/* Layout: header with chips, problem list on the left, one card on the right.
   On phones the list folds behind a button above the card. The setup screen has no list. */

:root {
  --bg: #f4f1ea;
  --surface: #fff;
  --panel: #faf8f4;
  --ink: #1c1a17;
  --muted: #6d675e;
  --line: #e4dfd4;
  --line-soft: #eeeae2;
  --control: #d9d3c7;
  --miss: #8a3b2b;
  --good: #2f6b3a;
  --font-body: "Iowan Old Style", "Palatino Linotype", Palatino, serif;
  --font-ui: system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  --font-mono: ui-monospace, "SF Mono", Menlo, monospace;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #161513; --surface: #201e1b; --panel: #1b1a17; --ink: #ece7dd; --muted: #a39c90;
    --line: #34312c; --line-soft: #2a2824; --control: #48443d; --miss: #e08a76; --good: #8cc79a; color-scheme: dark;
  }
}
:root[data-theme="dark"] {
  --bg: #161513; --surface: #201e1b; --panel: #1b1a17; --ink: #ece7dd; --muted: #a39c90;
  --line: #34312c; --line-soft: #2a2824; --control: #48443d; --miss: #e08a76; --good: #8cc79a; color-scheme: dark;
}
* { box-sizing: border-box; }
[hidden] { display: none !important; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font: 17px/1.5 var(--font-body);
  -webkit-text-size-adjust: 100%;
}

/* ---------- header ---------- */

header {
  display: flex;
  flex-wrap: wrap;
  gap: 0.45rem;
  align-items: center;
  padding: 0.8rem max(1rem, env(safe-area-inset-right)) 0.8rem max(1rem, env(safe-area-inset-left));
  background: var(--surface);
  border-bottom: 1px solid var(--line);
}
#brand { margin-right: 0.3rem; font-size: 1.05rem; font-weight: 650; color: inherit; text-decoration: none; }
#brand:hover { text-decoration: underline; text-underline-offset: 3px; }
.chip {
  font: 14px/1 var(--font-ui);
  color: var(--ink);
  border: 1px solid var(--control);
  background: var(--surface);
  border-radius: 999px;
  padding: 0.45rem 0.8rem;
  min-height: 2.1rem;
  display: inline-flex;
  align-items: center;
}
button.chip, summary.chip { cursor: pointer; }
.chip[aria-pressed="true"], .chip.primary { background: var(--ink); color: var(--surface); border-color: var(--ink); }
.chip:disabled { opacity: 0.4; cursor: not-allowed; }
.chip.warn { color: var(--miss); border-color: var(--miss); }
#timer { font-variant-numeric: tabular-nums; }
/* The part of a label that phones drop; pre keeps its leading space inside a flex chip. */
.long { white-space: pre; }
.chips { display: flex; flex-wrap: wrap; gap: 0.45rem; align-items: center; }
.tools { display: flex; flex-wrap: wrap; gap: 0.45rem; align-items: center; margin-left: auto; }
.field {
  font: 15px/1.2 var(--font-ui);
  color: var(--ink);
  border: 1px solid var(--control);
  background: var(--surface);
  border-radius: 8px;
  padding: 0.5rem 0.75rem;
  width: 6.5rem;
  font-variant-numeric: tabular-nums;
}
.select { width: auto; max-width: 100%; }
button:focus-visible, input:focus-visible, select:focus-visible, summary:focus-visible, a:focus-visible, .field:focus { outline: 2px solid var(--ink); outline-offset: 2px; }

.menu { position: relative; }
.menu summary { list-style: none; padding-inline: 0.65rem; }
.menu summary::-webkit-details-marker { display: none; }
.menu summary svg { width: 1.1rem; height: 1.1rem; fill: currentColor; }
.menu-list {
  position: absolute;
  right: 0;
  top: calc(100% + 0.35rem);
  z-index: 10;
  min-width: 15rem;
  display: grid;
  padding: 0.3rem;
  background: var(--surface);
  border: 1px solid var(--control);
  border-radius: 10px;
  box-shadow: 0 8px 24px rgb(0 0 0 / 0.14);
}
.menu-list button {
  text-align: left;
  border: 0;
  background: none;
  color: var(--ink);
  font: 15px/1.3 var(--font-ui);
  padding: 0.65rem 0.75rem;
  border-radius: 6px;
  cursor: pointer;
}
.menu-list button:hover { background: var(--panel); }

