*,*::before,*::after{box-sizing:border-box}
:root{
  --s:8px;
  --ink:#1b1638;
  --muted:#5c5678;
  --line:rgba(91,76,255,.14);
  --canvas:#f4f0ff;
  --card:#fff;
  --primary:#5b4cff;
  --primary-2:#7c6cff;
  --accent:#ff7a59;
  --teal:#14b8a6;
  --ok:#16a34a;
  --bad:#e11d48;
  --amber:#f5a524;
  --shadow:0 10px 30px rgba(91,76,255,.10),0 2px 8px rgba(27,22,56,.06);
  --shadow-sm:0 4px 14px rgba(91,76,255,.08);
  --radius:20px;
  --pill:999px;
  --font:"Nunito","Outfit",system-ui,sans-serif;
  --display:"Outfit","Nunito",system-ui,sans-serif;
  --ease:cubic-bezier(.22,.8,.28,1);
}
.dark{
  --ink:#f4f1ff;
  --muted:#b7b0d4;
  --line:rgba(167,155,255,.18);
  --canvas:#120e24;
  --card:#1c1733;
  --primary:#8b80ff;
  --primary-2:#a99eff;
  --accent:#ff9378;
  --teal:#2dd4bf;
  --ok:#4ade80;
  --bad:#fb7185;
  --amber:#fbbf24;
  --shadow:0 12px 32px rgba(0,0,0,.35);
  --shadow-sm:0 4px 16px rgba(0,0,0,.28);
}
html,body{margin:0;min-height:100%;font-family:var(--font);color:var(--ink);background:var(--canvas)}
body{
  background:
    radial-gradient(1100px 520px at -8% -18%, rgba(91,76,255,.22), transparent 55%),
    radial-gradient(820px 420px at 108% -8%, rgba(255,122,89,.16), transparent 50%),
    radial-gradient(720px 380px at 70% 115%, rgba(20,184,166,.12), transparent 46%),
    var(--canvas);
  background-attachment:fixed;
}
button,select{font:inherit;color:inherit}
a{color:inherit;text-decoration:none}
.ico{width:1.15rem;height:1.15rem;flex-shrink:0}
.shell{display:flex;min-height:100vh}
.sidebar{
  width:17.5rem;padding:8px 16px;display:flex;flex-direction:column;gap:16px;
  background:linear-gradient(180deg,#1a1440 0%,#2a1f66 100%);
  color:#f7f4ff;border-right:1px solid rgba(255,255,255,.06);
}
.dark .sidebar{background:linear-gradient(180deg,#0c091c 0%,#1a1440 100%)}
.brand{display:flex;gap:12px;align-items:center;padding:12px 8px 8px}
.brand-mark{
  width:42px;height:42px;border-radius:14px;display:grid;place-items:center;
  background:linear-gradient(135deg,#7c6cff,#ff7a59);color:#fff;
  font-weight:800;font-family:var(--display);box-shadow:0 8px 18px rgba(91,76,255,.35);
}
.brand-title{margin:0;font-family:var(--display);font-weight:700;font-size:.95rem}
.brand-sub{margin:0;opacity:.7;font-size:.78rem}
.sidebar nav{display:flex;flex-direction:column;gap:6px}
.sidebar a{
  display:flex;align-items:center;gap:10px;padding:12px 14px;border-radius:16px;
  color:rgba(255,255,255,.82);transition:transform .18s var(--ease),background .18s var(--ease);
}
.sidebar a:hover{background:rgba(255,255,255,.08);transform:translateX(2px)}
.sidebar a.active{
  background:linear-gradient(90deg,rgba(124,108,255,.95),rgba(255,122,89,.85));
  color:#fff;box-shadow:var(--shadow-sm);
}
.sidebar-note{margin-top:auto;font-size:.72rem;line-height:1.45;opacity:.62;padding:12px 10px 16px}
.main{flex:1;min-width:0;display:flex;flex-direction:column}
.topbar{
  display:flex;justify-content:space-between;align-items:center;padding:12px 24px;
  position:sticky;top:0;z-index:10;backdrop-filter:blur(14px);
  background:color-mix(in srgb, var(--canvas) 72%, transparent);
  border-bottom:1px solid var(--line);
}
.scrim{display:none}
#app{flex:1;overflow:auto;padding:32px 28px 48px}
.wrap{max-width:64rem;margin:0 auto}
.wrap-sm{max-width:46rem;margin:0 auto}
h1,h2{font-family:var(--display);margin:0;letter-spacing:-.02em}
h1{font-size:clamp(1.55rem,2.4vw,2.05rem);line-height:1.2}
.muted{color:var(--muted);font-size:.95rem;line-height:1.65}
.hero{
  position:relative;overflow:hidden;padding:28px;border-radius:28px;margin-bottom:28px;
  background:linear-gradient(135deg,#5b4cff 0%,#7c6cff 48%,#ff7a59 130%);
  color:#fff;box-shadow:var(--shadow);
}
.hero::after{
