/* ===== CSS VARIABLES ===== */
:root {
    --bg: hsl(225, 25%, 7%);
    --fg: hsl(225, 15%, 92%);
    --muted: hsl(225, 15%, 65%);
    --card: hsl(225, 25%, 11%);
    --accent: hsl(225, 100%, 74%);
    
    --border-subtle: hsla(0, 0%, 100%, 0.06);
    --border-normal: hsla(0, 0%, 100%, 0.12);
    --bg-subtle: hsla(0, 0%, 100%, 0.02);
    --bg-normal: hsla(0, 0%, 100%, 0.04);
    --bg-strong: hsla(0, 0%, 100%, 0.08);
    --accent-glow: hsla(225, 100%, 74%, 0.2);
    
    --hover-bg: hsla(0, 0%, 100%, 0.08);
    --hover-border: hsla(0, 0%, 100%, 0.2);
    
    --danger: hsl(6, 78%, 58%);
    --danger-bg: hsla(6, 78%, 58%, 0.1);
    
    --shadow-card: 0 10px 30px hsla(0, 0%, 0%, 0.25);
    --shadow-glow: 0 0 10px hsla(225, 100%, 74%, 0.2);
}

/* ===== BASE STYLES ===== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    background: #1a1a1a;
    color: #fff;
    overflow: hidden;
}

/* ===== LAYOUT COMPONENTS ===== */
.app {
    display: flex;
    height: 100vh;
    position: relative;
}

.background-canvas {
    position: fixed;
    top: 0;
    left: 0;
    width: 100vw;
    height: 100vh;
    z-index: -1;
    filter: blur(20px) brightness(0.3);
    opacity: 0.6;
    object-fit: cover;
    transform: scale(1.1);
    will-change: filter, opacity;
}

.canvas-container {
    flex: 1;
    display: flex;
    align-items: center;
    justify-content: center;
    background: #000;
    padding: 20px;
    box-sizing: border-box;
    position: relative;
    min-height: 0;
    overflow: hidden;
}

#canvas {
    border: 1px solid #333;
    display: block;
    border-radius: 8px;
    box-shadow: var(--shadow-card);
    cursor: grab;
    will-change: transform;
}

#canvas:active {
    cursor: grabbing;
}

/* ===== LOADING SCREEN ===== */
.loading {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    text-align: center;
    z-index: 10;
}

.spinner {
    width: 50px;
    height: 50px;
    border: 3px solid var(--border-normal);
    border-top: 3px solid var(--accent);
    border-radius: 50%;
    animation: spin 1s linear infinite;
    margin: 0 auto 20px;
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

/* ===== CONTROLS PANEL ===== */
.controls {
    width: 400px;
    background: rgba(16, 20, 28, 0.85);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    padding: 0.75rem;
    overflow-y: auto;
    border-left: 1px solid var(--border-subtle);
    flex-shrink: 0;
    display: flex;
    flex-direction: column;
    gap: 0.625rem;
}

.control-group {
    background: var(--card);
    border: 1px solid var(--border-subtle);
    border-radius: 1rem;
    padding: 0.75rem;
    box-shadow: var(--shadow-card);
    display: flex;
    flex-direction: column;
}

.control-group h3 {
    margin: 0 0 0.5rem 0;
    font-size: 1em;
    letter-spacing: .2px;
    color: var(--muted);
    text-transform: uppercase;
    font-weight: 600;
}

.control-group-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 0.5rem;
}

.control-group-header h3 {
    margin: 0;
}

.control-item {
    margin-bottom: 16px;
}

.control-item label {
    display: block;
    font-size: 0.75em;
    margin-bottom: 6px;
    color: var(--muted);
}

.value-display {
    float: right;
    font-size: 0.75em;
    color: var(--accent);
    font-variant-numeric: tabular-nums;
}

/* ===== FORM CONTROLS ===== */
.slider {
    width: 100%;
    height: 4px;
    background: var(--bg-strong);
    border-radius: 2px;
    outline: none;
    -webkit-appearance: none;
    appearance: none;
    cursor: pointer;
}

.slider::-webkit-slider-thumb {
    -webkit-appearance: none;
    width: 16px;
    height: 16px;
    background: var(--accent);
    border-radius: 50%;
    cursor: pointer;
    transition: all 0.2s ease;
}

.slider::-webkit-slider-thumb:hover {
    transform: scale(1.1);
    box-shadow: var(--shadow-glow);
}

.slider::-moz-range-thumb {
    width: 16px;
    height: 16px;
    background: var(--accent);
    border-radius: 50%;
    cursor: pointer;
    border: none;
    transition: all 0.2s ease;
}

input[type="checkbox"] {
    margin-right: 8px;
    accent-color: var(--accent);
}

/* ===== BUTTONS ===== */
.button {
    background: var(--accent);
    color: white;
    border: none;
    padding: 10px 16px;
    border-radius: 0.5rem;
    cursor: pointer;
    font-size: 0.75em;
    font-weight: 500;
    transition: all 0.2s ease;
    border: 1px solid var(--accent);
}

