/* ──────────────────────────────────────────────────────────────
   Python 练习场 —— 设计 token 沿用「草莓的小站」，保持一家人的观感。
   ────────────────────────────────────────────────────────────── */

:root {
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
    "Hiragino Sans GB", "Microsoft YaHei", "Noto Sans SC", sans-serif;
  --font-mono: "JetBrains Mono", "SF Mono", "Cascadia Code", Consolas,
    "Courier New", monospace;
  --header-h: 56px;
  --sidebar-w: 268px;
  --ease-out: cubic-bezier(0.16, 1, 0.3, 1);
}

:root[data-theme="light"] {
  color-scheme: light;
  --bg: #fdfcfb;
  --bg-soft: #f5f3f1;
  --bg-code: #f6f4f2;
  --bg-elev: #ffffff;
  --text: #1f1d1c;
  --text-secondary: #6f6a66;
  --text-tertiary: #a8a29d;
  --accent: #d9375c;
  --accent-soft: rgba(217, 55, 92, 0.08);
  --border: rgba(31, 29, 28, 0.09);
  --border-strong: rgba(31, 29, 28, 0.16);
  --shadow: 0 1px 2px rgba(31, 29, 28, 0.04), 0 8px 24px rgba(31, 29, 28, 0.05);
  --header-bg: rgba(253, 252, 251, 0.82);
  --ok: #1f8a5f;
  --ok-soft: rgba(31, 138, 95, 0.09);
  --bad: #c8324f;
  --bad-soft: rgba(200, 50, 79, 0.08);
  --warn: #9a6a00;
  --selection: rgba(217, 55, 92, 0.15);
}

:root[data-theme="dark"] {
  color-scheme: dark;
  --bg: #131110;
  --bg-soft: #1c1a18;
  --bg-code: #1d1a18;
  --bg-elev: #201d1b;
  --text: #ece9e6;
  --text-secondary: #9c968f;
  --text-tertiary: #635e59;
  --accent: #ff7d96;
  --accent-soft: rgba(255, 125, 150, 0.1);
  --border: rgba(236, 233, 230, 0.09);
  --border-strong: rgba(236, 233, 230, 0.18);
  --shadow: 0 1px 2px rgba(0, 0, 0, 0.3), 0 8px 24px rgba(0, 0, 0, 0.35);
  --header-bg: rgba(19, 17, 16, 0.82);
  --ok: #5fd39b;
  --ok-soft: rgba(95, 211, 155, 0.1);
  --bad: #ff8099;
  --bad-soft: rgba(255, 128, 153, 0.1);
  --warn: #e0ae53;
  --selection: rgba(255, 125, 150, 0.22);
}

*, *::before, *::after { margin: 0; padding: 0; box-sizing: border-box; }

html, body { height: 100%; }

body {
  font-family: var(--font-sans);
  font-size: 15px;
  line-height: 1.75;
  color: var(--text);
  background: var(--bg);
  transition: background-color 0.4s ease, color 0.4s ease;
  overflow: hidden;
}

::selection { background: var(--selection); }

code, pre, kbd { font-family: var(--font-mono); }

/* ───────── 顶栏 ───────── */

.site-header {
  position: fixed;
  inset: 0 0 auto 0;
  height: var(--header-h);
  display: flex;
  align-items: center;
  gap: 16px;
  padding: 0 16px;
  background: var(--header-bg);
  backdrop-filter: saturate(180%) blur(14px);
  border-bottom: 1px solid var(--border);
  z-index: 40;
}

.brand { display: flex; align-items: center; gap: 8px; flex-shrink: 0; }
.brand-icon { font-size: 1.15rem; }
.brand-name { font-weight: 700; letter-spacing: 0.01em; }

.progress { display: flex; align-items: center; gap: 10px; margin-left: auto; }

.progress-track {
  width: 150px;
  height: 5px;
  border-radius: 99px;
  background: var(--bg-soft);
  overflow: hidden;
  border: 1px solid var(--border);
}

.progress-fill {
  height: 100%;
  width: 0;
  background: var(--accent);
  border-radius: 99px;
  transition: width 0.45s var(--ease-out);
}

.progress-text {
  font-family: var(--font-mono);
  font-size: 0.76rem;
  color: var(--text-secondary);
  min-width: 56px;
}

