:root {
  --primary: #3b5bdb;
  --primary-dark: #2f4bc0;
  --bg: #f4f6fb;
  --card: #ffffff;
  --text: #1f2430;
  --muted: #6b7280;
  --border: #e6e9f0;
  --green: #1f9d55;
  --green-bg: #e7f7ee;
  --red: #e03131;
  --red-bg: #fdeaea;
  --radius: 14px;
  --shadow: 0 6px 20px rgba(31, 36, 48, .07);
}

* { box-sizing: border-box; -webkit-tap-highlight-color: transparent; }
html, body { margin: 0; padding: 0; }
body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.7;
  font-size: 16px;
  padding-bottom: env(safe-area-inset-bottom);
}
a { color: inherit; text-decoration: none; }

/* 顶栏 */
.topbar {
  position: sticky; top: 0; z-index: 20;
  background: rgba(255,255,255,.92);
  backdrop-filter: saturate(180%) blur(8px);
  border-bottom: 1px solid var(--border);
}
.topbar-inner {
  max-width: 920px; margin: 0 auto; padding: 12px 16px;
  display: flex; align-items: center; justify-content: space-between;
}
.brand { font-weight: 700; font-size: 18px; color: var(--primary); }
.topnav { display: flex; gap: 18px; }
.topnav a { color: var(--muted); font-size: 15px; padding: 4px 2px; }
.topnav a:hover { color: var(--primary); }

/* 主体 */
.app { max-width: 920px; margin: 0 auto; padding: 18px 16px 90px; }
.loading { text-align: center; color: var(--muted); padding: 60px 0; }

/* 卡片通用 */
.card {
  background: var(--card); border: 1px solid var(--border);
  border-radius: var(--radius); box-shadow: var(--shadow);
  padding: 18px; margin-bottom: 16px;
}

/* 首页 */
.hero { text-align: center; padding: 26px 18px; }
.hero h1 { margin: 0 0 6px; font-size: 22px; }
.hero .sub { color: var(--muted); font-size: 14px; }
.meta-row { display: flex; flex-wrap: wrap; gap: 8px; justify-content: center; margin-top: 14px; }
.meta-chip { background: #eef1fb; color: var(--primary-dark); font-size: 13px; padding: 4px 12px; border-radius: 999px; }

.section-title { font-size: 15px; color: var(--muted); margin: 4px 2px 12px; font-weight: 600; }

/* 模式选择 */
.mode-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 12px; }
.mode-card {
  background: var(--card); border: 1px solid var(--border); border-radius: var(--radius);
  padding: 16px 12px; text-align: center; cursor: pointer; transition: .15s;
  box-shadow: var(--shadow);
}
.mode-card:hover { transform: translateY(-2px); border-color: var(--primary); }
.mode-card .ic { font-size: 26px; }
.mode-card .t { font-weight: 700; margin-top: 6px; }
.mode-card .d { font-size: 12px; color: var(--muted); margin-top: 4px; }

/* 题型筛选 chips */
.chips { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 6px; }
.chip {
  border: 1px solid var(--border); background: #fff; color: var(--text);
  padding: 8px 14px; border-radius: 999px; font-size: 14px; cursor: pointer;
}
.chip.active { background: var(--primary); color: #fff; border-color: var(--primary); }
.chip .cnt { opacity: .7; font-size: 12px; margin-left: 4px; }

.quick-row { display: flex; gap: 12px; margin-top: 4px; }
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 6px;
  background: var(--primary); color: #fff; border: none; border-radius: 10px;
  padding: 12px 16px; font-size: 15px; cursor: pointer; font-weight: 600;
}
.btn:hover { background: var(--primary-dark); }
.btn.ghost { background: #fff; color: var(--primary); border: 1px solid var(--primary); }
.btn.block { width: 100%; }
.btn:disabled { opacity: .5; cursor: not-allowed; }

/* 刷题页 */
.prac-head {
  display: flex; align-items: center; justify-content: space-between;
  gap: 10px; margin-bottom: 12px; flex-wrap: wrap;
}
.prac-head .left { font-size: 14px; color: var(--muted); }
.prac-head .right { font-size: 14px; color: var(--muted); }
.timer { color: var(--primary); font-weight: 700; }
.progress { height: 8px; background: #e9edf6; border-radius: 999px; overflow: hidden; margin-bottom: 14px; }
.progress > i { display: block; height: 100%; background: var(--primary); border-radius: 999px; transition: width .2s; }

