:root{
  --bg:#f4f6fb;
  --panel:#ffffff;
  --panel2:#f8fafc;
  --text:#111827;
  --muted:#6b7280;
  --line:#e5e7eb;
  --primary:#4f46e5;
  --primary2:#7c3aed;
  --good:#16a34a;
  --warn:#d97706;
  --bad:#dc2626;
  --shadow:0 18px 50px rgba(15,23,42,.10);
  --radius:22px;
  --bottom:86px;
}
[data-theme="dark"]{
  --bg:#0f172a;
  --panel:#111827;
  --panel2:#1f2937;
  --text:#f8fafc;
  --muted:#9ca3af;
  --line:#334155;
  --shadow:0 18px 50px rgba(0,0,0,.28);
}
*{box-sizing:border-box}
html,body{margin:0;min-height:100%;font-family:-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,"PingFang SC","Microsoft YaHei",Arial,sans-serif;background:var(--bg);color:var(--text)}
body{overscroll-behavior-y:none}
button,input,textarea,select{font:inherit}
button{cursor:pointer;border:0}
.app-shell{min-height:100dvh;max-width:980px;margin:0 auto;position:relative;background:linear-gradient(180deg,rgba(79,70,229,.08),transparent 280px)}
.screen{padding:18px 16px calc(var(--bottom) + env(safe-area-inset-bottom));min-height:100dvh}
.center-screen{display:grid;place-items:center;text-align:center;color:var(--muted)}
.topbar{position:sticky;top:0;z-index:10;backdrop-filter:blur(18px);background:color-mix(in srgb,var(--bg) 84%,transparent);padding:12px 0 10px;margin:-18px -16px 10px;border-bottom:1px solid color-mix(in srgb,var(--line) 55%,transparent)}
.topbar-inner{display:flex;align-items:center;justify-content:space-between;gap:10px;padding:0 16px}
.brand{display:flex;align-items:center;gap:10px;min-width:0}
.logo{width:38px;height:38px;border-radius:15px;background:linear-gradient(135deg,var(--primary),var(--primary2));display:grid;place-items:center;color:#fff;font-weight:900;box-shadow:0 10px 24px rgba(79,70,229,.28)}
.brand h1{font-size:19px;margin:0;line-height:1.05;white-space:nowrap;overflow:hidden;text-overflow:ellipsis}.brand p{font-size:12px;margin:3px 0 0;color:var(--muted)}
.icon-btn{min-width:38px;height:38px;border-radius:14px;background:var(--panel);color:var(--text);box-shadow:0 4px 18px rgba(15,23,42,.08);border:1px solid var(--line)}
.grid{display:grid;gap:14px}.grid-2{grid-template-columns:repeat(2,minmax(0,1fr))}.grid-3{grid-template-columns:repeat(3,minmax(0,1fr))}
.card{background:var(--panel);border:1px solid var(--line);border-radius:var(--radius);box-shadow:var(--shadow);padding:16px}.card.soft{background:var(--panel2);box-shadow:none}.card h2,.card h3{margin:0 0 10px}.card h2{font-size:22px}.card h3{font-size:17px}.card p{color:var(--muted);line-height:1.72;margin:8px 0}
.hero{padding:20px;background:linear-gradient(135deg,#4f46e5,#8b5cf6);color:#fff;border:0;overflow:hidden;position:relative}.hero:after{content:"";position:absolute;right:-30px;top:-40px;width:170px;height:170px;border-radius:999px;background:rgba(255,255,255,.14)}.hero p{color:rgba(255,255,255,.82)}
.stat{display:flex;flex-direction:column;gap:4px;padding:14px;border-radius:18px;background:var(--panel);border:1px solid var(--line)}.stat b{font-size:26px}.stat span{font-size:12px;color:var(--muted)}
.row{display:flex;gap:10px;align-items:center}.row.wrap{flex-wrap:wrap}.row.between{justify-content:space-between}.grow{flex:1}.muted{color:var(--muted)!important}.small{font-size:12px}.tiny{font-size:11px}.danger{color:var(--bad)!important}.good{color:var(--good)!important}.warn{color:var(--warn)!important}
.btn{display:inline-flex;align-items:center;justify-content:center;gap:7px;min-height:42px;padding:10px 14px;border-radius:15px;background:var(--primary);color:#fff;font-weight:700;box-shadow:0 10px 24px rgba(79,70,229,.22)}.btn.secondary{background:var(--panel2);color:var(--text);box-shadow:none;border:1px solid var(--line)}.btn.ghost{background:transparent;color:var(--primary);box-shadow:none}.btn.good{background:var(--good);color:#fff}.btn.warn{background:var(--warn);color:#fff}.btn.bad{background:var(--bad);color:#fff}.btn:disabled{opacity:.55;cursor:not-allowed}
.input,textarea,select{width:100%;border:1px solid var(--line);background:var(--panel);color:var(--text);border-radius:15px;padding:12px 13px;outline:none}textarea{resize:vertical;min-height:84px;line-height:1.6}.input:focus,textarea:focus,select:focus{border-color:var(--primary);box-shadow:0 0 0 4px rgba(79,70,229,.10)}label{display:block;font-size:13px;color:var(--muted);margin:10px 0 6px}.form-grid{display:grid;grid-template-columns:1fr 1fr;gap:10px}.form-grid.one{grid-template-columns:1fr}
