/* Core */
:root{--bg:#f5f5f7;--card:#fff;--text:#1d1d1f;--muted:#86868b;--blue:#0071e3;--green:#34c759;--red:#ff3b30;--orange:#ff9500;--border:#d2d2d7;--radius:16px;--shadow:0 4px 20px rgba(0,0,0,.06);font-family:-apple-system,BlinkMacSystemFont,"SF Pro Display","PingFang SC","Microsoft YaHei",sans-serif}
*{box-sizing:border-box}body{margin:0;background:var(--bg);color:var(--text)}button,input,textarea{font:inherit}.container{max-width:920px;margin:0 auto;padding:28px 24px 90px}.navbar{height:62px;position:sticky;top:0;z-index:9;display:flex;align-items:center;gap:14px;padding:0 max(20px,calc((100vw - 920px)/2));background:rgba(245,245,247,.86);backdrop-filter:blur(18px);border-bottom:1px solid rgba(0,0,0,.06)}.brand{border:0;background:none;color:var(--text);font-weight:700;font-size:17px;padding:8px 0;white-space:nowrap;cursor:pointer}.navbar-nav{display:flex;gap:3px;flex:1}.nav-item,.account-menu button{border:0;background:transparent;border-radius:9px;padding:7px 10px;color:var(--muted);cursor:pointer;font-size:14px}.nav-item:hover,.nav-item.active{color:var(--blue);background:#e8f0fe}.account-menu{display:flex;align-items:center;gap:4px;color:var(--muted);font-size:13px;white-space:nowrap}.account-menu button{color:var(--text)}
/* Auth */.auth-page{min-height:100vh;display:grid;place-items:center;padding:24px}.auth-panel{width:min(100%,390px);background:var(--card);box-shadow:var(--shadow);padding:34px;border-radius:var(--radius);text-align:center}.auth-mark{width:50px;height:50px;display:grid;place-items:center;margin:0 auto 14px;border-radius:14px;background:#e8f0fe;color:var(--blue);font-size:30px;font-weight:700}.auth-panel h1{margin:0;font-size:25px}.auth-panel>p{color:var(--muted);font-size:14px;margin:8px 0 22px}.auth-panel label{display:block;text-align:left;font-size:13px;font-weight:600;margin:12px 0}.auth-panel input{display:block;width:100%;border:1px solid var(--border);border-radius:10px;padding:11px 12px;margin-top:6px;outline:0}.auth-panel input:focus{border-color:var(--blue)}.auth-actions{display:grid;grid-template-columns:1fr 1fr;gap:10px;margin-top:18px}.btn-primary,.btn-secondary{border-radius:10px;padding:10px 14px;cursor:pointer;font-weight:600}.btn-primary{border:1px solid var(--blue);background:var(--blue);color:#fff}.btn-secondary{border:1px solid var(--border);background:#fff;color:var(--text)}.auth-panel small{display:block;color:var(--muted);font-size:12px;margin-top:17px;line-height:1.5}.auth-error{color:var(--red);font-size:13px;min-height:18px;margin-top:8px}
/* Dashboard */.dashboard-hero{text-align:center;padding:18px 0 10px}.dashboard-hero h1{font-size:30px;margin:0}.dashboard-hero p{color:var(--muted);margin:6px}.progress-ring-container{display:flex;justify-content:center;margin:13px 0 22px}.progress-ring{width:140px;height:140px;position:relative}.progress-ring svg{transform:rotate(-90deg)}.progress-ring-bg,.progress-ring-fg{fill:none;stroke-width:8}.progress-ring-bg{stroke:var(--border)}.progress-ring-fg{stroke:var(--blue);stroke-linecap:round;transition:stroke-dashoffset .4s}.progress-ring-text{position:absolute;inset:0;display:flex;flex-direction:column;align-items:center;justify-content:center}.progress-ring-text b{font-size:27px}.progress-ring-text small{color:var(--muted)}.stats-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:12px;margin-bottom:12px}.stat-card{background:var(--card);border-radius:var(--radius);box-shadow:var(--shadow);padding:18px;text-align:center}.stat-card b{display:block;font-size:28px;color:var(--blue)}.stat-card span{font-size:13px;color:var(--muted)}.stat-card.green b{color:var(--green)}.stat-card.red