:root {
    --bg-color: #0f172a;
    --text-primary: #f8fafc;
    --text-secondary: #94a3b8;
    --accent-1: #3b82f6;
    --accent-2: #8b5cf6;
    --accent-3: #ec4899;
    --glass-bg: rgba(30, 41, 59, 0.7);
    --glass-border: rgba(255, 255, 255, 0.1);
    --glass-shadow: 0 8px 32px 0 rgba(0, 0, 0, 0.37);
    --success: #10b981;
}

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

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-primary);
    min-height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    overflow: hidden;
    position: relative;
}

/* Dynamic Animated Background */
.background-animation {
    position: absolute;
    top: 0;
    left: 0;
    width: 100vw;
    height: 100vh;
    z-index: 0;
    overflow: hidden;
    pointer-events: none;
}

.blob {
    position: absolute;
    border-radius: 50%;
    filter: blur(80px);
    opacity: 0.6;
    animation: float 20s infinite ease-in-out;
}

.blob-1 {
    top: -10%;
    left: -10%;
    width: 50vw;
    height: 50vw;
    background: radial-gradient(circle, var(--accent-1), transparent 70%);
    animation-delay: 0s;
}

.blob-2 {
    bottom: -20%;
    right: -10%;
    width: 60vw;
    height: 60vw;
    background: radial-gradient(circle, var(--accent-2), transparent 70%);
    animation-delay: -5s;
}

.blob-3 {
    top: 40%;
    left: 40%;
    width: 40vw;
    height: 40vw;
    background: radial-gradient(circle, var(--accent-3), transparent 70%);
    animation-delay: -10s;
}

@keyframes float {
    0%, 100% { transform: translate(0, 0) scale(1); }
    33% { transform: translate(30px, -50px) scale(1.1); }
    66% { transform: translate(-20px, 20px) scale(0.9); }
}

/* Main Container */
.app-container {
    position: relative;
    z-index: 10;
    width: 100%;
    max-width: 800px;
    padding: 2rem;
    display: flex;
    flex-direction: column;
    gap: 2rem;
}

/* Header */
.header {
    text-align: center;
}

.title {
    font-family: 'Outfit', sans-serif;
    font-size: 3.5rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
    letter-spacing: -0.05em;
}

.highlight {
    background: linear-gradient(135deg, var(--accent-1), var(--accent-2), var(--accent-3));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-size: 200% auto;
    animation: gradientFlow 5s ease infinite;
}

@keyframes gradientFlow {
    0% { background-position: 0% 50%; }
    50% { background-position: 100% 50%; }
    100% { background-position: 0% 50%; }
}

.subtitle {
    color: var(--text-secondary);
    font-size: 1.1rem;
    font-weight: 300;
}

/* Glass Panel */
.glass-panel {
    background: var(--glass-bg);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    border: 1px solid var(--glass-border);
    border-radius: 24px;
    padding: 3rem;
    box-shadow: var(--glass-shadow);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.glass-panel:hover {
    box-shadow: 0 12px 40px 0 rgba(0, 0, 0, 0.45);
}

/* Drop Zone */
.drop-zone {
    border: 2px dashed rgba(255, 255, 255, 0.2);
    border-radius: 16px;
    padding: 4rem 2rem;
    text-align: center;
    cursor: pointer;
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    background: rgba(255, 255, 255, 0.02);
}

.drop-zone:hover, .drop-zone.dragover {
    border-color: var(--accent-1);
    background: rgba(59, 130, 246, 0.1);
    transform: scale(1.02);
}

.upload-icon {
    color: var(--accent-1);
    margin-bottom: 1rem;
    animation: bounce 2s infinite ease-in-out;
}

@keyframes bounce {
    0%, 100% { transform: translateY(0); }
    50% { transform: translateY(-10px); }
}

.drop-text {
    font-size: 1.5rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
}

.support-text {
    color: var(--text-secondary);
    font-size: 0.9rem;
}

/* File Details & Controls */
.file-details {
    animation: slideUp 0.4s ease-out forwards;
}

@keyframes slideUp {
    from { opacity: 0; transform: translateY(20px); }
    to { opacity: 1; transform: translateY(0); }
}