.header-right { display: flex; align-items: center; gap: 12px; }

.engine {
  font-size: 0.74rem;
  font-family: var(--font-mono);
  padding: 3px 9px;
  border-radius: 99px;
  border: 1px solid var(--border);
  white-space: nowrap;
  transition: opacity 0.6s ease;
}
.engine.booting { color: var(--warn); background: var(--bg-soft); }
.engine.ready { color: var(--ok); background: var(--ok-soft); border-color: transparent; }
.engine.ready.fade { opacity: 0; pointer-events: none; }
.engine.error { color: var(--bad); background: var(--bad-soft); }

.icon-btn {
  display: grid;
  place-items: center;
  width: 34px;
  height: 34px;
  border: 1px solid var(--border);
  border-radius: 9px;
  background: transparent;
  color: var(--text-secondary);
  cursor: pointer;
  transition: all 0.2s ease;
  flex-shrink: 0;
}
.icon-btn:hover { color: var(--accent); border-color: var(--border-strong); }
.icon-btn svg { width: 17px; height: 17px; }

.menu-toggle { display: none; }

:root[data-theme="light"] .icon-sun { display: none; }
:root[data-theme="dark"] .icon-moon { display: none; }

/* ───────── 布局 ───────── */

.shell {
  display: flex;
  height: 100%;
  padding-top: var(--header-h);
}

.sidebar {
  width: var(--sidebar-w);
  flex-shrink: 0;
  border-right: 1px solid var(--border);
  background: var(--bg-soft);
  overflow-y: auto;
  display: flex;
  flex-direction: column;
}

.sidebar-top {
  padding: 14px 18px 8px;
  font-size: 0.72rem;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--text-tertiary);
  font-family: var(--font-mono);
}

.chapters { flex: 1; padding-bottom: 8px; }

.ch-group { margin-bottom: 4px; }

.ch-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 9px 18px 5px;
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--text-secondary);
}

.ch-count {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  color: var(--text-tertiary);
}
.ch-count.all { color: var(--ok); }

.ch-list { display: flex; flex-direction: column; }

.prob-item {
  display: flex;
  align-items: center;
  gap: 8px;
  width: 100%;
  padding: 6px 18px;
  border: none;
  background: transparent;
  color: var(--text-secondary);
  font-family: inherit;
  font-size: 0.84rem;
  text-align: left;
  cursor: pointer;
  border-left: 2px solid transparent;
  transition: background 0.15s ease, color 0.15s ease;
}
.prob-item:hover { background: var(--accent-soft); color: var(--text); }
.prob-item.active {
  background: var(--accent-soft);
  color: var(--accent);
  border-left-color: var(--accent);
  font-weight: 600;
}
.prob-item.solved .prob-mark { color: var(--ok); }

.prob-mark {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  width: 12px;
  flex-shrink: 0;
  color: var(--text-tertiary);
}
.prob-no {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  color: var(--text-tertiary);
  width: 13px;
  flex-shrink: 0;
}
.prob-name { overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }

.sidebar-foot {
  padding: 12px 18px 16px;
  font-size: 0.72rem;
  line-height: 1.6;
  color: var(--text-tertiary);
  border-top: 1px solid var(--border);
}

.backdrop {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.4);
  z-index: 25;
}

/* ───────── 主区 ───────── */

.main {
  flex: 1;
  overflow-y: auto;
  padding: 24px clamp(16px, 4vw, 44px) 56px;
  max-width: 920px;
}

.prob-meta { display: flex; align-items: center; gap: 10px; }

.crumb {
  font-family: var(--font-mono);
  font-size: 0.74rem;
  color: var(--text-tertiary);
}

.level {
  font-size: 0.7rem;
  padding: 1px 8px;
  border-radius: 99px;
  border: 1px solid var(--border);
  color: var(--text-secondary);
}
.level-1 { color: var(--ok); background: var(--ok-soft); border-color: transparent; }
.level-2 { color: var(--warn); background: var(--bg-soft); border-color: transparent; }
.level-3 { color: var(--bad); background: var(--bad-soft); border-color: transparent; }

.prob-title {
  margin-top: 4px;
  font-size: clamp(1.3rem, 3vw, 1.6rem);
  font-weight: 800;
  line-height: 1.4;
}

