:root{
  --red:#c0392b;--red-d:#962d22;--red-l:#fdecea;--ink:#222;--muted:#6b6b6b;--line:#e6e1da;
  --bg:#faf7f2;--card:#fff;--ok:#1e8e3e;--ok-l:#e6f4ea;--bad:#d93025;--bad-l:#fce8e6;--gold:#b7791f;
  --r:14px;--shadow:0 2px 10px rgba(0,0,0,.06);
}
*{box-sizing:border-box}
html{-webkit-text-size-adjust:100%}
body{margin:0;font-family:-apple-system,BlinkMacSystemFont,"PingFang SC","Hiragino Sans GB","Microsoft YaHei","Noto Sans CJK SC","Noto Sans SC",sans-serif;color:var(--ink);background:var(--bg);line-height:1.6;min-height:100vh;display:flex;flex-direction:column}
a{color:var(--red)}
button{font:inherit}
.zh{font-style:normal;color:var(--muted);font-size:.8em;margin-left:.4em;font-weight:400}
body.no-zh .zh{display:none!important}
.topbar{position:sticky;top:0;z-index:10;display:flex;align-items:center;justify-content:space-between;gap:8px;padding:8px 14px;padding-top:max(8px,env(safe-area-inset-top));background:#fff;border-bottom:1px solid var(--line)}
.brand{display:flex;align-items:center;gap:8px;text-decoration:none;color:var(--ink);font-weight:700}
.brand small{display:block;font-weight:400;font-size:.72rem;color:var(--muted);line-height:1}
.logo{width:36px;height:36px;border-radius:10px;background:var(--red);color:#fff;display:grid;place-items:center;font-size:1.2rem}
.nav{display:flex;align-items:center;gap:2px}
.nav a{padding:8px 9px;border-radius:10px;text-decoration:none;color:var(--ink);font-size:.95rem;min-height:44px;display:flex;align-items:center}
.nav a.active{background:var(--red-l);color:var(--red)}
.nav a .zh{display:none}
@media(min-width:760px){.nav a .zh{display:inline}}
@media(max-width:420px){.brand small{display:none}.nav a{padding:8px 6px}.nav{gap:0}}
.chip{border:1px solid var(--line);background:#fff;border-radius:999px;padding:6px 10px;min-height:36px;cursor:pointer;color:var(--muted)}
.chip[aria-pressed=true]{background:var(--red-l);color:var(--red);border-color:#f3c3bd}
main{flex:1;width:100%;max-width:980px;margin:0 auto;padding:16px 14px 40px;outline:none}
.foot{font-size:.78rem;color:var(--muted);text-align:center;padding:16px 14px calc(16px + env(safe-area-inset-bottom));border-top:1px solid var(--line)}
.loading{padding:40px;text-align:center;color:var(--muted)}
.card{background:var(--card);border:1px solid var(--line);border-radius:var(--r);box-shadow:var(--shadow);padding:16px}
.hero{display:grid;gap:16px;grid-template-columns:1fr;align-items:center;background:linear-gradient(135deg,#fff 0%,#fff6f2 100%)}
@media(min-width:760px){.hero{grid-template-columns:140px 1fr;padding:28px}}
.avatar{width:96px;height:96px;border-radius:50%;background:var(--red);color:#fff;display:grid;place-items:center;font-size:2.6rem;margin:0 auto;box-shadow:0 0 0 6px #fbd9d4}
@media(min-width:760px){.avatar{width:120px;height:120px;font-size:3.2rem}}
.hero h1{margin:0 0 6px;font-size:1.35rem}
@media(min-width:760px){.hero h1{font-size:1.7rem}}
.hero p{margin:4px 0;color:#444}
.stats{display:flex;flex-wrap:wrap;gap:8px;margin-top:10px}
.stat{background:#fff;border:1px solid var(--line);border-radius:10px;padding:6px 10px;font-size:.88rem}
.stat b{color:var(--red);font-size:1.05rem}
h2{font-size:1.15rem;margin:24px 0 10px}
.levels{display:grid;gap:12px;grid-template-columns:repeat(2,1fr)}
@media(min-width:760px){.levels{grid-template-columns:repeat(4,1fr)}}
.level{display:flex;flex-direction:column;gap:4px;text-decoration:none;color:var(--ink);background:#fff;border:1px solid var(--line);border-radius:var(--r);padding:14px;box-shadow:var(--shadow);transition:transform .12s,border-color .12s;min-height:120px}