.q-tag { display: inline-block; background: #eef1fb; color: var(--primary-dark); font-size: 13px; padding: 3px 10px; border-radius: 8px; margin-bottom: 10px; }
.q-no { font-weight: 700; margin-right: 8px; }
.material {
  background: #fafbff; border-left: 3px solid var(--primary);
  padding: 10px 14px; border-radius: 8px; margin-bottom: 12px; font-size: 14px; color: #374151;
}
.stem { font-size: 17px; font-weight: 600; margin: 6px 0 14px; }
.q-img { max-width: 100%; border-radius: 10px; margin: 8px 0; cursor: zoom-in; display: block; background: #f3f4f8; }

.options { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; }
.opt {
  display: flex; align-items: flex-start; gap: 10px;
  border: 1.5px solid var(--border); border-radius: 12px; padding: 12px 14px;
  cursor: pointer; background: #fff; transition: .12s; min-height: 52px;
}
.opt:hover { border-color: var(--primary); }
.opt .key {
  flex: 0 0 26px; height: 26px; border-radius: 50%; background: #eef1fb;
  color: var(--primary-dark); font-weight: 700; display: flex; align-items: center; justify-content: center; font-size: 14px;
}
.opt .body { flex: 1; }
.opt .body img { max-width: 100%; border-radius: 8px; margin-top: 4px; }
.opt.sel { border-color: var(--primary); background: #f0f4ff; }
.opt.correct { border-color: var(--green); background: var(--green-bg); }
.opt.correct .key { background: var(--green); color: #fff; }
.opt.wrong { border-color: var(--red); background: var(--red-bg); }
.opt.wrong .key { background: var(--red); color: #fff; }
.opt.disabled { cursor: default; }

.answer-box { margin-top: 16px; }
.answer-line { font-size: 16px; font-weight: 700; }
.answer-line .ans { color: var(--primary); }
.verdict { font-weight: 700; margin-left: 10px; }
.verdict.ok { color: var(--green); }
.verdict.no { color: var(--red); }
.explain-box {
  margin-top: 12px; background: #fafbff; border: 1px solid var(--border);
  border-radius: 10px; padding: 12px 14px; font-size: 15px;
}
.explain-box .h { color: var(--primary); font-weight: 700; margin-bottom: 4px; }
.explain-empty { color: var(--muted); font-size: 13px; }

/* 主观题作答框 */
.essay-write { margin-top: 14px; }
.essay-write .h, .essay-mine .h { font-weight: 700; color: var(--ink); margin-bottom: 6px; }
.essay-input {
  width: 100%; min-height: 150px; box-sizing: border-box;
  border: 1px solid var(--border); border-radius: 10px; padding: 12px 14px;
  font: inherit; font-size: 15px; line-height: 1.7; color: var(--ink);
  background: #fff; resize: vertical; outline: none;
}
.essay-input:focus { border-color: var(--primary); box-shadow: 0 0 0 3px rgba(29,111,204,.12); }
.essay-mine { margin-top: 14px; }
.essay-text {
  white-space: pre-wrap; word-break: break-word; line-height: 1.8;
  background: #f6f8fb; border: 1px solid var(--border); border-radius: 10px;
  padding: 12px 14px; font-size: 15px; color: var(--ink);
}
.btn.ghost.mini, .mini {
  padding: 2px 10px; font-size: 12px; border-radius: 12px; margin-left: 8px;
  vertical-align: middle; cursor: pointer;
}

.prac-foot { display: flex; gap: 12px; margin-top: 16px; }
.prac-foot .btn { flex: 1; }

/* 结果汇总 */
.summary { text-align: center; padding: 20px 10px; }
.summary .score { font-size: 48px; font-weight: 800; color: var(--primary); }
.summary .big { font-size: 20px; margin: 8px 0; }

