:root {
  --primary: #1e3a8a;
  --primary-dark: #172d6e;
  --accent: #fbbf24;
  --bg: #f1f5f9;
  --card: #ffffff;
  --text: #0f172a;
  --muted: #64748b;
  --ok: #16a34a;
  --bad: #dc2626;
  --half: #d97706;
  --border: #e2e8f0;
  --radius: 12px;
}
* { box-sizing: border-box; margin: 0; padding: 0; }
html { -webkit-text-size-adjust: 100%; }
body {
  font-family: "PingFang SC", "Microsoft YaHei", "Noto Sans SC", system-ui, sans-serif;
  background: var(--bg); color: var(--text); font-size: 15px; line-height: 1.65;
}
a { color: var(--primary); text-decoration: none; }
button { font-family: inherit; }

/* ---------- login ---------- */
.login-wrap {
  min-height: 100vh; display: flex; align-items: center; justify-content: center;
  background: linear-gradient(135deg, #1e3a8a 0%, #312e81 55%, #1e293b 100%);
  padding: 20px;
}
.login-card {
  background: var(--card); width: 100%; max-width: 420px; border-radius: 18px;
  padding: 40px 36px; box-shadow: 0 25px 60px rgba(0,0,0,.35);
}
.login-logo { text-align: center; margin-bottom: 8px; }
.login-logo .badge {
  display: inline-flex; width: 64px; height: 64px; border-radius: 16px;
  background: var(--primary); color: var(--accent); font-size: 34px; font-weight: 700;
  align-items: center; justify-content: center; font-family: serif;
}
.login-card h1 { font-size: 19px; text-align: center; color: var(--primary); }
.login-card .sub { text-align: center; color: var(--muted); font-size: 13px; margin: 6px 0 26px; }
.field { margin-bottom: 16px; }
.field label { display: block; font-size: 13px; color: var(--muted); margin-bottom: 6px; }
.field input {
  width: 100%; padding: 11px 14px; border: 1.5px solid var(--border); border-radius: 10px;
  font-size: 15px; outline: none; transition: border .15s;
}
.field input:focus { border-color: var(--primary); }
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 6px;
  background: var(--primary); color: #fff; border: none; cursor: pointer;
  padding: 11px 22px; border-radius: 10px; font-size: 15px; transition: .15s;
}
.btn:hover { background: var(--primary-dark); }
.btn.full { width: 100%; }
.btn.ghost { background: #fff; color: var(--primary); border: 1.5px solid var(--primary); }
.btn.ghost:hover { background: #eef2ff; }
.btn.small { padding: 6px 14px; font-size: 13px; border-radius: 8px; }
.btn.danger { background: var(--bad); }
.btn:disabled { opacity: .55; cursor: not-allowed; }
.login-tip { margin-top: 18px; font-size: 12.5px; color: var(--muted); text-align: center; line-height: 1.8; }
.err-msg { color: var(--bad); font-size: 13px; min-height: 18px; margin-bottom: 8px; text-align: center; }

/* ---------- layout ---------- */
.topbar {
  background: linear-gradient(90deg, var(--primary), #312e81); color: #fff;
  padding: 0 22px; display: flex; align-items: center; gap: 14px;
  position: sticky; top: 0; z-index: 50; height: 56px; box-shadow: 0 2px 10px rgba(30,58,138,.35);
}
.topbar .brand { display: flex; align-items: center; gap: 10px; font-weight: 700; font-size: 16px; white-space: nowrap; }
.topbar .brand .logo {
  width: 34px; height: 34px; border-radius: 9px; background: rgba(255,255,255,.12);
  color: var(--accent); display: inline-flex; align-items: center; justify-content: center;
  font-size: 19px; font-family: serif;
}
.nav { display: flex; gap: 2px; flex: 1; overflow-x: auto; scrollbar-width: none; }
.nav::-webkit-scrollbar { display: none; }
.nav a {
  color: #dbe3ff; padding: 8px 13px; border-radius: 8px; font-size: 14px; white-space: nowrap;
}
.nav a:hover { background: rgba(255,255,255,.1); color: #fff; }
.nav a.active { background: rgba(255,255,255,.16); color: #fff; font-weight: 600; }
.topbar .who { font-size: 13px; color: #c7d2fe; white-space: nowrap; }
.topbar .who b { color: #fff; }
.topbar .who a { color: #fca5a5; margin-left: 8px; cursor: pointer; }