.button:hover {
    background: hsl(from var(--accent) h s calc(l * 0.85));
    border-color: hsl(from var(--accent) h s calc(l * 0.85));
    transform: translateY(-1px);
    box-shadow: var(--shadow-glow);
}

.button.secondary {
    background: var(--bg-normal);
    color: var(--fg);
    border-color: var(--border-normal);
}

.button.secondary:hover {
    background: var(--hover-bg);
    border-color: var(--hover-border);
    color: var(--accent);
}

button:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

button:disabled:hover {
    background: var(--bg-normal);
    border-color: var(--border-subtle);
    transform: none;
}

/* ===== DROPDOWNS ===== */
.dropdown-container {
    position: relative;
    display: flex;
    align-items: center;
    gap: 8px;
}

.dropdown {
    flex: 1;
    padding: 8px 12px;
    border: 1px solid var(--border-subtle);
    border-radius: 6px;
    background: var(--bg);
    color: var(--text);
    font-size: 0.9em;
    outline: none;
    transition: border-color 0.2s;
}

.dropdown:focus {
    border-color: var(--accent);
}

.dropdown-nav {
    display: flex;
    flex-direction: column;
    gap: 2px;
}

.dropdown-nav-btn {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 20px;
    height: 16px;
    border: 1px solid var(--border-subtle);
    border-radius: 3px;
    background: var(--bg);
    color: var(--muted);
    cursor: pointer;
    transition: all 0.2s ease;
    font-size: 0.8em;
    padding: 0;
}

.dropdown-nav-btn:hover {
    background: var(--bg-strong);
    border-color: var(--accent);
    color: var(--accent);
    transform: scale3d(1.1, 1.1, 1);
    will-change: transform;
}

.dropdown-nav-btn:active {
    transform: scale(0.95);
}

/* ===== COLOR CONTROLS ===== */
.color-controls {
    display: grid;
    grid-template-columns: 1fr 1fr 1fr;
    gap: 8px;
}

.color-item {
    display: flex;
    align-items: center;
    gap: 6px;
    padding: 8px;
    border-radius: 6px;
    transition: all 0.2s ease;
    cursor: grab;
    position: relative;
}

.color-label-group {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 2px;
}

.color-item:hover {
    background: var(--bg-subtle);
}

.color-item.dragging {
    opacity: 0.5;
    transform: rotate(2deg) translateZ(0);
    background: var(--bg-strong);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.3);
    will-change: transform, opacity;
}

.color-item.drag-over-left::before {
    content: '';
    position: absolute;
    left: -4px;
    top: 0;
    bottom: 0;
    width: 3px;
    background: var(--accent);
    border-radius: 2px;
    z-index: 10;
}

.color-item.drag-over-right::after {
    content: '';
    position: absolute;
    right: -4px;
    top: 0;
    bottom: 0;
    width: 3px;
    background: var(--accent);
    border-radius: 2px;
    z-index: 10;
}

.add-color-item {
    display: flex;
    align-items: center;
    justify-content: center;
    height: 48px;
    border: 1px dashed var(--border-normal);
    border-radius: 6px;
    background: var(--bg-normal);
    color: var(--accent);
    cursor: pointer;
    transition: all 0.2s ease;
    font-size: 1.2em;
}

.add-color-item:hover {
    background: var(--bg-strong);
    border-color: var(--accent);
    transform: scale(1.02);
}

.add-color-item:disabled {
    opacity: 0.5;
    cursor: not-allowed;
    background: var(--bg-normal);
    border-color: var(--border-subtle);
    transform: none;
}

.color-item label {
    font-size: 0.85em;
    color: var(--muted);
    white-space: nowrap;
    min-width: auto;
    margin-right: 2px;
    cursor: grab;
}

.color-picker {
    width: 40px;
    height: 32px;
    border: 1px solid var(--border-normal);
    border-radius: 6px;
    background: transparent;
    cursor: pointer;
    transition: border-color 0.2s ease;
    position: relative;
}

.color-picker.transparent {
    background-image: 
        linear-gradient(45deg, #ccc 25%, transparent 25%), 
        linear-gradient(-45deg, #ccc 25%, transparent 25%), 
        linear-gradient(45deg, transparent 75%, #ccc 75%), 
        linear-gradient(-45deg, transparent 75%, #ccc 75%);
    background-size: 8px 8px;
    background-position: 0 0, 0 4px, 4px -4px, -4px 0px;
}

.color-picker.transparent::-webkit-color-swatch {
    opacity: 0;
}

.color-picker:hover {
    border-color: var(--hover-border);
}

.color-picker::-webkit-color-swatch-wrapper {
    padding: 0;
    border: none;
    border-radius: 4px;
}

.color-picker::-webkit-color-swatch {
    border: none;
    border-radius: 4px;
}

