/* 828 数电训练 — "示波器暗夜" 主题 v2 */
:root{
  --bg0:#070b11; --bg1:#0b1017;
  --card:#111a24; --card2:#16222f; --card3:#1c2b3a;
  --line:rgba(148,183,215,.14); --line2:rgba(148,183,215,.26);
  --tx:#e9f1f8; --tx2:#8fa3b8; --tx3:#5c7088;
  --acc:#38c6f4; --acc2:#5b8cff; --cyan-grad:linear-gradient(135deg,#38c6f4,#5b8cff);
  --ok:#3ddc97; --warn:#ffb454; --bad:#ff6b7d;
  --r:18px; --shadow:0 10px 34px rgba(0,0,0,.42);
  --fs:16px;
}
*{box-sizing:border-box;-webkit-tap-highlight-color:transparent}
html,body{margin:0;padding:0}
body{
  background:
    radial-gradient(1200px 500px at 85% -10%, rgba(56,198,244,.09), transparent 60%),
    radial-gradient(900px 420px at -10% 30%, rgba(91,140,255,.07), transparent 55%),
    var(--bg1);
  color:var(--tx);font:var(--fs)/1.62 "PingFang SC","HarmonyOS Sans SC","MiSans","Microsoft YaHei",system-ui,sans-serif;
  min-height:100vh;
}
::selection{background:rgba(56,198,244,.3)}
#topbar{
  position:sticky;top:0;z-index:9;
  display:flex;align-items:center;justify-content:space-between;
  padding:calc(10px + env(safe-area-inset-top)) 18px 10px;
  background:linear-gradient(180deg,rgba(9,13,20,.92),rgba(9,13,20,.72) 70%,transparent);
  backdrop-filter:blur(14px);-webkit-backdrop-filter:blur(14px);
}
.brand{display:flex;align-items:center;gap:7px;font-weight:800;font-size:19px;letter-spacing:1px}
.brand .lg{color:transparent;background:var(--cyan-grad);-webkit-background-clip:text;font-size:24px;transform:rotate(12deg)}
.brand .sub{color:var(--tx2);font-weight:600;font-size:12.5px;letter-spacing:2px}
.pill{font-size:11px;color:var(--tx3);border:1px solid var(--line);border-radius:20px;padding:3px 11px;white-space:nowrap}
main#view{padding:16px 16px calc(96px + env(safe-area-inset-bottom));max-width:760px;margin:0 auto}
/* 底部导航 */
#tabs{
  position:fixed;left:0;right:0;bottom:0;z-index:9;
  display:flex;
  padding:6px 10px calc(8px + env(safe-area-inset-bottom));
  background:rgba(12,17,25,.88);backdrop-filter:blur(18px);-webkit-backdrop-filter:blur(18px);
  border-top:1px solid var(--line);
}
#tabs button{
  flex:1;border:0;background:none;color:var(--tx3);
  font-size:11.5px;padding:6px 0 4px;display:flex;flex-direction:column;align-items:center;gap:1px;
  border-radius:14px;cursor:pointer;transition:color .18s;letter-spacing:.5px;
}
#tabs button i{font-style:normal;font-size:19px;line-height:1.15}
#tabs button b{font-weight:600}
#tabs button.active{color:var(--acc)}
#tabs button.active i{color:transparent;background:var(--cyan-grad);-webkit-background-clip:text}
#tabs button:active{transform:scale(.94)}
/* 卡片 */
.card{
  background:linear-gradient(180deg,rgba(23,33,46,.9),rgba(17,25,36,.94));
  border:1px solid var(--line);border-radius:var(--r);
  padding:18px;margin:12px 0;box-shadow:var(--shadow);position:relative;
}
.card::before{content:"";position:absolute;inset:0;border-radius:var(--r);pointer-events:none;
  background:radial-gradient(420px 120px at 20% 0%,rgba(91,140,255,.07),transparent 70%)}
h3{font-size:13px;letter-spacing:2px;color:var(--tx3);margin:20px 4px 10px;font-weight:700;display:flex;align-items:center;gap:8px}
h3::after{content:"";flex:1;height:1px;background:linear-gradient(90deg,var(--line2),transparent)}
/* 今日 hero */
.hero{text-align:center;overflow:hidden}
.hero .hl{font-size:13px;color:var(--tx3);letter-spacing:3px;margin-bottom:2px}
.hero-num{
  font-size:64px;font-weight:800;line-height:1.1;
  color:transparent;background:var(--cyan-grad);
  -webkit-background-clip:text;filter:drop-shadow(0 0 18px rgba(56,198,244,.35));
  font-variant-numeric:tabular-nums;
}
.hero-txt{color:var(--tx2);margin:2px 0 14px}
button{
  background:var(--cyan-grad);color:#03222e;border:0;border-radius:14px;
  font-weight:800;font-size:16px;padding:14px 20px;cursor:pointer;letter-spacing:1px;
