:root {
  /* palette and type shared with AlgoScope and the Java/DB Concepts Steppers */
  --bg: #0f151b;
  --surface: #161e26;
  --surface-2: #1b2530;
  --border: #2a3642;
  --text: #e3eaf0;
  --muted: #93a2b0;
  --accent: #5cb3ef;
  --accent-ink: #0f151b;
  --accent-soft: #16334a;
  --easy: #3ccf98;
  --medium: #f0b84a;
  --hard: #ff7b6e;
  --pass: #3ccf98;
  --fail: #ff7b6e;
  --link: #5cb3ef;
  --code-bg: #121a22;
  --shadow: 0 10px 30px rgba(0, 0, 0, 0.35);
  --radius: 14px;
  --mono: "JetBrains Mono", ui-monospace, "Cascadia Code", Consolas, monospace;
  --sans: "IBM Plex Sans", "Segoe UI", system-ui, -apple-system, sans-serif;
  --display: "Bricolage Grotesque", "IBM Plex Sans", system-ui, sans-serif;
  color-scheme: dark;
}

@media (prefers-color-scheme: light) {
  :root:not([data-theme="dark"]) {
    --bg: #eef2f5;
    --surface: #ffffff;
    --surface-2: #f4f7f9;
    --border: #d8e0e7;
    --text: #15202b;
    --muted: #5a6977;
    --accent: #0b6aa8;
    --accent-ink: #ffffff;
    --accent-soft: #dcecf7;
    --easy: #0a8a5f;
    --medium: #b7790a;
    --hard: #c43c3c;
    --pass: #0a8a5f;
    --fail: #c43c3c;
    --link: #0b6aa8;
    --code-bg: #f7f9fb;
    --shadow: 0 10px 30px rgba(21, 32, 43, 0.08);
    color-scheme: light;
  }
}

* { box-sizing: border-box; }
[hidden] { display: none !important; }
html, body { margin: 0; height: 100%; }
body {
  background: var(--bg);
  color: var(--text);
  font: 15px/1.55 var(--sans);
  display: flex;
  flex-direction: column;
}
a { color: var(--link); text-decoration: none; }
a:hover { text-decoration: underline; }
.muted { color: var(--muted); }
.small { font-size: 12px; }

/* ---------- top bar */
.topbar {
  display: flex; align-items: center; gap: 18px;
  padding: 10px 20px;
  border-bottom: 1px solid var(--border);
  background: var(--surface);
  position: sticky; top: 0; z-index: 5;
}
h1, h2, h3, .brand { font-family: var(--display); letter-spacing: -0.01em; }
.brand { display: flex; align-items: center; gap: 10px; font-weight: 700; color: var(--text); font-size: 17px; }
.brand:hover { text-decoration: none; }
.logo { display: inline-flex; }
.crumbs { flex: 1; color: var(--muted); font-size: 14px; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.crumbs a { color: var(--muted); }
.crumbs .sep { margin: 0 8px; opacity: .6; }
.crumbs strong { color: var(--text); font-weight: 600; }
.progress-pill {
  font-size: 13px; padding: 5px 12px; border-radius: 999px;
  background: var(--accent-soft); color: var(--accent); font-weight: 600; white-space: nowrap;
}

main { flex: 1; min-height: 0; display: flex; flex-direction: column; }

/* ---------- buttons & inputs */
.btn {
  display: inline-flex; align-items: center; gap: 6px;
  border: 1px solid var(--border); background: var(--surface-2); color: var(--text);
  padding: 7px 14px; border-radius: 10px; font: 600 13px var(--sans); cursor: pointer;
}
.btn:hover { border-color: var(--muted); text-decoration: none; }
.btn.primary { background: var(--accent); border-color: var(--accent); color: var(--accent-ink); }
.btn.primary:hover { filter: brightness(1.08); }
.btn.ghost { background: transparent; }
.btn.icon { padding: 7px 9px; }
.btn:disabled { opacity: .55; cursor: progress; }
input[type="search"], select {
  background: var(--surface); color: var(--text);
  border: 1px solid var(--border); border-radius: 10px;
  padding: 8px 12px; font: 14px var(--sans);
}
input[type="search"]:focus, select:focus, .btn:focus-visible { outline: 2px solid var(--accent); outline-offset: 1px; }

