.topbar{display:flex;align-items:center;gap:10px;padding:calc(10px + var(--safe-t)) 14px 6px;max-width:480px;margin:0 auto}
.icon-btn{width:40px;height:40px;border-radius:50%;display:grid;place-items:center;flex:none;background:var(--card);box-shadow:var(--shadow-1)}
.icon-btn:active{transform:scale(.92)}
.icon-btn svg{width:20px;height:20px;fill:none;stroke:currentColor;stroke-width:2;stroke-linecap:round;stroke-linejoin:round}
.topbar-title{flex:1;min-width:0;line-height:1.2}
.topbar-title b{display:block;font-size:18px}
.topbar-title span{font-size:13px;color:var(--muted)}
.timer{font-variant-numeric:tabular-nums;font-weight:700;font-size:15px;background:var(--ink);color:#FFF6EC;border-radius:999px;padding:6px 12px;letter-spacing:.04em}

.screen{padding-bottom:calc(20px + var(--safe-b));animation:rise .35s cubic-bezier(.2,.8,.2,1)}
@keyframes rise{from{opacity:0;transform:translateY(10px)}to{opacity:1;transform:none}}
.m,.q-text i,.mi{font-family:var(--font-math)}
.q-text i,.mi,.m i i{font-style:italic}

/* 开始页 */
.intro-card{overflow:hidden;margin-top:8px}
.paper-art{position:relative;height:150px;background:#FBF6EC;
  background-image:linear-gradient(rgba(70,110,160,.13) 1px,transparent 1px),linear-gradient(90deg,rgba(70,110,160,.13) 1px,transparent 1px);
  background-size:20px 20px;border-bottom:1px solid var(--line)}
.sc{position:absolute;font-family:var(--font-math);color:#2C3E5C;white-space:nowrap}
.sc.a{left:20px;top:26px;font-size:26px;transform:rotate(-5deg)}
.sc.b{right:30px;top:20px;font-size:30px;transform:rotate(6deg);color:var(--accent)}
.sc.c{left:44%;top:70px;font-size:24px;transform:rotate(-2deg);color:#4A5D7E}
.sc.d{left:24px;bottom:16px;font-size:20px;color:#4A5D7E}
.intro-body{padding:18px 18px 20px}
.intro-body h1{font-size:27px;line-height:1.3;margin:8px 0 10px;font-weight:800}
.intro-body p{margin:0;color:var(--ink-2)}
.intro-body p b{color:var(--accent)}
.topics{display:flex;flex-wrap:wrap;gap:6px;margin-top:14px}
.topics span{font-size:13px;padding:3px 10px;border-radius:999px;background:#F3ECE1;color:var(--ink-2)}
.btn.big{width:100%;height:54px;font-size:17px;margin-top:18px}
.small-note{text-align:center;color:var(--muted);font-size:13px;margin:10px 0 0}

/* 答题页 */
.prog{display:grid;grid-template-columns:repeat(5,1fr);gap:6px;margin:8px 0 14px}
.prog i{height:6px;border-radius:6px;background:#E6DCCD;transition:background .3s}
.prog i.done{background:var(--ink)}
.prog i.cur{background:var(--accent)}
.q-card{padding:18px 18px 20px}
.q-meta{display:flex;justify-content:space-between;align-items:baseline;margin-bottom:10px}
.q-meta span{font-size:14px;font-weight:700;color:var(--accent);letter-spacing:.04em}
.q-meta em{font-style:normal;font-size:13px;color:var(--muted)}
.q-text{font-size:18px;line-height:1.75;font-weight:500}
.q-text b{color:var(--accent)}
.q-text .m{font-size:21px;white-space:nowrap;display:inline-block;margin:6px 0}
.fr{display:inline-flex;flex-direction:column;vertical-align:middle;text-align:center;font-size:.92em;line-height:1.25;margin:0 2px}
.fr>i{font-style:normal;padding:0 4px}
.fr>i:first-child{border-bottom:1.5px solid currentColor}
.opts{display:grid;gap:10px;margin-top:14px}
.opt{
  display:flex;align-items:center;gap:12px;width:100%;min-height:58px;padding:10px 16px;border-radius:18px;text-align:left;
  background:var(--card);box-shadow:var(--shadow-1);border:1.5px solid transparent;font-size:17px;
  transition:transform .12s,border-color .2s,background .2s;
}
.opt:active{transform:scale(.98)}
.opt b{display:grid;place-items:center;width:32px;height:32px;border-radius:10px;background:#F3ECE1;font-size:15px;flex:none;transition:background .2s,color .2s}
.opt span{font-family:var(--font-math)}
.opt.pick{border-color:var(--ink);background:#FFF}
.opt.pick b{background:var(--ink);color:#fff}
.opts.locked .opt{pointer-events:none}

