:root {
    --bg-dark: #0a0a0f;
    --bg-card: #12121a;
    --bg-card-hover: #1a1a25;
    --accent: #6366f1;
    --accent-light: #818cf8;
    --accent-glow: rgba(99, 102, 241, 0.3);
    --success: #10b981;
    --warning: #f59e0b;
    --danger: #ef4444;
    --text-primary: #f8fafc;
    --text-secondary: #94a3b8;
    --text-muted: #64748b;
    --border: rgba(255, 255, 255, 0.08);
    --border-hover: rgba(255, 255, 255, 0.15);
}

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

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    background: var(--bg-dark);
    color: var(--text-primary);
    min-height: 100vh;
    line-height: 1.6;
}

/* Layout */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1.5rem;
}

/* Navigation */
.navbar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1.5rem 2rem;
    background: rgba(10, 10, 15, 0.8);
    backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--border);
    position: sticky;
    top: 0;
    z-index: 100;
}

.logo {
    font-size: 1.5rem;
    font-weight: 800;
    letter-spacing: -0.5px;
    background: linear-gradient(135deg, var(--text-primary) 0%, var(--accent-light) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.logo .accent {
    color: var(--accent);
    -webkit-text-fill-color: var(--accent);
}

.nav-links {
    display: flex;
    gap: 1rem;
    align-items: center;
}

.nav-links a, .nav-links button {
    color: var(--text-secondary);
    text-decoration: none;
    padding: 0.5rem 1rem;
    border-radius: 8px;
    transition: all 0.2s;
    border: none;
    background: none;
    cursor: pointer;
    font-size: 0.95rem;
}

.nav-links a:hover, .nav-links button:hover {
    color: var(--text-primary);
    background: var(--bg-card);
}

/* Hero Section */
.hero {
    text-align: center;
    padding: 4rem 2rem;
    max-width: 800px;
    margin: 0 auto;
}

.hero h1 {
    font-size: 3.5rem;
    font-weight: 800;
    margin-bottom: 1rem;
    line-height: 1.1;
    background: linear-gradient(135deg, var(--text-primary) 0%, var(--accent-light) 50%, var(--accent) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero p {
    font-size: 1.25rem;
    color: var(--text-secondary);
    margin-bottom: 2rem;
}

/* Upload Zone */
.upload-zone {
    background: var(--bg-card);
    border: 2px dashed var(--border);
    border-radius: 24px;
    padding: 4rem 2rem;
    text-align: center;
    transition: all 0.3s ease;
    cursor: pointer;
    position: relative;
    overflow: hidden;
}

.upload-zone::before {
    content: '';
    position: absolute;
    inset: 0;
    background: radial-gradient(circle at center, var(--accent-glow) 0%, transparent 70%);
    opacity: 0;
    transition: opacity 0.3s;
}

.upload-zone:hover, .upload-zone.dragover {
    border-color: var(--accent);
    background: var(--bg-card-hover);
}

.upload-zone:hover::before, .upload-zone.dragover::before {
    opacity: 1;
}

.upload-zone.dragover {
    transform: scale(1.02);
}

.upload-icon {
    font-size: 4rem;
    margin-bottom: 1rem;
    display: block;
}

.upload-zone h2 {
    font-size: 1.5rem;
    margin-bottom: 0.5rem;
    color: var(--text-primary);
    position: relative;
}

.upload-zone p {
    color: var(--text-muted);
    position: relative;
}

.browse-btn {
    display: inline-block;
    margin-top: 1.5rem;
    padding: 0.8rem 2rem;
    background: linear-gradient(135deg, var(--accent) 0%, var(--accent-light) 100%);
    color: white;
    border: none;
    border-radius: 12px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s;
    position: relative;
}

.browse-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 10px 30px var(--accent-glow);
}

/* File List */
.file-list {
    background: var(--bg-card);
    border-radius: 16px;
    border: 1px solid var(--border);
    margin-top: 2rem;
    overflow: hidden;
}

.file-item {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 1rem 1.5rem;
    border-bottom: 1px solid var(--border);
    transition: background 0.2s;
}

.file-item:last-child {
    border-bottom: none;
}

.file-item:hover {
    background: var(--bg-card-hover);
}

.file-info {
    display: flex;
    align-items: center;
    gap: 1rem;
    flex: 1;
    min-width: 0;
}

.file-icon {
    font-size: 1.5rem;
    flex-shrink: 0;
}

.file-details {
    min-width: 0;
}

.file-name {
    font-weight: 500;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

.file-size {
    color: var(--text-muted);
    font-size: 0.85rem;
}

.file-status {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    flex-shrink: 0;
}

.progress-bar {
    width: 100px;
    height: 4px;
    background: var(--border);
    border-radius: 2px;
    overflow: hidden;
}

.progress-fill {
    height: 100%;
    background: linear-gradient(90deg, var(--accent), var(--accent-light));
    width: 0%;
    transition: width 0.3s ease;
}

