/**
 * TY MP3 변환기 - 프리미엄 다크 테마 디자인 시스템
 * 
 * 디자인 컨셉:
 * - 딥 퍼플/인디고 그라디언트 배경
 * - 글래스모피즘 카드 (반투명 + blur)
 * - 부드러운 애니메이션
 * - 모바일 퍼스트 반응형
 */

/* ==================== CSS Variables ==================== */
:root {
    /* Colors - Dark Theme */
    --color-primary: #6366f1;
    --color-primary-dark: #4f46e5;
    --color-primary-light: #818cf8;
    --color-secondary: #8b5cf6;
    --color-accent: #ec4899;

    --color-bg-dark: #0f0f23;
    --color-bg-darker: #0a0a15;
    --color-bg-card: rgba(255, 255, 255, 0.05);
    --color-bg-glass: rgba(255, 255, 255, 0.08);

    --color-text-primary: #ffffff;
    --color-text-secondary: #a1a1aa;
    --color-text-muted: #71717a;

    --color-success: #10b981;
    --color-error: #ef4444;
    --color-warning: #f59e0b;

    /* Spacing */
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-2xl: 3rem;

    /* Typography */
    --font-main: 'Pretendard', -apple-system, BlinkMacSystemFont, system-ui, sans-serif;
    --font-size-xs: 0.75rem;
    --font-size-sm: 0.875rem;
    --font-size-base: 1rem;
    --font-size-lg: 1.125rem;
    --font-size-xl: 1.25rem;
    --font-size-2xl: 1.5rem;
    --font-size-3xl: 2rem;

    /* Border Radius */
    --radius-sm: 0.5rem;
    --radius-md: 0.75rem;
    --radius-lg: 1rem;
    --radius-xl: 1.5rem;
    --radius-full: 9999px;

    /* Shadows */
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.4);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.5);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.6);

    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-base: 300ms ease;
    --transition-slow: 500ms ease;
}

/* ==================== Reset & Base ==================== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    font-size: 16px;
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-main);
    font-size: var(--font-size-base);
    line-height: 1.6;
    color: var(--color-text-primary);
    background: linear-gradient(135deg, var(--color-bg-dark) 0%, #1a103f 50%, #0f0f23 100%);
    background-attachment: fixed;
    min-height: 100vh;
    overflow-x: hidden;
}

/* ==================== Glassmorphism Effects ==================== */
.glass-card {
    background: var(--color-bg-glass);
    backdrop-filter: blur(16px) saturate(180%);
    -webkit-backdrop-filter: blur(16px) saturate(180%);
    border: 1px solid rgba(255, 255, 255, 0.125);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-lg);
    transition: all var(--transition-base);
}

.glass-card:hover {
    background: rgba(255, 255, 255, 0.1);
    border-color: rgba(255, 255, 255, 0.2);
    transform: translateY(-2px);
    box-shadow: var(--shadow-xl);
}

/* ==================== Layout ==================== */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-lg);
}

/* ==================== Header ==================== */
.app-header {
    padding: var(--spacing-lg) 0;
    position: sticky;
    top: 0;
    background: rgba(15, 15, 35, 0.8);
    backdrop-filter: blur(12px);
    z-index: 100;
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
}

.header-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    animation: fadeInDown 0.6s ease;
}

.logo .material-symbols-rounded {
    font-size: 2rem;
    color: var(--color-primary);
}

.logo h1 {
    font-size: var(--font-size-2xl);
    font-weight: 700;
    background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-secondary) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.theme-toggle {
    padding: var(--spacing-sm);
    background: var(--color-bg-glass);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: var(--radius-md);
    color: var(--color-text-primary);
    cursor: pointer;
    transition: all var(--transition-fast);
}

.theme-toggle:hover {
    background: var(--color-primary);
    transform: rotate(15deg) scale(1.1);
}

/* ==================== Main Content ==================== */
.main-content {
    padding: var(--spacing-2xl) 0;
    min-height: calc(100vh - 200px);
}

/* Convert Section */
.convert-section {
    margin-bottom: var(--spacing-2xl);
    padding: var(--spacing-xl);
    animation: fadeInUp 0.6s ease 0.2s both;
}

