:root {
  --bg: #f6f8fa;
  --surface: #ffffff;
  --border: #d0d7de;
  --text: #1f2328;
  --muted: #59636e;
  --accent: #1a7f37;
  --accent-text: #ffffff;
  --error: #cf222e;
  --code-bg: #eff2f5;
  --term-bg: #0d1117;
  --term-text: #e6edf3;
  --term-green: #3fb950;
  --term-err: #ff7b72;
  --radius: 10px;
  --mono: ui-monospace, SFMono-Regular, Menlo, Consolas, "Liberation Mono", monospace;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0d1117;
    --surface: #161b22;
    --border: #30363d;
    --text: #e6edf3;
    --muted: #9198a1;
    --accent: #3fb950;
    --accent-text: #0d1117;
    --error: #ff7b72;
    --code-bg: #262c36;
    --term-bg: #010409;
  }
}

* { box-sizing: border-box; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font: 16px/1.55 system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
}

a { color: var(--accent); }
h1 { font-size: 1.6rem; line-height: 1.25; margin: 0.4em 0; }
h2 { font-size: 1.15rem; margin: 0 0 0.2em; }
code {
  font-family: var(--mono);
  font-size: 0.9em;
  background: var(--code-bg);
  padding: 0.1em 0.35em;
  border-radius: 4px;
  word-break: break-all;
}

.container { max-width: 860px; margin: 0 auto; padding: 16px 16px 64px; }
.muted { color: var(--muted); }
.small { font-size: 0.875rem; }
.sr-only { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0 0 0 0); }

/* шапка */
.top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding: 12px 16px;
  border-bottom: 1px solid var(--border);
  background: var(--surface);
}
.logo { font-weight: 700; text-decoration: none; color: var(--text); }
.logo-mark { font-family: var(--mono); color: var(--accent); }
.user-box { display: flex; align-items: center; gap: 10px; }

/* элементы */
.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 16px;
}
.btn {
  display: inline-block;
  font: inherit;
  font-weight: 600;
  padding: 9px 16px;
  border-radius: 8px;
  border: 1px solid var(--accent);
  background: var(--accent);
  color: var(--accent-text);
  cursor: pointer;
  text-decoration: none;
}
.btn:disabled { opacity: 0.6; cursor: wait; }
.btn.ghost { background: transparent; color: var(--text); border-color: var(--border); }
.btn.small { padding: 4px 10px; font-size: 0.875rem; }
.row { display: flex; gap: 10px; flex-wrap: wrap; margin-top: 12px; }
.error { color: var(--error); }
.back { display: inline-block; margin-top: 8px; text-decoration: none; font-size: 0.9rem; }
.badge {
  font-size: 0.8rem;
  font-weight: 600;
  margin-left: 10px;
  padding: 2px 8px;
  border-radius: 99px;
  background: var(--accent);
  color: var(--accent-text);
  vertical-align: middle;
}

input {
  font: inherit;
  width: 100%;
  padding: 9px 12px;
  margin-top: 4px;
  border-radius: 8px;
  border: 1px solid var(--border);
  background: var(--bg);
  color: var(--text);
}
input:focus-visible, .btn:focus-visible, a:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }

/* вход */
.auth { max-width: 400px; margin: 40px auto; display: grid; gap: 12px; }
.auth h1 { margin: 0; }
.auth p { margin: 0; }
.auth label { display: grid; font-weight: 600; font-size: 0.9rem; }

/* прогресс */
.bar { height: 8px; background: var(--code-bg); border-radius: 99px; overflow: hidden; margin: 8px 0; }
.bar-fill { height: 100%; background: var(--accent); border-radius: 99px; transition: width 0.3s; }

/* уровни */
.intro { margin-bottom: 20px; }
.levels { display: grid; gap: 12px; }
.level { display: flex; gap: 16px; align-items: flex-start; text-decoration: none; color: inherit; }
a.level:hover { border-color: var(--accent); }
.level.locked { opacity: 0.55; }
.level p { margin: 0.2em 0; }
.level-body { flex: 1; min-width: 0; }
.level-num {
  flex: none;
  width: 44px;
  height: 44px;
  display: grid;
  place-items: center;
  border-radius: 10px;
  font: 700 1.2rem var(--mono);
  background: var(--code-bg);
}
.level.passed .level-num { background: var(--accent); color: var(--accent-text); }