  box-shadow:0 6px 20px rgba(56,160,244,.28);transition:transform .12s,filter .2s;
}
button:active{transform:scale(.965)}
button:disabled{opacity:.38;box-shadow:none}
button.sec{background:var(--card3);color:var(--tx);border:1px solid var(--line2);box-shadow:none}
button.danger{background:transparent;color:var(--bad);border:1px solid rgba(255,107,125,.4);box-shadow:none}
button.back{background:none;color:var(--acc);font-size:26px;padding:0 10px 2px 0;box-shadow:none;font-weight:400}
button.sm{font-size:13px;padding:9px 13px;flex:0 0 auto}
.row{display:flex;gap:10px;margin-top:13px;flex-wrap:wrap}
.row button{flex:1;min-width:110px}
.hint{color:var(--tx3);font-size:12.5px;margin-top:10px;line-height:1.6}
/* 列表 */
.qlist{display:flex;flex-direction:column;gap:11px}
.qitem{
  background:linear-gradient(180deg,rgba(24,34,47,.92),rgba(16,23,33,.96));
  border:1px solid var(--line);border-radius:16px;padding:14px 15px;cursor:pointer;
  transition:border-color .18s,transform .12s;
}
.qitem:active{transform:scale(.985)}
.qi-head{display:flex;gap:8px;align-items:center;flex-wrap:wrap}
.qi-head b{font-size:16px;letter-spacing:.3px}
.pts{color:var(--warn);font-weight:800;font-size:12.5px;background:rgba(255,180,84,.1);padding:1px 9px;border-radius:8px}
.chip{
  background:rgba(56,198,244,.1);color:#7fd7f7;border:1px solid rgba(56,198,244,.22);
  border-radius:20px;font-size:11.5px;padding:1px 10px;letter-spacing:1px;
}
.badge{font-size:11.5px;border-radius:20px;padding:2px 10px;margin-left:auto;font-weight:600}
.s-new{background:rgba(143,163,184,.12);color:var(--tx2)}
.s-learn{background:rgba(61,220,151,.12);color:var(--ok)}
.s-hard{background:rgba(255,107,125,.13);color:var(--bad)}
.qi-tags{margin:8px 0 3px;display:flex;gap:6px;flex-wrap:wrap}
.qi-tags span{color:var(--tx2);font-size:11.5px;background:rgba(143,163,184,.09);border:1px solid var(--line);border-radius:7px;padding:1px 8px}
.qi-stem{font-size:14px;color:#c6d3e0;display:-webkit-box;-webkit-line-clamp:2;-webkit-box-orient:vertical;overflow:hidden}
/* 进度条 */
.bar{background:rgba(143,163,184,.12);border-radius:9px;height:10px;overflow:hidden;margin:9px 0}
.bar i{display:block;height:100%;border-radius:9px;background:var(--cyan-grad);box-shadow:0 0 12px rgba(56,198,244,.4)}
.kv{display:flex;gap:16px;color:var(--tx2);font-size:13px;flex-wrap:wrap}
/* 筛选 */
#filters{display:flex;gap:7px;overflow-x:auto;padding:2px 0 10px;scrollbar-width:none}
#filters::-webkit-scrollbar{display:none}
.chip-f{
  flex:0 0 auto;background:var(--card2);color:var(--tx2);
  border:1px solid var(--line);border-radius:22px;font-size:13px;padding:7px 16px;font-weight:600;
}
.chip-f.on{color:#062a36;background:var(--cyan-grad);border-color:transparent;font-weight:800}
/* 做题页 */
.qhead{display:flex;align-items:center;gap:8px;margin:4px 0 6px}
.qhead b{font-size:17px}
.qbody p.stem{font-size:15.5px;line-height:1.85;color:#eef5fb;white-space:pre-line;margin:2px 0 0}
.asks{margin:8px 0;padding-left:4px;list-style:none;counter-reset:a}
.asks li{counter-increment:a;font-size:14.5px;margin:7px 0;line-height:1.75;padding-left:34px;position:relative;color:#dbe6f0}
.asks li::before{
  content:counter(a);position:absolute;left:0;top:2px;width:24px;height:24px;
  background:rgba(56,198,244,.1);border:1px solid rgba(56,198,244,.3);color:#7fd7f7;
  border-radius:8px;font-size:12.5px;font-weight:700;display:flex;align-items:center;justify-content:center;
}
details.circ{margin-top:12px;background:rgba(10,15,22,.6);border:1px dashed var(--line2);border-radius:12px;padding:9px 13px}
summary{color:var(--acc);cursor:pointer;font-size:13.5px;font-weight:600;letter-spacing:.5px}
.circ p{font-size:13px;color:var(--tx2);line-height:1.75;margin:7px 0 2px}
