/* style.css — 现代简洁风 */
:root {
  --bg: #0f1419;
  --bg-elev: #1a2332;
  --bg-elev2: #232f42;
  --border: #2f3d55;
  --text: #e8edf5;
  --text-dim: #94a3b8;
  --accent: #3b82f6;
  --accent-2: #10b981;
  --warn: #f59e0b;
  --danger: #ef4444;
  --code-bg: #0d1117;
  --radius: 10px;
  --shadow: 0 4px 20px rgba(0,0,0,0.3);
}
* { box-sizing: border-box; }
html, body {
  margin: 0; padding: 0;
  font-family: -apple-system, "Segoe UI", "Microsoft YaHei", sans-serif;
  background: var(--bg); color: var(--text);
  height: 100%;
}

/* ===== Top bar ===== */
.topbar {
  display: flex; align-items: center; justify-content: space-between;
  padding: 14px 28px;
  background: linear-gradient(180deg, var(--bg-elev), var(--bg));
  border-bottom: 1px solid var(--border);
  position: sticky; top: 0; z-index: 10;
}
.brand { font-size: 18px; font-weight: 600; }
.clock, .timer {
  font-family: "SF Mono", Consolas, monospace;
  font-size: 16px; padding: 6px 14px;
  background: var(--bg-elev2); border-radius: 8px;
  color: var(--accent-2);
}

/* ===== 首页布局 ===== */
#app { padding: 24px 28px; max-width: 1200px; margin: 0 auto; }
.hero {
  display: grid; grid-template-columns: repeat(4, 1fr); gap: 16px;
  margin-bottom: 24px;
}
.stat-card {
  background: var(--bg-elev);
  padding: 20px; border-radius: var(--radius);
  border: 1px solid var(--border);
}
.stat-card.big { grid-column: span 1.5; }
.stat-num { font-size: 28px; font-weight: 700; color: var(--accent); }
.stat-num span { font-size: 16px; color: var(--text-dim); }
.stat-label { color: var(--text-dim); margin-top: 6px; font-size: 13px; }
.progress { margin-top: 10px; height: 8px; background: var(--bg-elev2); border-radius: 4px; overflow: hidden; }
.progress .bar { height: 100%; background: linear-gradient(90deg, var(--accent), var(--accent-2)); transition: width 0.5s; }

.grid-2 { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; margin-bottom: 24px; }
.card {
  background: var(--bg-elev); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 20px; margin-bottom: 16px;
}
.card h3 { margin: 0 0 16px 0; font-size: 15px; color: var(--text); }
.type-list .type-row { display: flex; justify-content: space-between; padding: 6px 0; border-bottom: 1px dashed var(--border); }
.type-list .type-row:last-child { border-bottom: 0; }
.muted { color: var(--text-dim); }

/* ===== Buttons ===== */
.btn-row { display: flex; gap: 8px; flex-wrap: wrap; }
.btn {
  padding: 8px 18px; border-radius: 8px;
  border: 1px solid var(--border);
  background: var(--bg-elev2); color: var(--text);
  cursor: pointer; font-size: 14px;
  transition: all 0.15s;
}
.btn:hover:not(:disabled) { background: var(--border); }
.btn:disabled { opacity: 0.4; cursor: not-allowed; }
.btn.primary { background: var(--accent); border-color: var(--accent); }
.btn.primary:hover:not(:disabled) { background: #2563eb; }
.btn.danger { background: var(--danger); border-color: var(--danger); }
.btn.ghost { background: transparent; border-color: var(--border); }

/* ===== 徽章 ===== */
.badge-warn { background: var(--warn); color: #000; padding: 2px 8px; border-radius: 10px; font-size: 12px; margin-left: 6px; }
.badge-ok { background: var(--accent-2); color: #000; padding: 2px 8px; border-radius: 10px; font-size: 12px; margin-left: 6px; }

/* ===== 表格 ===== */
.table { width: 100%; border-collapse: collapse; font-size: 13px; }
.table th, .table td { padding: 10px 12px; text-align: left; border-bottom: 1px solid var(--border); }
.table th { background: var(--bg-elev2); color: var(--text-dim); font-weight: 500; }
.due-row:hover { background: var(--bg-elev2); cursor: pointer; }
.q-title { max-width: 400px; overflow: hidden; text-overflow: ellipsis; }

/* ===== 章节网格 ===== */
.chapter-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(180px, 1fr)); gap: 12px; }
.chapter-card {
  background: var(--bg-elev); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 16px; cursor: pointer;
  transition: transform 0.15s, border-color 0.15s;
}
.chapter-card:hover { transform: translateY(-2px); border-color: var(--accent); }
.ch-id { font-family: monospace; color: var(--accent-2); font-size: 12px; margin-bottom: 4px; }
.ch-name { font-weight: 600; font-size: 14px; margin-bottom: 6px; }
.ch-count { color: var(--text-dim); font-size: 12px; }