.chip{display:inline-flex;align-items:center;gap:5px;padding:7px 10px;border-radius:999px;background:var(--panel2);border:1px solid var(--line);font-size:12px;color:var(--muted)}.chip.primary{background:rgba(79,70,229,.10);border-color:rgba(79,70,229,.22);color:var(--primary)}.chip.good{background:rgba(22,163,74,.10);border-color:rgba(22,163,74,.22);color:var(--good)}.chip.warn{background:rgba(217,119,6,.10);border-color:rgba(217,119,6,.22);color:var(--warn)}.chip.bad{background:rgba(220,38,38,.10);border-color:rgba(220,38,38,.22);color:var(--bad)}
.list{display:grid;gap:10px}.list-item{display:block;text-align:left;width:100%;padding:14px;border-radius:18px;background:var(--panel);border:1px solid var(--line);color:var(--text);box-shadow:0 8px 22px rgba(15,23,42,.06)}.list-item h4{margin:0 0 6px;font-size:16px}.list-item p{margin:0;color:var(--muted);font-size:13px;line-height:1.55}.list-actions{display:flex;gap:8px;margin-top:10px;flex-wrap:wrap}.mini-btn{padding:7px 10px;min-height:32px;border-radius:12px;background:var(--panel2);border:1px solid var(--line);color:var(--text);font-size:12px}
.nav{position:fixed;left:50%;transform:translateX(-50%);bottom:0;z-index:30;width:min(980px,100%);padding:9px 10px calc(9px + env(safe-area-inset-bottom));background:color-mix(in srgb,var(--panel) 92%,transparent);backdrop-filter:blur(20px);border-top:1px solid var(--line);display:grid;grid-template-columns:repeat(5,1fr);gap:6px}.nav button{display:flex;flex-direction:column;align-items:center;gap:4px;background:transparent;color:var(--muted);border-radius:15px;padding:8px 2px;font-size:11px}.nav button b{font-size:18px;line-height:1}.nav button.active{background:rgba(79,70,229,.10);color:var(--primary);font-weight:800}
.reader{font-family:Georgia,"Times New Roman","PingFang SC",serif}.article-title{font-size:30px;line-height:1.18;margin:0 0 10px}.paragraph{font-size:19px;line-height:2.05;margin:18px 0}.sentence{border-radius:9px;transition:.15s}.sentence:active{background:rgba(79,70,229,.12)}.word{display:inline;border-radius:6px;padding:0 1px;cursor:pointer}.word:hover,.word.active{background:rgba(79,70,229,.13);color:var(--primary)}.question{padding:14px;border-radius:18px;border:1px solid var(--line);background:var(--panel2);margin:10px 0}.option{display:flex;gap:8px;align-items:flex-start;margin:8px 0;padding:10px;border:1px solid var(--line);border-radius:14px;background:var(--panel)}.option.correct{border-color:rgba(22,163,74,.5);background:rgba(22,163,74,.09)}.option.wrong{border-color:rgba(220,38,38,.5);background:rgba(220,38,38,.08)}
.modal-backdrop{position:fixed;inset:0;z-index:50;background:rgba(15,23,42,.45);display:flex;align-items:flex-end;justify-content:center;padding:14px}.modal{width:min(720px,100%);max-height:min(84dvh,720px);overflow:auto;background:var(--panel);color:var(--text);border-radius:26px;padding:16px;box-shadow:0 30px 80px rgba(0,0,0,.35);border:1px solid var(--line)}.modal h3{margin:0 0 8px}.modal-section{padding:12px;border-radius:17px;background:var(--panel2);border:1px solid var(--line);margin:10px 0}.modal-close{position:sticky;top:0;float:right;background:var(--panel2);border:1px solid var(--line);border-radius:14px;width:38px;height:38px;color:var(--text)}
.toast{position:fixed;left:50%;bottom:96px;transform:translateX(-50%) translateY(20px);z-index:90;max-width:min(540px,calc(100% - 30px));background:#111827;color:#fff;padding:12px 14px;border-radius:15px;opacity:0;pointer-events:none;transition:.2s;box-shadow:0 14px 38px rgba(0,0,0,.28)}.toast.show{opacity:1;transform:translateX(-50%) translateY(0)}
.loader{width:36px;height:36px;border:4px solid rgba(79,70,229,.2);border-left-color:var(--primary);border-radius:50%;animation:spin 1s linear infinite}@keyframes spin{to{transform:rotate(360deg)}}
.empty{text-align:center;padding:32px 18px;color:var(--muted);border:1px dashed var(--line);border-radius:22px;background:var(--panel2)}.kbd{font-family:ui-monospace,SFMono-Regular,Menlo,Consolas,monospace;background:var(--panel2);border:1px solid var(--line);padding:2px 6px;border-radius:8px;font-size:12px}.hidden{display:none!important}
@media (min-width:760px){.screen{padding-left:22px;padding-right:22px}.desktop-2{display:grid;grid-template-columns:1.05fr .95fr;gap:14px}.paragraph{font-size:20px}.modal-backdrop{align-items:center}.nav{border-radius:26px 26px 0 0}.topbar-inner{padding:0 22px}}
@media (max-width:520px){.grid-2,.grid-3,.form-grid{grid-template-columns:1fr}.article-title{font-size:25px}.paragraph{font-size:18px}.hero{padding:17px}.brand h1{font-size:17px}.btn{width:100%}.row .btn{width:auto}.row.mobile-stack{align-items:stretch;flex-direction:column}.nav{grid-template-columns:repeat(5,1fr)}}