:root {
  --bg: #eef1ec;
  --panel: #ffffff;
  --panel-2: #f6f8f4;
  --ink: #1d2320;
  --muted: #5f6b63;
  --line: #d9dfd6;
  --line-strong: #c3ccc0;
  --accent: #1f7a33;
  --accent-hover: #186629;
  --accent-soft: #e2f1e4;
  --accent-ink: #ffffff;
  --err: #c0322b;
  --err-soft: #fdecea;
  --warn: #9a5b00;
  --warn-soft: #fff4dc;
  --ok: #1f7a33;
  --ok-soft: #e2f1e4;
  --band: rgba(255, 214, 10, 0.28);

  --code-bg: #ffffff;
  --code-kw: #1437a8;
  --code-rb: #0b7a4f;
  --code-num: #a2440c;
  --code-str: #8c2d86;
  --code-cm: #7d887f;
  --margin-bg: #f3f6f1;

  /* Цвета поля — как в Кумире */
  --f-bg: #289628;
  --f-grid: rgba(200, 200, 0, 0.55);
  --f-wall: #e2e21c;
  --f-paint: #8c9290;
  --f-robot: #f5f5f5;
  --f-robot-line: #151515;

  --radius: 10px;
  --radius-sm: 7px;
  --shadow: 0 1px 2px rgba(20, 30, 20, 0.06), 0 2px 10px rgba(20, 30, 20, 0.05);
  --font: "Segoe UI", system-ui, -apple-system, Roboto, "Helvetica Neue", Arial, sans-serif;
  --mono: "Cascadia Mono", Consolas, "JetBrains Mono", "DejaVu Sans Mono", Menlo, monospace;
  --code-size: 15px;
  --code-line: 23px;
  color-scheme: light;
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #111513;
    --panel: #1a1f1c;
    --panel-2: #20261f;
    --ink: #e5ebe6;
    --muted: #9aa69d;
    --line: #2c342f;
    --line-strong: #3b453e;
    --accent: #3fae5a;
    --accent-hover: #4cc068;
    --accent-soft: #1d3324;
    --accent-ink: #07140b;
    --err: #ff7b72;
    --err-soft: #3a1d1b;
    --warn: #f0b44c;
    --warn-soft: #33290f;
    --ok: #5fd07a;
    --ok-soft: #173020;
    --band: rgba(255, 214, 10, 0.16);
    --code-bg: #161a18;
    --code-kw: #8fb3ff;
    --code-rb: #62d6a0;
    --code-num: #f0a36b;
    --code-str: #e59ae0;
    --code-cm: #7f8b82;
    --margin-bg: #1b201d;
    --shadow: 0 1px 2px rgba(0, 0, 0, 0.3);
    color-scheme: dark;
  }
}

:root[data-theme="dark"] {
  --bg: #111513;
  --panel: #1a1f1c;
  --panel-2: #20261f;
  --ink: #e5ebe6;
  --muted: #9aa69d;
  --line: #2c342f;
  --line-strong: #3b453e;
  --accent: #3fae5a;
  --accent-hover: #4cc068;
  --accent-soft: #1d3324;
  --accent-ink: #07140b;
  --err: #ff7b72;
  --err-soft: #3a1d1b;
  --warn: #f0b44c;
  --warn-soft: #33290f;
  --ok: #5fd07a;
  --ok-soft: #173020;
  --band: rgba(255, 214, 10, 0.16);
  --code-bg: #161a18;
  --code-kw: #8fb3ff;
  --code-rb: #62d6a0;
  --code-num: #f0a36b;
  --code-str: #e59ae0;
  --code-cm: #7f8b82;
  --margin-bg: #1b201d;
  color-scheme: dark;
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  height: 100%;
}

body {
  background: var(--bg);
  color: var(--ink);
  font: 15px/1.5 var(--font);
  display: flex;
  flex-direction: column;
  min-height: 100vh;
}

h1, h2, h3 { margin: 0; line-height: 1.25; }
code, kbd, pre { font-family: var(--mono); }
code { font-size: 0.92em; background: var(--panel-2); border: 1px solid var(--line); border-radius: 4px; padding: 0 4px; }
kbd { font-size: 0.85em; border: 1px solid var(--line-strong); border-bottom-width: 2px; border-radius: 4px; padding: 0 5px; background: var(--panel); }
.muted { color: var(--muted); }
.small { font-size: 13px; }
[hidden] { display: none !important; }