.container { max-width: 1080px; margin: 22px auto; padding: 0 18px 60px; }
.page-title { font-size: 21px; font-weight: 700; margin-bottom: 4px; color: var(--primary); }
.page-sub { color: var(--muted); font-size: 13.5px; margin-bottom: 20px; }

.card {
  background: var(--card); border-radius: var(--radius); padding: 20px 22px;
  box-shadow: 0 1px 4px rgba(15,23,42,.06); border: 1px solid var(--border);
  margin-bottom: 16px;
}
.grid { display: grid; gap: 14px; }
.grid.c2 { grid-template-columns: 1fr 1fr; }
.grid.c3 { grid-template-columns: repeat(3, 1fr); }
.grid.c4 { grid-template-columns: repeat(4, 1fr); }
@media (max-width: 760px) {
  .grid.c2, .grid.c3, .grid.c4 { grid-template-columns: 1fr 1fr; }
}
@media (max-width: 480px) {
  .grid.c2, .grid.c3, .grid.c4 { grid-template-columns: 1fr; }
  .topbar { padding: 0 12px; gap: 8px; }
  .topbar .brand span:not(.logo) { display: none; }
  .topbar .who { font-size: 12px; }
  .container { padding-left: 12px; padding-right: 12px; }
  .card { padding: 16px; }
  .palette .pi { width: 29px; height: 29px; }
}

.stat { text-align: center; padding: 16px 8px; border-radius: var(--radius); background: var(--card); border: 1px solid var(--border); }
.stat .num { font-size: 28px; font-weight: 800; color: var(--primary); }
.stat .lab { font-size: 12.5px; color: var(--muted); margin-top: 2px; }

.home-cards { display: grid; grid-template-columns: repeat(auto-fit, minmax(240px, 1fr)); gap: 16px; margin-bottom: 20px; }
.mode-card {
  background: var(--card); border: 1px solid var(--border); border-radius: 14px; padding: 20px;
  cursor: pointer; transition: .15s; position: relative; overflow: hidden;
}
.mode-card:hover { transform: translateY(-3px); box-shadow: 0 10px 24px rgba(30,58,138,.12); border-color: #c7d2fe; }
.mode-card .tag {
  display: inline-block; font-size: 12px; padding: 2px 10px; border-radius: 999px;
  background: #eef2ff; color: var(--primary); font-weight: 600; margin-bottom: 10px;
}
.mode-card .tag.gold { background: #fef3c7; color: #92400e; }
.mode-card h3 { font-size: 17px; margin-bottom: 6px; }
.mode-card p { font-size: 13px; color: var(--muted); }
.mode-card .go { margin-top: 12px; font-size: 13px; color: var(--primary); font-weight: 600; }

