:root {
    --primary: #2563eb;
    --primary-hover: #1d4ed8;
    --success: #10b981;
    --bg: #f8fafc;
    --card: #ffffff;
    --text: #1e293b;
    --text-muted: #64748b;
    --border: #e2e8f0;
    --radius: 12px;
    --shadow: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    background: var(--bg);
    color: var(--text);
    line-height: 1.6;
    min-height: 100vh;
}

.container {
    max-width: 640px;
    margin: 0 auto;
    padding: 2rem 1rem;
}

header {
    text-align: center;
    margin-bottom: 2rem;
}

header h1 {
    font-size: 2rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
}

.tagline {
    color: var(--text-muted);
    font-size: 1.1rem;
    margin-bottom: 1rem;
}

.badges {
    display: flex;
    justify-content: center;
    gap: 0.75rem;
    flex-wrap: wrap;
}

.privacy-badge,
.korean-badge {
    display: inline-flex;
    flex-direction: column;
    align-items: center;
    gap: 0.25rem;
    padding: 0.75rem 1.25rem;
    border-radius: var(--radius);
}

.privacy-badge {
    background: linear-gradient(135deg, #ecfdf5 0%, #d1fae5 100%);
    border: 1px solid #a7f3d0;
}

.privacy-badge .badge {
    color: #047857;
}

.privacy-badge .badge-desc {
    color: #059669;
}

.korean-badge {
    background: linear-gradient(135deg, #eff6ff 0%, #dbeafe 100%);
    border: 1px solid #93c5fd;
}

.korean-badge .badge {
    color: #1d4ed8;
}

.korean-badge .badge-desc {
    color: #2563eb;
}

.badge {
    font-weight: 600;
    font-size: 0.9rem;
}

.badge-desc {
    font-size: 0.8rem;
}

.drop-zone {
    background: var(--card);
    border: 2px dashed var(--border);
    border-radius: var(--radius);
    padding: 3rem 2rem;
    text-align: center;
    cursor: pointer;
    transition: all 0.2s ease;
}

.drop-zone:hover,
.drop-zone.drag-over {
    border-color: var(--primary);
    background: #eff6ff;
}

.drop-icon {
    font-size: 3rem;
    margin-bottom: 1rem;
}

.drop-text {
    color: var(--text-muted);
    margin-bottom: 1rem;
}

.browse-btn {
    background: var(--primary);
    color: white;
    border: none;
    padding: 0.75rem 1.5rem;
    border-radius: 8px;
    font-size: 1rem;
    font-weight: 500;
    cursor: pointer;
    transition: background 0.2s;
}

.browse-btn:hover {
    background: var(--primary-hover);
}

.file-info {
    display: flex;
    align-items: center;
    justify-content: space-between;
    background: var(--card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 1rem 1.25rem;
    margin-top: 1rem;
    box-shadow: var(--shadow);
}

.file-details {
    display: flex;
    flex-direction: column;
    gap: 0.25rem;
}

.file-name {
    font-weight: 600;
    color: var(--text);
}

.file-meta {
    font-size: 0.875rem;
    color: var(--text-muted);
}

.remove-btn {
    background: none;
    border: none;
    font-size: 1.25rem;
    color: var(--text-muted);
    cursor: pointer;
    padding: 0.5rem;
    border-radius: 6px;
    transition: all 0.2s;
}

.remove-btn:hover {
    background: #fee2e2;
    color: #dc2626;
}

.options {
    background: var(--card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 1.5rem;
    margin-top: 1rem;
    box-shadow: var(--shadow);
}

.options h3 {
    font-size: 1rem;
    font-weight: 600;
    margin-bottom: 1rem;
    color: var(--text);
}

.option-group {
    margin-bottom: 1rem;
}

.radio-label {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    cursor: pointer;
    padding: 0.5rem 0;
}

.radio-label input[type="radio"] {
    display: none;
}

.radio-custom {
    width: 20px;
    height: 20px;
    border: 2px solid var(--border);
    border-radius: 50%;
    position: relative;
    transition: all 0.2s;
}

.radio-label input[type="radio"]:checked + .radio-custom {
    border-color: var(--primary);
}

.radio-label input[type="radio"]:checked + .radio-custom::after {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 10px;
    height: 10px;
    background: var(--primary);
    border-radius: 50%;
}