/* список задач */
.tasks { list-style: none; padding: 0; display: grid; gap: 8px; margin-top: 16px; }
.task-row { display: flex; align-items: center; gap: 12px; padding: 12px 16px; text-decoration: none; color: inherit; }
.task-row:hover { border-color: var(--accent); }
.task-id { font-family: var(--mono); color: var(--muted); width: 2.4em; flex: none; }
.task-title { flex: 1; min-width: 0; }
.task-status { width: 1.2em; color: var(--accent); font-weight: 700; flex: none; }
.task-row.solved .task-title { color: var(--muted); }
.tag { font-size: 0.75rem; padding: 2px 8px; border-radius: 99px; border: 1px solid var(--border); color: var(--muted); flex: none; }
.tag.terminal { border-color: var(--accent); color: var(--accent); }

/* задача */
.rich { overflow-wrap: anywhere; }
.answer-form { margin-top: 16px; }
.options { border: 0; padding: 0; margin: 0; display: grid; gap: 8px; }
.option {
  display: flex;
  gap: 10px;
  align-items: flex-start;
  padding: 10px 14px;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: var(--surface);
  cursor: pointer;
}
.option:has(input:checked) { border-color: var(--accent); }
.option input { width: auto; margin: 4px 0 0; accent-color: var(--accent); }
.answer-label { display: grid; font-weight: 600; font-size: 0.9rem; }
.answer-input { font-family: var(--mono); }
.hint { border-left: 3px solid var(--accent); padding: 4px 12px; color: var(--muted); }
.result { margin-top: 16px; }
.success { border: 1px solid var(--accent); border-radius: var(--radius); padding: 16px; background: var(--surface); }
.ok { color: var(--accent); font-weight: 700; margin-top: 0; }
.unlock { font-weight: 700; }

/* терминал */
.term-wrap { margin-top: 16px; }
.term {
  background: var(--term-bg);
  color: var(--term-text);
  font: 14px/1.45 var(--mono);
  border-radius: var(--radius);
  border: 1px solid var(--border);
  padding: 12px 14px;
  height: 360px;
  overflow-y: auto;
  cursor: text;
}
.term-out { margin: 0; white-space: pre-wrap; word-break: break-word; font: inherit; }
.term-echo { color: var(--term-text); }
.term-err { color: var(--term-err); }
.term-line { display: flex; align-items: baseline; }
.term-prompt { color: var(--term-green); white-space: pre; flex: none; }
.term-input {
  flex: 1;
  min-width: 0;
  margin: 0;
  padding: 0;
  border: 0;
  background: transparent;
  color: var(--term-text);
  font: inherit;
  outline: none;
}
.term-input:focus-visible { outline: none; }

@media (max-width: 560px) {
  h1 { font-size: 1.35rem; }
  .term { height: 300px; font-size: 13px; }
  .tag { display: none; }
}

/* навигация */
.user-box { flex-wrap: wrap; justify-content: flex-end; }
.nav-link { text-decoration: none; font-weight: 600; font-size: 0.95rem; color: var(--text); }
.nav-link:hover { color: var(--accent); }
.eyebrow { margin: 16px 0 0; font-size: 0.8rem; font-weight: 700; text-transform: uppercase; letter-spacing: 0.06em; color: var(--accent); }
.eyebrow + h1 { margin-top: 4px; }

/* теория */
.lesson { margin-top: 8px; }
.lesson h2 { margin: 1.6em 0 0.5em; font-size: 1.2rem; }
.lesson p, .lesson li { max-width: 72ch; }
.lesson ul { padding-left: 1.2em; }
.lesson li { margin: 0.3em 0; }
.note {
  border-left: 3px solid var(--accent);
  background: var(--surface);
  border-radius: 0 8px 8px 0;
  padding: 10px 14px;
  margin: 12px 0;
}
.table-wrap { overflow-x: auto; margin: 12px 0; border: 1px solid var(--border); border-radius: var(--radius); background: var(--surface); }
table { border-collapse: collapse; width: 100%; font-size: 0.92rem; }
th, td { text-align: left; padding: 8px 12px; border-bottom: 1px solid var(--border); vertical-align: top; }
th { background: var(--code-bg); font-weight: 600; white-space: nowrap; }
tbody tr:last-child td { border-bottom: 0; }
.cta { margin-top: 32px; }
.cta p { margin-top: 0; }

/* статистика */
.tiles { display: grid; grid-template-columns: repeat(auto-fit, minmax(170px, 1fr)); gap: 12px; margin: 16px 0 8px; }
.tile-value { font-size: 1.9rem; font-weight: 700; line-height: 1.1; font-variant-numeric: tabular-nums; }
.tile-label { font-weight: 600; margin-top: 4px; }
.tile-sub { margin-top: 2px; }
#app > h2 { margin-top: 28px; font-size: 1.1rem; }
.two-col h2 { margin-top: 28px; font-size: 1.1rem; }