.level:hover,.level:focus-visible{transform:translateY(-2px);border-color:var(--red)}
.level .lv{font-size:1.3rem;font-weight:800;color:var(--red)}
.level .meta{font-size:.82rem;color:var(--muted)}
.bar{height:6px;border-radius:99px;background:#f0ebe4;overflow:hidden;margin-top:auto}
.bar>i{display:block;height:100%;background:var(--red);border-radius:99px}
.tips{display:grid;gap:10px;grid-template-columns:1fr}
@media(min-width:760px){.tips{grid-template-columns:repeat(3,1fr)}}
.tips .card h3{margin:0 0 4px;font-size:1rem}
.tips .card p{margin:0;font-size:.9rem;color:#555}
.crumbs{font-size:.88rem;color:var(--muted);margin-bottom:10px}
.crumbs a{text-decoration:none}
.modes{display:grid;gap:12px;grid-template-columns:1fr}
@media(min-width:640px){.modes{grid-template-columns:repeat(2,1fr)}}
.mode h3{margin:0 0 6px}
.mode p{margin:0 0 10px;color:#555;font-size:.92rem}
.seg{display:flex;flex-wrap:wrap;gap:8px;margin:8px 0}
.seg button,.seg label{flex:1 1 auto}
.btn{display:inline-flex;align-items:center;justify-content:center;gap:6px;min-height:48px;padding:10px 18px;border-radius:12px;border:1px solid var(--line);background:#fff;color:var(--ink);cursor:pointer;text-decoration:none;font-weight:600;font-size:1rem}
.btn:hover{border-color:var(--red)}
.btn.primary{background:var(--red);border-color:var(--red);color:#fff}
.btn.primary:hover{background:var(--red-d)}
.btn.sel{background:var(--red-l);border-color:var(--red);color:var(--red)}
.btn.small{min-height:40px;padding:6px 12px;font-size:.9rem}
.btn[disabled]{opacity:.45;cursor:not-allowed}
.row{display:flex;gap:10px;flex-wrap:wrap;align-items:center}
.row.end{justify-content:flex-end}
.grow{flex:1}
.qhead{display:flex;justify-content:space-between;align-items:center;gap:8px;font-size:.85rem;color:var(--muted);margin-bottom:8px;flex-wrap:wrap}
.tag{display:inline-block;padding:2px 8px;border-radius:99px;background:#f4efe8;font-size:.78rem;color:#555}
.tag.red{background:var(--red-l);color:var(--red)}
.progress{height:6px;background:#f0ebe4;border-radius:99px;overflow:hidden;margin-bottom:12px}
.progress>i{display:block;height:100%;background:var(--red);transition:width .2s}
.qtext{font-size:1.3rem;line-height:1.8;margin:6px 0 4px;word-break:break-word}
@media(min-width:760px){.qtext{font-size:1.5rem}}
.qtext .blank{display:inline-block;min-width:3.2em;border-bottom:2px solid var(--red);text-align:center;color:var(--red);font-weight:700;padding:0 4px}
.qsub{color:var(--muted);font-size:.92rem;margin-bottom:12px}
.opts{display:grid;gap:10px;grid-template-columns:1fr;margin:12px 0}
@media(min-width:640px){.opts.short{grid-template-columns:1fr 1fr}}
.opt{display:flex;align-items:flex-start;gap:10px;width:100%;text-align:left;min-height:56px;padding:12px 14px;border-radius:12px;border:2px solid var(--line);background:#fff;cursor:pointer;color:var(--ink);font-size:1.1rem;line-height:1.45;transition:border-color .1s,background .1s}
.opt:hover:not([disabled]){border-color:#e8a59d}
.opt .k{flex:none;width:28px;height:28px;border-radius:8px;background:#f4efe8;display:grid;place-items:center;font-weight:700;font-size:.9rem;margin-top:1px}
.opt .body{display:flex;flex-direction:column}
.opt .py{font-size:.82rem;color:var(--red);font-family:system-ui,sans-serif}
.opt .gloss{font-size:.82rem;color:var(--muted);font-family:system-ui,sans-serif}
.opt[disabled]{cursor:default}
.opt.correct{border-color:var(--ok);background:var(--ok-l)}
