:root{--bg: #0b0f14;--bg-elevated: #111820;--card: #161f2b;--border: #243142;--text: #e8edf2;--text-muted: #8b9cb3;--primary: #3b82f6;--primary-hover: #2563eb;--success: #22c55e;--error: #ef4444;--warning: #f59e0b;--accent: #8b5cf6;--shadow: 0 10px 30px rgba(0,0,0,.35);--radius: 14px;--radius-sm: 8px;--transition: .18s ease}*{box-sizing:border-box;margin:0;padding:0}html,body,#app{height:100%}body{font-family:Inter,system-ui,sans-serif;background:var(--bg);color:var(--text);line-height:1.6;-webkit-font-smoothing:antialiased}.mono{font-family:JetBrains Mono,monospace}a{color:var(--primary);text-decoration:none}a:hover{text-decoration:underline}.app{min-height:100vh;display:flex;flex-direction:column}.header{padding:18px 24px;border-bottom:1px solid var(--border);background:#111820d9;backdrop-filter:blur(8px);position:sticky;top:0;z-index:10}.header-inner{max-width:960px;margin:0 auto;display:flex;align-items:center;justify-content:space-between;gap:16px}.logo{display:flex;align-items:center;gap:10px;font-weight:700;font-size:1.2rem;color:var(--text)}.logo svg{width:28px;height:28px;color:var(--primary)}.nav{display:flex;gap:6px}.nav-btn{padding:8px 16px;border:1px solid transparent;background:transparent;color:var(--text-muted);border-radius:var(--radius-sm);font-weight:500;cursor:pointer;transition:var(--transition)}.nav-btn:hover{color:var(--text);background:var(--card);border-color:var(--border)}.nav-btn.active{color:var(--primary);background:#3b82f61f;border-color:var(--primary)}.main{flex:1;padding:32px 24px}.main-inner{max-width:860px;margin:0 auto;width:100%}.card{background:var(--card);border:1px solid var(--border);border-radius:var(--radius);padding:28px;box-shadow:var(--shadow)}.card-title{font-size:1.15rem;font-weight:600;margin-bottom:20px;display:flex;align-items:center;gap:10px}.card-title svg{width:22px;height:22px;color:var(--primary)}.btn{display:inline-flex;align-items:center;justify-content:center;gap:8px;padding:12px 22px;border-radius:var(--radius-sm);font-weight:600;font-size:.95rem;border:none;cursor:pointer;transition:var(--transition)}.btn:disabled{opacity:.5;cursor:not-allowed}.btn-primary{background:var(--primary);color:#fff}.btn-primary:hover:not(:disabled){background:var(--primary-hover)}.btn-secondary{background:var(--bg-elevated);color:var(--text);border:1px solid var(--border)}.btn-secondary:hover:not(:disabled){background:var(--border)}.btn-success{background:var(--success);color:#fff}.btn-danger{background:var(--error);color:#fff}.btn-ghost{background:transparent;color:var(--text-muted)}.btn-ghost:hover{color:var(--text)}.btn-icon{padding:10px;border-radius:50%}.btn-icon svg{width:20px;height:20px}.input-wrap{position:relative}.input{width:100%;padding:14px 16px;background:var(--bg);border:1px solid var(--border);border-radius:var(--radius-sm);color:var(--text);font-size:1rem;font-family:inherit;transition:var(--transition)}.input:focus{outline:none;border-color:var(--primary);box-shadow:0 0 0 3px #3b82f626}.input::placeholder{color:var(--text-muted)}.audio-player{display:flex;align-items:center;gap:14px;padding:16px;background:var(--bg-elevated);border:1px solid var(--border);border-radius:var(--radius-sm);margin-bottom:20px}.audio-btn{width:48px;height:48px;border-radius:50%;background:var(--primary);color:#fff;border:none;cursor:pointer;display:flex;align-items:center;justify-content:center;transition:var(--transition);flex-shrink:0}.audio-btn:hover{background:var(--primary-hover);transform:scale(1.05)}.audio-btn:disabled{opacity:.4;cursor:not-allowed;transform:none}.audio-btn svg{width:22px;height:22px}.audio-progress{flex:1;height:6px;background:var(--border);border-radius:3px;cursor:pointer;position:relative}.audio-progress-fill{height:100%;background:var(--primary);border-radius:3px;width:0%;transition:width .1s