/* Layout: three working panes like a test screen. Drill list | problem | editor over results. */
:root {
  --bg: #f4f3ee;
  --panel: #ffffff;
  --ink: #16222a;
  --muted: #45545d;
  --line: #dcd9cf;
  --accent: #F5CE0F;
  --accent-ink: #2b2700;
  --accent-soft: #fbf1c2;
  --accent-text: #6e5700;
  --pass: #1d7a4b;
  --pass-soft: #e3f3ea;
  --fail: #b0352a;
  --fail-soft: #fbe9e6;
  --code-bg: #f8f7f2;
  --gutter: #8a99a2;
  --sans: "IBM Plex Sans", system-ui, -apple-system, "Segoe UI", sans-serif;
  --mono: "IBM Plex Mono", ui-monospace, "SF Mono", Menlo, Consolas, monospace;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #0C0D10; --panel: #131519; --ink: #ECE9E0; --muted: #c4c8d0; --line: #2c3038;
    --accent: #F5CE0F; --accent-ink: #2b2700; --accent-soft: #2a2506; --accent-text: #F5CE0F;
    --pass: #52c58d; --pass-soft: #12291e; --fail: #f07b6f; --fail-soft: #2f1714;
    --code-bg: #0f1013; --gutter: #93a3ad; color-scheme: dark;
  }
}
:root[data-theme="dark"] {
  --bg: #0C0D10; --panel: #131519; --ink: #ECE9E0; --muted: #c4c8d0; --line: #2c3038;
    --accent: #F5CE0F; --accent-ink: #2b2700; --accent-soft: #2a2506; --accent-text: #F5CE0F;
  --pass: #52c58d; --pass-soft: #12291e; --fail: #f07b6f; --fail-soft: #2f1714;
  --code-bg: #0f1013; --gutter: #93a3ad; color-scheme: dark;
}
* { box-sizing: border-box; }
html, body { height: 100%; }
body { background: var(--bg); color: var(--ink); font-family: var(--sans); font-size: 17.5px; line-height: 1.5; }
button { font: inherit; cursor: pointer; }
:focus-visible { outline: 2px solid var(--accent-text); outline-offset: 2px; }

.app { height: 100%; display: grid; grid-template-rows: auto 1fr; }
header.top {
  display: flex; align-items: center; gap: 16px; flex-wrap: wrap;
  padding: 10px 16px; border-bottom: 1px solid var(--line); background: var(--panel);
}
.brand { font-weight: 700; font-size: 18.5px; letter-spacing: 0.01em; }
.brand small { font-weight: 400; color: var(--muted); margin-left: 8px; font-size: 16.5px; }
.spacer { flex: 1; }
.timer { display: flex; align-items: center; gap: 8px; }
.timer .clock { font-family: var(--mono); font-variant-numeric: tabular-nums; font-size: 18.5px; min-width: 5ch; text-align: right; }
.timer .clock.low { color: var(--fail); }
.btn {
  border: 1px solid var(--line); background: var(--panel); color: var(--ink);
  padding: 5px 12px; border-radius: 6px; font-size: 16.5px;
}
.btn:hover { border-color: var(--accent); }
.btn.primary { background: var(--accent); color: var(--accent-ink); border-color: var(--accent); font-weight: 600; }
.btn.primary:hover { filter: brightness(1.08); }
.btn.warn { border-color: var(--fail); color: var(--fail); }

.work { display: grid; grid-template-columns: 270px minmax(0, 1fr) minmax(0, 1.15fr); min-height: 0; }
nav.drills { border-right: 1px solid var(--line); overflow: auto; padding-block: 12px; background: var(--panel); }
.group-label { font-size: 14px; text-transform: uppercase; letter-spacing: 0.09em; color: var(--muted); padding: 10px 16px 4px; font-weight: 600; }
.drill-btn {
  display: flex; align-items: center; gap: 8px; width: 100%; text-align: left;
  border: 0; background: none; color: var(--ink); padding: 6px 16px; font-size: 17px;
}
.drill-btn:hover { background: var(--accent-soft); }
.drill-btn[aria-current="true"] { background: var(--accent-soft); color: var(--accent-text); font-weight: 600; box-shadow: inset 3px 0 0 var(--accent); }
.dot { width: 8px; height: 8px; border-radius: 50%; border: 1.5px solid var(--gutter); flex: none; }
.dot.done { background: var(--pass); border-color: var(--pass); }
.drill-id { font-family: var(--mono); font-size: 14.5px; color: var(--muted); flex: none; }