/* ---------- Кнопки ---------- */

.btn {
  font: inherit;
  font-size: 14px;
  color: var(--ink);
  background: var(--panel);
  border: 1px solid var(--line-strong);
  border-radius: var(--radius-sm);
  padding: 6px 12px;
  min-height: 34px;
  cursor: pointer;
  white-space: nowrap;
  transition: background 0.12s, border-color 0.12s;
}
.btn:hover:not(:disabled) { background: var(--panel-2); border-color: var(--muted); }
.btn:active:not(:disabled) { transform: translateY(1px); }
.btn:disabled { opacity: 0.45; cursor: default; }
.btn:focus-visible, button:focus-visible, select:focus-visible, input:focus-visible, textarea:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}
.btn.primary {
  background: var(--accent);
  border-color: var(--accent);
  color: var(--accent-ink);
  font-weight: 600;
}
.btn.primary:hover:not(:disabled) { background: var(--accent-hover); border-color: var(--accent-hover); }
.btn.ghost { background: transparent; border-color: transparent; }
.btn.ghost:hover:not(:disabled) { background: var(--panel-2); border-color: var(--line); }
.btn.big { width: 100%; min-height: 42px; font-size: 15px; }
.btn.small { min-height: 26px; padding: 2px 8px; font-size: 13px; }
.btn.icon { min-width: 34px; padding: 4px 8px; font-size: 16px; line-height: 1; }
.btn[aria-pressed="true"], .btn[aria-expanded="true"] { background: var(--accent-soft); border-color: var(--accent); }
.btn-row { display: flex; gap: 8px; }
.btn-row > .btn { flex: 1; }

/* ---------- Шапка ---------- */

.topbar {
  display: flex;
  align-items: center;
  gap: 16px;
  padding: 8px 16px;
  background: var(--panel);
  border-bottom: 1px solid var(--line);
  flex: none;
}
.brand { display: flex; align-items: center; gap: 10px; color: inherit; text-decoration: none; border-radius: var(--radius-sm); }
.brand:hover strong { color: var(--accent); }
.brand:focus-visible { outline: 2px solid var(--accent); outline-offset: 3px; }
.brand-logo { width: 32px; height: 32px; flex: none; }
.brand-logo rect { fill: var(--f-bg); }
.brand-logo path { fill: var(--f-robot); stroke: var(--f-robot-line); stroke-width: 2; }
.brand-text { display: flex; flex-direction: column; line-height: 1.15; }
.brand-text strong { font-size: 16px; }
.brand-text span { font-size: 12.5px; color: var(--muted); }
.modes {
  display: flex;
  background: var(--panel-2);
  border: 1px solid var(--line);
  border-radius: 999px;
  padding: 3px;
  margin-left: auto;
}
.modes button {
  font: inherit;
  font-size: 14px;
  border: 0;
  background: transparent;
  color: var(--muted);
  padding: 5px 14px;
  border-radius: 999px;
  cursor: pointer;
}
.modes button[aria-selected="true"] { background: var(--panel); color: var(--ink); font-weight: 600; box-shadow: var(--shadow); }
.modes { margin-left: 8px; }
.brand-logo path { fill: none; stroke: #ffffff; stroke-width: 2; }
a.btn { display: inline-flex; align-items: center; text-decoration: none; }
.spacer { flex: 1; }
.mono { font-family: var(--mono); }

/* ---------- Раскладка ---------- */

.layout {
  flex: 1;
  min-height: 0;
  display: grid;
  gap: 12px;
  padding: 12px;
  height: calc(100vh - 57px);
}
.layout-file { grid-template-columns: minmax(420px, 1.25fr) minmax(360px, 1fr); }
.layout-practice { grid-template-columns: minmax(330px, 400px) minmax(420px, 1fr); }

.side, .pane {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  min-height: 0;
  min-width: 0;
}
.side { overflow: auto; padding: 16px; }
.pane { display: flex; flex-direction: column; overflow: hidden; }

