:root {
    /* Colors - Dark Mode (Default) */
    --bg-gradient: linear-gradient(135deg, #1a1c2c 0%, #4a192c 100%);
    --glass-bg: rgba(255, 255, 255, 0.05);
    --glass-border: rgba(255, 255, 255, 0.1);
    --text-primary: #ffffff;
    --text-secondary: rgba(255, 255, 255, 0.7);
    --accent: #ff6b6b;
    --accent-glow: rgba(255, 107, 107, 0.3);
    --card-hover: rgba(255, 255, 255, 0.1);

    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;

    /* Radius */
    --radius-sm: 8px;
    --radius-md: 16px;
    --radius-lg: 24px;
}

[data-theme="light"] {
    --bg-gradient: linear-gradient(135deg, #e0e7ff 0%, #fce7f3 100%);
    --glass-bg: rgba(255, 255, 255, 0.4);
    --glass-border: rgba(255, 255, 255, 0.4);
    --text-primary: #1f2937;
    --text-secondary: rgba(31, 41, 55, 0.7);
    --accent: #4f46e5;
    --accent-glow: rgba(79, 70, 229, 0.3);
    --card-hover: rgba(255, 255, 255, 0.6);
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    -webkit-tap-highlight-color: transparent;
}

body {
    font-family: 'Outfit', sans-serif;
    background: var(--bg-gradient);
    color: var(--text-primary);
    min-height: 100vh;
    overflow-x: hidden;
    transition: background 0.5s ease;
}

.app-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: var(--spacing-md);
    padding-bottom: 100px;
    /* Space for footer */
    display: flex;
    flex-direction: column;
    gap: var(--spacing-lg);
}

/* Glassmorphism Utilities */
.glass-panel {
    background: var(--glass-bg);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border: 1px solid var(--glass-border);
    border-radius: var(--radius-md);
    box-shadow: 0 8px 32px 0 rgba(0, 0, 0, 0.1);
}

/* Header */
.header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-md) var(--spacing-lg);
}

.logo {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    font-weight: 600;
    font-size: 1.2rem;
}

.icon-btn {
    background: none;
    border: none;
    color: var(--text-primary);
    cursor: pointer;
    padding: var(--spacing-xs);
    border-radius: 50%;
    transition: background 0.2s;
}

.icon-btn:hover {
    background: var(--card-hover);
}

/* Presets */
.presets-section {
    padding: var(--spacing-md);
}

.presets-section h2 {
    font-size: 1.1rem;
    margin-bottom: var(--spacing-md);
    color: var(--text-secondary);
    font-weight: 500;
}

.presets-grid {
    display: flex;
    gap: var(--spacing-sm);
    overflow-x: auto;
    padding-bottom: var(--spacing-xs);
    scrollbar-width: none;
}

.preset-chip {
    background: var(--glass-bg);
    border: 1px solid var(--glass-border);
    color: var(--text-primary);
    padding: 8px 16px;
    border-radius: 20px;
    white-space: nowrap;
    cursor: pointer;
    transition: all 0.2s;
    font-size: 0.9rem;
}

.preset-chip:hover {
    background: var(--card-hover);
    transform: translateY(-1px);
}

.preset-chip.active {
    background: var(--accent);
    color: white;
    border-color: var(--accent);
    box-shadow: 0 4px 12px var(--accent-glow);
}

/* Sounds Grid */
.sounds-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(140px, 1fr));
    gap: var(--spacing-md);
}

.sound-card {
    background: var(--glass-bg);
    border: 1px solid var(--glass-border);
    border-radius: var(--radius-md);
    padding: var(--spacing-md);
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--spacing-sm);
    cursor: pointer;
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    position: relative;
    overflow: hidden;
}

.sound-card:hover {
    background: var(--card-hover);
    transform: translateY(-2px);
}

.sound-card.active {
    border-color: var(--accent);
    background: rgba(var(--accent), 0.1);
}

.sound-card.active .sound-icon {
    color: var(--accent);
    animation: pulse 2s infinite;
}

.sound-icon {
    width: 40px;
    height: 40px;
    color: var(--text-secondary);
    transition: color 0.3s;
}

.sound-name {
    font-size: 0.9rem;
    font-weight: 500;
    text-align: center;
}