.file-info {
    display: flex;
    justify-content: space-between;
    align-items: center;
    background: rgba(0, 0, 0, 0.2);
    padding: 1rem 1.5rem;
    border-radius: 12px;
    margin-bottom: 2rem;
    border: 1px solid rgba(255, 255, 255, 0.05);
}

.file-name {
    font-weight: 600;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
    max-width: 70%;
}

.file-size {
    color: var(--text-secondary);
    font-size: 0.9rem;
}

.conversion-controls {
    display: flex;
    gap: 1.5rem;
    align-items: flex-end;
}

.format-select-wrapper {
    flex: 1;
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.format-select-wrapper label {
    color: var(--text-secondary);
    font-size: 0.9rem;
}

.format-select {
    width: 100%;
    padding: 1rem;
    background: rgba(0, 0, 0, 0.3);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: 12px;
    color: white;
    font-size: 1rem;
    outline: none;
    appearance: none;
    cursor: pointer;
    transition: border-color 0.3s;
}

.format-select:focus {
    border-color: var(--accent-2);
}

.format-select option, .format-select optgroup {
    background-color: var(--bg-color);
    color: white;
}

/* Buttons */
.btn-primary, .btn-success {
    padding: 1rem 2rem;
    border: none;
    border-radius: 12px;
    font-size: 1rem;
    font-weight: 600;
    color: white;
    cursor: pointer;
    transition: all 0.3s ease;
    display: flex;
    justify-content: center;
    align-items: center;
    min-width: 140px;
    position: relative;
    overflow: hidden;
}

.btn-primary {
    background: linear-gradient(135deg, var(--accent-1), var(--accent-2));
    box-shadow: 0 4px 15px rgba(59, 130, 246, 0.4);
}

.btn-primary:hover:not(:disabled) {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(59, 130, 246, 0.6);
}

.btn-primary:disabled {
    background: #475569;
    box-shadow: none;
    cursor: not-allowed;
    opacity: 0.7;
}

.btn-success {
    background: var(--success);
    box-shadow: 0 4px 15px rgba(16, 185, 129, 0.4);
    margin: 1.5rem auto;
}

.btn-success:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(16, 185, 129, 0.6);
}

.btn-text-only {
    background: transparent;
    border: none;
    color: var(--text-secondary);
    cursor: pointer;
    font-size: 0.9rem;
    transition: color 0.3s;
    text-decoration: underline;
}

.btn-text-only:hover {
    color: white;
}

/* Loader */
.loader {
    width: 20px;
    height: 20px;
    border: 3px solid rgba(255,255,255,0.3);
    border-radius: 50%;
    border-top-color: white;
    animation: spin 1s ease-in-out infinite;
}

@keyframes spin {
    to { transform: rotate(360deg); }
}

/* Progress */
.progress-container {
    margin-top: 2rem;
    animation: fadeIn 0.3s ease forwards;
}

.progress-status {
    text-align: center;
    margin-bottom: 0.5rem;
    font-weight: 600;
}

.progress-bar {
    width: 100%;
    height: 8px;
    background: rgba(0, 0, 0, 0.3);
    border-radius: 4px;
    overflow: hidden;
}

.progress-fill {
    height: 100%;
    width: 0%;
    background: linear-gradient(90deg, var(--accent-1), var(--accent-2));
    border-radius: 4px;
    transition: width 0.3s ease;
}

/* Result Container */
.result-container {
    text-align: center;
    animation: scaleIn 0.5s cubic-bezier(0.175, 0.885, 0.32, 1.275) forwards;
}

@keyframes scaleIn {
    from { opacity: 0; transform: scale(0.9); }
    to { opacity: 1; transform: scale(1); }
}

.success-icon {
    color: var(--success);
    margin-bottom: 1rem;
    display: inline-block;
    animation: popIn 0.5s ease forwards 0.2s;
    opacity: 0;
    transform: scale(0);
}

@keyframes popIn {
    to { opacity: 1; transform: scale(1); }
}

/* Utilities */
.hidden {
    display: none !important;
}

/* Responsive */
@media (max-width: 600px) {
    .conversion-controls {
        flex-direction: column;
        align-items: stretch;
    }
    
    .btn-primary {
        width: 100%;
    }
    
    .glass-panel {
        padding: 2rem;
    }
    
    .title {
        font-size: 2.5rem;
    }
}