/* ---------- practice ---------- */
.filters { display: flex; flex-wrap: wrap; gap: 10px; align-items: flex-end; margin-bottom: 16px; }
.filters .f { flex: 1; min-width: 160px; }
.filters label { font-size: 12.5px; color: var(--muted); display: block; margin-bottom: 4px; }
select {
  width: 100%; padding: 9px 12px; border: 1.5px solid var(--border); border-radius: 9px;
  font-size: 14px; background: #fff; outline: none; font-family: inherit;
}
.qmeta { display: flex; justify-content: space-between; align-items: center; flex-wrap: wrap; gap: 8px; margin-bottom: 12px; }
.qmeta .chips { display: flex; gap: 8px; flex-wrap: wrap; }
.chip { font-size: 12px; background: #eef2ff; color: var(--primary); padding: 3px 10px; border-radius: 999px; font-weight: 600; }
.chip.gray { background: #f1f5f9; color: var(--muted); }
.chip.good { background: #dcfce7; color: var(--ok); }
.chip.warn { background: #fee2e2; color: var(--bad); }
.stem { font-size: 16px; font-weight: 600; margin-bottom: 16px; white-space: pre-wrap; word-break: break-word; }
.opts { display: flex; flex-direction: column; gap: 10px; }
.opt {
  display: flex; gap: 10px; padding: 12px 14px; border: 1.5px solid var(--border);
  border-radius: 10px; cursor: pointer; transition: .12s; align-items: flex-start;
}
.opt:hover { border-color: #a5b4fc; background: #f8faff; }
.opt.sel { border-color: var(--primary); background: #eef2ff; }
.opt.right { border-color: var(--ok); background: #f0fdf4; }
.opt.wrong { border-color: var(--bad); background: #fef2f2; }
.opt .letter {
  flex: none; width: 26px; height: 26px; border-radius: 50%; background: #f1f5f9;
  display: flex; align-items: center; justify-content: center; font-weight: 700; font-size: 13.5px;
  color: var(--muted); margin-top: 1px;
}
.opt.sel .letter { background: var(--primary); color: #fff; }
.opt.right .letter { background: var(--ok); color: #fff; }
.opt.wrong .letter { background: var(--bad); color: #fff; }
.opt .txt { flex: 1; word-break: break-word; }

.blank-input {
  width: 100%; max-width: 420px; padding: 11px 14px; border: 1.5px solid var(--border);
  border-radius: 10px; font-size: 15px; outline: none;
}
.blank-input:focus { border-color: var(--primary); }

.feedback { margin-top: 14px; padding: 12px 16px; border-radius: 10px; font-size: 14.5px; }
.feedback.ok { background: #f0fdf4; color: var(--ok); border: 1px solid #bbf7d0; }
.feedback.bad { background: #fef2f2; color: var(--bad); border: 1px solid #fecaca; }
.feedback b { font-weight: 700; }

.qnav { display: flex; justify-content: space-between; align-items: center; gap: 10px; margin-top: 18px; flex-wrap: wrap; }
.qprogress { font-size: 13px; color: var(--muted); }
.bar { height: 6px; background: #e2e8f0; border-radius: 999px; overflow: hidden; margin: 10px 0 4px; }
.bar i { display: block; height: 100%; background: linear-gradient(90deg, var(--primary), #6366f1); border-radius: 999px; transition: width .25s; }
.source-note { margin-top: 12px; font-size: 12.5px; color: var(--muted); }
.final-score-card { border-left: 4px solid var(--accent); }
.final-score { color: var(--primary); font-size: 42px; font-weight: 900; line-height: 1.15; margin: 4px 0; }
.final-score small { color: var(--muted); font-size: 18px; font-weight: 600; }

/* ---------- exam ---------- */
.exam-header {
  position: sticky; top: 56px; z-index: 40; background: #fff; border: 1px solid var(--border);
  border-radius: var(--radius); padding: 12px 18px; display: flex; align-items: center;
  justify-content: space-between; gap: 12px; flex-wrap: wrap; margin-bottom: 16px;
  box-shadow: 0 2px 8px rgba(15,23,42,.05);
}
.timer { font-size: 20px; font-weight: 800; color: var(--primary); font-variant-numeric: tabular-nums; }
.timer.warn { color: var(--bad); animation: blink 1s infinite; }
@keyframes blink { 50% { opacity: .45; } }
.palette { display: flex; flex-wrap: wrap; gap: 6px; margin: 8px 0; }
.palette .pi {
  width: 32px; height: 32px; border-radius: 8px; border: 1.5px solid var(--border);
  display: flex; align-items: center; justify-content: center; font-size: 12.5px; cursor: pointer;
  background: #fff; color: var(--muted); font-weight: 600;
}
.palette .pi.done { background: #dbeafe; border-color: #93c5fd; color: var(--primary); }
.palette .pi.cur { border-color: var(--primary); box-shadow: 0 0 0 2px #bfdbfe; }
.exam-q { border-left: 4px solid var(--primary); }
.exam-actions { display: flex; gap: 10px; flex-wrap: wrap; margin-top: 16px; }
.blank-exam-row { display: flex; gap: 10px; align-items: center; flex-wrap: wrap; }
.blank-exam-row .blank-input { flex: 1; min-width: 220px; max-width: 560px; }