/* ---------- list ---------- */

.layout { display: grid; grid-template-columns: 22rem minmax(0, 1fr); min-height: calc(100vh - 3.4rem); }
.layout.solo { grid-template-columns: minmax(0, 1fr); }
.list-toggle { display: none; }
aside { border-right: 1px solid var(--line); overflow: auto; max-height: calc(100vh - 3.4rem); background: var(--panel); position: sticky; top: 0; }
.filters { display: grid; grid-template-columns: minmax(0, 1fr) auto; gap: 0.45rem; padding: 0.65rem 0.9rem; border-bottom: 1px solid var(--line-soft); }
.filters .field { width: 100%; font-size: 14px; }
.filters .select { width: 9.5rem; }
#list .item {
  display: block;
  width: 100%;
  text-align: left;
  border: 0;
  border-bottom: 1px solid var(--line-soft);
  background: transparent;
  padding: 0.65rem 0.9rem;
  font: 14px/1.35 var(--font-ui);
  color: inherit;
  cursor: pointer;
}
#list .item[aria-current="true"] { background: var(--surface); font-weight: 600; box-shadow: inset 3px 0 0 var(--ink); }
.item-title { display: block; }
.item-meta { display: block; margin-top: 0.15rem; font-size: 12px; font-weight: 400; color: var(--muted); }
.mark { display: block; margin-top: 0.15rem; font-size: 12px; font-weight: 600; }
.mark:empty { display: none; }
.mark.muted { color: var(--muted); font-weight: 400; }
.count { padding: 0.55rem 0.9rem; font: 12px/1.4 var(--font-ui); color: var(--muted); font-variant-numeric: tabular-nums; }
.count.warn { color: var(--miss); font-weight: 600; }
.count.flash { color: var(--good); font-weight: 600; }
.share, .result-share { display: grid; gap: 0.45rem; border-bottom: 1px solid var(--line-soft); }
.result-share { padding-bottom: 0.8rem; }
.result-share .field, .link-field { width: 100%; font-size: 13px; }
.result-share .chip { justify-self: start; }

/* ---------- card ---------- */

main { padding: 1.5rem; min-width: 0; }
article {
  max-width: 46rem;
  margin: 0 auto;
  padding: 2rem 2.2rem 2.4rem;
  background: var(--surface);
  scroll-margin-top: 0.5rem;
}
.meta { margin: 0 0 0.8rem; color: var(--muted); font: 13px/1.4 var(--font-ui); }
h2 { margin: 0 0 1rem; font-size: 1.35rem; text-wrap: balance; }
.title-row { display: flex; gap: 0.6rem; align-items: flex-start; justify-content: space-between; margin: 0 0 1rem; }
.title-row h2 { margin: 0; }
.title-row + .link-field { margin: -0.35rem 0 1.1rem; }
p { margin: 0 0 0.85rem; overflow-wrap: anywhere; }
.answer, .solution { font-weight: 650; }
figure { margin: 0.4rem 0 1rem; }
figure img { max-width: 100%; height: auto; background: #fff; }
.katex-display { margin: 0.55rem 0 0.9rem; overflow-x: auto; overflow-y: hidden; padding-bottom: 2px; }
.empty { color: var(--muted); }
.icon {
  flex: none;
  display: inline-grid;
  place-items: center;
  width: 2.25rem;
  height: 2.25rem;
  padding: 0;
  color: var(--muted);
  border: 1px solid var(--control);
  background: var(--surface);
  border-radius: 8px;
  cursor: pointer;
}
.icon:hover { color: var(--ink); }
.icon.done { color: var(--good); border-color: var(--good); }
.icon svg { width: 1.05rem; height: 1.05rem; }

.gate {
  margin-top: 1.4rem;
  padding: 0.9rem 1rem;
  border: 1px dashed var(--control);
  background: var(--panel);
  font-family: var(--font-ui);
}
.gate > p { margin: 0 0 0.65rem; font-size: 14px; line-height: 1.4; }
.gate > p:last-child { margin-bottom: 0; }
.gate code {
  font: 16px/1 var(--font-mono);
  letter-spacing: 0.14em;
  background: var(--surface);
  border: 1px solid var(--control);
  padding: 0.15rem 0.45rem;
}
.gate form, .gate-actions { display: flex; flex-wrap: wrap; gap: 0.45rem; align-items: center; }
.gate input, .gate button {
  font: 14px/1 var(--font-ui);
  color: var(--ink);
  border: 1px solid var(--control);
  background: var(--surface);
  border-radius: 8px;
  padding: 0.6rem 0.8rem;
  cursor: pointer;
}
.gate input { cursor: text; width: 8rem; font-size: 16px; }
.gate .miss { color: var(--miss); margin: 0.5rem 0 0; }
.hint-box { margin: 0 0 0.9rem; padding-bottom: 0.6rem; border-bottom: 1px solid var(--line-soft); font-family: var(--font-body); }
.hint-box .meta { margin-bottom: 0.4rem; }
.solution-box { margin-top: 1.4rem; padding-top: 1rem; border-top: 1px solid var(--line-soft); }

