: flex; gap: 2px; border-bottom: 2px solid var(--border); margin-bottom: var(--sp-4); flex-wrap: wrap; }
.tab-btn {
  background: none; border: none; padding: 10px 18px; cursor: pointer;
  font-size: var(--fs-md); color: var(--dim); border-bottom: 2px solid transparent; margin-bottom: -2px;
}
.tab-btn:hover { color: var(--text); background: var(--panel2); border-radius: var(--r-sm) var(--r-sm) 0 0; }
.tab-btn.active { color: var(--text); font-weight: 700; border-bottom-color: var(--link); }
.tab-pane { display: none; }
.tab-pane.active { display: block; }
.md { font-size: var(--fs-base); line-height: var(--lh-body); overflow-wrap: anywhere; }
.md h1 { font-size: var(--fs-2xl); margin: 1.2em 0 .5em; }
.md h2 { font-size: var(--fs-xl); margin: 1.2em 0 .5em; }
.md h3 { font-size: var(--fs-lg); margin: 1.2em 0 .5em; color: var(--text); }
.md pre {
  background: var(--panel2); border: 1px solid var(--border); color: var(--text);
  border-radius: var(--r-sm); padding: var(--sp-3) 14px; overflow-x: auto;
  font-family: var(--mono); font-size: var(--fs-xs);
}
.md code { font-family: var(--mono); background: var(--panel2); border: 1px solid var(--border); padding: 0 5px; border-radius: 4px; font-size: var(--fs-xs); }
.md pre code { background: none; border: none; padding: 0; }
.md ul { padding-left: 20px; }
.md li { margin: 3px 0; }

