/* 学生页和后台共用的样式。手机优先，电脑上居中一栏。 */
:root {
  --brand: #1f5eff;
  --brand-deep: #1446c9;
  --brand-soft: #eaf1ff;
  --ink: #0f1e3d;
  --ink-2: #44506a;
  --muted: #7a869e;
  --line: #e2e8f2;
  --bg: #f3f6fb;
  --ok: #138a52;
  --ok-soft: #e6f6ee;
  --bad: #d93a4a;
  --bad-soft: #fdecee;
  --warn: #e8890c;
  --radius: 14px;
}
* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font: 16px/1.6 -apple-system, "PingFang SC", "Microsoft YaHei", "Noto Sans SC", sans-serif;
}
button, input, select, textarea { font: inherit; color: inherit; }
h1, h2 { margin: 0; line-height: 1.3; }
h1 { font-size: 20px; }
h2 { font-size: 17px; }
p { margin: 6px 0; }
.app { max-width: 640px; margin: 0 auto; padding: 0 0 40px; }
.loading { padding: 40px; text-align: center; color: var(--muted); }
.muted { color: var(--muted); }
.small { font-size: 13px; }
.err { color: var(--bad); min-height: 0; }
.ok { color: var(--ok); }
.empty { text-align: center; color: var(--muted); padding: 12px; }

/* 顶上 */
.hero {
  padding: 36px 20px 64px;
  background: var(--brand);
  color: #fff;
  text-align: center;
}
.hero h1 { font-size: 26px; letter-spacing: 1px; }
.hero .when { opacity: 0.88; margin-top: 10px; font-size: 14px; }
.bar {
  position: sticky; top: 0; z-index: 5;
  display: flex; align-items: center; gap: 10px;
  padding: 12px 16px;
  background: #fff;
  border-bottom: 1px solid var(--line);
}
.bar h1 { flex: 1; font-size: 17px; }
.back, .link {
  border: 0; background: none; padding: 4px 2px; cursor: pointer;
  color: var(--brand); font-weight: 600;
}
.link.right { margin-left: auto; }

/* 卡片 */
.card {
  margin: 12px 14px; padding: 16px;
  background: #fff; border: 1px solid var(--line); border-radius: var(--radius);
}
.card h2 { margin-bottom: 6px; }
.row { display: flex; align-items: center; justify-content: space-between; gap: 10px; }
.groups { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; margin: -40px 14px 0; }
.group {
  display: flex; flex-direction: column; align-items: center; gap: 2px;
  padding: 16px 8px; background: #fff; border-radius: var(--radius); border: 1px solid var(--line);
  box-shadow: 0 6px 18px rgba(15, 30, 61, 0.08);
}
.group b { font-size: 18px; color: var(--brand-deep); }
.group span { color: var(--ink-2); font-size: 14px; }
.group.primary b { color: #0f8a6a; }
.rules p { color: var(--ink-2); font-size: 15px; }
.redeem .code-input {
  width: 100%; margin-top: 10px; padding: 14px 16px;
  border: 2px solid var(--line); border-radius: 12px;
  font-size: 22px; letter-spacing: 4px; text-align: center; text-transform: uppercase;
}
.redeem .code-input:focus, .field input:focus, .admin input:focus, .admin select:focus, .admin textarea:focus { outline: none; border-color: var(--brand); }

/* 按钮 */
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 6px;
  padding: 10px 16px; border: 1px solid var(--line); border-radius: 12px;
  background: #fff; cursor: pointer; font-weight: 600;
}
.btn:disabled { opacity: 0.55; cursor: not-allowed; }
.btn.primary { background: var(--brand); border-color: var(--brand); color: #fff; }
.btn.primary:not(:disabled):active { background: var(--brand-deep); }
.btn.danger { color: var(--bad); }
.btn.big { width: 100%; padding: 14px 16px; font-size: 17px; margin-top: 10px; }
.btn.small { padding: 6px 12px; font-size: 14px; }
.actions { margin: 4px 14px; display: flex; flex-direction: column; }

/* 表单 */
.field { display: block; margin-top: 12px; }
.field span { display: block; font-size: 14px; color: var(--ink-2); margin-bottom: 4px; }
.field i { color: var(--bad); font-style: normal; }
.field input { width: 100%; padding: 12px 14px; border: 1px solid var(--line); border-radius: 10px; }