linear}.audio-time{font-size:.8rem;color:var(--text-muted);font-variant-numeric:tabular-nums;min-width:80px;text-align:right}.dictation-sentence{font-size:1.1rem;line-height:1.8;margin-bottom:16px;min-height:2.5em}.dictation-sentence .word{display:inline-block;padding:2px 4px;border-radius:4px;margin:0 2px;transition:var(--transition)}.dictation-sentence .word.correct{background:#22c55e26;color:var(--success)}.dictation-sentence .word.incorrect{background:#ef444426;color:var(--error);text-decoration:underline;text-decoration-color:var(--error)}.dictation-sentence .word.pending{color:var(--text-muted)}.dictation-input{font-size:1.1rem;line-height:1.8}.shadowing-wave{height:60px;display:flex;align-items:flex-end;gap:3px;justify-content:center;margin:20px 0}.wave-bar{width:4px;background:var(--primary);border-radius:2px;transition:height .05s ease}.shadowing-result{margin-top:20px}.accuracy-ring{width:140px;height:140px;margin:0 auto 16px}.accuracy-text{text-align:center;font-size:2.5rem;font-weight:700;color:var(--primary)}.accuracy-label{text-align:center;color:var(--text-muted);margin-top:4px}.quiz-options{display:grid;gap:10px}.quiz-option{padding:14px 18px;background:var(--bg-elevated);border:2px solid var(--border);border-radius:var(--radius-sm);color:var(--text);font-size:1rem;cursor:pointer;text-align:left;transition:var(--transition)}.quiz-option:hover{border-color:var(--primary)}.quiz-option.selected{border-color:var(--primary);background:#3b82f61a}.quiz-option.correct{border-color:var(--success);background:#22c55e26}.quiz-option.incorrect{border-color:var(--error);background:#ef444426}.stats-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(140px,1fr));gap:16px;margin-top:20px}.stat-card{background:var(--bg-elevated);border:1px solid var(--border);border-radius:var(--radius-sm);padding:18px;text-align:center}.stat-value{font-size:2rem;font-weight:700;color:var(--primary)}.stat-label{font-size:.8rem;color:var(--text-muted);margin-top:4px}.progress-bar{height:8px;background:var(--border);border-radius:4px;overflow:hidden;margin:16px 0}.progress-fill{height:100%;background:var(--primary);border-radius:4px;transition:width .3s ease}.lesson-list{display:grid;gap:12px}.lesson-item{display:flex;align-items:center;justify-content:space-between;padding:16px;background:var(--bg-elevated);border:1px solid var(--border);border-radius:var(--radius-sm);cursor:pointer;transition:var(--transition)}.lesson-item:hover{border-color:var(--primary);background:#3b82f60d}.lesson-info{flex:1}.lesson-title{font-weight:600;margin-bottom:4px}.lesson-meta{font-size:.85rem;color:var(--text-muted);display:flex;gap:16px}.lesson-progress{width:80px;height:6px;background:var(--border);border-radius:3px;overflow:hidden;margin-left:16px}.lesson-progress-fill{height:100%;background:var(--success);border-radius:3px}.mode-badge{display:inline-flex;align-items:center;gap:6px;padding:4px 12px;border-radius:999px;font-size:.75rem;font-weight:600;text-transform:uppercase;letter-spacing:.05em}.mode-dictation{background:#3b82f626;color:var(--primary)}.mode-shadowing{background:#8b5cf626;color:var(--accent)}.mode-quiz{background:#f59e0b26;color:var(--warning)}.toast-container{position:fixed;bottom:24px;right:24px;z-index:100;display:flex;flex-direction:column;gap:10px}.toast{padding:14px 20px;background:var(--card);border:1px solid var(--border);border-radius:var(--radius-sm);box-shadow:var(--shadow);display:flex;align-items:center;gap:10px;animation:slideIn .3s ease}.toast.success{border-left:4px solid var(--success)}.toast.error{border-left:4px solid var(--error)}@keyframes slideIn{0%{opacity:0;transform:translate(100px)}to{opacity:1;transform:translate(0)}}.empty-state{text-align:center;padding:60px 20px;color:var(--text-muted)}.empty-state svg{width:64px;height:64px;margin-bottom:16px;opacity:.5}@media (max-width: 640px){.header{padding:14px 16px}.main{padding:20px 16px}.card{padding:20px}.nav-btn{padding:6px 12px;font-size:.85rem}.stats-grid{grid-template-columns:1fr 1fr}}