.lang-group { display: flex; gap: 2px; background: var(--panel2); border: 1px solid var(--border); border-radius: var(--r-sm); padding: 2px; }
.lang-btn {
  background: transparent; color: var(--dim); border: none; border-radius: 6px;
  padding: 5px 14px; cursor: pointer; font-size: var(--fs-sm);
}
.lang-btn.active { background: var(--field); color: var(--text); font-weight: 600; box-shadow: var(--shadow-sm); }
.dropzone {
  border: 1px dashed var(--border); border-radius: var(--r-sm);
  text-align: center; padding: var(--sp-5); margin: 14px 0 10px;
  cursor: pointer; font-size: var(--fs-sm); color: var(--dim); background: var(--field);
}
.dropzone:hover, .dropzone.over { border-color: var(--text); color: var(--text); background: var(--panel2); }
.dropzone p { margin: 4px 0; }
.file-chip {
  display: flex; align-items: center; gap: 10px;
  background: var(--panel2); border: 1px solid var(--border);
  border-radius: var(--r-sm); padding: 6px var(--sp-3); margin-bottom: 10px; font-size: var(--fs-xs);
  font-family: var(--mono);
}
.file-chip button { cursor: pointer; font-size: var(--fs-xs); background: none; border: none; color: var(--link); padding: 0; }
#file-clear { margin-left: auto; }
.hidden { display: none !important; }
#editor {
  width: 100%; min-height: 300px; resize: vertical;
  background: var(--panel2); color: var(--text);
  border: 1px solid var(--border); border-radius: var(--r-sm);
  font-family: var(--mono); font-size: var(--fs-xs); line-height: 1.6;
  padding: 14px; tab-size: 4;
}
#editor:focus { outline: none; border-color: var(--text); background: var(--field); }
.submit-row { display: flex; gap: 10px; margin-top: var(--sp-3); align-items: center; }
#draft-hint { margin-left: auto; font-size: var(--fs-xs); }
.ghost-btn {
  background: transparent; color: var(--dim);
  border: none; padding: var(--sp-2) 4px; cursor: pointer; font-size: var(--fs-sm);
  text-decoration: none;
}
.ghost-btn:hover { color: var(--text); }
.submit-btn {
  margin-left: auto; background: var(--acc); color: var(--on-acc);
  border: 1px solid var(--acc); border-radius: var(--r-sm); padding: 9px 28px;
  font-weight: 600; cursor: pointer; font-size: var(--fs-md);
}
.submit-btn:hover:not(:disabled) { opacity: .8; }
.submit-btn:disabled { opacity: 0.5; cursor: wait; }
.status { font-size: var(--fs-xs); margin-top: var(--sp-2); font-family: var(--mono); color: var(--dim); }
.status.bad { color: var(--red); }
.auth-card { max-width: 460px; }
.sep { border: none; border-top: 1px solid var(--border); margin: 20px 0; }
tr.test-row { cursor: pointer; }
tr.test-row:hover td { background: var(--panel2); }
.detail-cell pre {
  background: var(--panel2); border: 1px solid var(--border); color: var(--text);
  border-radius: var(--r-sm); padding: 10px var(--sp-3); overflow-x: auto;
  font-size: var(--fs-xs); white-space: pre-wrap; margin: 6px 0;
  font-family: var(--mono);
}
.score-big { font-size: var(--fs-2xl); font-weight: 700; letter-spacing: -0.5px; }
.score-big.ok { color: var(--green); }
.score-big.bad { color: var(--red); }
/* "fix this first" line + the coloured diff */
.verdict-sum { margin: 10px 0 4px; font-size: var(--fs-md); line-height: 1.6; }
.verdict-sum.ok { color: var(--green); }
.verdict-sum.bad { color: var(--red); }
.diff-pre {
  background: var(--panel2); border: 1px solid var(--border); color: var(--text);
  border-radius: var(--r-sm); padding: 10px var(--sp-3); margin: 6px 0; overflow-x: auto;
  font-family: var(--mono); font-size: var(--fs-xs); line-height: 1.55; white-space: pre;
}
.diff-pre span { display: block; }
.d-add { color: var(--green); }
.d-del { color: var(--red); }
.d-hunk { color: var(--dim); }
.d-ctx { color: var(--text); }
.code-view { margin-top: 14px; }
.code-view summary { cursor: pointer; font-size: var(--fs-sm); color: var(--dim); }
.code-view summary:hover { color: var(--text); }
.code-view pre {
  background: var(--panel2); border: 1px solid var(--border); border-radius: var(--r-sm);
  padding: var(--sp-3) 14px; overflow-x: auto; font-size: var(--fs-xs); max-height: 420px;
  overflow-y: auto; font-family: var(--mono); white-space: pre;
}
.tk-k { color: var(--tk-k); font-weight: 600; }
.tk-s { color: var(--tk-s); }
.tk-c { color: var(--tk-c); font-style: italic; }
.tk-n { color: var(--tk-n); }
.tk-f { color: var(--tk-f); }
.tk-p { color: var(--tk-p); }

/* history */
.history-tools { display: flex; gap: var(--sp-2); align-items: center; margin-left: auto; flex-wrap: wrap; }
.mine-check { display: inline-flex; align-items: center; gap: 6px; font-size: var(--fs-sm); color: var(--dim); }
#hist-stats { margin-bottom: var(--sp-3); }

.foot {
  display: flex; align-items: baseline; gap: var(--sp-4);
  padding: var(--sp-5) 28px; border-top: 1px solid var(--border);
  font-size: var(--fs-xs); color: var(--dim);
}
.foot-brand { font-weight: 700; letter-spacing: 2px; font-size: var(--fs-xs); color: var(--text); display: inline-flex; align-items: center; gap: var(--sp-2); }
.foot-brand .brand-logo { width: 22px; height: 22px; border-radius: 6px; }
.foot p { margin: 0; }

/* ---- async judging status (spinner + live state) ---- */
#submit-status, #run-status { display: flex; align-items: center; flex-wrap: wrap; gap: 2px; }
.spinner {
  flex: none; width: 13px; height: 13px; margin-right: var(--sp-2);
  border: 2px solid var(--border); border-top-color: var(--link);
  border-radius: 50%; animation: spin .8s linear infinite;
}
@keyframes spin { to { transform: rotate(360deg); } }

/* ---- hidden tests, playground + contest verdicts ---- */
.b-hidden, .b-ended { background: var(--neutral-solid); }
.b-OK, .b-running { background: var(--green-solid); }
.b-upcoming { background: var(--yellow-solid); }