/* 错题本 / 统计 列表 */
.list-item {
  display: flex; align-items: center; gap: 12px; cursor: pointer;
  border-bottom: 1px solid var(--border); padding: 12px 4px;
}
.list-item:last-child { border-bottom: none; }
.list-item .no { flex: 0 0 34px; color: var(--muted); font-weight: 700; }
.list-item .txt { flex: 1; font-size: 15px; overflow: hidden; text-overflow: ellipsis; display: -webkit-box; -webkit-line-clamp: 2; -webkit-box-orient: vertical; }
.list-item .tag { flex: 0 0 auto; font-size: 12px; color: var(--primary-dark); background: #eef1fb; padding: 2px 8px; border-radius: 6px; }
.list-item .x { color: var(--red); font-size: 18px; }

.stat-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 12px; text-align: center; }
.stat-box { background: var(--card); border: 1px solid var(--border); border-radius: var(--radius); padding: 16px 8px; box-shadow: var(--shadow); }
.stat-box .n { font-size: 26px; font-weight: 800; color: var(--primary); }
.stat-box .l { font-size: 13px; color: var(--muted); margin-top: 2px; }

.empty { text-align: center; color: var(--muted); padding: 50px 0; }
.empty .big { font-size: 40px; }

/* 搜索 / 年份筛选 / 多选合并 */
.filter-row { margin-bottom: 10px; }
.search-input {
  width: 100%; padding: 10px 12px; font-size: 15px;
  border: 1px solid var(--border); border-radius: 10px; outline: none;
  font-family: inherit; background: #fff; color: var(--text);
}
.search-input:focus { border-color: var(--primary); }
.list-item .check {
  flex: 0 0 30px; text-align: center; font-size: 19px;
  color: var(--primary); cursor: pointer; user-select: none;
}
.list-item .check.on { color: var(--primary-dark); }
.merge-bar {
  display: flex; align-items: center; gap: 10px; flex-wrap: wrap;
  margin-top: 12px; padding-top: 12px; border-top: 1px solid var(--border);
}
.src-note { font-size: 12px; color: var(--muted); margin-top: 10px; line-height: 1.6; }

/* 图片放大 */
.lightbox {
  position: fixed; inset: 0; z-index: 50; background: rgba(0,0,0,.85);
  align-items: center; justify-content: center; padding: 20px;
  display: none;                 /* 默认隐藏，不依赖 hidden 属性 */
}
.lightbox[hidden] { display: none; }  /* 兼容语义属性（须在 .show 之前） */
.lightbox.show { display: flex; }     /* 放最后：特异性相同则 .show 优先，保证能打开 */
.lightbox img { max-width: 100%; max-height: 100%; border-radius: 8px; }

/* 底部导航（移动端） */
.bottomnav {
  display: none;
  position: fixed; left: 0; right: 0; bottom: 0; z-index: 30;
  background: #fff; border-top: 1px solid var(--border);
  padding: 6px 0 calc(6px + env(safe-area-inset-bottom));
  grid-template-columns: repeat(4, 1fr);
}
.bottomnav a { display: flex; flex-direction: column; align-items: center; font-size: 12px; color: var(--muted); gap: 2px; }
.bottomnav a span { font-size: 11px; }

.site-footer { max-width: 920px; margin: 0 auto; padding: 18px 16px 100px; text-align: center; color: var(--muted); font-size: 12px; }

/* 桌面端优化 */
@media (min-width: 768px) {
  .app { padding-top: 24px; }
  .hero { padding: 34px 18px; }
  .hero h1 { font-size: 26px; }
  .stem { font-size: 18px; }
  .options { gap: 14px; }
  .opt { padding: 14px 16px; }
  .site-footer { padding-bottom: 30px; }
}
/* 移动端：隐藏顶栏导航、显示底部导航、选项单列 */
@media (max-width: 640px) {
  .topnav { display: none; }
  .bottomnav { display: grid; }
  .options { grid-template-columns: 1fr; }
  .mode-grid { grid-template-columns: 1fr; }
  .quick-row { flex-direction: column; }
  .app { padding-bottom: 86px; }
}