.opt.correct .k{background:var(--ok);color:#fff}
.opt.wrong{border-color:var(--bad);background:var(--bad-l)}
.opt.wrong .k{background:var(--bad);color:#fff}
.opt.picked{border-color:var(--red);background:var(--red-l)}
.feedback{border-radius:12px;padding:12px 14px;margin:6px 0 12px;font-size:.95rem}
.feedback.ok{background:var(--ok-l);color:#14532d}
.feedback.bad{background:var(--bad-l);color:#7f1d1d}
.feedback .say{font-weight:700;margin-bottom:4px}
.explain{margin-top:6px;display:grid;gap:4px}
.explain div{font-size:.9rem;color:#333}
.explain b{color:var(--ink)}
.toolbar{display:flex;gap:8px;flex-wrap:wrap;margin-top:10px}
.sticky-actions{position:sticky;bottom:0;background:linear-gradient(transparent,var(--bg) 30%);padding:14px 0 calc(8px + env(safe-area-inset-bottom))}
.sticky-actions .btn{flex:1}
.score{text-align:center;padding:24px 16px}
.score .big{font-size:3rem;font-weight:800;color:var(--red);line-height:1.1}
.review-item{border-top:1px solid var(--line);padding:12px 0}
.review-item:first-child{border-top:0}
.review-item .q{font-size:1.05rem}
.ok-t{color:var(--ok);font-weight:600}.bad-t{color:var(--bad);font-weight:600}
input[type=search],input[type=text],select{font:inherit;min-height:48px;padding:10px 12px;border-radius:12px;border:1px solid var(--line);background:#fff;width:100%}
input:focus,select:focus,.btn:focus-visible,.opt:focus-visible{outline:3px solid #f3c3bd;outline-offset:1px}
.list{display:grid;gap:8px}
.li{display:flex;gap:10px;align-items:flex-start;justify-content:space-between;background:#fff;border:1px solid var(--line);border-radius:12px;padding:10px 12px}
.li .q{flex:1;min-width:0;word-break:break-word}
.li .id{font-family:ui-monospace,Menlo,monospace;font-size:.8rem;color:var(--muted)}
.empty{text-align:center;color:var(--muted);padding:30px 10px}
.pager{display:flex;gap:8px;justify-content:center;align-items:center;margin-top:12px}
.toggle{display:flex;align-items:center;gap:8px;font-size:.9rem;color:#444;cursor:pointer;min-height:40px}
.toggle input{width:20px;height:20px;accent-color:var(--red)}
.teacher-say{display:flex;gap:10px;align-items:flex-start;margin:10px 0}
.teacher-say .mini{flex:none;width:36px;height:36px;border-radius:50%;background:var(--red);color:#fff;display:grid;place-items:center}
.teacher-say .bubble{background:#fff;border:1px solid var(--line);border-radius:4px 14px 14px 14px;padding:8px 12px;font-size:.93rem}
.brand,.nav a,.chip{white-space:nowrap}
.btn.primary .zh{color:rgba(255,255,255,.85)}
.feedback .zh{color:inherit;opacity:.75}
@media(max-width:420px){.brand{font-size:.95rem;gap:6px}.logo{width:32px;height:32px}.nav a{font-size:.88rem;padding:8px 5px}.chip{padding:4px 8px}.topbar{padding-left:10px;padding-right:10px}.sticky-actions .btn{padding:10px 8px;white-space:nowrap;font-size:.95rem}}
[hidden]{display:none!important}
/* account */
#accountSlot{display:flex;align-items:center;margin-left:4px}
.acct-btn{min-height:38px;padding:6px 12px;font-size:.9rem;white-space:nowrap}
.acct{position:relative}
.avatar-btn{position:relative;width:38px;height:38px;border-radius:50%;border:0;background:#2c3e50;color:#fff;font-weight:700;cursor:pointer;font-size:1rem}
.sync-dot{position:absolute;right:-1px;bottom:-1px;width:12px;height:12px;border-radius:50%;border:2px solid #fff;background:var(--ok)}
.sync-dot[data-state=saving]{background:var(--gold)}
.sync-dot[data-state=error],.sync-dot[data-state=offline]{background:var(--bad)}
