* {
            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;
            display: flex;
            justify-content: center;
            align-items: center;
            padding: 20px;
        }
        
        .container {
            background: white;
            border-radius: 20px;
            box-shadow: 0 20px 60px rgba(0, 0, 0, 0.3);
            padding: 40px;
            max-width: 450px;
            width: 100%;
        }
        
        h1 {
            color: #333;
            margin-bottom: 10px;
            text-align: center;
        }
        
        .subtitle {
            color: #666;
            text-align: center;
            margin-bottom: 30px;
            font-size: 14px;
        }
        
        .tabs {
            display: flex;
            margin-bottom: 30px;
            border-bottom: 2px solid #e0e0e0;
        }
        
        .tab {
            flex: 1;
            padding: 15px;
            text-align: center;
            cursor: pointer;
            background: none;
            border: none;
            font-size: 16px;
            color: #666;
            transition: all 0.3s;
            position: relative;
        }
        
        .tab.active {
            color: #667eea;
            font-weight: 600;
        }
        
        .tab.active::after {
            content: '';
            position: absolute;
            bottom: -2px;
            left: 0;
            right: 0;
            height: 2px;
            background: #667eea;
        }
        
        .form-container {
            display: none;
        }
        
        .form-container.active {
            display: block;
        }
        
        .form-group {
            margin-bottom: 20px;
        }
        
        label {
            display: block;
            margin-bottom: 8px;
            color: #333;
            font-weight: 500;
            font-size: 14px;
        }
        
        input[type="text"],
        input[type="email"],
        input[type="password"] {
            width: 100%;
            padding: 12px 15px;
            border: 2px solid #e0e0e0;
            border-radius: 8px;
            font-size: 15px;
            transition: border-color 0.3s;
        }
        
        input:focus {
            outline: none;
            border-color: #667eea;
        }
        
        .btn {
            width: 100%;
            padding: 14px;
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            color: white;
            border: none;
            border-radius: 8px;
            font-size: 16px;
            font-weight: 600;
            cursor: pointer;
            transition: transform 0.2s, box-shadow 0.2s;
            margin-top: 10px;
        }
        
        .btn:hover {
            transform: translateY(-2px);
            box-shadow: 0 5px 15px rgba(102, 126, 234, 0.4);
        }
        
        .btn:active {
            transform: translateY(0);
        }
        
        .error-message {
            background: #fee;
            color: #c33;
            padding: 12px;
            border-radius: 8px;
            margin-bottom: 20px;
            font-size: 14px;
            display: none;
        }
        
        .error-message.show {
            display: block;
        }
        
        .success-message {
            background: #efe;
            color: #3c3;
            padding: 12px;
            border-radius: 8px;
            margin-bottom: 20px;
            font-size: 14px;
            display: none;
        }
        
        .success-message.show {
            display: block;
        }