:root{--bg: #1f1633;--bg-deep: #150f23;--bg-elevated: #261d3f;--surface: rgba(255, 255, 255, .06);--surface-hover: rgba(255, 255, 255, .1);--surface-active: rgba(255, 255, 255, .14);--primary: #6a5fc1;--primary-dark: #584674;--primary-light: rgba(106, 95, 193, .15);--primary-glow: rgba(106, 95, 193, .25);--muted-purple: #79628c;--muted-purple-border: #584674;--accent: #c2ef4e;--accent-bg: rgba(194, 239, 78, .12);--success: #c2ef4e;--success-bg: rgba(194, 239, 78, .12);--danger: #fa7faa;--danger-bg: rgba(250, 127, 170, .12);--coral: #ffb287;--coral-bg: rgba(255, 178, 135, .12);--gold: #ffb287;--gold-bg: rgba(255, 178, 135, .12);--text: #ffffff;--text-soft: #e5e7eb;--text-light: #9ca3af;--text-muted: #6b7280;--border: rgba(255, 255, 255, .08);--border-hover: rgba(255, 255, 255, .15);--border-subtle: rgba(255, 255, 255, .05);--shadow-sm: 0 1px 2px rgba(0, 0, 0, .3);--shadow: 0 4px 12px rgba(0, 0, 0, .25), 0 2px 4px rgba(0, 0, 0, .2);--shadow-lg: 0 10px 30px rgba(0, 0, 0, .35), 0 4px 12px 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var(--border),var(--shadow-inset);text-align:center;font-size:1.875rem;font-weight:700;font-family:var(--font-mono);background:var(--bg-elevated);color:var(--text);transition:all .12s;outline:none}.letter-box:focus{box-shadow:0 0 0 2px var(--primary),var(--shadow-inset);background:#6a5fc126}.letter-correct{box-shadow:0 0 0 2px var(--accent)!important;background:var(--accent-bg)!important;color:var(--accent)!important}.letter-wrong{box-shadow:0 0 0 2px var(--danger)!important;background:var(--danger-bg)!important;color:var(--danger)!important;animation:shake .35s}.result-screen{display:flex;justify-content:center;align-items:center;min-height:60vh}.result-card{background:var(--surface);border-radius:var(--radius-xl);padding:44px 36px;text-align:center;box-shadow:0 0 0 1px 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16px;cursor:pointer}.unit-card-left{display:flex;align-items:center;gap:10px}.unit-key-badge{background:var(--primary-light);color:var(--primary);font-size:.625rem;font-weight:700;padding:3px 8px;border-radius:4px;text-transform:uppercase;letter-spacing:.3px}.unit-title-text{font-size:.875rem;font-weight:600;color:var(--text)}.unit-card-right{display:flex;align-items:center;gap:10px}.unit-stars{font-size:.875rem}.unit-stars .star-lit{color:var(--coral)}.unit-score{font-size:.6875rem;color:var(--text-light);min-width:40px;text-align:right}.expand-icon{font-size:.625rem;color:var(--text-light)}.unit-progress-mini{height:5px;background:#0003;border-radius:3px;display:flex;margin:0 16px;overflow:hidden;box-shadow:var(--shadow-inset)}.prog-bar-segment{height:100%}.prog-bar-segment.mastered{background:var(--accent)}.prog-bar-segment.learning{background:var(--primary)}.prog-bar-segment.need{background:var(--danger)}.unit-progress-labels{display:flex;justify-content:space-between;padding:8px 16px 12px;font-size:.625rem}.unit-progress-labels .label{display:flex;align-items:center;gap:4px}.unit-progress-labels .label.mastered{color:var(--accent)}.unit-progress-labels .label.learning{color:var(--primary)}.unit-progress-labels .label.need{color:var(--danger)}.unit-card-details{padding:0 16px 16px;border-top:1px solid var(--border);margin-top:4px}.detail-section{margin-top:14px}.detail-section h4{font-size:.75rem;font-weight:600;color:var(--text-soft);margin-bottom:8px}.word-tags{display:flex;flex-wrap:wrap;gap:5px}.word-tag{font-size:.6875rem;padding:4px 10px;border-radius:14px;font-weight:600}.word-tag.mastered{background:var(--accent-bg);color:var(--accent)}.word-tag.learning{background:var(--primary-light);color:var(--primary)}.word-tag.need{background:var(--danger-bg);color:var(--danger)}.word-tag small{font-size:.5625rem;opacity:.7;margin-left:3px}.no-words{font-size:.75rem;color:var(--text-light);text-align:center;padding:10px}.hard-words-grid{display:grid;grid-template-columns:repeat(4,1fr);gap:8px}.hard-word-card{background:var(--surface);box-shadow:0 0 0 1px #fa7faa26;border-radius:var(--radius);padding:10px 8px;text-align:center}.hw-word{display:block;font-size:.75rem;font-weight:600;color:var(--text);margin-bottom:3px}.hw-pct{font-size:.875rem;font-weight:700}.stats-footer{display:flex;align-items:center;justify-content:space-between;padding:14px 0}.stats-footer p{font-size:.6875rem;color:var(--text-light)}.btn-giveup{background:var(--surface);color:var(--text-soft);box-shadow:0 0 0 1px var(--border);padding:6px 12px;font-size:.75rem;border-radius:var(--radius-sm);cursor:pointer;text-transform:uppercase;letter-spacing:.2px;font-weight:600}.btn-giveup:hover{box-shadow:0 0 0 1px var(--danger);color:var(--danger)}.app-header-row{display:flex;align-items:flex-start;justify-content:space-between;gap:14px;margin-bottom:24px}.stats-card-btn{display:flex;align-items:center;gap:14px;background:var(--surface);box-shadow:0 0 0 1px var(--border);border-radius:var(--radius-lg);padding:12px 16px;cursor:pointer;transition:all .12s;flex-shrink:0;min-width:180px}.stats-card-btn:hover{background:var(--surface-hover);box-shadow:0 0 0 1px var(--border-hover),var(--shadow-glow);transform:translateY(-2px)}.stats-card-btn .stats-card-label{color:var(--text);font-size:.875rem;font-weight:600;line-height:1}.stats-card-btn .stats-card-arrow{color:var(--text-light);margin-left:auto;flex-shrink:0;transition:transform .12s,color .12s}.stats-card-btn .stats-card-icon{color:var(--primary)}.stats-card-icon{width:24px;height:24px;flex-shrink:0;color:var(--primary)}.stats-card-label{font-size:.875rem;font-weight:600;color:var(--text);line-height:1}.stats-card-arrow{font-size:1rem;color:var(--text-light);margin-left:auto;flex-shrink:0;transition:transform .12s,color .12s}.stats-card-btn:hover .stats-card-arrow{transform:translate(3px);color:var(--primary)}@media (max-width: 520px){.app{padding:16px 12px 48px}.app-header h1{font-size:1.75rem}.course-grid,.unit-grid{grid-template-columns:1fr}.result-card{padding:32px 24px}.result-score{font-size:3rem}.letter-box{width:48px;height:56px;font-size:1.5rem}}