/* ---------- list page */
.list-page { overflow-y: auto; }
.list-inner { width: 100%; max-width: 1180px; margin: 0 auto; padding: 28px 20px 60px; }
.hero {
  display: grid; grid-template-columns: 1.25fr 1fr; gap: 28px; align-items: center;
  background: linear-gradient(135deg, var(--surface) 0%, var(--surface-2) 100%);
  border: 1px solid var(--border); border-radius: 20px; padding: 34px; box-shadow: var(--shadow);
}
.eyebrow { text-transform: uppercase; letter-spacing: .12em; font-size: 12px; color: var(--accent); font-weight: 700; margin: 0 0 6px; }
.hero h1 { font-size: 38px; line-height: 1.1; margin: 0 0 12px; letter-spacing: -0.02em; }
.lead { color: var(--muted); margin: 0 0 20px; max-width: 56ch; }
.hero-actions { display: flex; align-items: center; gap: 14px; flex-wrap: wrap; }
.hero-art pre {
  margin: 0; background: var(--code-bg); border: 1px solid var(--border); border-radius: 14px;
  padding: 18px; font: 13px/1.6 var(--mono); color: var(--text); overflow: hidden;
}
.hero-art .k { color: #c084fc; }
.hero-art .f { color: #60a5fa; }
.hero-art .c { color: var(--accent); }

.filters { display: flex; flex-wrap: wrap; gap: 10px; margin: 26px 0 18px; }
.filters input[type="search"] { flex: 1 1 220px; }

.grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(300px, 1fr)); gap: 16px; }
.card {
  display: flex; flex-direction: column; gap: 10px;
  background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius);
  padding: 18px; color: var(--text); transition: transform .12s ease, border-color .12s ease;
  position: relative;
}
.card:hover { transform: translateY(-2px); border-color: var(--accent); text-decoration: none; }
.card-top { display: flex; align-items: center; gap: 10px; }
.card-icon {
  width: 38px; height: 38px; border-radius: 10px; display: grid; place-items: center;
  background: var(--accent-soft); color: var(--accent); flex: none;
}
.card-icon.debug { background: color-mix(in srgb, var(--hard) 14%, transparent); color: var(--hard); }
.card h3 { margin: 0; font-size: 16px; }
.card .kind { font-size: 11px; text-transform: uppercase; letter-spacing: .08em; color: var(--muted); }
.card p { margin: 0; color: var(--muted); font-size: 14px; flex: 1; }
.chips { display: flex; flex-wrap: wrap; gap: 6px; }
.chip { font-size: 12px; padding: 2px 9px; border-radius: 999px; background: var(--surface-2); color: var(--muted); border: 1px solid var(--border); }
.card-foot { display: flex; align-items: center; gap: 12px; font-size: 13px; }
.diff-Easy { color: var(--easy); font-weight: 700; }
.diff-Medium { color: var(--medium); font-weight: 700; }
.diff-Hard { color: var(--hard); font-weight: 700; }
.status-badge { margin-left: auto; font-size: 12px; font-weight: 600; }
.status-badge.solved { color: var(--pass); }
.status-badge.attempted { color: var(--medium); }
.empty { text-align: center; padding: 40px; }

/* ---------- workspace */
.workspace { flex: 1; min-height: 0; display: flex; }
.pane { display: flex; flex-direction: column; min-width: 0; min-height: 0; background: var(--surface); }
.pane.left { width: 42%; border-right: 1px solid var(--border); }
.pane.right { flex: 1; }
.splitter { width: 6px; cursor: col-resize; background: transparent; margin-left: -3px; margin-right: -3px; z-index: 2; }
.splitter:hover, .splitter.dragging { background: var(--accent-soft); }
.pane-head {
  display: flex; align-items: center; gap: 10px; padding: 8px 12px;
  border-bottom: 1px solid var(--border); background: var(--surface-2); min-height: 50px;
}
.tabs { display: flex; gap: 4px; overflow-x: auto; flex: 1; min-width: 0; }
.tabs button {
  background: transparent; border: 0; color: var(--muted); padding: 6px 12px; border-radius: 8px;
  font: 600 13px var(--sans); cursor: pointer; white-space: nowrap;
}
.tabs button.active { background: var(--surface); color: var(--text); box-shadow: 0 0 0 1px var(--border); }
.tabs button .dirty { color: var(--medium); margin-left: 4px; }
.toolbar { display: flex; align-items: center; gap: 8px; flex: none; }
.toolbar select { padding: 6px 10px; font-size: 13px; }
.pane-body { flex: 1; overflow-y: auto; padding: 22px 26px 40px; }