/* ---------- Задание ---------- */

.panel { display: flex; flex-direction: column; gap: 14px; }
.panel h1 { font-size: 20px; }
.panel h2 { font-size: 15.5px; display: flex; align-items: center; gap: 8px; }
.task-picker { display: flex; gap: 6px; }
.task-picker select {
  flex: 1 1 0;
  width: 0;
  min-width: 0;
  font: inherit;
  font-size: 14px;
  color: var(--ink);
  background: var(--panel);
  border: 1px solid var(--line-strong);
  border-radius: var(--radius-sm);
  padding: 6px 8px;
  min-height: 34px;
}
.task-card { display: flex; flex-direction: column; gap: 8px; }
.task-meta { display: flex; gap: 6px; flex-wrap: wrap; }
.chip {
  font-size: 12px;
  font-weight: 600;
  padding: 2px 9px;
  border-radius: 999px;
  background: var(--panel-2);
  border: 1px solid var(--line);
  color: var(--muted);
}
.chip.lvl-1 { background: #e8f3ff; border-color: #c9defa; color: #1b4f8f; }
.chip.lvl-2 { background: #fff1dc; border-color: #f5d9a8; color: #7a4a00; }
.chip-score.s3 { background: var(--ok-soft); border-color: var(--ok); color: var(--ok); }
.chip-score.s1, .chip-score.s2 { background: var(--warn-soft); border-color: var(--warn); color: var(--warn); }
.chip-score.s0 { background: var(--err-soft); border-color: var(--err); color: var(--err); }
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) .chip.lvl-1 { background: #16263a; border-color: #24405f; color: #9cc6ff; }
  :root:not([data-theme="light"]) .chip.lvl-2 { background: #33260f; border-color: #54401a; color: #f3c46e; }
}
.task-source { margin: 0; font-size: 12.5px; color: var(--muted); }
.task-source:empty { display: none; }
.task-text p { margin: 0 0 10px; }
.task-text .task-do { margin-top: 4px; }
.questions { margin: 0 0 10px; padding-left: 22px; display: flex; flex-direction: column; gap: 8px; }

.preview-wrap { overflow-x: auto; margin: 0 0 10px; }
.preview { border-collapse: collapse; font-size: 13.5px; }
.preview th, .preview td { border: 1px solid var(--line-strong); padding: 3px 10px; white-space: nowrap; }
.preview thead th, .preview tbody th { background: var(--panel-2); color: var(--muted); font-weight: 600; font-size: 12.5px; text-align: center; }
.preview tbody tr:first-child td { font-weight: 600; }

.step { display: flex; flex-direction: column; gap: 8px; }
.step p { margin: 0; }
.step-num {
  display: inline-grid;
  place-items: center;
  width: 22px;
  height: 22px;
  border-radius: 50%;
  background: var(--accent);
  color: var(--accent-ink);
  font-size: 13px;
  flex: none;
}
#download-name { font-weight: 400; opacity: 0.85; font-size: 13px; }
.btn-row { display: flex; gap: 8px; flex-wrap: wrap; }
.btn-row > .btn { flex: 1; }

.drop {
  position: relative;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 4px;
  text-align: center;
  padding: 18px 12px;
  border: 2px dashed var(--line-strong);
  border-radius: var(--radius);
  background: var(--panel-2);
  cursor: pointer;
  transition: border-color 0.12s, background 0.12s;
}
.drop:hover, .drop.is-over { border-color: var(--accent); background: var(--accent-soft); }
.drop:focus-within { outline: 2px solid var(--accent); outline-offset: 2px; }
.drop input { position: absolute; inset: 0; opacity: 0; cursor: pointer; width: 100%; }
.drop-icon { font-size: 26px; line-height: 1; color: var(--accent); }

.note {
  background: var(--warn-soft);
  border: 1px solid color-mix(in srgb, var(--warn) 35%, transparent);
  border-radius: var(--radius-sm);
  padding: 10px 12px;
  font-size: 14px;
}
.note p { margin: 0 0 6px; }
.note p:last-child { margin-bottom: 0; }
.alert {
  background: var(--err-soft);
  border: 1px solid var(--err);
  border-radius: var(--radius-sm);
  padding: 10px 12px;
  font-size: 14px;
}
.solution {
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
  padding: 10px 12px;
  background: var(--panel-2);
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: 8px;
}
.solution p { margin: 0; }
.sol-table { border-collapse: collapse; font-size: 13.5px; }
.sol-table th { text-align: left; padding: 3px 10px 3px 0; color: var(--muted); font-weight: 600; vertical-align: top; }
.sol-table td { padding: 3px 0; }
.sol-code { white-space: pre-wrap; word-break: break-word; }
.answers { margin: 0; padding-left: 18px; }
.rules { font-size: 13.5px; color: var(--muted); }
.rules summary { cursor: pointer; color: var(--ink); }
.rules ul { margin: 6px 0 0; padding-left: 18px; }
.rules li { margin-bottom: 4px; }

