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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    padding: 20px;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    background: white;
    border-radius: 15px;
    box-shadow: 0 20px 40px rgba(0,0,0,0.1);
    overflow: hidden;
}

header {
    background: linear-gradient(135deg, #2c3e50, #3498db);
    color: white;
    padding: 40px;
    text-align: center;
}

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

.subtitle {
    font-size: 1.2em;
    opacity: 0.9;
}

.tabs {
    display: flex;
    background: #f8f9fa;
    border-bottom: 1px solid #dee2e6;
}

.tab-button {
    flex: 1;
    padding: 15px 20px;
    border: none;
    background: transparent;
    cursor: pointer;
    font-size: 16px;
    font-weight: 500;
    transition: all 0.3s ease;
    border-bottom: 3px solid transparent;
}

.tab-button:hover {
    background: #e9ecef;
}

.tab-button.active {
    background: white;
    border-bottom-color: #3498db;
    color: #3498db;
}

.tab-content {
    display: none;
    padding: 30px;
}

.tab-content.active {
    display: block;
}

.tab-content h2 {
    color: #2c3e50;
    margin-bottom: 20px;
    font-size: 1.8em;
}

.upload-area {
    border: 2px dashed #3498db;
    border-radius: 10px;
    padding: 40px;
    text-align: center;
    margin-bottom: 20px;
    transition: all 0.3s ease;
    background: #f8f9fa;
}

.upload-area:hover {
    border-color: #2980b9;
    background: #e9ecef;
}

.upload-placeholder {
    cursor: pointer;
}

.upload-placeholder p {
    font-size: 18px;
    color: #6c757d;
    margin-bottom: 10px;
}

.file-types {
    font-size: 14px !important;
    color: #adb5bd !important;
}

.input-group {
    margin-bottom: 20px;
}

.input-group label {
    display: block;
    margin-bottom: 5px;
    font-weight: 500;
    color: #495057;
}

.input-group input, .input-group select {
    width: 100%;
    padding: 10px;
    border: 1px solid #ced4da;
    border-radius: 5px;
    font-size: 16px;
}

.input-group small {
    color: #6c757d;
    font-size: 12px;
}

.action-buttons {
    display: flex;
    gap: 10px;
    margin-bottom: 20px;
    flex-wrap: wrap;
}

.conversion-options {
    display: flex;
    align-items: center;
    gap: 10px;
    margin-bottom: 20px;
    flex-wrap: wrap;
}

.btn {
    padding: 12px 24px;
    border: none;
    border-radius: 5px;
    cursor: pointer;
    font-size: 16px;
    font-weight: 500;
    transition: all 0.3s ease;
    text-decoration: none;
    display: inline-block;
}

.btn-primary {
    background: #3498db;
    color: white;
}

.btn-primary:hover {
    background: #2980b9;
}

.btn-success {
    background: #27ae60;
    color: white;
}

.btn-success:hover {
    background: #219a52;
}

.btn-info {
    background: #17a2b8;
    color: white;
}

.btn-info:hover {
    background: #138496;
}

.result-area {
    background: #f8f9fa;
    border: 1px solid #dee2e6;
    border-radius: 5px;
    padding: 20px;
    min-height: 100px;
    max-height: 400px;
    overflow-y: auto;
    white-space: pre-wrap;
    font-family: 'Courier New', monospace;
}

.status-message {
    position: fixed;
    top: 20px;
    right: 20px;
    padding: 15px 20px;
    border-radius: 5px;
    color: white;
    font-weight: 500;
    z-index: 1000;
    display: none;
}

.status-success {
    background: #27ae60;
}

.status-error {
    background: #e74c3c;
}

.status-info {
    background: #3498db;
}

.download-link {
    display: inline-block;
    margin-top: 10px;
    padding: 10px 15px;
    background: #27ae60;
    color: white;
    text-decoration: none;
    border-radius: 5px;
    transition: background 0.3s ease;
}

.download-link:hover {
    background: #219a52;
}

@media (max-width: 768px) {
    .container {
        margin: 10px;
        border-radius: 10px;
    }
    
    .tabs {
        flex-direction: column;
    }
    
    .tab-button {
        border-bottom: 1px solid #dee2e6;
        border-right: none;
    }
    
    .action-buttons {
        flex-direction: column;
    }
    
    .conversion-options {
        flex-direction: column;
        align-items: stretch;
    }
}