/* ---- sample viewer / monospace io blocks (input, output, stdout, ids) ---- */
.sample-box { margin-top: 22px; border-top: 1px solid var(--border); padding-top: 6px; }
.chip-row { display: flex; gap: 6px; flex-wrap: wrap; margin-bottom: 10px; }
.chip-btn {
  font: inherit; font-size: var(--fs-xs); font-family: var(--mono);
  background: var(--panel2); color: var(--dim);
  border: 1px solid var(--border); border-radius: var(--r-pill);
  padding: 4px var(--sp-3); cursor: pointer;
}
.chip-btn:hover { color: var(--text); border-color: var(--text); }
.chip-btn.active { color: var(--text); border-color: var(--link); font-weight: 600; }
.io-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 10px; margin-top: 6px; }
.io-block { min-width: 0; }
.io-head { display: flex; align-items: center; justify-content: space-between; gap: var(--sp-2); }
.io-title {
  font-size: var(--fs-2xs); color: var(--dim); font-family: var(--mono);
  overflow-wrap: anywhere;
}
.io-pre {
  background: var(--panel2); border: 1px solid var(--border); color: var(--text);
  border-radius: var(--r-sm); padding: 10px var(--sp-3); margin: 4px 0 0;
  font-family: var(--mono); font-size: var(--fs-xs); white-space: pre-wrap;
  overflow-wrap: anywhere; max-height: 340px; overflow: auto;
}
.icon-btn.copied { color: var(--green); border-color: var(--green); }

/* ---- playground (Run tab) ---- */
#run-input {
  width: 100%; min-height: 110px; resize: vertical;
  background: var(--panel2); color: var(--text);
  border: 1px solid var(--border); border-radius: var(--r-sm);
  font-family: var(--mono); font-size: var(--fs-xs); line-height: 1.6; padding: var(--sp-3);
  tab-size: 4;
}
#run-input:focus { outline: none; border-color: var(--text); background: var(--field); }
.run-head { display: flex; align-items: center; gap: 10px; flex-wrap: wrap; margin: 4px 0 6px; }

/* ---- contests ---- */
.tlink { color: var(--link); text-decoration: none; font-weight: 600; font-family: var(--mono); font-size: var(--fs-sm); }
.tlink:hover { text-decoration: underline; }

/* ---- admin tools ---- */
.mono-num { font-family: var(--mono); color: var(--text); }
.check-row { display: flex; align-items: center; gap: var(--sp-2); }
#plag-body, #ct-list { overflow-x: auto; }
#ct-problems { min-height: 170px; }
#run-btn { margin-left: 0; }
.sim-hi { color: var(--red); font-weight: 700; }
.sim-mid { color: var(--yellow); font-weight: 700; }
.sim-lo { color: var(--dim); }

/* press feedback: every clickable surface reacts on mousedown */
.btn-primary:active, .submit-btn:active:not(:disabled), .signup-btn:active,
.btn-ghost:active, .ghost-btn:active, .icon-btn:active, .chip-btn:active,
.lang-btn:active, .tab-btn:active, .side-btn:active, .tag-row:active,
.task-card:active, .archive-card:active, .tlink:active { transform: translateY(1px); }

@media (max-width: 900px) {
  .features { grid-template-columns: 1fr; }
  .feature + .feature { padding-left: 0; border-left: none; border-top: 1px solid var(--border); padding-top: 16px; }
  .hero h1 { font-size: var(--fs-stat); }
  main { padding: var(--sp-6) var(--sp-4) 48px; }
  .io-grid { grid-template-columns: 1fr; }
}

/* numeric problem id (#19) — shown before titles so numbers are scannable */
.pno {
  display: inline-block;
  min-width: 2.6em;
  margin-right: 6px;
  padding: 1px 6px;
  border: 1px solid var(--border);
  border-radius: 6px;
  background: var(--panel2);
  color: var(--dim);
  font-variant-numeric: tabular-nums;
  font-weight: 600;
  font-size: 0.85em;
}

/* contest join bar (Register / countdown / participants) */
.join-bar { display: flex; flex-wrap: wrap; align-items: center; gap: 8px; margin: 6px 0 2px; }