section.problem { overflow: auto; border-right: 1px solid var(--line); min-width: 0; }
.tabs { display: flex; gap: 4px; padding: 10px 16px 0; border-bottom: 1px solid var(--line); position: sticky; top: 0; background: var(--bg); z-index: 1; }
.tab { border: 0; background: none; padding: 8px 12px; color: var(--muted); border-bottom: 2px solid transparent; font-weight: 500; }
.tab[aria-selected="true"] { color: var(--ink); border-bottom-color: var(--accent); }
.prose { padding: 16px 20px 32px; max-width: 72ch; }
.prose h1 { font-size: 25.5px; margin: 4px 0 2px; text-wrap: balance; }
.prose .kind { font-size: 15.5px; color: var(--muted); text-transform: uppercase; letter-spacing: 0.08em; font-weight: 600; }
.prose h2 { font-size: 16.5px; text-transform: uppercase; letter-spacing: 0.07em; color: var(--muted); margin: 22px 0 6px; }
.prose p { margin: 6px 0; }
.prose ul { margin: 6px 0; padding-left: 20px; }
.prose li { margin: 3px 0; }
.prose code { font-family: var(--mono); font-size: 16px; background: var(--code-bg); border: 1px solid var(--line); border-radius: 4px; padding: 0 4px; }
.prose pre { font-family: var(--mono); font-size: 16px; background: var(--code-bg); border: 1px solid var(--line); border-radius: 6px; padding: 10px 12px; overflow-x: auto; line-height: 1.55; }
.prose pre code { border: 0; padding: 0; background: none; }
.note { font-size: 16px; color: var(--muted); border-left: 2px solid var(--line); padding-left: 10px; margin-top: 20px; }
.tbl-wrap { overflow-x: auto; margin: 6px 0 12px; }
table.data { border-collapse: collapse; font-family: var(--mono); font-size: 15.5px; font-variant-numeric: tabular-nums; }
table.data th, table.data td { border: 1px solid var(--line); padding: 3px 8px; text-align: left; white-space: nowrap; }
table.data th { background: var(--code-bg); font-weight: 500; }
table.data td.null { color: var(--muted); font-style: italic; }
.tname { font-family: var(--mono); font-weight: 500; font-size: 16.5px; margin-top: 12px; }

section.coding { display: grid; grid-template-rows: auto minmax(0, 1.3fr) auto minmax(0, 1fr); min-width: 0; min-height: 0; }
.bar { display: flex; align-items: center; gap: 8px; padding: 8px 12px; border-bottom: 1px solid var(--line); flex-wrap: wrap; }
.bar .lang { font-family: var(--mono); font-size: 15.5px; color: var(--muted); }
.bar .hint { font-size: 15.5px; color: var(--muted); }
.editor { display: grid; grid-template-columns: auto 1fr; min-height: 0; background: var(--code-bg); overflow: hidden; }
.gutter, #code {
  font-family: var(--mono); font-size: 16.5px; line-height: 25px; padding: 10px 0; margin: 0;
}
.gutter { color: var(--gutter); text-align: right; padding-left: 12px; padding-right: 10px; overflow: hidden; user-select: none; border-right: 1px solid var(--line); font-variant-numeric: tabular-nums; }
#code {
  width: 100%; height: 100%; border: 0; resize: none; background: transparent; color: var(--ink);
  padding-left: 12px; padding-right: 12px; white-space: pre; overflow: auto; tab-size: 4; outline: none;
}
.out-head { display: flex; align-items: center; gap: 10px; padding: 8px 12px; border-block: 1px solid var(--line); background: var(--panel); }
.out-head strong { font-size: 16.5px; }
.summary { font-size: 16.5px; font-weight: 600; }
.summary.pass { color: var(--pass); }
.summary.fail { color: var(--fail); }
.output { overflow: auto; padding: 10px 12px 24px; background: var(--panel); }
.empty { color: var(--muted); font-size: 16.5px; }
.case { border: 1px solid var(--line); border-radius: 6px; margin-bottom: 8px; overflow: hidden; }
.case-head { display: flex; align-items: center; gap: 8px; padding: 6px 10px; font-size: 16.5px; }
.pill { font-size: 14px; font-weight: 700; letter-spacing: 0.05em; text-transform: uppercase; padding: 1px 7px; border-radius: 10px; flex: none; }
.pill.pass { background: var(--pass-soft); color: var(--pass); }
.pill.fail { background: var(--fail-soft); color: var(--fail); }
.case-call { font-family: var(--mono); font-size: 15.5px; overflow-wrap: anywhere; min-width: 0; }
.case-meta { margin-left: auto; font-size: 14.5px; color: var(--muted); flex: none; font-variant-numeric: tabular-nums; }
.case-body { padding: 4px 10px 10px; border-top: 1px solid var(--line); }
.kv { font-size: 14.5px; text-transform: uppercase; letter-spacing: 0.06em; color: var(--muted); margin-top: 8px; font-weight: 600; }
.val { font-family: var(--mono); font-size: 15.5px; white-space: pre-wrap; overflow-wrap: anywhere; background: var(--code-bg); border-radius: 4px; padding: 6px 8px; margin-top: 3px; max-height: 220px; overflow: auto; }
.err { color: var(--fail); }
details summary { cursor: pointer; font-size: 15.5px; color: var(--muted); margin-top: 8px; }

@media (max-width: 1000px) {
  html, body { height: auto; }
  .app { height: auto; }
  .work { grid-template-columns: minmax(0, 1fr); }
  nav.drills { border-right: 0; border-bottom: 1px solid var(--line); display: flex; overflow-x: auto; padding: 8px 16px; gap: 4px; }
  .group-label { display: none; }
  .drill-btn { width: auto; white-space: nowrap; border-radius: 6px; padding: 6px 10px; }
  .drill-btn[aria-current="true"] { box-shadow: none; }
  .drill-btn .drill-name { display: none; }
  section.problem { border-right: 0; border-bottom: 1px solid var(--line); }
  section.coding { grid-template-rows: auto 420px auto auto; }
  .output { min-height: 200px; }
}
@media (prefers-reduced-motion: reduce) { * { transition: none !important; } }