.menu{position:absolute;right:0;top:46px;min-width:240px;background:#fff;border:1px solid var(--line);border-radius:12px;box-shadow:0 8px 30px rgba(0,0,0,.15);padding:6px;z-index:30}
.menu-head{padding:8px 10px 10px;border-bottom:1px solid var(--line);margin-bottom:4px;display:flex;flex-direction:column;word-break:break-all}
.menu-head small{color:var(--muted)}
.menu-head .sync-note{color:var(--ok);margin-top:2px}
.menu button{display:block;width:100%;text-align:left;border:0;background:none;padding:12px 10px;border-radius:8px;cursor:pointer;font-size:.95rem;color:var(--ink)}
.menu button:hover{background:#f6f2ec}
.menu button.danger{color:var(--bad)}
.linkish{border:0;background:none;padding:0;color:var(--red);font:inherit;font-weight:700;text-decoration:underline;cursor:pointer}
/* modal */
body.modal-open{overflow:hidden}
.modal-wrap{position:fixed;inset:0;background:rgba(20,20,20,.45);z-index:50;display:flex;align-items:flex-end;justify-content:center}
@media(min-width:640px){.modal-wrap{align-items:center}}
.modal{position:relative;background:#fff;width:100%;max-width:440px;max-height:92vh;overflow:auto;border-radius:18px 18px 0 0;padding:18px 18px calc(22px + env(safe-area-inset-bottom));box-shadow:0 10px 40px rgba(0,0,0,.25)}
@media(min-width:640px){.modal{border-radius:18px;padding:24px 26px}}
.modal h2{margin:4px 0 8px;font-size:1.3rem}
.modal-x{position:absolute;right:10px;top:8px;width:44px;height:44px;border:0;background:none;font-size:1.7rem;color:var(--muted);cursor:pointer;border-radius:10px}
.modal-hd .teacher-say{margin:0 40px 4px 0}
.modal-sub{color:#555;font-size:.92rem;margin:4px 0 12px}
.modal-note{font-size:.84rem;color:var(--muted);margin:10px 0 0}
.tabs{display:flex;background:#f4efe8;border-radius:12px;padding:4px;margin:6px 0 8px}
.tabs button{flex:1;border:0;background:none;min-height:42px;border-radius:9px;font-weight:600;cursor:pointer;color:var(--muted)}
.tabs button[aria-selected=true]{background:#fff;color:var(--ink);box-shadow:0 1px 4px rgba(0,0,0,.08)}
.modal form{display:flex;flex-direction:column;gap:10px}
.modal label{display:flex;flex-direction:column;gap:4px;font-weight:600;font-size:.92rem}
.modal label small{font-weight:400;color:var(--muted)}
.modal input{font-size:16px}
.pw{position:relative;display:block}
.pw input{padding-right:70px}
.pw-toggle{position:absolute;right:6px;top:50%;transform:translateY(-50%);border:0;background:none;color:var(--red);font-weight:600;min-height:40px;padding:0 10px;cursor:pointer}
.hint{color:var(--muted);font-size:.82rem;margin-top:-4px}
.form-err{color:var(--bad);font-size:.9rem;min-height:1.2em}
.btn.block{width:100%}
.danger-btn{background:var(--bad);border-color:var(--bad);color:#fff}
.gbtn{display:flex;justify-content:center;min-height:44px;margin:6px 0}
.or{display:flex;align-items:center;gap:10px;color:var(--muted);font-size:.85rem;margin:8px 0}
.or:before,.or:after{content:"";flex:1;height:1px;background:var(--line)}
.toast{position:fixed;left:50%;bottom:calc(20px + env(safe-area-inset-bottom));transform:translateX(-50%);background:#2c2c2c;color:#fff;padding:12px 16px;border-radius:12px;max-width:min(92vw,520px);z-index:60;font-size:.92rem;box-shadow:0 6px 24px rgba(0,0,0,.25)}
@media(max-width:420px){.acct-btn{padding:6px 9px;font-size:.85rem}.nav a[data-nav=home]{display:none}}
.modal input{min-height:48px;padding:10px 12px;border-radius:12px;border:1px solid #d9d2c8;background:#fff;width:100%;font:inherit;font-size:16px}
.modal input:focus{border-color:var(--red)}
@media(max-width:420px){.brand>span:last-child{display:none}.topbar{gap:4px}}