b{color:var(--red)}.stat-card.orange b{color:var(--orange)}.section-title{font-size:22px;margin:30px 0 14px}.chapter-list{display:grid;gap:10px}.chapter-card{width:100%;display:flex;align-items:center;justify-content:space-between;text-align:left;border:0;background:var(--card);border-radius:var(--radius);box-shadow:var(--shadow);padding:18px 20px;cursor:pointer;color:var(--text)}.chapter-card:hover{transform:translateY(-1px);box-shadow:0 8px 28px rgba(0,0,0,.09)}.chapter-card b{display:block;font-size:16px}.chapter-card small{display:block;color:var(--muted);font-size:13px;margin-top:3px}.chapter-card strong{font-size:24px;color:var(--muted)}.chapter-progress-bar{width:100px;height:5px;border-radius:4px;background:var(--border);overflow:hidden;margin-top:9px}.chapter-progress-bar i{display:block;height:100%;background:var(--blue)}
/* Practice */.question-header{display:flex;align-items:center;justify-content:space-between;margin-bottom:16px}.breadcrumb{font-size:14px;color:var(--muted)}.breadcrumb button{border:0;background:transparent;color:var(--blue);padding:0;cursor:pointer}.question-nav{display:flex;align-items:center;gap:10px}.question-nav button{border:1px solid var(--border);background:#fff;border-radius:50%;width:32px;height:32px;cursor:pointer}.question-nav button:disabled{opacity:.35;cursor:default}.question-image-container{background:#fff;border-radius:var(--radius);box-shadow:var(--shadow);padding:22px;text-align:center}.question-image{max-width:100%;height:auto}.image-error{color:var(--red);padding:50px}.status-section,.notes-section{background:#fff;border-radius:var(--radius);box-shadow:var(--shadow);padding:19px;margin-top:16px}.status-section>b,.notes-section>b{display:block;color:var(--muted);font-size:14px;margin-bottom:10px}.status-buttons{display:flex;gap:9px}.status-buttons button{flex:1;border:2px solid var(--border);background:#fff;border-radius:10px;padding:11px;cursor:pointer;font-weight:600}.status-buttons .correct{border-color:var(--green);background:#edf9f0;color:#219842}.status-buttons .wrong{border-color:var(--red);background:#fff0ef;color:#d92c23}.status-buttons .flagged{border-color:var(--orange);background:#fff7e7;color:#cc7a00}.notes-section textarea{width:100%;height:100px;border:1px solid var(--border);border-radius:10px;padding:10px;resize:vertical}.note-save{margin-top:9px}.empty-state{padding:70px 20px;text-align:center;color:var(--muted)}
/* Upload */.upload-zone{background:#fff;border:2px dashed var(--border);border-radius:var(--radius);padding:48px 20px;text-align:center;cursor:pointer;display:grid;gap:8px}.upload-zone:hover,.upload-zone.drag-over{border-color:var(--blue);background:#f3f8ff}.upload-icon{font-size:42px}.upload-zone small{color:var(--muted)}.upload-progress-area{background:#fff;border-radius:var(--radius);box-shadow:var(--shadow);padding:17px;margin:14px 0}.progress-bar-container{height:8px;background:var(--border);border-radius:5px;overflow:hidden}.progress-bar-container i{display:block;height:100%;width:0;background:var(--blue);transition:width .35s}.admin-book{cursor:default}.btn-delete{border:1px solid var(--red);background:#fff1f0;color:var(--red);border-radius:9px;padding:8px 12px;cursor:pointer}
@media(max-width:720px){.navbar{padding:0 12px;gap:8px}.brand{font-size:0}.brand:first-letter{font-size:22px}.navbar-nav{overflow:auto}.nav-item{padding:7px}.account-menu span{display:none}.container{padding:20px 14px 70px}.stats-grid{grid-template-columns:repeat(2,1fr)}.dashboard-hero h1{font-size:25px}.status-buttons{flex-direction:column}.question-header{align-items:flex-start;gap:10px;flex-direction:column}.auth-panel{padding:28px 22px}}