  content:"";position:absolute;right:-40px;top:-50px;width:220px;height:220px;border-radius:50%;
  background:rgba(255,255,255,.14);pointer-events:none;
}
.hero .badge{background:rgba(255,255,255,.18);color:#fff}
.hero h1,.hero p{position:relative;z-index:1}
.hero h1{margin:.55rem 0 .5rem}
.hero p{margin:0;max-width:40rem;opacity:.94;font-size:1.02rem;line-height:1.6}
.grid-4{display:grid;gap:20px;grid-template-columns:repeat(auto-fit,minmax(220px,1fr))}
.grid-3{display:grid;gap:16px;grid-template-columns:repeat(auto-fit,minmax(150px,1fr))}
.card{
  background:var(--card);border:1px solid var(--line);border-radius:var(--radius);
  padding:24px;display:flex;flex-direction:column;gap:14px;box-shadow:var(--shadow-sm);
}
.card > .btn,.card > a.btn{align-self:flex-start}
.mode{transition:transform .18s var(--ease),box-shadow .18s var(--ease)}
.mode:hover{transform:translateY(-2px);box-shadow:var(--shadow)}
.mode .icon-box{width:48px;height:48px;border-radius:16px;color:#fff}
.mode-practice .icon-box{background:linear-gradient(135deg,#5b4cff,#7c6cff)}
.mode-review .icon-box{background:linear-gradient(135deg,#f5a524,#ff7a59)}
.mode-exam .icon-box{background:linear-gradient(135deg,#14b8a6,#2dd4bf)}
.mode-stats .icon-box{background:linear-gradient(135deg,#ec4899,#a78bfa)}
.icon-box{width:2.5rem;height:2.5rem;border-radius:14px;background:rgba(91,76,255,.12);color:var(--primary);display:grid;place-items:center}
.btn{
  border:0;border-radius:var(--pill);padding:12px 20px;min-height:44px;cursor:pointer;
  background:linear-gradient(135deg,var(--primary),var(--primary-2));color:#fff;font-weight:700;
  box-shadow:0 8px 18px rgba(91,76,255,.28);
  transition:transform .16s var(--ease),filter .16s var(--ease);
  display:inline-flex;align-items:center;justify-content:center;gap:8px;
}
.btn:hover{transform:translateY(-1px) scale(1.01);filter:brightness(1.05)}
.btn.secondary{background:rgba(91,76,255,.1);color:var(--primary);box-shadow:none}
.btn.ghost,.ghost{
  background:transparent;border:1.5px solid var(--line);border-radius:var(--pill);
  padding:10px 16px;min-height:40px;cursor:pointer;color:var(--ink);font-weight:700;
  display:inline-flex;align-items:center;gap:8px;
  transition:background .16s var(--ease),transform .16s var(--ease);
}
.ghost:hover,.btn.ghost:hover{background:rgba(91,76,255,.08);transform:translateY(-1px)}
.ghost.on{background:rgba(91,76,255,.12);border-color:var(--primary);color:var(--primary)}
.btn.danger{background:linear-gradient(135deg,#e11d48,#fb7185);box-shadow:0 8px 16px rgba(225,29,72,.25)}
.btn:disabled,.ghost:disabled{opacity:.5;cursor:not-allowed;transform:none}
.icon-btn{width:44px;height:44px;padding:0;justify-content:center;border-radius:16px}
.badge{
  display:inline-flex;align-items:center;gap:6px;border-radius:var(--pill);
  padding:5px 12px;font-size:.78rem;font-weight:800;background:rgba(91,76,255,.1);color:var(--primary);
}
.badge.k1{background:rgba(20,184,166,.14);color:#0f766e}
.badge.k2{background:rgba(91,76,255,.12);color:var(--primary)}
.badge.k3{background:rgba(255,122,89,.16);color:#c2410c}
.dark .badge.k1{color:#5eead4}
.dark .badge.k3{color:#fdba74}
.hint{
  background:linear-gradient(180deg,rgba(91,76,255,.08),rgba(255,122,89,.06));
  border:1px solid var(--line);border-radius:18px;padding:16px 18px;font-size:.9rem;color:var(--muted);line-height:1.55;
}
.row{display:flex;gap:10px;flex-wrap:wrap;align-items:center}
.mt{margin-top:16px}
.option{
  display:flex;align-items:flex-start;gap:14px;width:100%;text-align:left;
  padding:16px 18px;border:1.5px solid var(--line);border-radius:18px;
  background:var(--card);cursor:pointer;margin:8px 0;
  transition:transform .16s var(--ease),border-color .16s var(--ease),box-shadow .16s var(--ease),background .16s var(--ease);