/* ---------- Результат проверки ---------- */

.check { display: flex; flex-direction: column; gap: 10px; }
.check > p { margin: 0; }
.score {
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 12px 14px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--line);
}
.score-num { font-size: 34px; font-weight: 700; line-height: 1; font-variant-numeric: tabular-nums; }
.score-num small { font-size: 15px; font-weight: 600; color: var(--muted); }
.score p { margin: 0; font-size: 14px; word-break: break-word; }
.score .score-note { margin-top: 3px; font-size: 13px; color: var(--muted); }
.score.s3 { background: var(--ok-soft); border-color: var(--ok); }
.score.s3 .score-num { color: var(--ok); }
.score.s1, .score.s2 { background: var(--warn-soft); border-color: var(--warn); }
.score.s1 .score-num, .score.s2 .score-num { color: var(--warn); }
.score.s0 { background: var(--err-soft); border-color: var(--err); }
.score.s0 .score-num { color: var(--err); }

.results { list-style: none; margin: 0; padding: 0; display: flex; flex-direction: column; gap: 8px; }
.results > li {
  display: grid;
  grid-template-columns: 22px 1fr;
  gap: 8px;
  padding: 10px 12px;
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
  font-size: 14px;
}
.results > li.ok { border-left: 4px solid var(--ok); }
.results > li.bad { border-left: 4px solid var(--err); }
.results p { margin: 4px 0 0; }
.r-icon { font-weight: 700; font-size: 16px; }
.ok > .r-icon { color: var(--ok); }
.bad > .r-icon { color: var(--err); }
.why { color: var(--ink); background: var(--err-soft); border-radius: 6px; padding: 6px 8px; }
.r-note { color: var(--muted); font-size: 13px; }
.problems { margin: 6px 0 0; padding-left: 18px; }
.problems li { margin-bottom: 4px; }
.chart-preview summary { cursor: pointer; font-size: 13.5px; }
.chart-preview p { margin: 4px 0 0; }

/* ---------- Круговая диаграмма ---------- */

.pie-box { max-width: 380px; }
.pie { width: 100%; height: auto; display: block; }
.pie-label { font: 600 13px var(--font); fill: #ffffff; paint-order: stroke; stroke: rgba(0, 0, 0, 0.35); stroke-width: 2px; }
.pie-legend { font: 13px var(--font); fill: var(--ink); }
.pie-empty { fill: var(--panel-2); stroke: var(--line-strong); }
.pie-note { font: 13px var(--font); fill: var(--muted); }

/* ---------- Практикум: вопросы ---------- */

.qlist { list-style: none; margin: 0; padding: 0; display: flex; flex-wrap: wrap; gap: 6px; }
.qlist button {
  font: inherit;
  background: transparent;
  border: 0;
  border-radius: 50%;
  padding: 2px;
  cursor: pointer;
}
.q-icon {
  display: grid;
  place-items: center;
  width: 30px;
  height: 30px;
  border-radius: 50%;
  border: 1px solid var(--line-strong);
  background: var(--panel);
  font-size: 13px;
  font-weight: 600;
  color: var(--muted);
}
.qlist button:hover .q-icon { border-color: var(--muted); }
.qlist .ok .q-icon { background: var(--ok-soft); border-color: var(--ok); color: var(--ok); }
.qlist .bad .q-icon { background: var(--err-soft); border-color: var(--err); color: var(--err); }
.qlist .is-active .q-icon { outline: 2px solid var(--ink); outline-offset: 1px; color: var(--ink); }

.qcard {
  display: flex;
  flex-direction: column;
  gap: 10px;
  border-top: 1px solid var(--line);
  padding-top: 14px;
}
.q-text { margin: 0; font-size: 15.5px; }
.field { display: flex; flex-direction: column; gap: 4px; font-size: 13px; color: var(--muted); }
.field input {
  font-size: 15px;
  color: var(--ink);
  background: var(--code-bg);
  border: 1px solid var(--line-strong);
  border-radius: var(--radius-sm);
  padding: 8px 10px;
}
.chart-opts { display: flex; flex-wrap: wrap; gap: 8px 16px; font-size: 14px; margin: 8px 0; align-items: center; }
.chart-opts select {
  font: inherit;
  font-size: 14px;
  color: var(--ink);
  background: var(--panel);
  border: 1px solid var(--line-strong);
  border-radius: 6px;
  padding: 4px 6px;
  margin-left: 4px;
}
.chart-opts input { accent-color: var(--accent); }
.q-result { border-radius: var(--radius-sm); padding: 10px 12px; font-size: 14px; }
.q-result.ok { background: var(--ok-soft); border: 1px solid var(--ok); }
.q-result.bad { background: var(--err-soft); border: 1px solid var(--err); }
.q-result .tips, .q-result .problems { margin: 6px 0 0; padding-left: 18px; }