.volume-slider-container {
    width: 100%;
    height: 0;
    opacity: 0;
    transition: all 0.3s;
    overflow: hidden;
}

.sound-card.active .volume-slider-container {
    height: 24px;
    opacity: 1;
    margin-top: var(--spacing-xs);
}

/* Custom Range Slider */
input[type=range] {
    -webkit-appearance: none;
    appearance: none;
    width: 100%;
    background: transparent;
}

input[type=range]::-webkit-slider-thumb {
    -webkit-appearance: none;
    appearance: none;
    height: 12px;
    width: 12px;
    border-radius: 50%;
    background: var(--text-primary);
    cursor: pointer;
    margin-top: -4px;
    box-shadow: 0 2px 6px rgba(0, 0, 0, 0.2);
}

input[type=range]::-webkit-slider-runnable-track {
    width: 100%;
    height: 4px;
    cursor: pointer;
    background: var(--glass-border);
    border-radius: 2px;
}

/* Footer Controls */
.footer-controls {
    position: fixed;
    bottom: var(--spacing-md);
    left: 50%;
    transform: translateX(-50%);
    width: calc(100% - var(--spacing-md) * 2);
    max-width: 600px;
    padding: var(--spacing-sm) var(--spacing-md);
    z-index: 100;
}

.global-controls {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
}

.play-btn {
    background: var(--accent);
    color: white;
    border: none;
    width: 48px;
    height: 48px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    box-shadow: 0 4px 12px var(--accent-glow);
    transition: transform 0.2s;
    flex-shrink: 0;
}

.play-btn:hover {
    transform: scale(1.05);
}

.volume-control {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    flex: 1;
}

.footer-actions {
    display: flex;
    gap: var(--spacing-sm);
}

.secondary-btn {
    background: transparent;
    border: 1px solid var(--glass-border);
    color: var(--text-primary);
    padding: 6px 12px;
    border-radius: var(--radius-sm);
    font-size: 0.8rem;
    cursor: pointer;
    transition: background 0.2s;
}

.secondary-btn:hover {
    background: var(--card-hover);
}

.secondary-btn.active {
    background: var(--accent);
    color: white;
    border-color: var(--accent);
}

/* Animations */
@keyframes pulse {
    0% {
        transform: scale(1);
        opacity: 1;
    }

    50% {
        transform: scale(1.1);
        opacity: 0.8;
    }

    100% {
        transform: scale(1);
        opacity: 1;
    }
}

/* Modal */
.modal {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.5);
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 1000;
    opacity: 0;
    pointer-events: none;
    transition: opacity 0.3s;
}

.modal.visible {
    opacity: 1;
    pointer-events: auto;
}

.modal-content {
    background: var(--glass-bg);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    border: 1px solid var(--glass-border);
    border-radius: var(--radius-md);
    padding: var(--spacing-lg);
    min-width: 300px;
    text-align: center;
    box-shadow: 0 8px 32px 0 rgba(0, 0, 0, 0.2);
}

.modal-content h3 {
    margin-bottom: var(--spacing-md);
}

.timer-options {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-sm);
}

.timer-options button {
    background: var(--glass-bg);
    border: 1px solid var(--glass-border);
    color: var(--text-primary);
    padding: 10px;
    border-radius: var(--radius-sm);
    cursor: pointer;
    transition: background 0.2s;
}

.timer-options button:hover {
    background: var(--card-hover);
}

.hidden {
    display: none;
}

@media (max-width: 600px) {
    .sounds-grid {
        grid-template-columns: repeat(3, 1fr);
        gap: var(--spacing-sm);
    }

    .sound-card {
        padding: var(--spacing-sm);
    }

    .footer-actions {
        /* On mobile, we might want to show these or put them in a menu. 
           For now, let's show them but smaller or wrapped if needed. 
           Actually, the prompt said "Convenient mobile interface". 
           Hiding them is bad if they are needed. 
           Let's make them visible but maybe smaller. */
        display: flex;
    }

    .footer-controls {
        flex-direction: column;
        gap: var(--spacing-sm);
        padding-bottom: var(--spacing-md);
    }

    .global-controls {
        width: 100%;
        justify-content: space-between;
    }

    .footer-actions {
        width: 100%;
        justify-content: space-around;
    }
}