.reply { display: grid; gap: 0.4rem; margin-top: 1.4rem; }
.reply .meta { margin: 0; }
.reply textarea.field { width: 100%; min-height: 5.5rem; resize: vertical; font: 16px/1.45 var(--font-ui); }
.reply textarea.field[readonly] { background: var(--panel); }
.student-answer { margin: 0; padding: 0.7rem 0.9rem; background: var(--panel); border-left: 3px solid var(--control); font: 16px/1.45 var(--font-ui); white-space: pre-wrap; }
.verdict { margin: 0; font: 600 14px/1.4 var(--font-ui); }
.reply-actions { display: flex; flex-wrap: wrap; gap: 0.6rem; align-items: center; }
.reply-actions .meta { margin: 0; }
.reply-actions .sent { font: 600 14px/1.4 var(--font-ui); color: var(--ink); }
.verdict.good, .mark.good { color: var(--good); }
.verdict.bad, .mark.bad { color: var(--miss); }
.score { display: grid; gap: 0.5rem; margin-top: 1.4rem; padding-top: 1rem; border-top: 1px solid var(--line-soft); }
.score .meta, .score .note { margin: 0; }
.score-chips .chip { min-width: 2.5rem; justify-content: center; font-variant-numeric: tabular-nums; }
.nav { display: flex; flex-wrap: wrap; gap: 0.45rem; margin-top: 1.4rem; }
.nav #next { margin-left: auto; }

/* ---------- setup ---------- */

.setup { display: grid; gap: 1.3rem; }
.setup fieldset { border: 0; margin: 0; padding: 0; display: grid; gap: 0.5rem; min-width: 0; }
.setup legend { padding: 0; margin-bottom: 0.5rem; font: 600 12px/1.3 var(--font-ui); letter-spacing: 0.06em; text-transform: uppercase; color: var(--muted); }
.note { margin: 0; font: 14px/1.4 var(--font-ui); color: var(--muted); font-variant-numeric: tabular-nums; }
.note.warn { color: var(--miss); }
.setup .actions { display: flex; flex-wrap: wrap; gap: 0.6rem; align-items: center; border-top: 1px solid var(--line-soft); padding-block: 1.1rem 0; }
.setup .actions .chip { font-size: 15px; padding: 0.6rem 1rem; }
.daily { display: grid; gap: 0.5rem; padding: 0.9rem 1rem; background: var(--panel); border: 1px solid var(--line-soft); }
.linkish { background: none; border: 0; padding: 0.3rem 0; font: 14px/1.3 var(--font-ui); color: var(--muted); text-decoration: underline; text-underline-offset: 3px; cursor: pointer; }

/* ---------- phones ---------- */

@media (max-width: 800px) {
  #grades { display: none !important; }
  .layout { grid-template-columns: minmax(0, 1fr); min-height: 0; }
  .list-toggle {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 0.5rem;
    width: 100%;
    padding: 0.75rem 1rem;
    border: 0;
    border-bottom: 1px solid var(--line);
    background: var(--panel);
    color: var(--ink);
    font: 600 14px/1.3 var(--font-ui);
    text-align: left;
    cursor: pointer;
  }
  .list-toggle::after { content: "▾"; color: var(--muted); }
  .layout.list-open .list-toggle::after { content: "▴"; }
  aside { display: none; position: static; max-height: 65vh; border-right: 0; border-bottom: 1px solid var(--line); }
  .layout.list-open aside { display: block; }
  main { padding: 0.75rem; }
  article { padding: 1.25rem 1rem 1.5rem; }
  h2 { font-size: 1.2rem; }
  .tools { margin-left: auto; }
  .long { display: none; }
  header[data-mode="test"] #testinfo { display: none; }
  #grade-select { flex: 1; min-width: 0; }
  .filters .select { width: 8.5rem; }
  .nav .chip { flex: 1; justify-content: center; min-height: 2.6rem; }
  .reply-actions .keys { display: none; }
  .menu-list { min-width: min(16rem, calc(100vw - 2rem)); }
  .chip { min-height: 2.4rem; }
}
@media (min-width: 801px) {
  #grade-select { display: none !important; }
}

/* ---------- print ---------- */

#print { display: none; }
@media print {
  body { background: #fff; color: #000; font-size: 12pt; }
  header, .layout, noscript { display: none !important; }
  #print { display: block; }
  #print h1 { font-size: 16pt; margin: 0 0 0.3rem; }
  #print h2 { font-size: 13pt; margin: 1rem 0 0.4rem; }
  .print-fill { margin-bottom: 1rem; font-family: var(--font-ui); }
  .print-problem { break-inside: avoid; }
  .print-solutions { break-before: page; }
  #print figure img { max-width: 70%; }
}