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

:root {
    --primary-color: #3b82f6;
    --primary-dark: #1e40af;
    --secondary-color: #6b7280;
    --success-color: #10b981;
    --error-color: #ef4444;
    --border-color: #e5e7eb;
    --bg-light: #f9fafb;
    --bg-white: #ffffff;
    --text-primary: #111827;
    --text-secondary: #6b7280;
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
}

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

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 20px;
    display: flex;
    flex-direction: column;
    min-height: 100vh;
}

/* Header */
.header {
    text-align: center;
    margin-bottom: 40px;
    padding: 30px 0;
}

.header h1 {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 10px;
    color: var(--primary-color);
}

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

/* Main Content */
.main-content {
    flex: 1;
    margin-bottom: 40px;
}

/* Upload Section */
.upload-section {
    margin-bottom: 30px;
}

.upload-area {
    border: 2px dashed var(--border-color);
    border-radius: 12px;
    padding: 60px 20px;
    text-align: center;
    cursor: pointer;
    transition: all 0.3s ease;
    background-color: var(--bg-white);
}

.upload-area:hover {
    border-color: var(--primary-color);
    background-color: rgba(59, 130, 246, 0.02);
}

.upload-area.dragover {
    border-color: var(--primary-color);
    background-color: rgba(59, 130, 246, 0.05);
    box-shadow: var(--shadow-md);
}

.upload-icon {
    width: 60px;
    height: 60px;
    color: var(--primary-color);
    margin-bottom: 20px;
    stroke-width: 1.5;
}

.upload-area h2 {
    font-size: 1.5rem;
    margin-bottom: 10px;
    color: var(--text-primary);
}

.upload-area p {
    color: var(--text-secondary);
    margin-bottom: 5px;
}

.file-types {
    font-size: 0.9rem;
    color: var(--secondary-color);
    margin-top: 15px;
}

/* Loading State */
.loading-state {
    text-align: center;
    padding: 40px;
}

.spinner {
    width: 40px;
    height: 40px;
    border: 4px solid var(--border-color);
    border-top-color: var(--primary-color);
    border-radius: 50%;
    animation: spin 1s linear infinite;
    margin: 0 auto 20px;
}

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

/* Error Message */
.error-message {
    background-color: #fee2e2;
    border: 1px solid #fecaca;
    border-radius: 8px;
    padding: 15px 20px;
    color: #991b1b;
    margin-bottom: 20px;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.error-message::before {
    content: "⚠️";
    margin-right: 10px;
}

/* Metadata Section */
.metadata-section {
    background-color: var(--bg-white);
    border-radius: 12px;
    padding: 30px;
    box-shadow: var(--shadow-md);
}

.metadata-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 25px;
    padding-bottom: 15px;
    border-bottom: 1px solid var(--border-color);
}

.metadata-header h2 {
    font-size: 1.5rem;
    color: var(--text-primary);
}

/* Metadata Container */
.metadata-container {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 15px;
}

.metadata-item {
    display: grid;
    grid-template-columns: 1fr;
    gap: 8px;
    padding: 15px;
    background-color: var(--bg-light);
    border-radius: 8px;
    border-left: 4px solid var(--primary-color);
    transition: all 0.2s ease;
}

.metadata-item:hover {
    background-color: #f3f4f6;
    box-shadow: var(--shadow-sm);
}

.metadata-key {
    font-weight: 600;
    color: var(--text-primary);
    word-break: break-word;
    font-size: 0.9rem;
}

.metadata-value {
    color: var(--text-secondary);
    word-break: break-all;
    font-family: 'Monaco', 'Menlo', 'Ubuntu Mono', monospace;
    font-size: 0.85rem;
}

/* Buttons */
.btn {
    padding: 10px 20px;
    border: none;
    border-radius: 8px;
    font-size: 1rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.3s ease;
    display: inline-flex;
    align-items: center;
    gap: 8px;
}

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

.btn-primary:hover {
    background-color: var(--primary-dark);
    box-shadow: var(--shadow-md);
}

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

.btn-secondary:hover {
    background-color: #4b5563;
    box-shadow: var(--shadow-md);
}

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

/* Footer */
.footer {
    text-align: center;
    padding: 20px;
    color: var(--text-secondary);
    border-top: 1px solid var(--border-color);
    margin-top: auto;
}

/* Responsive Design */
@media (max-width: 768px) {
    .container {
        padding: 15px;
    }

    .header h1 {
        font-size: 2rem;
    }

    .header {
        margin-bottom: 30px;
        padding: 20px 0;
    }

    .upload-area {
        padding: 40px 15px;
    }

    .upload-icon {
        width: 50px;
        height: 50px;
    }

    .upload-area h2 {
        font-size: 1.2rem;
    }

    .metadata-section {
        padding: 20px;
    }

    .metadata-container {
        grid-template-columns: 1fr;
    }

    .metadata-header {
        flex-direction: column;
        align-items: flex-start;
        gap: 15px;
    }

    .metadata-header h2 {
        font-size: 1.2rem;
    }

    .btn {
        width: 100%;
        justify-content: center;
    }
}

@media (max-width: 480px) {
    .header h1 {
        font-size: 1.5rem;
    }

    .subtitle {
        font-size: 1rem;
    }

    .upload-area {
        padding: 30px 10px;
    }

    .upload-icon {
        width: 40px;
        height: 40px;
    }

    .upload-area h2 {
        font-size: 1rem;
    }

    .metadata-section {
        padding: 15px;
    }

    .metadata-container {
        grid-template-columns: 1fr;
    }

    .metadata-key {
        font-size: 0.85rem;
    }

    .metadata-value {
        font-size: 0.8rem;
    }
}