.prob-desc {
  margin: 14px 0 20px;
  color: var(--text);
}
.prob-desc code {
  background: var(--bg-code);
  border: 1px solid var(--border);
  border-radius: 5px;
  padding: 1px 5px;
  font-size: 0.85em;
}
.prob-desc pre {
  background: var(--bg-code);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 12px 16px;
  margin: 10px 0;
  font-size: 0.84rem;
  line-height: 1.65;
  overflow-x: auto;
  white-space: pre;
}
.prob-desc b { font-weight: 700; }

/* ───────── 编辑器 ───────── */

.editor-wrap {
  border: 1px solid var(--border);
  border-radius: 12px;
  overflow: hidden;
  background: var(--bg-code);
}

.editor-bar, .output-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding: 7px 14px;
  background: var(--bg-soft);
  border-bottom: 1px solid var(--border);
  font-size: 0.74rem;
  font-family: var(--font-mono);
  color: var(--text-tertiary);
}

.editor-tip { font-size: 0.68rem; }

kbd {
  font-size: 0.92em;
  padding: 0 4px;
  border: 1px solid var(--border-strong);
  border-bottom-width: 2px;
  border-radius: 4px;
  background: var(--bg-elev);
  color: var(--text-secondary);
}

.editor-host { display: flex; flex-direction: column; }

/* CodeMirror 高度跟着内容走，但留一个最小写作区。
   min-height 必须加在 .CodeMirror-scroll 上而不是 .CodeMirror 上，
   否则内容比容器矮时它会误以为需要滚动，冒出一条多余的横向滚动条。 */
.CodeMirror {
  height: auto;
  font-family: var(--font-mono);
  font-size: 13.5px;
  line-height: 1.65;
  background: var(--bg-code);
  color: var(--text);
}
.CodeMirror-scroll { min-height: 184px; }

/* 已经开了 lineWrapping，横向永远不需要滚动 */
.CodeMirror-hscrollbar { display: none !important; }
.CodeMirror-gutters {
  background: var(--bg-code);
  border-right: 1px solid var(--border);
}
.CodeMirror-linenumber { color: var(--text-tertiary); }
.CodeMirror-cursor { border-left-color: var(--accent); }
.CodeMirror-selected { background: var(--selection) !important; }
.CodeMirror-matchingbracket {
  color: var(--accent) !important;
  font-weight: 700;
  text-decoration: none !important;
}
.cm-s-pp-light .cm-keyword, .cm-s-pp-dark .cm-keyword { color: #c0398c; }
.cm-s-pp-light .cm-string, .cm-s-pp-dark .cm-string { color: #1f8a5f; }
.cm-s-pp-light .cm-number, .cm-s-pp-dark .cm-number { color: #c26a1b; }
.cm-s-pp-light .cm-comment, .cm-s-pp-dark .cm-comment { color: var(--text-tertiary); font-style: italic; }
.cm-s-pp-light .cm-def, .cm-s-pp-dark .cm-def { color: #2d6fd6; }
.cm-s-pp-light .cm-builtin, .cm-s-pp-dark .cm-builtin { color: #7a5cc4; }
.cm-s-pp-light .cm-operator, .cm-s-pp-dark .cm-operator { color: var(--text-secondary); }
.cm-s-pp-dark .cm-keyword { color: #ff92c2; }
.cm-s-pp-dark .cm-string { color: #7ddcaa; }
.cm-s-pp-dark .cm-number { color: #e8a862; }
.cm-s-pp-dark .cm-def { color: #7fb5ff; }
.cm-s-pp-dark .cm-builtin { color: #b89bff; }

/* ───────── 按钮 ───────── */

.actions {
  display: flex;
  align-items: center;
  gap: 8px;
  margin: 14px 0;
  flex-wrap: wrap;
}
.spacer { flex: 1; }

.btn {
  font-family: inherit;
  font-size: 0.85rem;
  padding: 7px 15px;
  border: 1px solid var(--border-strong);
  border-radius: 9px;
  background: var(--bg-elev);
  color: var(--text);
  cursor: pointer;
  transition: all 0.18s ease;
  white-space: nowrap;
}
.btn:hover:not(:disabled) { border-color: var(--accent); color: var(--accent); }
.btn:disabled { opacity: 0.45; cursor: not-allowed; }

