/* TRACK HEADERS (LEFT) */
.track-headers {
    width: 130px; /* Reduced drastically from 250px */
    background: var(--bg-dark);
    border-right: 1px solid rgba(255,255,255,0.1);
    z-index: 10;
    overflow-y: hidden;
    overflow-x: hidden;
    display: flex;
    flex-direction: column;
    padding-top: var(--ruler-h); /* Align with lanes */
}

.track-header {
    height: var(--track-h);
    padding: 5px 8px; /* Reduced padding */
    border-bottom: 2px solid rgba(255,255,255,0.15); /* Match track lane divider */
    display: flex;
    flex-direction: column;
    justify-content: center;
    gap: 3px;
    transition: background 0.2s;
}

.track-header.drag-over {
    background: rgba(139, 92, 246, 0.3); /* Primary color */
    border-right: 3px solid var(--primary);
}

.track-top {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 2px;
}

.track-btn-group {
    display: flex;
    gap: 4px;
}

.track-name {
    font-size: 0.85rem;
    font-weight: bold;
    color: var(--text);
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
    flex: 1;
}

.btn-mute, .btn-add-file {
    background: rgba(255,255,255,0.1);
    border: none;
    color: white;
    width: 20px;
    height: 20px;
    border-radius: 4px;
    cursor: pointer;
    font-size: 0.7rem;
    font-weight: bold;
    display: flex;
    align-items: center;
    justify-content: center;
}

.btn-mute:hover, .btn-add-file:hover {
    background: rgba(255,255,255,0.2);
}

.btn-mute.muted {
    background: #ef4444; /* red */
}

.btn-add-file {
    background: var(--primary); /* subtle purple */
}

.btn-add-file:hover {
    background: var(--accent); /* green on hover */
}

.vol-slider {
    width: 100%;
    accent-color: var(--primary);
}