:root {
    /* Brand Colors */
    --primary: #6366F1;
    --primary-hover: #4F46E5;
    --secondary: #818CF8;
    --accent: #F59E0B;
    
    /* Dark Theme Basics */
    --bg-base: #0F1219;
    --bg-surface: #1E222B;
    --bg-panel: rgba(30, 34, 43, 0.7);
    --border: #333A48;
    
    /* Text */
    --text-main: #F8FAFC;
    --text-muted: #94A3B8;
    --text-dim: #64748B;
    
    /* UI Elements */
    --radius-sm: 6px;
    --radius-md: 12px;
    --radius-lg: 24px;
    --shadow-glass: 0 8px 32px rgba(0, 0, 0, 0.2);
    
    /* Dynamic Theme Color (updated via JS) */
    --theme-color: #6366F1;
    --theme-text: #FFFFFF;
}

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

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
    background-color: var(--bg-base);
    color: var(--text-main);
    line-height: 1.5;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

.hidden { display: none !important; }

/* Utilities */
.glass-panel {
    background: var(--bg-panel);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border: 1px solid rgba(255, 255, 255, 0.05);
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-glass);
}

.icon-btn {
    display: inline-flex; align-items: center; justify-content: center;
    width: 32px; height: 32px; border-radius: 8px; border: 1px solid var(--border);
    background: var(--bg-surface); color: var(--text-muted); cursor: pointer; transition: all 0.2s;
}
.icon-btn:hover { background: rgba(255,255,255,0.1); color: var(--text-main); border-color: var(--text-muted); }
.icon-btn:active { transform: scale(0.95); }

/* Header */
.app-header {
    background: rgba(15, 18, 25, 0.8);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--border);
    padding: 16px 32px; height: 72px;
    display: flex; justify-content: space-between; align-items: center;
    position: sticky; top: 0; z-index: 50;
}
.brand { display: flex; align-items: center; gap: 12px; color: var(--primary); }
.brand h1 { font-size: 18px; font-weight: 600; color: var(--text-main); letter-spacing: -0.02em; }

/* Main Container */
.app-container {
    flex: 1; display: grid;
    grid-template-columns: 360px 1fr;
    gap: 0;
}

@media (max-width: 900px) {
    .app-container { grid-template-columns: 1fr; }
}

/* Left: Visualizer Area */
.visualizer-section {
    padding: 40px 32px;
    display: flex; flex-direction: column; gap: 32px;
    border-right: 1px solid var(--border);
    background: linear-gradient(180deg, rgba(99, 102, 241, 0.05) 0%, transparent 400px);
    transition: background 0.5s ease;
    align-items: center;
}

.color-preview-container {
    position: relative;
    width: 220px; height: 220px;
    border-radius: 50%;
    padding: 8px;
    background: conic-gradient(from 90deg, #ff0000, #ffff00, #00ff00, #00ffff, #0000ff, #ff00ff, #ff0000);
    box-shadow: 0 0 40px rgba(0,0,0,0.5);
    animation: rotate 20s linear infinite;
}
@keyframes rotate { 100% { transform: rotate(360deg); } }

.color-preview {
    width: 100%; height: 100%;
    border-radius: 50%;
    background-color: var(--theme-color);
    border: 4px solid var(--bg-base);
    box-shadow: inset 0 4px 20px rgba(0,0,0,0.2);
    position: relative;
    display: flex; align-items: center; justify-content: center;
    transition: background-color 0.2s;
    /* Counter-rotate to keep content upright */
    animation: counter-rotate 20s linear infinite;
}
@keyframes counter-rotate { 100% { transform: rotate(-360deg); } }


.hidden-native-picker {
    position: absolute; opacity: 0; width: 0; height: 0; pointer-events: none;
}
.btn-picker-overlay {
    width: 48px; height: 48px; border-radius: 50%;
    background: rgba(0,0,0,0.3); border: 2px solid rgba(255,255,255,0.5);
    color: white; cursor: pointer; display: flex; align-items: center; justify-content: center;
    transition: all 0.2s; backdrop-filter: blur(4px);
}
.btn-picker-overlay:hover { transform: scale(1.1); background: rgba(0,0,0,0.5); border-color: white; }

.gamut-warning {
    position: absolute; bottom: 20px; right: 20px;
    background: var(--accent); color: #000;
    width: 28px; height: 28px; border-radius: 50%;
    display: flex; align-items: center; justify-content: center;
    box-shadow: 0 2px 10px rgba(0,0,0,0.5);
}