.btn-primary {
  background: var(--accent);
  border-color: var(--accent);
  color: #fff;
  font-weight: 600;
}
.btn-primary:hover:not(:disabled) { filter: brightness(1.08); color: #fff; }

.btn-ghost {
  background: transparent;
  border-color: var(--border);
  color: var(--text-secondary);
  font-size: 0.82rem;
  padding: 6px 12px;
}

/* ───────── 提示 / 输出 ───────── */

.hint-box {
  margin: 0 0 14px;
  padding: 12px 16px;
  border-left: 3px solid var(--warn);
  border-radius: 0 10px 10px 0;
  background: var(--bg-soft);
  font-family: var(--font-sans);
  font-size: 0.88rem;
  line-height: 1.75;
  white-space: pre-wrap;
  color: var(--text-secondary);
}

.output-wrap {
  border: 1px solid var(--border);
  border-radius: 12px;
  overflow: hidden;
}

.output {
  padding: 14px 16px;
  min-height: 72px;
  font-size: 0.88rem;
  background: var(--bg-code);
  transition: background 0.3s ease;
}
.output.pass { background: var(--ok-soft); }
.output.fail { background: var(--bad-soft); }

.muted { color: var(--text-tertiary); font-size: 0.85rem; }

.output pre {
  font-size: 0.82rem;
  line-height: 1.6;
  white-space: pre-wrap;
  word-break: break-word;
  margin: 0;
}

.stdout {
  padding: 9px 12px;
  border-radius: 8px;
  background: var(--bg-elev);
  border: 1px solid var(--border);
  margin-bottom: 10px !important;
}

.ok-title, .err-title {
  font-weight: 700;
  font-size: 0.95rem;
  margin-bottom: 9px;
}
.ok-title { color: var(--ok); }
.err-title { color: var(--bad); }

.err { color: var(--bad); }

.next-tip {
  margin-top: 10px;
  font-size: 0.78rem;
  color: var(--text-tertiary);
}

.checks { display: flex; flex-direction: column; gap: 8px; }

.check {
  border: 1px solid var(--border);
  border-radius: 9px;
  background: var(--bg-elev);
  overflow: hidden;
}
.check.pass { border-left: 3px solid var(--ok); }
.check.fail { border-left: 3px solid var(--bad); }

.check-head {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 7px 12px;
  font-size: 0.82rem;
}
.check-head code {
  font-size: 0.86em;
  color: var(--text);
  word-break: break-all;
}
.check-mark { font-family: var(--font-mono); flex-shrink: 0; }
.check.pass .check-mark { color: var(--ok); }
.check.fail .check-mark { color: var(--bad); }

.check-body {
  display: grid;
  gap: 8px;
  padding: 0 12px 10px;
  border-top: 1px dashed var(--border);
  padding-top: 9px;
}
@media (min-width: 640px) {
  .check-body { grid-template-columns: 1fr 1fr; }
}

.tag {
  display: block;
  font-size: 0.7rem;
  font-family: var(--font-mono);
  color: var(--text-tertiary);
  margin-bottom: 3px;
}
.check-body pre {
  padding: 7px 10px;
  border-radius: 7px;
  background: var(--bg-code);
  border: 1px solid var(--border);
  font-size: 0.8rem;
}

/* ───────── 翻页 / 页脚 ───────── */

.pager {
  display: flex;
  justify-content: space-between;
  gap: 10px;
  margin-top: 22px;
}

.site-foot {
  margin-top: 30px;
  padding-top: 16px;
  border-top: 1px solid var(--border);
  font-size: 0.76rem;
  color: var(--text-tertiary);
  text-align: center;
}

/* ───────── 窄屏 ───────── */

@media (max-width: 860px) {
  .menu-toggle { display: grid; }
  .progress-track { width: 84px; }
  .engine { display: none; }

  .sidebar {
    position: fixed;
    top: var(--header-h);
    bottom: 0;
    left: 0;
    z-index: 30;
    transform: translateX(-100%);
    transition: transform 0.3s var(--ease-out);
    box-shadow: var(--shadow);
  }
  .sidebar.open { transform: translateX(0); }

  .main { padding: 18px 16px 48px; }
  .brand-name { display: none; }
}

@media (max-width: 460px) {
  .actions .btn { flex: 1; }
  .spacer { display: none; }
  .editor-tip { display: none; }
}