/* 结果页 */
.res-card{padding:24px 18px 18px;text-align:center;margin-top:8px;position:relative;overflow:hidden}
.res-card::before{content:"";position:absolute;left:0;right:0;top:0;height:120px;
  background:linear-gradient(rgba(70,110,160,.10) 1px,transparent 1px),linear-gradient(90deg,rgba(70,110,160,.10) 1px,transparent 1px);background-size:20px 20px;
  -webkit-mask-image:linear-gradient(#000,transparent);mask-image:linear-gradient(#000,transparent)}
.ring-wrap{position:relative;width:148px;height:148px;margin:0 auto}
.ring{width:100%;height:100%;transform:rotate(-90deg)}
.ring circle{fill:none;stroke-width:10;stroke-linecap:round}
.ring-bg{stroke:#EDE4D7}
.ring-fg{stroke:var(--accent);stroke-dasharray:326.7;stroke-dashoffset:326.7;transition:stroke-dashoffset 1.1s cubic-bezier(.2,.8,.2,1)}
.ring-num{position:absolute;inset:0;display:flex;align-items:baseline;justify-content:center;padding-top:44px}
.ring-num b{font-size:50px;line-height:1;font-variant-numeric:tabular-nums;letter-spacing:-.03em}
.ring-num span{font-size:16px;color:var(--muted);margin-left:2px}
.grade{display:inline-block;margin-top:10px;font-size:13px;font-weight:800;letter-spacing:.1em;color:var(--accent);border:1.5px solid var(--accent);border-radius:8px;padding:1px 10px}
.res-card h2{margin:8px 0 2px;font-size:25px}
.title-sub{margin:0;color:var(--ink-2)}
.res-stats{display:grid;grid-template-columns:repeat(3,1fr);margin-top:18px;border-top:1px solid var(--line);padding-top:14px}
.res-stats div+div{border-left:1px solid var(--line)}
.res-stats b{display:block;font-size:20px;font-variant-numeric:tabular-nums}
.res-stats span{font-size:13px;color:var(--muted)}
.res-actions .btn.big{margin-top:16px}
.row2{display:flex;gap:10px;margin-top:10px}
.row2 .btn{flex:1;padding:0 8px;font-size:15px}
.sec-h{font-size:17px;font-weight:700;margin:26px 2px 10px}
.rv{padding:16px;margin-bottom:12px}
.rv-head{display:flex;align-items:center;gap:8px;margin-bottom:6px}
.rv-mark{width:24px;height:24px;border-radius:50%;display:grid;place-items:center;color:#fff;font-size:14px;font-weight:800;flex:none}
.rv-mark.ok{background:var(--good)}
.rv-mark.no{background:var(--bad)}
.rv-head b{font-size:15px}
.rv-head em{font-style:normal;font-size:13px;color:var(--muted);margin-left:auto}
.rv-q{font-size:15px;line-height:1.7;color:var(--ink-2)}
.rv-q .m{font-size:17px;white-space:nowrap;display:inline-block}
.rv-ans{display:flex;flex-wrap:wrap;gap:6px;margin:10px 0}
.rv-ans span{font-size:13px;padding:3px 10px;border-radius:999px;background:#F3ECE1}
.rv-ans .r{background:#E2EFE6;color:#2C6346;font-weight:700}
.rv-ans .w{background:var(--accent-soft);color:#8A3A1C}
.rv-why{font-size:13px;color:#8A3A1C;margin:-2px 0 8px}
.rv-exp{font-size:14px;line-height:1.75;color:var(--ink-2);background:#F7F1E7;border-radius:12px;padding:10px 12px}
.rv-exp b{color:var(--ink)}

.field{display:block;width:100%;height:48px;border-radius:14px;border:1px solid var(--line);background:#fff;padding:0 14px;font-size:16px;margin:4px 0 14px;outline:none}
.field:focus{border-color:var(--accent)}
.sheet .row{display:flex;gap:10px}
.sheet .row .btn{flex:1}
.fig{display:block;width:100%;max-width:320px;height:auto;margin:10px auto 0;font-family:var(--font)}
.rv-q .fig{max-width:260px}