/* Master Input */
.master-input-container {
    width: 100%; max-width: 320px;
    padding: 20px;
    display: flex; flex-direction: column; gap: 8px;
}
.master-input-container label {
    font-size: 12px; font-weight: 600; text-transform: uppercase; letter-spacing: 0.05em; color: var(--text-muted);
}
.input-wrapper { display: flex; gap: 8px; }
.input-wrapper input {
    flex: 1; background: rgba(0,0,0,0.2); border: 1px solid var(--border);
    color: var(--text-main); font-family: 'Inter', monospace; font-size: 15px;
    padding: 10px 14px; border-radius: 8px; outline: none; transition: border 0.2s;
}
.input-wrapper input:focus { border-color: var(--primary); box-shadow: 0 0 0 2px rgba(99,102,241,0.2); }
.error-msg { color: #EF4444; font-size: 12px; font-weight: 500; margin-top: 4px; }

/* Quick Swatches */
.quick-swatches {
    display: grid; grid-template-columns: repeat(4, 1fr); gap: 12px;
    width: 100%; max-width: 240px; margin-top: auto;
}
.swatch {
    aspect-ratio: 1; border-radius: 50%; cursor: pointer;
    border: 2px solid transparent; box-shadow: 0 2px 8px rgba(0,0,0,0.2);
    transition: transform 0.2s, border 0.2s;
}
.swatch:hover, .swatch:focus { transform: scale(1.15); border-color: white; outline: none; }

/* Right: Conversions Grid */
.conversions-section {
    padding: 40px; overflow-y: auto;
}

.section-header {
    display: flex; justify-content: space-between; align-items: center; margin-bottom: 32px;
    flex-wrap: wrap; gap: 16px;
}
.section-header h2 { font-size: 24px; font-weight: 600; letter-spacing: -0.02em; }

.tabs { display: flex; gap: 8px; background: rgba(0,0,0,0.2); padding: 4px; border-radius: 10px; }
.tab-btn {
    background: transparent; border: none; color: var(--text-muted);
    padding: 6px 12px; font-size: 13px; font-weight: 500; border-radius: 6px;
    cursor: pointer; transition: all 0.2s;
}
.tab-btn:hover { color: var(--text-main); }
.tab-btn.active { background: var(--bg-surface); color: var(--text-main); box-shadow: 0 1px 3px rgba(0,0,0,0.2); }

/* Grid */
.conversions-grid {
    display: grid; grid-template-columns: repeat(auto-fill, minmax(300px, 1fr)); gap: 24px;
}

.conversion-card {
    display: flex; flex-direction: column; padding: 20px; gap: 16px;
    border-top: 2px solid var(--theme-color); /* dynamic accent */
}

.card-header { display: flex; justify-content: space-between; align-items: center; }
.space-name { font-size: 14px; font-weight: 600; text-transform: uppercase; letter-spacing: 0.05em; color: var(--text-muted); }

.card-body input.space-value {
    width: 100%; background: transparent; border: none;
    color: var(--text-main); font-family: monospace; font-size: 16px; font-weight: 500;
    outline: none; cursor: pointer; padding: 4px 0;
}
.card-body input.space-value:focus { color: var(--primary); }

.space-components {
    display: grid; grid-template-columns: repeat(auto-fit, minmax(60px, 1fr)); gap: 8px;
    border-top: 1px solid var(--border); padding-top: 16px;
}
.comp-group { display: flex; flex-direction: column; gap: 4px; }
.comp-label { font-size: 11px; color: var(--text-dim); font-weight: 600; text-transform: uppercase; }
.comp-val {
    background: rgba(0,0,0,0.2); border: 1px solid transparent; color: var(--text-main);
    font-size: 13px; padding: 6px; border-radius: 4px; text-align: center; font-variant-numeric: tabular-nums;
    outline: none; transition: border 0.2s;
}
.comp-val:focus { border-color: var(--primary); background: var(--bg-surface); }

/* Toast */
.toast {
    position: fixed; bottom: -50px; left: 50%; transform: translateX(-50%);
    background: var(--text-main); color: var(--bg-base);
    padding: 10px 24px; border-radius: 20px; font-size: 14px; font-weight: 600;
    opacity: 0; transition: all 0.3s; z-index: 1000; box-shadow: 0 10px 25px rgba(0,0,0,0.5);
}
.toast.show { bottom: 32px; opacity: 1; }

/* Tooltips */
.tooltip { position: relative; }
.tooltip::after {
    content: attr(data-tooltip); position: absolute; bottom: 100%; left: 50%; transform: translateX(-50%) translateY(-8px);
    background: var(--text-main); color: var(--bg-base); padding: 6px 10px; border-radius: 6px; font-size: 12px; font-weight: 600;
    white-space: nowrap; opacity: 0; pointer-events: none; transition: 0.2s; z-index: 100; box-shadow: 0 4px 12px rgba(0,0,0,0.3);
}
.tooltip::before {
    content: ''; position: absolute; bottom: 100%; left: 50%; transform: translateX(-50%) translateY(0);
    border: 6px solid transparent; border-top-color: var(--text-main);
    opacity: 0; pointer-events: none; transition: 0.2s; z-index: 100;
}
.tooltip:hover::after, .tooltip:hover::before { opacity: 1; transform: translateX(-50%) translateY(-4px); }