/* 首页 */
.who { display: flex; align-items: center; gap: 14px; }
.avatar {
  flex: none; width: 52px; height: 52px; border-radius: 50%;
  display: grid; place-items: center; background: var(--brand-soft); color: var(--brand); font-size: 22px; font-weight: 700;
}
.who b { font-size: 18px; margin-right: 8px; }
.tag { display: inline-block; padding: 1px 10px; border-radius: 999px; font-size: 13px; background: var(--brand-soft); color: var(--brand-deep); }
.tag.primary { background: #e4f7f1; color: #0f8a6a; }
.score { display: grid; grid-template-columns: 1fr 1fr; gap: 8px; text-align: center; }
.score > div { padding: 8px; background: var(--bg); border-radius: 10px; }
.score small { display: block; color: var(--muted); }
.score strong { font-size: 30px; color: var(--brand-deep); }
.score em { font-style: normal; color: var(--muted); }
.score p { grid-column: 1 / -1; font-size: 13px; }
.history { list-style: none; margin: 0; padding: 0; }
.history li { display: flex; flex-wrap: wrap; align-items: center; gap: 4px 12px; padding: 8px 0; border-top: 1px solid var(--line); }
.history li:first-child { border-top: 0; }
.history .link { margin-left: auto; }

/* 答题 */
.exam-bar { justify-content: space-between; }
.progress { font-weight: 700; }
.timer { font-variant-numeric: tabular-nums; font-weight: 700; color: var(--brand-deep); padding: 4px 10px; border-radius: 999px; background: var(--brand-soft); }
.timer.hurry { color: #fff; background: var(--bad); }
.qhead { display: flex; align-items: center; gap: 8px; flex-wrap: wrap; }
.type { padding: 2px 10px; border-radius: 6px; font-size: 13px; font-weight: 700; background: var(--brand-soft); color: var(--brand-deep); }
.type.multi { background: #fff3e2; color: #b56200; }
.stem { font-size: 17px; font-weight: 600; margin: 12px 0; white-space: pre-wrap; }
.options { display: flex; flex-direction: column; gap: 10px; }
.opt {
  display: flex; align-items: flex-start; gap: 12px; width: 100%; text-align: left;
  padding: 12px 14px; border: 1.5px solid var(--line); border-radius: 12px; background: #fff; cursor: pointer;
}
.opt .letter {
  flex: none; width: 28px; height: 28px; border-radius: 50%; display: grid; place-items: center;
  border: 1.5px solid var(--line); font-weight: 700; font-size: 14px;
}
.opt.on { border-color: var(--brand); background: var(--brand-soft); }
.opt.on .letter { background: var(--brand); border-color: var(--brand); color: #fff; }
.opt.ans { border-color: var(--ok); background: var(--ok-soft); }
.opt.ans .letter { background: var(--ok); border-color: var(--ok); color: #fff; }
.opt.miss { border-color: var(--bad); background: var(--bad-soft); }
.opt.miss .letter { background: var(--bad); border-color: var(--bad); color: #fff; }
.opt:disabled { cursor: default; color: inherit; opacity: 1; }
.qnav { display: grid; grid-template-columns: 1fr 1fr 1fr; gap: 8px; margin-top: 16px; }
.feedback { margin-top: 12px; }
.analysis { padding: 10px 12px; border-radius: 10px; background: var(--bg); color: var(--ink-2); font-size: 14px; }
.sheet { margin: 0 14px; padding: 14px; background: #fff; border: 1px solid var(--line); border-radius: var(--radius); }
.sheet-head { display: flex; justify-content: space-between; margin-bottom: 10px; }
.sheet-grid { display: grid; grid-template-columns: repeat(8, 1fr); gap: 6px; }
.cell { padding: 6px 0; border: 1px solid var(--line); border-radius: 8px; background: #fff; cursor: pointer; font-variant-numeric: tabular-nums; }
.cell.done { background: var(--brand-soft); border-color: #b8ccff; color: var(--brand-deep); }
.cell.cur { outline: 2px solid var(--brand); }