}
.option:hover{border-color:var(--primary);transform:translateY(-1px);box-shadow:var(--shadow-sm)}
.opt-letter{
  width:32px;height:32px;border-radius:12px;flex-shrink:0;display:grid;place-items:center;
  font-weight:800;font-family:var(--display);background:rgba(91,76,255,.1);color:var(--primary);
}
.opt-text{padding-top:4px;line-height:1.5}
.option.picked{border-color:var(--primary);background:rgba(91,76,255,.07);box-shadow:0 0 0 4px rgba(91,76,255,.12)}
.option.ok{border-color:var(--ok);background:rgba(22,163,74,.1)}
.option.ok .opt-letter{background:var(--ok);color:#fff}
.option.bad{border-color:var(--bad);background:rgba(225,29,72,.08)}
.option.bad .opt-letter{background:var(--bad);color:#fff}
.bar{height:8px;background:rgba(91,76,255,.12);border-radius:var(--pill);overflow:hidden}
.bar>i{display:block;height:100%;background:linear-gradient(90deg,var(--primary),var(--accent));border-radius:inherit;transition:width .25s var(--ease)}
.bar>i.ok{background:var(--ok)}
.bar>i.warn{background:var(--amber)}
.bar>i.bad{background:var(--bad)}
.bar>i.idle{background:rgba(92,86,120,.28)}
.q-num{font-family:var(--display);font-weight:800;font-size:1.35rem;letter-spacing:-.03em}
.q-num span{color:var(--muted);font-size:.95rem;font-weight:700}
.q-body{white-space:pre-line;line-height:1.65;font-size:1.05rem}
.explain{background:rgba(91,76,255,.05);border:1px solid var(--line);padding:18px;border-radius:18px;font-size:.95rem;line-height:1.6}
.breakdown{margin:.4rem 0 0;padding:0;display:flex;flex-direction:column;gap:10px;font-size:.9rem}
.breakdown li{list-style:none;padding:14px 16px;border:1px solid var(--line);border-radius:16px;background:var(--card)}
.stat{border:1px solid var(--line);border-radius:16px;padding:14px 16px;background:var(--card)}
.stat b{display:block;font-size:1.25rem;font-family:var(--display);margin-top:4px}
label{font-size:.88rem;font-weight:800;margin-top:4px}
select{
  width:100%;padding:12px 14px;min-height:44px;border-radius:14px;
  border:1.5px solid var(--line);background:var(--card);color:var(--ink);
}
.timer{
  font-variant-numeric:tabular-nums;font-weight:800;font-family:var(--display);
  padding:8px 14px;border-radius:var(--pill);background:rgba(91,76,255,.1);color:var(--primary);
}
.qnav{display:flex;gap:8px;flex-wrap:wrap}
.qnav button{
  width:40px;height:40px;border-radius:14px;border:1px solid var(--line);
  background:var(--card);cursor:pointer;font-weight:800;color:inherit;
  transition:transform .14s var(--ease),background .14s var(--ease);
}
.qnav button:hover{transform:translateY(-1px)}
.qnav button.on{background:linear-gradient(135deg,var(--primary),var(--primary-2));color:#fff;border-color:transparent}
.qnav button.done{background:rgba(20,184,166,.16);border-color:transparent}
.section-title{display:flex;align-items:center;gap:10px;margin:28px 0 12px;font-size:1.05rem;font-family:var(--display)}
.result-ok{background:linear-gradient(135deg,rgba(22,163,74,.12),rgba(20,184,166,.08))}
.result-bad{background:linear-gradient(135deg,rgba(225,29,72,.1),rgba(255,122,89,.06))}
.ch-row{margin:10px 0}
.ch-head{display:flex;justify-content:space-between;gap:12px;margin-bottom:8px}
@media(max-width:860px){
  .sidebar{position:fixed;inset:0 auto 0 0;z-index:30;transform:translateX(-105%);transition:transform .22s var(--ease);box-shadow:var(--shadow)}
  .sidebar.open{transform:none}
  .scrim.open{display:block;position:fixed;inset:0;background:rgba(18,10,40,.45);z-index:25;backdrop-filter:blur(2px)}
  #app{padding:20px 16px 40px}
  .hero{padding:22px 18px;border-radius:22px}
  .topbar{padding:10px 14px}
}
@media(prefers-reduced-motion:reduce){
  *,*::before,*::after{transition:none!important}
}