/* 验证码 */
.cap-row { display: flex; gap: 10px; align-items: stretch; }
.cap-img {
  width: 132px; height: 46px; flex: none; border: 1px solid var(--border);
  border-radius: 10px; overflow: hidden; cursor: pointer; background: #f1f3f5;
  display: flex; align-items: center; justify-content: center;
}
.cap-img svg { display: block; width: 132px; height: 46px; }
.cap-load { font-size: 12px; color: var(--muted); }
.link { color: var(--primary); cursor: pointer; font-size: 13px; }

/* 密保码展示框 */
.recovery-box {
  margin: 10px 0; padding: 12px 14px; font-size: 18px; font-weight: 700; letter-spacing: 2px;
  font-family: "SFMono-Regular", Consolas, monospace; text-align: center;
  background: #fff9db; border: 1px dashed #f08c00; border-radius: 10px; color: #a15c00;
  user-select: all;
}

/* ===== 打印 / 导出 PDF ===== */
#printArea { display: none; }
@media print {
  @page { margin: 14mm; }
  body > *:not(#printArea) { display: none !important; }
  #printArea { display: block !important; }
  .print-page { font-family: "PingFang SC", "Microsoft YaHei", sans-serif; color: #111; }
  .print-page h1 { font-size: 20px; margin: 0 0 4px; }
  .print-meta { font-size: 12px; color: #666; margin-bottom: 14px; border-bottom: 1px solid #ccc; padding-bottom: 8px; }
  .print-item { display: flex; gap: 8px; padding: 10px 0; border-bottom: 1px dotted #ccc; break-inside: avoid; }
  .pi-no { font-weight: 700; flex: none; width: 22px; }
  .pi-body { flex: 1; }
  .pi-src { font-size: 12px; color: #888; margin-bottom: 3px; }
  .pi-stem { font-size: 14px; line-height: 1.6; white-space: pre-wrap; }
  .pi-ans { font-size: 13px; margin-top: 6px; }
}

/* 账号 / 云同步 */
.field { margin-bottom: 12px; }
.field .lb { font-size: 13px; color: var(--muted); margin-bottom: 6px; }
.field input {
  width: 100%; box-sizing: border-box; padding: 11px 12px; font-size: 15px;
  border: 1px solid var(--border); border-radius: 10px; background: #fff; color: var(--text);
}
.field input:focus { outline: none; border-color: var(--primary); }
.acct-head { display: flex; align-items: center; gap: 12px; }
.acct-avatar {
  width: 46px; height: 46px; border-radius: 50%; background: var(--primary);
  color: #fff; display: flex; align-items: center; justify-content: center; font-size: 20px; flex: none;
}
.acct-name { font-size: 17px; font-weight: 600; }
.sync-state { font-size: 13px; color: var(--muted); margin-top: 8px; line-height: 1.7; }
.sync-state .dot { display: inline-block; width: 8px; height: 8px; border-radius: 50%; margin-right: 6px; }
.sync-state .ok { background: #37b24d; }
.sync-state .warn { background: #f59f00; }
.sync-state .off { background: #adb5bd; }

/* ---------- 会员开通弹窗 ---------- */
.modal-mask {
  position: fixed; inset: 0; background: rgba(15,23,42,.55);
  display: none; align-items: center; justify-content: center; z-index: 200;
  padding: 16px;
}
.modal-box {
  position: relative; background: #fff; color: var(--text); width: 100%; max-width: 360px;
  border-radius: 16px; padding: 22px 20px; box-shadow: 0 18px 50px rgba(0,0,0,.25);
}
.modal-close {
  position: absolute; top: 10px; right: 12px; border: none; background: transparent;
  font-size: 24px; line-height: 1; color: var(--muted); cursor: pointer;
}
.modal-title { font-size: 18px; font-weight: 700; margin-bottom: 6px; }
.member-pay { margin-top: 12px; }
.qr-wrap { display: flex; justify-content: center; padding: 8px 0; }
.qr-wrap #memberQR { width: 200px; height: 200px; padding: 8px; border: 1px solid var(--border); border-radius: 10px; }
.member-badge {
  display: inline-block; margin-left: 6px; font-size: 12px; color: #fff; background: #f59f00;
  padding: 1px 8px; border-radius: 999px; vertical-align: middle;
}
.sync-state .err { color: #e03131; }