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var(--border-color);flex-shrink:0;justify-content:space-between;align-items:center;padding:0 20px;display:flex}.header-left{align-items:center;gap:12px;display:flex}.header-title{color:var(--accent-blue);letter-spacing:-.02em;font-size:1.2rem;font-weight:700}.header-subtitle{color:var(--text-muted);font-size:.85rem}.header-right{align-items:center;gap:8px;display:flex}.btn-icon{color:var(--text-secondary);cursor:pointer;border-radius:var(--radius-sm);background:0 0;border:none;padding:4px 8px;font-size:1.2rem;transition:background .15s}.btn-icon:hover{background:var(--bg-tertiary)}.btn-icon:focus-visible{outline:2px solid var(--accent-blue);outline-offset:2px}.empty-content{text-align:center;height:100%;color:var(--text-muted);flex-direction:column;justify-content:center;align-items:center;display:flex}.empty-content h2{color:var(--accent-blue);margin-bottom:8px;font-size:1.5rem}.empty-content p{font-size:.9rem}.btn-primary{background:var(--accent-blue);color:#fff;border-radius:var(--radius-sm);cursor:pointer;border:none;padding:8px 20px;font-size:.85rem;font-weight:600;transition:opacity .15s}.btn-primary:hover{opacity:.9}.btn-primary:focus-visible{outline:2px solid var(--accent-blue);outline-offset:2px}.btn-primary:disabled{opacity:.5;cursor:not-allowed}.btn-secondary{border:1px solid var(--border-color);color:var(--text-muted);border-radius:var(--radius-sm);cursor:pointer;background:0 0;padding:8px 20px;font-size:.85rem;transition:all .15s}.btn-secondary:hover{border-color:var(--text-secondary);color:var(--text-secondary)}.btn-secondary:focus-visible{outline:2px solid var(--accent-blue);outline-offset:2px}.btn-lg{padding:12px 32px;font-size:1rem}.btn-challenge{border:2px solid var(--accent-orange);color:var(--accent-orange);cursor:pointer;border-radius:var(--radius-sm);background:0 0;padding:4px 10px;font-size:1.1rem;transition:all 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