.result-hero { text-align: center; padding: 28px 20px; }
.result-hero .score { font-size: 52px; font-weight: 900; color: var(--primary); line-height: 1.1; }
.result-hero .score small { font-size: 20px; color: var(--muted); font-weight: 600; }
.result-hero .sub { color: var(--muted); margin-top: 4px; }

.review-item { border: 1px solid var(--border); border-radius: 10px; padding: 14px 16px; margin-bottom: 12px; }
.review-item .rv-head { display: flex; gap: 8px; align-items: center; margin-bottom: 8px; flex-wrap: wrap; }

/* ---------- practical ---------- */
.ch-card { border: 1px solid var(--border); border-radius: 12px; padding: 18px 20px; margin-bottom: 14px; background: var(--card); }
.ch-head { display: flex; justify-content: space-between; align-items: flex-start; gap: 10px; flex-wrap: wrap; }
.ch-head h3 { font-size: 16.5px; }
.ch-desc { white-space: pre-wrap; word-break: break-word; color: #334155; margin: 10px 0; font-size: 14.5px; }
.ch-desc img, .sol img { max-width: 100%; border-radius: 8px; border: 1px solid var(--border); margin: 8px 0; display: block; }
.flag-row { display: flex; gap: 8px; flex-wrap: wrap; margin-top: 10px; }
.flag-row input {
  flex: 1; min-width: 220px; padding: 10px 13px; border: 1.5px solid var(--border);
  border-radius: 9px; font-size: 14px; font-family: ui-monospace, Consolas, monospace; outline: none;
}
.flag-row input:focus { border-color: var(--primary); }
.sol { margin-top: 14px; border-top: 1px dashed var(--border); padding-top: 12px; }
.sol h4 { font-size: 14px; color: var(--primary); margin: 10px 0 6px; }
.sol pre {
  background: #0f172a; color: #e2e8f0; padding: 14px; border-radius: 10px; overflow-x: auto;
  font-size: 12.5px; line-height: 1.6; font-family: ui-monospace, "SF Mono", Consolas, monospace;
  white-space: pre-wrap; word-break: break-all;
}
.ch-solved { color: var(--ok); font-weight: 700; font-size: 13px; }

/* ---------- table ---------- */
table.tbl { width: 100%; border-collapse: collapse; font-size: 14px; }
.tbl th, .tbl td { padding: 10px 12px; border-bottom: 1px solid var(--border); text-align: left; }
.tbl th { color: var(--muted); font-weight: 600; font-size: 13px; background: #f8fafc; }
.tbl tr:last-child td { border-bottom: none; }

.empty { text-align: center; color: var(--muted); padding: 40px 0; font-size: 14px; }
.muted { color: var(--muted); font-size: 13px; }
.mt8 { margin-top: 8px; } .mt16 { margin-top: 16px; }
.spin {
  width: 26px; height: 26px; border: 3px solid #e2e8f0; border-top-color: var(--primary);
  border-radius: 50%; animation: sp .7s linear infinite; margin: 40px auto;
}
@keyframes sp { to { transform: rotate(360deg); } }
.toast {
  position: fixed; bottom: 28px; left: 50%; transform: translateX(-50%);
  background: #0f172a; color: #fff; padding: 10px 22px; border-radius: 999px; font-size: 14px;
  z-index: 99; opacity: 0; transition: .25s; pointer-events: none; max-width: 90vw;
}
.toast.show { opacity: .95; }