/* ===== 练习模式 ===== */
.practice-wrap { max-width: 900px; margin: 0 auto; }
.progress-bar {
  position: relative; height: 6px; background: var(--bg-elev2);
  border-radius: 3px; margin-bottom: 20px;
}
.progress-bar .fill { height: 100%; background: var(--accent); border-radius: 3px; transition: width 0.3s; }
.progress-bar span {
  position: absolute; right: 0; top: -22px; font-size: 12px; color: var(--text-dim);
}
.question-card {
  background: var(--bg-elev); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 24px; margin-bottom: 16px;
}
.q-title { font-size: 16px; font-weight: 500; line-height: 1.7; margin-bottom: 12px; }
.q-meta { display: flex; gap: 14px; font-size: 12px; color: var(--text-dim); margin-bottom: 20px; }
.opts { display: flex; flex-direction: column; gap: 8px; }
.opt {
  display: flex; align-items: flex-start; gap: 10px;
  padding: 12px 16px; border: 1px solid var(--border);
  border-radius: 8px; cursor: pointer; transition: all 0.15s;
}
.opt:hover { border-color: var(--accent); background: var(--bg-elev2); }
.opt input { margin-top: 3px; accent-color: var(--accent); }
.opt-letter { font-weight: 600; color: var(--accent); font-family: monospace; }
.opt-text { line-height: 1.6; white-space: pre-wrap; }
.opt.correct { border-color: var(--accent-2); background: rgba(16,185,129,0.1); }
.opt.wrong { border-color: var(--danger); background: rgba(239,68,68,0.1); }
.opt.missed { border-color: var(--warn); background: rgba(245,158,11,0.1); }
.nav-row { display: flex; justify-content: space-between; gap: 12px; }

/* ===== 操作题 ===== */
.op-body h4 { margin: 0 0 10px 0; color: var(--text-dim); font-size: 13px; font-weight: 500; }
textarea, #code-editor {
  width: 100%; min-height: 260px;
  background: var(--code-bg); color: #e6edf3;
  border: 1px solid var(--border); border-radius: 8px;
  padding: 14px; font-family: "SF Mono", Consolas, "Cascadia Code", monospace;
  font-size: 14px; line-height: 1.6;
  resize: vertical; outline: none;
}
textarea:focus, #code-editor:focus { border-color: var(--accent); }
.fill-input { min-height: 120px; }
.run-output {
  background: var(--code-bg); color: #7dd3fc;
  border: 1px solid var(--border); border-radius: 8px;
  padding: 12px; margin-top: 12px; font-size: 13px;
  white-space: pre-wrap; max-height: 300px; overflow: auto;
}
.explain { margin-top: 16px; background: var(--bg-elev2); padding: 14px; border-radius: 8px; }
.explain summary { cursor: pointer; font-weight: 600; color: var(--accent); }

/* ===== 结果 ===== */
.result-card {
  background: var(--bg-elev); border: 1px solid var(--accent);
  border-radius: var(--radius); padding: 40px; text-align: center;
}
.result-card h2 { font-size: 36px; margin: 0 0 10px 0; color: var(--accent); }

/* ===== 题目中的图片 ===== */
.q-img {
  display: block;
  max-width: 100%;
  max-height: 420px;
  margin: 12px 0;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: var(--bg-elev2);
  padding: 4px;
  cursor: zoom-in;
  transition: border-color 0.15s, transform 0.15s;
}
.q-img:hover { border-color: var(--accent); transform: translateY(-1px); }
.q-img[src=""], .q-img:not([src]) { display: none; }

/* ===== 答题反馈条 ===== */
.feedback {
  margin-top: 16px; padding: 12px 16px;
  border-radius: 8px; font-size: 14px;
  display: flex; align-items: center; gap: 8px;
}
.feedback.ok {
  background: rgba(16,185,129,0.12);
  border: 1px solid rgba(16,185,129,0.4);
  color: var(--accent-2);
}
.feedback.bad {
  background: rgba(239,68,68,0.12);
  border: 1px solid rgba(239,68,68,0.5);
  color: var(--danger);
}
.feedback strong { font-family: monospace; letter-spacing: 2px; }

/* ===== 图片查看器（原生 <dialog>） ===== */
dialog.q-img-viewer {
  border: none; padding: 0; background: rgba(0,0,0,0.85);
  width: 92vw; height: 92vh; max-width: 1400px;
  color: #fff; border-radius: 12px; overflow: hidden;
  box-shadow: 0 20px 80px rgba(0,0,0,0.6);
}
dialog.q-img-viewer::backdrop { background: rgba(0,0,0,0.75); backdrop-filter: blur(4px); }
dialog.q-img-viewer form {
  position: relative; width: 100%; height: 100%;
  display: flex; align-items: center; justify-content: center;
}
dialog.q-img-viewer img {
  max-width: 96%; max-height: 92%; object-fit: contain;
  border-radius: 6px; background: #fff;
}
dialog.q-img-viewer .close-btn {
  position: absolute; top: 16px; right: 16px;
  width: 40px; height: 40px; border-radius: 50%;
  border: 1px solid rgba(255,255,255,0.4);
  background: rgba(255,255,255,0.1); color: #fff;
  font-size: 18px; cursor: pointer;
  transition: background 0.15s, transform 0.15s;
}
dialog.q-img-viewer .close-btn:hover { background: rgba(255,255,255,0.3); transform: scale(1.1); }

/* ===== 响应式 ===== */
@media (max-width: 900px) {
  .hero { grid-template-columns: repeat(2, 1fr); }
  .grid-2 { grid-template-columns: 1fr; }
  #app { padding: 16px; }
}
@media (max-width: 600px) {
  .hero { grid-template-columns: 1fr; }
}