.convert-section h2 {
    font-size: var(--font-size-2xl);
    margin-bottom: var(--spacing-sm);
    background: linear-gradient(135deg, #ffffff 0%, var(--color-primary-light) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.subtitle {
    color: var(--color-text-secondary);
    margin-bottom: var(--spacing-lg);
}

.url-input-wrapper {
    display: flex;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-lg);
}

.url-input {
    flex: 1;
    padding: var(--spacing-md) var(--spacing-lg);
    background: var(--color-bg-card);
    border: 2px solid rgba(255, 255, 255, 0.1);
    border-radius: var(--radius-md);
    color: var(--color-text-primary);
    font-size: var(--font-size-base);
    font-family: var(--font-main);
    transition: all var(--transition-fast);
}

.url-input:focus {
    outline: none;
    border-color: var(--color-primary);
    background: var(--color-bg-glass);
    box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.2);
}

.url-input::placeholder {
    color: var(--color-text-muted);
}

/* Progress */
.progress-container {
    margin-top: var(--spacing-lg);
    animation: fadeIn var(--transition-base);
}

.progress-bar {
    height: 8px;
    background: var(--color-bg-card);
    border-radius: var(--radius-full);
    overflow: hidden;
    margin-bottom: var(--spacing-sm);
}

.progress-fill {
    height: 100%;
    background: linear-gradient(90deg, var(--color-primary), var(--color-secondary));
    border-radius: var(--radius-full);
    transition: width var(--transition-base);
    animation: shimmer 2s infinite;
}

@keyframes shimmer {
    0% {
        background-position: -200% 0;
    }

    100% {
        background-position: 200% 0;
    }
}

.progress-text {
    text-align: center;
    color: var(--color-text-secondary);
    font-size: var(--font-size-sm);
}

/* Video Preview */
.video-preview {
    display: flex;
    gap: var(--spacing-md);
    padding: var(--spacing-md);
    background: var(--color-bg-card);
    border-radius: var(--radius-md);
    margin-top: var(--spacing-lg);
    animation: fadeIn var(--transition-base);
}

.video-preview img {
    width: 120px;
    height: 68px;
    object-fit: cover;
    border-radius: var(--radius-sm);
}

.preview-info h3 {
    font-size: var(--font-size-lg);
    margin-bottom: var(--spacing-xs);
}

.preview-info p {
    color: var(--color-text-secondary);
    font-size: var(--font-size-sm);
}

/* ==================== Buttons ==================== */
.btn {
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-md) var(--spacing-lg);
    font-size: var(--font-size-base);
    font-weight: 600;
    font-family: var(--font-main);
    border: none;
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: all var(--transition-fast);
    white-space: nowrap;
}

.btn:active {
    transform: scale(0.98);
}

.btn-primary {
    background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-secondary) 100%);
    color: white;
    box-shadow: 0 4px 12px rgba(99, 102, 241, 0.4);
}

.btn-primary:hover {
    box-shadow: 0 6px 20px rgba(99, 102, 241, 0.6);
    transform: translateY(-2px);
}

.btn-secondary {
    background: var(--color-bg-glass);
    color: var(--color-text-primary);
    border: 1px solid rgba(255, 255, 255, 0.2);
}

.btn-secondary:hover {
    background: rgba(255, 255, 255, 0.15);
}

/* ==================== Library Section ==================== */
.library-section {
    animation: fadeInUp 0.6s ease 0.4s both;
}

.section-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: var(--spacing-lg);
    flex-wrap: wrap;
    gap: var(--spacing-md);
}

.section-header h2 {
    font-size: var(--font-size-2xl);
}

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

.sort-select {
    padding: var(--spacing-sm) var(--spacing-md);
    background: var(--color-bg-glass);
    border: 1px solid rgba(255, 255, 255, 0.2);
    border-radius: var(--radius-md);
    color: var(--color-text-primary);
    font-family: var(--font-main);
    cursor: pointer;
}

/* Folder Tabs */
.folder-tabs {
    display: flex;
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-lg);
    overflow-x: auto;
    padding-bottom: var(--spacing-sm);
}