.remove-btn {
    background: none;
    border: none;
    color: var(--text-muted);
    cursor: pointer;
    padding: 0.5rem;
    border-radius: 8px;
    transition: all 0.2s;
}

.remove-btn:hover {
    color: var(--danger);
    background: rgba(239, 68, 68, 0.1);
}

/* Transfer Controls */
.transfer-controls {
    background: var(--bg-card);
    border-radius: 16px;
    border: 1px solid var(--border);
    padding: 1.5rem;
    margin-top: 2rem;
}

.transfer-summary {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1rem;
}

.transfer-btn {
    padding: 1rem 3rem;
    background: linear-gradient(135deg, var(--accent) 0%, var(--accent-light) 100%);
    color: white;
    border: none;
    border-radius: 12px;
    font-size: 1.1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s;
    width: 100%;
}

.transfer-btn:hover:not(:disabled) {
    transform: translateY(-2px);
    box-shadow: 0 10px 30px var(--accent-glow);
}

.transfer-btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

/* Success Screen */
.success-screen {
    text-align: center;
    padding: 3rem;
}

.success-icon {
    font-size: 5rem;
    margin-bottom: 1rem;
}

.download-link-container {
    background: var(--bg-card);
    border-radius: 12px;
    border: 1px solid var(--border);
    padding: 1rem;
    display: flex;
    align-items: center;
    gap: 1rem;
    margin: 2rem auto;
    max-width: 600px;
}

.download-link {
    flex: 1;
    padding: 0.8rem 1rem;
    background: var(--bg-dark);
    border: 1px solid var(--border);
    border-radius: 8px;
    color: var(--text-primary);
    font-family: 'Fira Code', monospace;
    font-size: 0.9rem;
}

.copy-btn {
    padding: 0.8rem 1.5rem;
    background: var(--accent);
    color: white;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    font-weight: 600;
    transition: all 0.2s;
}

.copy-btn:hover {
    background: var(--accent-light);
}

/* Features */
.features {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 1.5rem;
    padding: 4rem 2rem;
    max-width: 1000px;
    margin: 0 auto;
}

.feature-card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 16px;
    padding: 2rem;
    text-align: center;
    transition: all 0.3s;
}

.feature-card:hover {
    border-color: var(--accent);
    transform: translateY(-4px);
}

.feature-icon {
    font-size: 2.5rem;
    margin-bottom: 1rem;
}

.feature-card h3 {
    margin-bottom: 0.5rem;
    color: var(--text-primary);
}

.feature-card p {
    color: var(--text-muted);
    font-size: 0.95rem;
}

/* Buttons */
.btn {
    padding: 0.75rem 1.5rem;
    border-radius: 10px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s;
    border: none;
    font-size: 0.95rem;
}

.btn-primary {
    background: linear-gradient(135deg, var(--accent) 0%, var(--accent-light) 100%);
    color: white;
}

.btn-secondary {
    background: var(--bg-card);
    color: var(--text-primary);
    border: 1px solid var(--border);
}

/* Forms */
.form-group {
    margin-bottom: 1.5rem;
}

.form-group label {
    display: block;
    margin-bottom: 0.5rem;
    color: var(--text-secondary);
    font-size: 0.9rem;
}

.form-group input, .form-group textarea {
    width: 100%;
    padding: 0.9rem 1rem;
    background: var(--bg-dark);
    border: 1px solid var(--border);
    border-radius: 10px;
    color: var(--text-primary);
    font-size: 1rem;
    transition: border-color 0.2s;
}

.form-group input:focus, .form-group textarea:focus {
    outline: none;
    border-color: var(--accent);
}

/* Modal */
.modal-overlay {
    position: fixed;
    inset: 0;
    background: rgba(0, 0, 0, 0.8);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 1000;
    opacity: 0;
    visibility: hidden;
    transition: all 0.3s;
}

.modal-overlay.active {
    opacity: 1;
    visibility: visible;
}

.modal {
    background: var(--bg-card);
    border-radius: 20px;
    padding: 2rem;
    max-width: 450px;
    width: 90%;
    border: 1px solid var(--border);
    transform: scale(0.9);
    transition: transform 0.3s;
}

.modal-overlay.active .modal {
    transform: scale(1);
}

.modal-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1.5rem;
}

.modal-close {
    background: none;
    border: none;
    color: var(--text-muted);
    font-size: 1.5rem;
    cursor: pointer;
}

/* Footer */
.footer {
    text-align: center;
    padding: 3rem 2rem;
    color: var(--text-muted);
    border-top: 1px solid var(--border);
    margin-top: 4rem;
}

/* Responsive */
@media (max-width: 768px) {
    .hero h1 {
        font-size: 2.5rem;
    }

    .upload-zone {
        padding: 2rem 1rem;
    }

    .navbar {
        padding: 1rem;
    }

    .nav-links {
        gap: 0.5rem;
    }

    .features {
        padding: 2rem 1rem;
    }
}