/* 结果 */
.result { text-align: center; }
.big-score { font-size: 54px; color: var(--brand-deep); line-height: 1.1; }
.reviews { list-style: none; margin: 8px 0 0; padding: 0; }
.review { padding: 12px 0; border-top: 1px solid var(--line); }
.review:first-child { border-top: 0; }
.review .stem { font-size: 16px; margin: 6px 0; }
.review .mark { margin-left: auto; font-weight: 700; }
.review.right .mark { color: var(--ok); }
.review.wrong .mark { color: var(--bad); }
.opts-view { list-style: none; margin: 4px 0; padding: 0; font-size: 15px; }
.opts-view li { padding: 3px 8px; border-radius: 6px; }
.opts-view li.mine { background: var(--bad-soft); }
.opts-view li.ans { background: var(--ok-soft); color: var(--ok); font-weight: 600; }
.check { font-size: 14px; color: var(--ink-2); }

.toast {
  position: fixed; left: 50%; bottom: 40px; transform: translate(-50%, 20px);
  max-width: 86vw; padding: 10px 18px; border-radius: 999px;
  background: rgba(15, 30, 61, 0.92); color: #fff; font-size: 15px;
  opacity: 0; pointer-events: none; transition: opacity 0.2s, transform 0.2s; z-index: 50;
}
.toast.on { opacity: 1; transform: translate(-50%, 0); }
.toast.bad { background: var(--bad); }

@media (min-width: 700px) {
  .app { padding-top: 16px; }
  .hero { border-radius: var(--radius); margin: 0 14px; }
  .bar { border-radius: var(--radius); margin: 0 14px; border: 1px solid var(--line); }
}

/* ───────── 后台 ───────── */
.admin { max-width: 1180px; }
.admin .tabs { display: flex; gap: 4px; flex-wrap: wrap; margin: 12px 14px 0; }
.admin .tabs button { border: 0; background: none; padding: 8px 14px; border-radius: 10px; cursor: pointer; font-weight: 600; color: var(--ink-2); }
.admin .tabs button.on { background: var(--brand); color: #fff; }
.admin form.card > input[type=password] { width: 100%; margin-top: 8px; }
.admin input, .admin select, .admin textarea { padding: 8px 10px; border: 1px solid var(--line); border-radius: 8px; background: #fff; }
.admin textarea { width: 100%; min-height: 80px; resize: vertical; }
.admin .tools { display: flex; flex-wrap: wrap; gap: 8px; align-items: center; margin-bottom: 12px; }
.admin .grow { flex: 1; }
.admin table { width: 100%; border-collapse: collapse; font-size: 14px; }
.admin th, .admin td { padding: 8px 6px; border-bottom: 1px solid var(--line); text-align: left; vertical-align: top; }
.admin th { color: var(--muted); font-weight: 600; white-space: nowrap; }
.admin td.stem-cell { max-width: 420px; }
.admin .table-wrap { overflow-x: auto; }
.admin .stats { display: grid; grid-template-columns: repeat(auto-fit, minmax(260px, 1fr)); gap: 12px; }
.admin .stat-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 8px; margin-top: 8px; }
.admin .stat-grid div { padding: 8px 10px; background: var(--bg); border-radius: 10px; }
.admin .stat-grid b { display: block; font-size: 22px; color: var(--brand-deep); }
.admin .warn { color: var(--warn); }
.admin .form-grid { display: grid; grid-template-columns: 120px 1fr; gap: 10px 12px; align-items: center; }
.admin .form-grid label { color: var(--ink-2); font-size: 14px; }
.admin .opt-row { display: flex; gap: 8px; align-items: center; margin-bottom: 6px; }
.admin .opt-row input[type=text] { flex: 1; }
.admin dialog { border: 0; border-radius: var(--radius); padding: 18px; width: min(680px, 94vw); box-shadow: 0 20px 60px rgba(0, 0, 0, 0.25); }
.admin dialog::backdrop { background: rgba(15, 30, 61, 0.4); }
.admin .codes-out { width: 100%; min-height: 160px; font-family: Consolas, monospace; }
.admin .pill { display: inline-block; padding: 0 8px; border-radius: 999px; font-size: 12px; background: var(--bg); color: var(--ink-2); }
.admin .pill.used { background: var(--ok-soft); color: var(--ok); }
.admin .pill.off { background: var(--bad-soft); color: var(--bad); }