.folder-tab {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-sm) var(--spacing-lg);
    background: var(--color-bg-glass);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: var(--radius-md);
    color: var(--color-text-secondary);
    cursor: pointer;
    transition: all var(--transition-fast);
    white-space: nowrap;
}

.folder-tab:hover {
    background: rgba(255, 255, 255, 0.1);
    color: var(--color-text-primary);
}

.folder-tab.active {
    background: var(--color-primary);
    color: white;
    border-color: var(--color-primary);
}

/* Track List */
.track-list {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: var(--spacing-lg);
}

.track-card {
    background: var(--color-bg-glass);
    backdrop-filter: blur(12px);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: var(--radius-lg);
    padding: var(--spacing-md);
    cursor: pointer;
    transition: all var(--transition-base);
    animation: fadeIn var(--transition-base);
}

.track-card:hover {
    background: rgba(255, 255, 255, 0.12);
    transform: translateY(-4px);
    box-shadow: var(--shadow-xl);
}

.track-thumbnail {
    width: 100%;
    aspect-ratio: 16/9;
    object-fit: cover;
    border-radius: var(--radius-md);
    margin-bottom: var(--spacing-md);
}

.track-info h3 {
    font-size: var(--font-size-lg);
    margin-bottom: var(--spacing-xs);
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
}

.track-meta {
    display: flex;
    justify-content: space-between;
    align-items: center;
    color: var(--color-text-secondary);
    font-size: var(--font-size-sm);
    margin-bottom: var(--spacing-md);
}

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

.icon-btn {
    padding: var(--spacing-sm);
    background: var(--color-bg-card);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: var(--radius-sm);
    color: var(--color-text-secondary);
    cursor: pointer;
    transition: all var(--transition-fast);
}

.icon-btn:hover {
    background: var(--color-primary);
    color: white;
    transform: scale(1.1);
}

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

/* Empty State */
.empty-state {
    grid-column: 1 / -1;
    text-align: center;
    padding: var(--spacing-2xl);
    color: var(--color-text-muted);
}

.empty-state .material-symbols-rounded {
    font-size: 4rem;
    opacity: 0.3;
    margin-bottom: var(--spacing-md);
}

.empty-subtitle {
    font-size: var(--font-size-sm);
}

/* ==================== Audio Player ==================== */
.audio-player {
    position: fixed;
    bottom: 0;
    left: 0;
    right: 0;
    background: rgba(15, 15, 35, 0.95);
    backdrop-filter: blur(20px);
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    padding: var(--spacing-md) var(--spacing-lg);
    display: grid;
    grid-template-columns: 1fr auto 1fr auto;
    gap: var(--spacing-lg);
    align-items: center;
    z-index: 100;
    animation: slideUp 0.4s ease;
}

.player-track-info {
    display: flex;
    gap: var(--spacing-md);
    align-items: center;
    overflow: hidden;
}

.player-thumbnail {
    width: 56px;
    height: 56px;
    border-radius: var(--radius-sm);
    object-fit: cover;
}

.player-text {
    overflow: hidden;
}

.player-text h4 {
    font-size: var(--font-size-base);
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
}

.player-text p {
    font-size: var(--font-size-sm);
    color: var(--color-text-secondary);
}

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

.player-btn {
    padding: var(--spacing-sm);
    background: transparent;
    border: none;
    color: var(--color-text-primary);
    cursor: pointer;
    border-radius: var(--radius-full);
    transition: all var(--transition-fast);
}

.player-btn:hover {
    background: var(--color-bg-glass);
    transform: scale(1.1);
}

.player-btn-large {
    padding: var(--spacing-md);
    background: var(--color-primary);
}

.player-btn-large:hover {
    background: var(--color-primary-dark);
    transform: scale(1.15);
}

.player-progress {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    font-size: var(--font-size-sm);
    color: var(--color-text-secondary);
}

.progress-bar-slim {
    position: relative;
    flex: 1;
    height: 4px;
    background: var(--color-bg-card);
    border-radius: var(--radius-full);
}