.label-text {
    font-weight: 500;
}

.size-input-group {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    margin-left: 2rem;
    margin-top: 0.5rem;
}

.size-input-group select {
    padding: 0.5rem 0.75rem;
    border: 1px solid var(--border);
    border-radius: 6px;
    font-size: 0.9rem;
    background: white;
}

.size-desc {
    color: var(--text-muted);
    font-size: 0.9rem;
}

.prefix-group {
    margin-top: 1.5rem;
    padding-top: 1rem;
    border-top: 1px solid var(--border);
}

.prefix-group label {
    display: block;
    font-weight: 500;
    margin-bottom: 0.5rem;
    font-size: 0.9rem;
}

.prefix-group input {
    width: 100%;
    padding: 0.625rem 0.875rem;
    border: 1px solid var(--border);
    border-radius: 6px;
    font-size: 0.9rem;
}

.prefix-group input:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

.split-btn {
    width: 100%;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    background: var(--primary);
    color: white;
    border: none;
    padding: 1rem;
    border-radius: 8px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    margin-top: 1.5rem;
    transition: background 0.2s;
}

.split-btn:hover {
    background: var(--primary-hover);
}

.split-btn:disabled {
    background: #94a3b8;
    cursor: not-allowed;
}

.results {
    background: var(--card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 1.5rem;
    margin-top: 1rem;
    box-shadow: var(--shadow);
}

.results h3 {
    font-size: 1rem;
    font-weight: 600;
    margin-bottom: 1rem;
}

.result-summary {
    background: linear-gradient(135deg, #ecfdf5 0%, #d1fae5 100%);
    border: 1px solid #a7f3d0;
    border-radius: 8px;
    padding: 1rem;
    margin-bottom: 1rem;
    color: #047857;
    font-weight: 500;
}

.result-list {
    max-height: 300px;
    overflow-y: auto;
    border: 1px solid var(--border);
    border-radius: 8px;
}

.result-item {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0.75rem 1rem;
    border-bottom: 1px solid var(--border);
}

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

.result-item-info {
    display: flex;
    flex-direction: column;
    gap: 0.125rem;
}

.result-item-name {
    font-weight: 500;
    font-size: 0.9rem;
}

.result-item-meta {
    font-size: 0.8rem;
    color: var(--text-muted);
}

.download-btn {
    background: none;
    border: 1px solid var(--primary);
    color: var(--primary);
    padding: 0.375rem 0.75rem;
    border-radius: 6px;
    font-size: 0.8rem;
    cursor: pointer;
    transition: all 0.2s;
}

.download-btn:hover {
    background: var(--primary);
    color: white;
}

.result-actions {
    display: flex;
    gap: 0.75rem;
    margin-top: 1rem;
}

.download-all-btn {
    flex: 1;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    background: var(--success);
    color: white;
    border: none;
    padding: 0.875rem;
    border-radius: 8px;
    font-size: 0.95rem;
    font-weight: 600;
    cursor: pointer;
    transition: background 0.2s;
}

.download-all-btn:hover {
    background: #059669;
}

.reset-btn {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    background: none;
    border: 1px solid var(--border);
    color: var(--text-muted);
    padding: 0.875rem 1.25rem;
    border-radius: 8px;
    font-size: 0.95rem;
    cursor: pointer;
    transition: all 0.2s;
}

.reset-btn:hover {
    border-color: var(--text-muted);
    color: var(--text);
}

.loading {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 1rem;
    padding: 3rem;
}

.spinner {
    width: 40px;
    height: 40px;
    border: 3px solid var(--border);
    border-top-color: var(--primary);
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
}

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

.hidden {
    display: none !important;
}

footer {
    text-align: center;
    margin-top: 2rem;
    padding-top: 1.5rem;
    border-top: 1px solid var(--border);
    color: var(--text-muted);
    font-size: 0.875rem;
}

footer a {
    color: var(--primary);
    text-decoration: none;
}

footer a:hover {
    text-decoration: underline;
}

.footer-note {
    margin-top: 0.5rem;
    font-size: 0.8rem;
}

@media (max-width: 480px) {
    .container {
        padding: 1rem;
    }
    
    header h1 {
        font-size: 1.5rem;
    }
    
    .drop-zone {
        padding: 2rem 1rem;
    }
    
    .result-actions {
        flex-direction: column;
    }
}