.alpha-toggle {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 16px;
    height: 16px;
    border: 1px solid var(--border-normal);
    border-radius: 3px;
    background: var(--bg-normal);
    color: var(--muted);
    cursor: pointer;
    transition: all 0.2s ease;
    font-size: 0.7em;
    padding: 0;
}

.alpha-toggle:hover {
    background: var(--bg-strong);
    border-color: var(--accent);
    color: var(--accent);
    transform: scale3d(1.1, 1.1, 1);
    will-change: transform;
}

.alpha-toggle[data-alpha="0"] {
    color: var(--danger);
    border-color: var(--danger);
}

.alpha-toggle[data-alpha="0"] i {
    opacity: 0.5;
}

.drag-handle {
    color: var(--muted);
    font-size: 1.2em;
    cursor: grab;
    transition: color 0.2s ease;
    justify-self: center;
}

.drag-handle:hover {
    color: var(--accent);
}

.drag-handle:active {
    cursor: grabbing;
}

.trash-bin {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 100%;
    height: 36px;
    border: 1px dashed var(--border-normal);
    border-radius: 6px;
    background: var(--bg-normal);
    color: var(--muted);
    transition: all 0.2s ease;
    font-size: 1.2em;
    margin-top: 8px;
}

.trash-bin:hover {
    border-color: var(--danger);
}

.trash-bin.drag-over {
    border-color: var(--danger);
    background: var(--danger-bg);
    color: var(--danger);
    transform: scale(1.1);
}

.randomize-colors-btn {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 36px;
    height: 36px;
    border: 1px solid var(--border-normal);
    border-radius: 6px;
    background: var(--bg-normal);
    color: var(--accent);
    cursor: pointer;
    transition: all 0.2s ease;
    font-size: 1.2em;
}

.randomize-colors-btn:hover {
    background: var(--bg-strong);
    border-color: var(--accent);
    transform: scale(1.02);
}

/* ===== DIMENSION CONTROLS ===== */
.dimension-controls {
    margin: 8px 0;
    display: none;
}

.dimension-controls .control-item {
    margin: 0;
}

.dimension-controls:not(.hidden) {
    display: block;
}

.dimension-input {
    width: 100px;
    padding: 6px 8px;
    border: 1px solid var(--border-normal);
    border-radius: 6px;
    background: var(--bg-normal);
    color: var(--fg);
    font-size: 0.9em;
    text-align: center;
}

.dimension-input:focus {
    outline: none;
    border-color: var(--accent);
    box-shadow: 0 0 0 2px var(--accent-glow);
}

.dimension-row {
    display: flex;
    gap: 16px;
    align-items: center;
}

.dimension-group {
    display: flex;
    flex-direction: column;
    gap: 4px;
}

.dimension-group label {
    font-size: 0.75em;
    color: var(--muted);
    margin-bottom: 0;
}

/* ===== HISTORY CONTROLS ===== */
.history-controls {
    display: flex;
    gap: 8px;
    margin: 0;
}

.control-group-header .history-controls {
    margin: 0;
}

/* ===== COMPOSITION CONTROLS ===== */
.composition-controls {
    margin: 12px 0;
    padding: 8px;
    border: 1px solid var(--border-subtle);
    border-radius: 6px;
    background: var(--bg-normal);
}

.composition-controls h4 {
    margin: 0 0 8px 0;
    font-size: 0.9em;
    color: var(--text);
    font-weight: 600;
}

.composition-status {
    margin: 8px 0;
    text-align: center;
}

.composition-info {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin: 8px 0;
    gap: 12px;
}

.composition-values {
    display: flex;
    flex-direction: column;
    gap: 2px;
    font-family: 'Courier New', monospace;
    flex: 1;
}

.composition-values small {
    color: var(--muted);
    font-size: 0.8em;
}

.composition-help {
    margin-top: 12px;
    padding-top: 8px;
    border-top: 1px solid var(--border-subtle);
    text-align: center;
}

.composition-help small {
    color: var(--muted);
    font-size: 0.75em;
    font-style: italic;
}


/* ===== EXPORT & STATUS GROUP ===== */
.export-status-group {
    order: 100;
}

.export-controls {
    display: flex;
    align-items: center;
    gap: 12px;
}

.export-button {
    flex: 1;
}

@media (min-width: 769px) {
    .export-status-group {
        position: sticky;
        bottom: 0;
        background: var(--card);
        border-top: 1px solid var(--border-normal);
        margin-top: auto;
        z-index: 5;
    }
}

/* ===== RESPONSIVE DESIGN ===== */
@media (max-width: 768px) {
    .app {
        flex-direction: column;
    }
    
    .canvas-container {
        flex: 1;
        padding: 10px;
        min-height: 50vh;
    }
    
    .controls {
        width: 100%;
        min-width: 100%;
        height: 50vh;
        border-left: none;
        border-top: 1px solid var(--border-subtle);
        padding: 0.5rem;
        max-height: 50vh;
    }
}