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

:root {
    --primary-color: #0f172a;
    --primary-hover: #334155;
    --success-color: #059669;
    --background: #ffffff;
    --card-bg: #f8fafc;
    --text-primary: #0f172a;
    --text-secondary: #64748b;
    --border-color: #e2e8f0;
    --shadow: 0 1px 3px 0 rgba(0, 0, 0, 0.1), 0 1px 2px 0 rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Inter', Roboto, sans-serif;
    background: var(--background);
    color: var(--text-primary);
    line-height: 1.5;
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 20px;
    letter-spacing: -0.01em;
}

.container {
    max-width: 600px;
    width: 100%;
}

header {
    text-align: center;
    margin-bottom: 40px;
}

h1 {
    font-size: 2rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 8px;
    letter-spacing: -0.02em;
}

.subtitle {
    font-size: 1rem;
    color: var(--text-secondary);
    font-weight: 400;
}

main {
    background: var(--card-bg);
    border-radius: 12px;
    padding: 48px;
    box-shadow: var(--shadow-lg);
    border: 1px solid var(--border-color);
}

.upload-area {
    border: 2px dashed var(--border-color);
    border-radius: 8px;
    padding: 64px 40px;
    text-align: center;
    transition: all 0.2s ease;
    cursor: pointer;
    background: #ffffff;
}

.upload-area:hover,
.upload-area.drag-over {
    border-color: var(--text-primary);
    background: #fafafa;
}

.upload-icon {
    width: 56px;
    height: 56px;
    color: var(--text-secondary);
    margin: 0 auto 24px;
    stroke-width: 1.5;
}

.upload-area h2 {
    font-size: 1.125rem;
    font-weight: 500;
    color: var(--text-primary);
    margin-bottom: 8px;
    letter-spacing: -0.01em;
}

.upload-area p {
    color: var(--text-secondary);
    margin-bottom: 16px;
    font-size: 0.9375rem;
}

.file-button {
    display: inline-block;
    background: var(--primary-color);
    color: white;
    padding: 10px 28px;
    border-radius: 6px;
    font-weight: 500;
    font-size: 0.9375rem;
    cursor: pointer;
    transition: all 0.15s ease;
    margin-bottom: 16px;
    letter-spacing: -0.01em;
}

.file-button:hover {
    background: var(--primary-hover);
    transform: translateY(-1px);
    box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
}

.file-info {
    font-size: 0.8125rem;
    color: var(--text-secondary);
    margin-top: 16px;
}

.status-area {
    text-align: center;
    padding: 40px;
}

.spinner {
    width: 48px;
    height: 48px;
    border: 3px solid var(--border-color);
    border-top-color: var(--primary-color);
    border-radius: 50%;
    margin: 0 auto 20px;
    animation: spin 0.8s linear infinite;
}

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

#statusText {
    font-size: 0.9375rem;
    color: var(--text-secondary);
    margin-bottom: 20px;
    font-weight: 400;
}

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

.progress-fill {
    height: 100%;
    background: var(--primary-color);
    width: 0%;
    transition: width 0.3s ease;
    border-radius: 2px;
}

.result-area {
    text-align: center;
    padding: 40px 20px;
}

.success-icon {
    width: 56px;
    height: 56px;
    color: var(--success-color);
    margin: 0 auto 20px;
    stroke-width: 1.5;
}

.result-area h2 {
    font-size: 1.125rem;
    font-weight: 500;
    color: var(--text-primary);
    margin-bottom: 28px;
    letter-spacing: -0.01em;
}

.download-button {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    background: var(--primary-color);
    color: white;
    padding: 11px 28px;
    border: none;
    border-radius: 6px;
    font-size: 0.9375rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.15s ease;
    margin-bottom: 12px;
    width: 100%;
    justify-content: center;
    letter-spacing: -0.01em;
}

.download-button:hover {
    background: var(--primary-hover);
    transform: translateY(-1px);
    box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
}

.download-button svg {
    width: 18px;
    height: 18px;
    stroke-width: 2;
}

.secondary-button {
    display: inline-block;
    background: transparent;
    color: var(--text-secondary);
    padding: 11px 24px;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    font-size: 0.9375rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.15s ease;
    width: 100%;
    letter-spacing: -0.01em;
}

.secondary-button:hover {
    border-color: var(--text-primary);
    color: var(--text-primary);
    background: #fafafa;
}

.instructions {
    margin-top: 32px;
    padding: 20px;
    background: #ffffff;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    text-align: left;
}

.instructions h3 {
    font-size: 0.9375rem;
    font-weight: 500;
    color: var(--text-primary);
    margin-bottom: 12px;
    letter-spacing: -0.01em;
}

.instructions ol {
    padding-left: 20px;
}

.instructions li {
    color: var(--text-secondary);
    margin-bottom: 6px;
    font-size: 0.875rem;
}

footer {
    text-align: center;
    margin-top: 24px;
    padding: 16px;
}

footer p {
    font-size: 0.8125rem;
    color: var(--text-secondary);
}

@media (max-width: 640px) {
    h1 {
        font-size: 1.5rem;
    }
    
    .subtitle {
        font-size: 0.9375rem;
    }
    
    main {
        padding: 32px 24px;
    }
    
    .upload-area {
        padding: 48px 24px;
    }
    
    .upload-icon {
        width: 48px;
        height: 48px;
    }
}