:root {
    --bg-color: #1e1e1e;
    --panel-color: #2a2a2a;
    --border-color: #444;
    --text-color: #d4d4d4;
    --accent-color: #00aaff;
    --accent-color-dim: #0077b3;
    --active-color: #4CAF50;
    --pad-color: #3c3c3c;
    --pad-active-color: var(--accent-color);
    --grid-line-color: #333;
    --font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol";
    --track-header-width: 180px;
    --timeline-ruler-height: 30px;
    --solo-color: #ffc107;
    --mute-color: #2196F3;
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html, body {
    height: 100%;
    overflow: hidden;
    font-family: var(--font-family);
    background-color: var(--bg-color);
    color: var(--text-color);
    font-size: 14px;
}

#app {
    display: grid;
    grid-template-areas:
        "header"
        "main"
        "mixer";
    grid-template-rows: auto 1fr auto;
    grid-template-columns: 1fr;
    height: 100vh;
    gap: 8px;
    padding: 8px;
}

button, input, select {
    font-family: inherit;
    background-color: var(--panel-color);
    color: var(--text-color);
    border: 1px solid var(--border-color);
    border-radius: 4px;
    padding: 6px 10px;
    font-size: 1em;
}

button {
    cursor: pointer;
    transition: background-color 0.2s;
}

button:hover {
    background-color: #3f3f3f;
}

button:active {
    background-color: var(--accent-color-dim);
}

input[type="number"], input[type="text"], select {
    width: 80px;
}

input[type="text"]#seed {
    width: 120px;
}

/* Header */
#global-controls {
    grid-area: header;
    background-color: var(--panel-color);
    border-radius: 4px;
    padding: 10px 20px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    border: 1px solid var(--border-color);
}

.header-left-controls, .header-right-controls {
    display: flex;
    align-items: center;
    gap: 20px;
}

#global-controls h1 {
    font-size: 1.5em;
    margin: 0;
}

.control-group {
    display: flex;
    align-items: center;
    gap: 8px;
}

#random-seed {
    padding: 6px;
    width: 36px;
}

/* Main Content Layout */
#main-content {
    grid-area: main;
    display: flex;
    overflow: hidden;
    background-color: var(--panel-color);
    border: 1px solid var(--border-color);
    border-radius: 4px;
}

#main-content:focus {
    outline: none;
}

#track-headers {
    width: var(--track-header-width);
    flex-shrink: 0;
    padding-top: var(--timeline-ruler-height);
    background-color: #252525;
}

.track-header {
    height: 100px;
    padding: 10px;
    border-bottom: 1px solid var(--border-color);
    display: grid;
    grid-template-columns: 1fr;
    grid-template-rows: auto 1fr 1fr;
    gap: 6px;
    align-items: center;
    cursor: pointer;
    transition: background-color 0.2s ease;
}

.track-header.focused {
    background-color: #3a3a3a;
    box-shadow: inset 4px 0 0 var(--accent-color);
}


.track-header h2 {
    font-size: 1.2em;
    grid-column: 1 / -1;
    grid-row: 1;
    margin: 0;
}

.track-header .generate-btn,
.track-header .export-track-midi-btn {
    width: 100%;
    height: 100%;
}

.track-header .generate-btn {
    grid-row: 2;
}
.track-header .export-track-midi-btn {
    grid-row: 3;
}

.export-track-midi-btn {
    background-color: var(--accent-color-dim);
    font-size: 0.9em;
    opacity: 0.8;
}

.export-track-midi-btn:hover {
    background-color: var(--accent-color);
    opacity: 1;
}

#timeline-view {
    flex-grow: 1;
    overflow-x: auto;
    overflow-y: hidden;
}

#timeline-ruler {
    height: var(--timeline-ruler-height);
    background-color: #252525;
    position: sticky;
    top: 0;
    z-index: 5;
    border-bottom: 1px solid var(--border-color);
    display: flex;
}

.ruler-marker {
    flex-shrink: 0;
    border-left: 1px solid #666;
    padding-left: 5px;
    font-size: 0.8em;
    color: #999;
}

#track-lanes-container {
    position: relative;
}

#playhead {
    position: absolute;
    top: 0;
    left: 0;
    width: 2px;
    height: 100%;
    background-color: var(--active-color);
    pointer-events: none;
    z-index: 10;
    transition: transform 0.05s linear;
}

.track-lane {
    height: 100px;
    position: relative;
    border-bottom: 1px solid var(--border-color);
    cursor: cell;
}

.piano-roll-note {
    position: absolute;
    background-color: var(--accent-color-dim);
    border: 1px solid var(--accent-color);
    border-radius: 2px;
    opacity: 0.9;
    overflow: hidden;
    white-space: nowrap;
    font-size: 0.8em;
    padding-left: 4px;
    cursor: grab;
    user-select: none;
    box-shadow: 0 0 0 1px var(--bg-color); /* Creates a visual gap */
}

.piano-roll-note:active {
    cursor: grabbing;
}

.piano-roll-note .resize-handle {
    position: absolute;
    right: 0;
    top: 0;
    width: 8px;
    height: 100%;
    cursor: ew-resize;
}

.piano-roll-note:hover {
    opacity: 1;
}

.piano-roll-note.drum-note {
    background-color: #ff9800;
    border-color: #f57c00;
}

