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

:root {
    --primary-color: #4f46e5;
    --primary-hover: #4338ca;
    --success-color: #10b981;
    --success-hover: #059669;
    --secondary-color: #6b7280;
    --secondary-hover: #4b5563;
    --background: #f9fafb;
    --card-background: #ffffff;
    --text-primary: #1f2937;
    --text-secondary: #6b7280;
    --border-color: #e5e7eb;
    --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', 'Roboto', 'Oxygen', 'Ubuntu', 'Cantarell', 'Fira Sans', 'Droid Sans', 'Helvetica Neue', sans-serif;
    background: var(--background);
    color: var(--text-primary);
    line-height: 1.6;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 20px;
}

header {
    text-align: center;
    padding: 40px 20px;
}

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

.subtitle {
    font-size: 1.25rem;
    color: var(--text-secondary);
}

main {
    margin: 40px 0;
}

.converter-section {
    background: var(--card-background);
    border-radius: 12px;
    padding: 40px;
    box-shadow: var(--shadow-lg);
    margin-bottom: 40px;
}

.drop-zone {
    border: 3px dashed var(--border-color);
    border-radius: 12px;
    padding: 60px 20px;
    text-align: center;
    transition: all 0.3s ease;
    cursor: pointer;
}

.drop-zone:hover,
.drop-zone.dragover {
    border-color: var(--primary-color);
    background: #f0f1ff;
}

.drop-zone-content {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 15px;
}

.upload-icon {
    width: 80px;
    height: 80px;
    color: var(--primary-color);
}

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

.drop-zone p {
    color: var(--text-secondary);
    font-size: 1rem;
}

.file-info {
    font-size: 0.875rem !important;
    color: var(--text-secondary) !important;
}

.btn-primary,
.btn-success,
.btn-secondary {
    padding: 12px 30px;
    border: none;
    border-radius: 8px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    display: inline-block;
    text-decoration: none;
}

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

.btn-primary:hover {
    background: var(--primary-hover);
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

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

.btn-success:hover {
    background: var(--success-hover);
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

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

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

.btn-large {
    padding: 16px 40px;
    font-size: 1.125rem;
}

.options-section {
    margin-top: 30px;
    padding-top: 30px;
    border-top: 1px solid var(--border-color);
}

.options-section h3 {
    margin-bottom: 20px;
    color: var(--text-primary);
}

.options-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(120px, 1fr));
    gap: 15px;
}

.checkbox-label {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 12px 20px;
    background: var(--background);
    border-radius: 8px;
    cursor: pointer;
    transition: all 0.3s ease;
    border: 2px solid transparent;
}

.checkbox-label:hover {
    border-color: var(--primary-color);
}

.checkbox-label input[type="checkbox"] {
    width: 20px;
    height: 20px;
    cursor: pointer;
}

.checkbox-label span {
    font-weight: 500;
}

.preview-section {
    margin-top: 30px;
    padding-top: 30px;
    border-top: 1px solid var(--border-color);
}

.preview-section h3 {
    margin-bottom: 20px;
    color: var(--text-primary);
}

.preview-container {
    display: grid;
    grid-template-columns: 1fr auto 1fr;
    gap: 30px;
    align-items: center;
}

.preview-item {
    text-align: center;
}

.preview-item p {
    font-weight: 600;
    margin-bottom: 15px;
    color: var(--text-primary);
}

.preview-item img {
    max-width: 200px;
    max-height: 200px;
    border-radius: 8px;
    box-shadow: var(--shadow);
    display: block;
    margin: 0 auto;
}

.size-label {
    display: block;
    margin-top: 10px;
    font-size: 0.875rem;
    color: var(--text-secondary);
}

.preview-arrow {
    font-size: 2rem;
    color: var(--primary-color);
    font-weight: bold;
}

.ico-preview-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 15px;
    max-width: 250px;
    margin: 0 auto;
}

.ico-preview-grid img {
    width: 100%;
    height: auto;
    border: 2px solid var(--border-color);
    border-radius: 4px;
    padding: 10px;
    background: var(--background);
}

.actions-section {
    margin-top: 30px;
    padding-top: 30px;
    border-top: 1px solid var(--border-color);
    display: flex;
    gap: 15px;
    justify-content: center;
    flex-wrap: wrap;
}

.progress-section {
    margin-top: 30px;
    padding-top: 30px;
    border-top: 1px solid var(--border-color);
}

.progress-bar {
    width: 100%;
    height: 8px;
    background: var(--border-color);
    border-radius: 4px;
    overflow: hidden;
    margin-bottom: 15px;
}

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

.progress-section p {
    text-align: center;
    color: var(--text-secondary);
}

.info-section {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 30px;
    margin-bottom: 40px;
}

.info-card {
    background: var(--card-background);
    padding: 30px;
    border-radius: 12px;
    box-shadow: var(--shadow);
    text-align: center;
    transition: all 0.3s ease;
}

.info-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
}

.info-icon {
    width: 60px;
    height: 60px;
    color: var(--primary-color);
    margin: 0 auto 20px;
}

.info-card h3 {
    margin-bottom: 15px;
    color: var(--text-primary);
    font-size: 1.25rem;
}

.info-card p {
    color: var(--text-secondary);
    line-height: 1.8;
}

.faq-section {
    background: var(--card-background);
    border-radius: 12px;
    padding: 40px;
    box-shadow: var(--shadow);
    margin-bottom: 40px;
}

.faq-section h2 {
    text-align: center;
    margin-bottom: 30px;
    color: var(--primary-color);
    font-size: 2rem;
}

.faq-item {
    margin-bottom: 25px;
    padding-bottom: 25px;
    border-bottom: 1px solid var(--border-color);
}

.faq-item:last-child {
    border-bottom: none;
    margin-bottom: 0;
    padding-bottom: 0;
}

.faq-item h3 {
    margin-bottom: 10px;
    color: var(--text-primary);
    font-size: 1.125rem;
}

.faq-item p {
    color: var(--text-secondary);
    line-height: 1.8;
}

footer {
    text-align: center;
    padding: 30px 20px;
    color: var(--text-secondary);
    border-top: 1px solid var(--border-color);
}

@media (max-width: 768px) {
    header h1 {
        font-size: 2rem;
    }

    .subtitle {
        font-size: 1rem;
    }

    .converter-section {
        padding: 20px;
    }

    .drop-zone {
        padding: 40px 15px;
    }

    .upload-icon {
        width: 60px;
        height: 60px;
    }

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

    .preview-arrow {
        transform: rotate(90deg);
    }

    .options-grid {
        grid-template-columns: repeat(2, 1fr);
    }

    .actions-section {
        flex-direction: column;
    }

    .actions-section button {
        width: 100%;
    }
}