.markdown h1 { font-size: 24px; margin: 0 0 12px; }
.markdown h2 { font-size: 18px; margin: 26px 0 10px; padding-bottom: 6px; border-bottom: 1px solid var(--border); }
.markdown h3 { font-size: 15px; margin: 20px 0 8px; }
.markdown p, .markdown li { color: var(--text); }
.markdown code { font: 13px var(--mono); background: var(--code-bg); padding: 1px 6px; border-radius: 6px; border: 1px solid var(--border); }
.markdown pre { background: var(--code-bg); border: 1px solid var(--border); border-radius: 10px; padding: 14px; overflow-x: auto; }
.markdown pre code { border: 0; padding: 0; background: none; }
.markdown table { border-collapse: collapse; width: 100%; margin: 12px 0; font-size: 14px; display: block; overflow-x: auto; }
.markdown th, .markdown td { border: 1px solid var(--border); padding: 7px 10px; text-align: left; vertical-align: top; }
.markdown th { background: var(--surface-2); }
.meta-row { display: flex; gap: 14px; align-items: center; margin-bottom: 14px; font-size: 13px; }

.code-view { margin: 0 0 18px; }
.code-view h4 { margin: 0 0 6px; font: 600 13px var(--mono); color: var(--muted); }
.code-view pre { margin: 0; background: var(--code-bg); border: 1px solid var(--border); border-radius: 10px; padding: 14px; overflow-x: auto; font: 12.5px/1.55 var(--mono); }
.reveal { text-align: center; padding: 50px 20px; }
.reveal p { color: var(--muted); max-width: 44ch; margin: 0 auto 16px; }

.editor-wrap { flex: 1; min-height: 0; position: relative; }
.editor-wrap .CodeMirror, .editor-wrap textarea.fallback {
  position: absolute; inset: 0; height: 100%; width: 100%;
  font: 13.5px/1.6 var(--mono);
}
.editor-wrap textarea.fallback { background: var(--code-bg); color: var(--text); border: 0; padding: 12px; resize: none; }
.CodeMirror { background: var(--code-bg) !important; }
.CodeMirror-gutters { background: var(--code-bg) !important; border-right: 1px solid var(--border) !important; }

.results { height: 34%; min-height: 140px; border-top: 1px solid var(--border); display: flex; flex-direction: column; background: var(--surface); }
.results-head { display: flex; align-items: center; gap: 12px; padding: 8px 14px; border-bottom: 1px solid var(--border); font-size: 13px; }
.results-head .spacer { flex: 1; }
.results-body { flex: 1; overflow-y: auto; padding: 6px 0; font-size: 13px; }
.result-row { display: grid; grid-template-columns: 22px 1fr auto; gap: 8px; padding: 5px 14px; align-items: start; }
.result-row:hover { background: var(--surface-2); }
.result-row .msg { grid-column: 2 / 4; color: var(--fail); font: 12px/1.5 var(--mono); white-space: pre-wrap; word-break: break-word; }
.result-row .ms { color: var(--muted); font-size: 12px; }
.dot { width: 10px; height: 10px; border-radius: 50%; margin-top: 5px; flex: none; }
.dot.pass { background: var(--pass); }
.dot.fail { background: var(--fail); }
.dot.none { background: transparent; box-shadow: inset 0 0 0 2px var(--border); }
.dot.running { background: transparent; border: 2px solid var(--border); border-top-color: var(--accent); animation: spin .8s linear infinite; }