/* ---------- Практикум: таблица ---------- */

.formula-bar {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 8px 10px;
  border-bottom: 1px solid var(--line);
  flex: none;
}
.cell-name {
  min-width: 52px;
  text-align: center;
  font: 600 13.5px var(--mono);
  border: 1px solid var(--line-strong);
  border-radius: 6px;
  padding: 5px 6px;
  background: var(--panel-2);
}
.fx { color: var(--muted); font-style: italic; }
#formula-input {
  flex: 1;
  min-width: 0;
  font-size: 14.5px;
  color: var(--ink);
  background: var(--code-bg);
  border: 1px solid var(--line-strong);
  border-radius: 6px;
  padding: 6px 8px;
}
#formula-input[readonly] { color: var(--muted); background: var(--panel-2); }
.grid-wrap { flex: 1; min-height: 0; overflow: auto; outline: none; }
.grid-wrap:focus-visible { box-shadow: inset 0 0 0 2px var(--accent); }
.grid {
  border-collapse: separate;
  border-spacing: 0;
  table-layout: fixed;
  font-size: 13.5px;
  user-select: none;
}
.grid .rowhead-col { width: 42px; }
.grid th {
  position: sticky;
  background: var(--panel-2);
  color: var(--muted);
  font-weight: 600;
  font-size: 12px;
  border-right: 1px solid var(--line-strong);
  border-bottom: 1px solid var(--line-strong);
  padding: 2px 4px;
  z-index: 1;
}
.grid thead th { top: 0; z-index: 2; }
.grid tbody th { left: 0; text-align: center; }
.grid .corner { left: 0; z-index: 3; }
.grid td {
  height: 24px;
  padding: 1px 6px;
  border-right: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  background: var(--code-bg);
  cursor: cell;
}
.grid td.locked { background: var(--panel-2); }
.grid td.head { font-weight: 600; }
.grid td.num { text-align: right; font-variant-numeric: tabular-nums; }
.grid td.formula { color: var(--code-kw); }
.grid td.err { color: var(--err); font-weight: 600; }
.grid td.sel { outline: 2px solid var(--accent); outline-offset: -2px; }
.grid-note { margin: 0; padding: 6px 12px; border-top: 1px solid var(--line); flex: none; }

/* ---------- Справка ---------- */

.help {
  width: min(760px, calc(100vw - 24px));
  max-height: calc(100vh - 40px);
  padding: 0;
  border: 1px solid var(--line-strong);
  border-radius: var(--radius);
  background: var(--panel);
  color: var(--ink);
  box-shadow: 0 20px 60px rgba(0, 0, 0, 0.3);
}
.help::backdrop { background: rgba(10, 20, 12, 0.45); }
.help-head {
  position: sticky;
  top: 0;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 12px 18px;
  background: var(--panel);
  border-bottom: 1px solid var(--line);
}
.help-body { padding: 4px 18px 20px; }
.help-body h3 { font-size: 15.5px; margin: 18px 0 8px; }
.help-body p { margin: 6px 0; }
.help-body table { border-collapse: collapse; width: 100%; font-size: 14px; }
.help-body td { border-top: 1px solid var(--line); padding: 6px 8px 6px 0; vertical-align: top; }
.help-body td:first-child { width: 48%; }
.help-body ul, .help-body ol { padding-left: 20px; margin: 6px 0; }
.help-body li { margin-bottom: 4px; }

/* ---------- Адаптивность ---------- */

@media (max-width: 900px) {
  .link-other span { display: none; }
}

@media (max-width: 1000px) {
  .layout { display: flex; flex-direction: column; height: auto; flex: none; }
  .side { overflow: visible; }
  .pane-grid { height: 70vh; min-height: 420px; flex: none; }
}

@media (max-width: 700px) {
  .topbar { gap: 8px; padding: 8px 12px; flex-wrap: wrap; }
  .brand-text span, .link-other span, .modes .wide { display: none; }
  .modes { margin-left: 0; order: 10; flex-basis: 100%; }
  .modes button { padding: 5px 10px; flex: 1; }
  .topbar .btn { padding: 6px 8px; }
  .layout { padding: 8px; gap: 8px; }
  .side { padding: 12px; }
  .formula-bar { flex-wrap: wrap; }
  #formula-input { flex-basis: 60%; }
}

/* Внутри платформы репетитора готовое решение не показываем: балл идёт в домашнее задание */
.in-platform #btn-solution, .in-platform #solution, .in-platform #btn-use-solution,
.in-platform #btn-hint, .in-platform #hint { display: none !important; }