.imgs{display:flex;gap:8px;flex-wrap:wrap;margin-top:12px}
.pgbtn{background:var(--card3);border:1px dashed var(--line2);border-radius:9px;font-size:12px;color:#a9c4da;padding:7px 11px;cursor:pointer}
.work textarea{
  width:100%;background:rgba(7,11,17,.8);border:1px solid var(--line);
  border-radius:13px;color:var(--tx);font-size:14.5px;padding:12px;font-family:inherit;resize:vertical;
}
.work textarea:focus{outline:none;border-color:rgba(56,198,244,.5);box-shadow:0 0 0 3px rgba(56,198,244,.12)}
.sol{
  font-size:14.5px;line-height:1.9;white-space:pre-line;
  border-left:3px solid;border-image:linear-gradient(180deg,var(--ok),var(--acc)) 1;
  padding:4px 0 4px 14px;color:#d9e5ef;
}
#solution h4{margin:16px 0 6px;color:var(--ok);font-size:14px;letter-spacing:2px}
#solution details{margin-top:10px}
/* 自评四档 */
.rate-row{display:grid;grid-template-columns:repeat(4,1fr);gap:8px;margin-top:18px}
.rate-row button{flex:none;min-width:0;font-size:13.5px;padding:16px 2px;border-radius:13px;box-shadow:none;display:flex;flex-direction:column;gap:2px;font-weight:800}
.rate-row button small{font-weight:500;opacity:.75;font-size:10.5px;letter-spacing:1px}
.r0{background:rgba(255,107,125,.14)!important;color:#ff9aa8!important}
.r1{background:rgba(255,180,84,.14)!important;color:#ffce8a!important}
.r2{background:rgba(56,198,244,.14)!important;color:#8fdcff!important}
.r3{background:rgba(61,220,151,.14)!important;color:#9cf0c8!important}
/* 原卷图弹层 */
#imgmodal{position:fixed;inset:0;background:rgba(4,6,10,.95);display:none;z-index:20}
#imgmodal.on{display:flex;align-items:flex-start;justify-content:center;overflow:auto;padding:54px 6px 40px;-webkit-overflow-scrolling:touch}
#imgmodal .imb img{max-width:100%;height:auto;border-radius:8px;box-shadow:0 0 40px rgba(0,0,0,.6)}
#imclose{position:fixed;top:calc(12px + env(safe-area-inset-top));right:14px;background:rgba(255,255,255,.08);color:#fff;backdrop-filter:blur(8px);width:40px;height:40px;border-radius:20px;font-size:17px;padding:0;display:flex;align-items:center;justify-content:center}
/* 教材页 */
.kangimg{background:#05080c;border:1px solid var(--line);border-radius:14px;overflow:auto;-webkit-overflow-scrolling:touch;max-height:76vh}
.kangimg img{width:100%;height:auto;display:block}
.kangbar{align-items:center}
.kangbar button{flex:0 0 auto}
.kpn{color:var(--tx2);font-size:13.5px;text-align:center;flex:1;font-variant-numeric:tabular-nums}
/* 知识关联 */
.kno{margin-top:14px;border-top:1px dashed var(--line2);padding-top:6px}
.kno summary{color:var(--ok)}
.kitem{margin:9px 0;padding:10px 12px;background:rgba(13,19,28,.7);border:1px solid var(--line);border-radius:12px}
.kitem b{display:block;color:#cfe3f5;font-size:14.5px;margin-bottom:3px}
.kitem p{font-size:13.5px;color:#c3ced9;line-height:1.75;margin:5px 0}
.ksrc{color:var(--tx3);font-size:11.5px;font-style:normal;display:block;letter-spacing:1px}
.kex{color:var(--warn);opacity:.9}
/* 杂项 */
.empty{color:var(--tx3);padding:44px 20px;text-align:center;font-size:14px}
.empty::before{content:"⌁";display:block;font-size:40px;color:var(--tx3);opacity:.5;margin-bottom:8px}
.imp{margin-top:14px}
.imp summary{color:var(--tx2)}
#toast{
  position:fixed;bottom:calc(92px + env(safe-area-inset-bottom));left:50%;transform:translateX(-50%) translateY(14px);
  background:rgba(38,52,68,.96);border:1px solid var(--line2);color:#fff;
  padding:10px 20px;border-radius:24px;font-size:14px;opacity:0;pointer-events:none;
  transition:.25s;z-index:30;max-width:86vw;text-align:center;backdrop-filter:blur(10px);
  box-shadow:0 8px 30px rgba(0,0,0,.45);
}
#toast.on{opacity:1;transform:translateX(-50%) translateY(0)}
@media (min-width:900px){
  body{font-size:16.5px}
  main#view{max-width:860px}
  .rate-row button{font-size:15px}
}