.chart { display: flex; gap: 2px; align-items: stretch; height: 160px; }
.chart-col { flex: 1; display: flex; flex-direction: column; position: relative; min-width: 0; border-radius: 4px; outline-offset: 2px; }
.chart-col:focus-visible { outline: 2px solid var(--accent); }
.chart-track { flex: 1; display: flex; align-items: flex-end; border-bottom: 1px solid var(--border); }
.chart-bar { width: 100%; background: var(--accent); border-radius: 4px 4px 0 0; }
.chart-day { text-align: center; font-size: 0.72rem; color: var(--muted); padding-top: 4px; font-variant-numeric: tabular-nums; }
.chart-col:hover .chart-bar, .chart-col:focus .chart-bar { filter: brightness(1.15); }
.chart-col:hover::after, .chart-col:focus::after {
  content: attr(data-tip);
  position: absolute;
  bottom: calc(100% + 6px);
  left: 50%;
  transform: translateX(-50%);
  white-space: nowrap;
  background: var(--text);
  color: var(--bg);
  font-size: 0.8rem;
  padding: 4px 8px;
  border-radius: 6px;
  pointer-events: none;
  z-index: 2;
}
.chart-col:first-child:hover::after, .chart-col:first-child:focus::after { left: 0; transform: none; }
.chart-col:last-child:hover::after, .chart-col:last-child:focus::after { left: auto; right: 0; transform: none; }
.chart-note { margin: 10px 0 0; }

.level-stats { display: grid; gap: 12px; }
.level-stat-head { display: flex; justify-content: space-between; gap: 12px; font-size: 0.92rem; }
.level-stat .bar { margin: 4px 0 0; }

.two-col { display: grid; grid-template-columns: 1fr 1fr; gap: 0 16px; }
.list { list-style: none; margin: 0; padding: 4px 16px; }
.list li { display: flex; justify-content: space-between; gap: 12px; padding: 8px 0; border-bottom: 1px solid var(--border); }
.list li:last-child { border-bottom: 0; }
.list a { text-decoration: none; min-width: 0; }

@media (max-width: 640px) {
  .two-col { grid-template-columns: 1fr; }
  .username { display: none; }
  .chart { height: 120px; }
}

/* маршрут изучения */
.route { list-style: none; padding: 0; margin: 16px 0; display: grid; gap: 4px; }
.route-btn {
  width: 100%;
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 8px 10px;
  border: 0;
  border-radius: 8px;
  background: transparent;
  color: var(--text);
  font: inherit;
  text-align: left;
  cursor: pointer;
}
.route-btn:hover { background: var(--surface); }
.route-dot {
  flex: none;
  width: 28px;
  height: 28px;
  border-radius: 50%;
  display: grid;
  place-items: center;
  font: 700 0.85rem var(--mono);
  border: 2px solid var(--border);
  color: var(--muted);
}
.route-item.done .route-dot { background: var(--accent); border-color: var(--accent); color: var(--accent-text); }
.route-item.current .route-dot { border-color: var(--accent); color: var(--accent); }
.route-item.current .route-title { font-weight: 700; }
.route-item.next .route-title { color: var(--muted); }
.route-title { flex: 1; min-width: 0; }
.route-time { flex: none; }

.steps { display: grid; gap: 12px; }
.step { padding: 0; scroll-margin-top: 16px; }
.step.current { border-color: var(--accent); }
.step summary {
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 14px 16px;
  cursor: pointer;
  list-style: none;
}
.step summary::-webkit-details-marker { display: none; }
.step summary::after { content: "▸"; margin-left: auto; color: var(--muted); transition: transform 0.2s; }
.step[open] summary::after { transform: rotate(90deg); }
.step-num {
  flex: none;
  width: 36px;
  height: 36px;
  border-radius: 10px;
  display: grid;
  place-items: center;
  font: 700 1rem var(--mono);
  background: var(--code-bg);
}
.step.done .step-num { background: var(--accent); color: var(--accent-text); }
.step.current .step-num { border: 2px solid var(--accent); color: var(--accent); }
.step-head { display: grid; min-width: 0; }
.step-title { font-weight: 700; font-size: 1.05rem; }
.step-body { padding: 0 16px 16px; border-top: 1px solid var(--border); }
.step-body h3 { font-size: 1rem; margin: 1.3em 0 0.4em; }
.step-body p, .step-body li { max-width: 72ch; }
.step-body ul { padding-left: 1.2em; }
.step-body li { margin: 0.3em 0; }

.materials { margin-top: 8px; }
.materials ul { list-style: none; padding: 0; display: grid; gap: 8px; }
.materials li {
  display: flex;
  gap: 12px;
  align-items: flex-start;
  padding: 10px 12px;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: var(--bg);
  max-width: none;
}
.mat-icon { flex: none; width: 1.5em; text-align: center; }
.materials a { font-weight: 600; }

table .rich { overflow-wrap: normal; }
td code { word-break: normal; }