/* per-test list */
.results-head input[type="checkbox"], .test-row input[type="checkbox"] { accent-color: var(--accent); width: 15px; height: 15px; margin: 0; cursor: pointer; }
.test-row { display: grid; grid-template-columns: 18px 14px 1fr auto 28px; gap: 8px; padding: 4px 10px 4px 14px; align-items: center; }
.test-row:hover { background: var(--surface-2); }
.test-row .dot { margin-top: 0; }
.test-row .tname { background: none; border: 0; padding: 0; color: var(--text); font: 13px var(--sans); text-align: left; cursor: pointer; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.test-row .tname:hover { color: var(--link); text-decoration: underline; }
.test-row .ms { color: var(--muted); font-size: 12px; }
.test-row .run1 { background: none; border: 1px solid transparent; color: var(--muted); border-radius: 6px; width: 26px; height: 24px; cursor: pointer; display: grid; place-items: center; }
.test-row .run1:hover { color: var(--accent); border-color: var(--border); }
.test-row .msg { grid-column: 3 / 6; color: var(--fail); font: 12px/1.5 var(--mono); white-space: pre-wrap; word-break: break-word; padding-bottom: 2px; }
.test-row.stale .dot, .test-row.stale .ms, .test-row.stale .msg { opacity: .45; }
.test-row.stale .ms::after { content: " · out of date"; }
.suite-label { padding: 8px 14px 2px; font: 600 11px var(--sans); text-transform: uppercase; letter-spacing: .08em; color: var(--muted); }
.results-foot { padding: 5px 14px; border-top: 1px solid var(--border); }
.btn.sm { padding: 4px 10px; font-size: 12px; border-radius: 8px; }
.code-line { display: block; min-height: 1.55em; padding: 0 4px; border-radius: 4px; }
.code-line.flash { background: var(--accent-soft); box-shadow: inset 3px 0 0 var(--accent); }
.compile-out { margin: 8px 14px; padding: 12px; background: var(--code-bg); border: 1px solid var(--border); border-radius: 10px; font: 12px/1.5 var(--mono); white-space: pre-wrap; color: var(--fail); }
.summary-pass { color: var(--pass); font-weight: 700; }
.summary-fail { color: var(--fail); font-weight: 700; }
.spinner { width: 14px; height: 14px; border: 2px solid var(--border); border-top-color: var(--accent); border-radius: 50%; animation: spin .8s linear infinite; display: inline-block; }
@keyframes spin { to { transform: rotate(360deg); } }

.toast {
  position: fixed; bottom: 20px; left: 50%; transform: translateX(-50%) translateY(20px);
  background: var(--surface-2); border: 1px solid var(--border); color: var(--text);
  padding: 10px 16px; border-radius: 10px; box-shadow: var(--shadow); opacity: 0; pointer-events: none;
  transition: opacity .2s, transform .2s; font-size: 14px; z-index: 20;
}
.toast.show { opacity: 1; transform: translateX(-50%) translateY(0); }

@media (max-width: 900px) {
  .hero { grid-template-columns: 1fr; padding: 24px; }
  .hero-art { display: none; }
  .hero h1 { font-size: 30px; }
  .workspace { flex-direction: column; overflow-y: auto; }
  .pane.left { width: 100% !important; border-right: 0; border-bottom: 1px solid var(--border); max-height: 45vh; }
  .splitter { display: none; }
  .pane.right { min-height: 75vh; }
  .toolbar .btn.ghost { padding: 7px 10px; }
  .crumbs { display: none; }
}
@media (max-width: 520px) {
  .topbar { padding: 10px 16px; }
  .list-inner { padding: 18px 16px 40px; }
  .grid { grid-template-columns: 1fr; }
  .pane-head { flex-wrap: wrap; }
  .toolbar { width: 100%; justify-content: flex-end; }
}

/* language picker & per-language availability */
.lang-picker { display: inline-flex; align-items: center; gap: 6px; color: var(--muted); }
.lang-picker select { padding: 5px 8px; font-size: 13px; border-radius: 8px; }
.card-langs { position: absolute; top: 14px; right: 14px; display: flex; gap: 4px; }
.lang-dot { font: 600 10px var(--sans); padding: 1px 6px; border-radius: 999px; border: 1px solid var(--border); color: var(--muted); }
.lang-dot.current { border-color: var(--accent); color: var(--accent); background: var(--accent-soft); }
.card.unavailable { opacity: .55; }
.card.unavailable:hover { opacity: .8; }
.status-badge.muted { color: var(--muted); font-weight: 500; }
.card-top { padding-right: 120px; }
@media (max-width: 520px) { .lang-picker select { max-width: 130px; } }

/* completion dropdown (CodeMirror show-hint) and go-to-definition */
.CodeMirror-hints {
  z-index: 50; font-family: var(--mono); font-size: 13px; padding: 4px; max-height: 18em;
  background: var(--surface); border: 1px solid var(--border); border-radius: 8px; box-shadow: var(--shadow);
}
li.CodeMirror-hint {
  display: flex; justify-content: space-between; gap: 18px; padding: 2px 8px; border-radius: 5px;
  color: var(--text); white-space: pre;
}
li.CodeMirror-hint-active { background: var(--accent-soft); color: var(--text); }
.hint-kind { color: var(--muted); font-size: 11px; font-family: var(--sans); }
.cm-goto-link { text-decoration: underline; color: var(--link) !important; cursor: pointer; }
.cm-goto-flash { background: var(--accent-soft); box-shadow: inset 3px 0 0 var(--accent); }