.piano-roll-note.selected {
    outline: 2px solid white;
    z-index: 20;
    opacity: 1;
    background-color: var(--accent-color);
}

.piano-roll-note.drum-note.selected {
    background-color: #ffb74d;
    border-color: #ffa726;
}


/* Mixer */
#mixer {
    grid-area: mixer;
    background-color: var(--panel-color);
    border: 1px solid var(--border-color);
    border-top: 2px solid var(--border-color);
    border-radius: 4px;
    padding: 15px;
    display: grid;
    grid-template-columns: repeat(4, 1fr) 1fr;
    gap: 20px;
    height: 310px;
    align-items: end;
}

.channel-strip {
    padding: 10px;
    background-color: #252525;
    border-radius: 4px;
    border: 1px solid var(--border-color);
    width: auto; /* Fill grid cell */
}

.channel-strip-inner {
    display: grid;
    grid-template-rows: 24px 1fr auto;
    gap: 10px;
    align-items: center;
    justify-items: center;
    width: 100%;
    height: 100%;
}

.fader-container {
    display: flex;
    gap: 4px;
    height: 100%;
    width: 100%;
    align-items: center;
    justify-content: center;
    background-color: #1a1a1a;
    border: 1px solid #111;
    border-radius: 3px;
    padding: 8px 4px;
}

.meter-container {
    height: 100%;
    max-height: 150px;
    display: flex;
    gap: 4px;
    background-color: #111;
    border: 1px solid #111;
    border-radius: 2px;
    position: relative;
    overflow: hidden;
    padding: 2px;
}

.vu-meter {
    display: block;
    width: 10px;
}

.volume-fader {
    -webkit-appearance: none;
    appearance: none;
    width: 150px; /* This is the length of the slider, matches VU meter height */
    height: 8px;  /* This is the thickness of the track */
    background: #111;
    outline: none;
    margin: 0;
    transform-origin: 50% 50%;
    transform: rotate(270deg);
    cursor: pointer;
    border: 1px solid #111;
    border-radius: 4px;
}


.volume-fader::-webkit-slider-thumb {
    -webkit-appearance: none;
    appearance: none;
    width: 32px;
    height: 30px;
    background: #5a5a5a;
    border: 1px solid #888;
    cursor: pointer;
    border-radius: 3px;
    box-shadow: 0 1px 1px rgba(0,0,0,0.5);
}

.volume-fader::-moz-range-thumb {
    width: 32px;
    height: 30px;
    background: #5a5a5a;
    border: 1px solid #888;
    cursor: pointer;
    border-radius: 3px;
    box-shadow: 0 1px 1px rgba(0,0,0,0.5);
}

.pan-container {
    display: flex;
    flex-direction: column;
    align-items: center;
    width: 100%;
    height: 100%;
}

.pan-slider {
    -webkit-appearance: none;
    appearance: none;
    width: 90px;
    height: 10px;
    background-color: transparent;
    cursor: pointer;
    margin: 0;
}

.pan-slider::-webkit-slider-runnable-track {
    width: 100%;
    height: 4px;
    background: #1a1a1a;
    border-radius: 2px;
    border: 1px solid #111;
}

.pan-slider::-moz-range-track {
    width: 100%;
    height: 4px;
    background: #1a1a1a;
    border-radius: 2px;
    border: 1px solid #111;
}

.pan-slider::-webkit-slider-thumb {
    -webkit-appearance: none;
    appearance: none;
    height: 16px;
    width: 16px;
    background-color: #ccc;
    border-radius: 50%;
    border: 1px solid #555;
    margin-top: -7px; /* Center thumb */
}

.pan-slider::-moz-range-thumb {
    height: 16px;
    width: 16px;
    background-color: #ccc;
    border-radius: 50%;
    border: 1px solid #555;
}

.channel-controls {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 4px;
    width: 100%;
    padding-bottom: 4px;
}

.mute-solo-container {
    display: flex;
    gap: 6px;
    min-height: 25px; /* Ensures placeholder takes up space */
}

.mute-solo-container .mute-btn,
.mute-solo-container .solo-btn {
    width: 30px;
    height: 25px;
    padding: 0;
    font-size: 0.9em;
    font-weight: bold;
    border-radius: 3px;
}

.track-name-label {
    background-color: transparent;
    border: none;
    color: var(--text-color);
    width: 100%;
    text-align: center;
    padding: 0;
    border-radius: 0;
    font-size: 0.9em;
    opacity: 0.8;
}

.master-channel {
    /* Special styling for the master channel if needed, e.g., slight separation */
    border-left: 2px solid var(--border-color);
    padding-left: 20px;
}

.mute-btn.active {
    background-color: var(--mute-color);
    color: #fff;
}
.solo-btn.active {
    background-color: var(--solo-color);
    color: #111;
}


/* Transport & Footer */
.transport-controls {
    display: flex;
    align-items: center;
    gap: 10px;
}
#play-btn, #stop-btn {
    font-size: 1.2em;
    width: 44px;
    height: 36px;
}
#play-btn.playing {
    color: var(--active-color);
}

#position-display {
    font-family: 'monospace';
    font-size: 1.5em;
    color: var(--accent-color);
}

.export-controls button {
    background-color: var(--accent-color-dim);
}
.export-controls button:hover {
    background-color: var(--accent-color);
}