.progress-fill-slim {
    height: 100%;
    background: var(--color-primary);
    border-radius: var(--radius-full);
    transition: width 0.1s linear;
}

.progress-slider {
    position: absolute;
    top: -6px;
    left: 0;
    width: 100%;
    height: 16px;
    opacity: 0;
    cursor: pointer;
}

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

.volume-slider {
    width: 100px;
    height: 4px;
    -webkit-appearance: none;
    background: var(--color-bg-card);
    border-radius: var(--radius-full);
    outline: none;
}

.volume-slider::-webkit-slider-thumb {
    -webkit-appearance: none;
    width: 12px;
    height: 12px;
    background: var(--color-primary);
    border-radius: 50%;
    cursor: pointer;
}

/* ==================== Modal ==================== */
.modal {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.7);
    backdrop-filter: blur(8px);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 200;
    animation: fadeIn var(--transition-base);
}

.modal-content {
    width: 90%;
    max-width: 500px;
    padding: var(--spacing-xl);
    animation: scaleIn var(--transition-base);
}

.modal-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: var(--spacing-lg);
}

.modal-header h3 {
    font-size: var(--font-size-xl);
}

.modal-close {
    padding: var(--spacing-sm);
    background: transparent;
    border: none;
    color: var(--color-text-secondary);
    cursor: pointer;
    border-radius: var(--radius-sm);
    transition: all var(--transition-fast);
}

.modal-close:hover {
    background: var(--color-bg-card);
    color: var(--color-text-primary);
}

.modal-body {
    margin-bottom: var(--spacing-lg);
}

.input {
    width: 100%;
    padding: var(--spacing-md);
    background: var(--color-bg-card);
    border: 2px solid rgba(255, 255, 255, 0.1);
    border-radius: var(--radius-md);
    color: var(--color-text-primary);
    font-family: var(--font-main);
    font-size: var(--font-size-base);
}

.input:focus {
    outline: none;
    border-color: var(--color-primary);
}

.modal-footer {
    display: flex;
    gap: var(--spacing-md);
    justify-content: flex-end;
}

/* ==================== Toast ==================== */
.toast {
    position: fixed;
    bottom: var(--spacing-2xl);
    left: 50%;
    transform: translateX(-50%);
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-md) var(--spacing-xl);
    background: var(--color-bg-glass);
    backdrop-filter: blur(12px);
    border: 1px solid rgba(255, 255, 255, 0.2);
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-xl);
    z-index: 300;
    animation: slideUp var(--transition-base);
}

.toast.success {
    border-color: var(--color-success);
}

.toast.error {
    border-color: var(--color-error);
}

/* ==================== Animations ==================== */
@keyframes fadeIn {
    from {
        opacity: 0;
    }

    to {
        opacity: 1;
    }
}

@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }

    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes fadeInDown {
    from {
        opacity: 0;
        transform: translateY(-20px);
    }

    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes slideUp {
    from {
        transform: translateY(100%);
    }

    to {
        transform: translateY(0);
    }
}

@keyframes scaleIn {
    from {
        opacity: 0;
        transform: scale(0.9);
    }

    to {
        opacity: 1;
        transform: scale(1);
    }
}

/* ==================== Responsive Design ==================== */
@media (max-width: 768px) {
    .url-input-wrapper {
        flex-direction: column;
    }

    .section-header {
        flex-direction: column;
        align-items: flex-start;
    }

    .track-list {
        grid-template-columns: 1fr;
    }

    .audio-player {
        grid-template-columns: 1fr;
        grid-template-rows: auto auto auto;
        gap: var(--spacing-md);
    }

    .player-volume {
        justify-content: center;
    }

    .player-progress {
        order: -1;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 var(--spacing-md);
    }

    .convert-section,
    .modal-content {
        padding: var(--spacing-lg);
    }

    .logo h1 {
        font-size: var(--font-size-xl);
    }
}

/* ==================== Accessibility ==================== */
button:focus-visible,
input:focus-visible,
select:focus-visible {
    outline: 2px solid var(--color-primary);
    outline-offset: 2px;
}

.material-symbols-rounded {
    user-select: none;
    -webkit-user-select: none;
}