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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    padding: 20px;
}

.container {
    max-width: 900px;
    margin: 0 auto;
}

header {
    text-align: center;
    color: white;
    margin-bottom: 40px;
    padding: 20px;
}

header h1 {
    font-size: 2.5rem;
    margin-bottom: 10px;
}

header p {
    font-size: 1.1rem;
    opacity: 0.9;
}

main {
    background: white;
    border-radius: 20px;
    padding: 40px;
    box-shadow: 0 20px 60px rgba(0, 0, 0, 0.3);
}

.converter-box {
    margin-bottom: 30px;
}

.upload-area {
    border: 3px dashed #667eea;
    border-radius: 15px;
    padding: 60px 20px;
    text-align: center;
    transition: all 0.3s ease;
    cursor: pointer;
}

.upload-area:hover {
    border-color: #764ba2;
    background: #f8f9ff;
}

.upload-area.drag-over {
    border-color: #764ba2;
    background: #f0f4ff;
    transform: scale(1.02);
}

.upload-icon {
    font-size: 4rem;
    margin-bottom: 20px;
}

.upload-area h3 {
    color: #333;
    margin-bottom: 10px;
}

.upload-area p {
    color: #666;
    margin: 10px 0;
}

.security-note {
    font-size: 0.85rem;
    color: #10b981;
    margin-top: 15px;
    font-weight: 500;
}

.size-limit {
    font-size: 0.8rem;
    color: #999;
    margin-top: 5px;
}

.file-label {
    display: inline-block;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 12px 30px;
    border-radius: 25px;
    cursor: pointer;
    transition: transform 0.2s ease;
    margin-top: 10px;
}

.file-label:hover {
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(102, 126, 234, 0.4);
}

.file-label input {
    display: none;
}

.file-info {
    background: #f8f9ff;
    border-radius: 15px;
    padding: 20px;
    margin-bottom: 20px;
    border: 2px solid #e5e7eb;
}

.file-details {
    display: flex;
    align-items: center;
    gap: 15px;
}

.file-icon {
    font-size: 2rem;
}

.file-text {
    flex: 1;
}

.file-name {
    font-weight: 600;
    color: #333;
    margin-bottom: 5px;
    word-break: break-all;
}

.file-size {
    color: #666;
    font-size: 0.9rem;
}

.remove-btn {
    background: #ff4757;
    color: white;
    border: none;
    width: 30px;
    height: 30px;
    border-radius: 50%;
    cursor: pointer;
    font-size: 1.2rem;
    transition: transform 0.2s ease;
    flex-shrink: 0;
}

.remove-btn:hover {
    transform: scale(1.1);
    background: #e84118;
}

.conversion-options {
    margin-top: 20px;
}

.conversion-options label {
    display: block;
    color: #333;
    font-weight: 600;
    margin-bottom: 10px;
}

.conversion-options select {
    width: 100%;
    padding: 12px;
    border: 2px solid #ddd;
    border-radius: 10px;
    font-size: 1rem;
    margin-bottom: 20px;
    cursor: pointer;
    transition: border-color 0.3s ease;
    background: white;
}

.conversion-options select:focus {
    outline: none;
    border-color: #667eea;
}

.convert-btn,
.download-btn,
.reset-btn {
    width: 100%;
    padding: 15px;
    border: none;
    border-radius: 10px;
    font-size: 1.1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
}

.convert-btn {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
}

.convert-btn:hover:not(:disabled) {
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(102, 126, 234, 0.4);
}

.convert-btn:disabled {
    background: #ccc;
    cursor: not-allowed;
    transform: none;
}

.progress-area {
    margin-top: 20px;
}

.progress-bar {
    width: 100%;
    height: 10px;
    background: #e0e0e0;
    border-radius: 10px;
    overflow: hidden;
    margin-bottom: 10px;
}

.progress-fill {
    height: 100%;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    width: 0%;
    transition: width 0.3s ease;
}

.progress-text {
    text-align: center;
    color: #666;
    font-weight: 500;
}

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

.success-message {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 10px;
    margin-bottom: 20px;
    color: #10b981;
    font-size: 1.2rem;
    font-weight: 600;
}

.success-icon {
    background: #10b981;
    color: white;
    width: 40px;
    height: 40px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.5rem;
}

.download-btn {
    background: #10b981;
    color: white;
    margin-bottom: 10px;
}

.download-btn:hover {
    background: #059669;
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(16, 185, 129, 0.4);
}

.reset-btn {
    background: #6b7280;
    color: white;
}

.reset-btn:hover {
    background: #4b5563;
}

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

.error-message {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 10px;
    margin-bottom: 20px;
    color: #ef4444;
    font-size: 1.1rem;
    font-weight: 600;
}

.error-icon {
    background: #ef4444;
    color: white;
    width: 40px;
    height: 40px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.5rem;
}

.error-text {
    margin-top: 10px;
}

.security-features {
    margin: 30px 0;
    padding: 25px;
    background: #f0fdf4;
    border-radius: 15px;
    border: 2px solid #10b981;
}

.security-features h3 {
    color: #065f46;
    margin-bottom: 15px;
    text-align: center;
}

.security-features ul {
    list-style: none;
    padding: 0;
}

.security-features li {
    padding: 8px 0;
    color: #047857;
    font-size: 0.95rem;
}

.supported-formats {
    margin-top: 40px;
    padding-top: 30px;
    border-top: 2px solid #e5e7eb;
}

.supported-formats h3 {
    text-align: center;
    color: #333;
    margin-bottom: 20px;
}

.format-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 15px;
}

.format-item {
    background: #f8f9ff;
    padding: 15px;
    border-radius: 10px;
    text-align: center;
    font-weight: 500;
    color: #667eea;
    border: 2px solid #e5e7eb;
    transition: all 0.3s ease;
}

.format-item:hover {
    border-color: #667eea;
    transform: translateY(-2px);
}

footer {
    text-align: center;
    color: white;
    margin-top: 30px;
    opacity: 0.9;
}

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

    main {
        padding: 25px;
    }

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

    .format-grid {
        grid-template-columns: 1fr;
    }

    .security-features {
        padding: 20px;
    }
}