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

:root {
    --primary-color: #007bff;
    --primary-hover: #0056b3;
    --danger-color: #dc3545;
    --danger-hover: #c82333;
    --secondary-color: #6c757d;
    --secondary-hover: #5a6268;
    --text-primary: #212529;
    --text-secondary: #6c757d;
    --border-color: #dee2e6;
    --background: #f8f9fa;
    --card-background: #ffffff;
    --error-color: #dc3545;
    --error-background: #f8d7da;
    --warning-background: #fff3cd;
    --warning-border: #ffc107;
    --success-color: #28a745;
    --success-background: #d4edda;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 20px;
    color: var(--text-primary);
}

.container {
    width: 100%;
    max-width: 500px;
}

.page {
    display: none;
}

.page.active {
    display: block;
    animation: fadeIn 0.3s ease-in;
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.card {
    background: var(--card-background);
    border-radius: 16px;
    box-shadow: 0 10px 40px rgba(0, 0, 0, 0.2);
    padding: 40px;
}

.header {
    text-align: center;
    margin-bottom: 32px;
}

.header h1 {
    font-size: 32px;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 8px;
}

.subtitle {
    font-size: 16px;
    color: var(--text-secondary);
    margin-top: 8px;
}

.user-info {
    margin-top: 12px;
    padding: 12px;
    background: var(--background);
    border-radius: 8px;
    font-size: 14px;
    color: var(--text-secondary);
}

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

.form-group label {
    display: block;
    font-size: 14px;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 8px;
}

.form-group input {
    width: 100%;
    padding: 12px 16px;
    font-size: 16px;
    border: 2px solid var(--border-color);
    border-radius: 8px;
    transition: all 0.2s;
    background: var(--card-background);
}

.form-group input:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(0, 123, 255, 0.1);
}

.btn {
    width: 100%;
    padding: 14px 24px;
    font-size: 16px;
    font-weight: 600;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    transition: all 0.2s;
    text-align: center;
}

.btn:disabled {
    opacity: 0.6;
    cursor: not-allowed;
}

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

.btn-primary:hover:not(:disabled) {
    background: var(--primary-hover);
    transform: translateY(-1px);
    box-shadow: 0 4px 12px rgba(0, 123, 255, 0.3);
}

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

.btn-danger:hover:not(:disabled) {
    background: var(--danger-hover);
    transform: translateY(-1px);
    box-shadow: 0 4px 12px rgba(220, 53, 69, 0.3);
}

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

.btn-secondary:hover:not(:disabled) {
    background: var(--secondary-hover);
    transform: translateY(-1px);
}

.button-group {
    display: flex;
    gap: 12px;
    margin-top: 24px;
}

.button-group .btn {
    flex: 1;
}

.error-message {
    display: none;
    padding: 12px 16px;
    margin-bottom: 20px;
    background: var(--error-background);
    color: var(--error-color);
    border-radius: 8px;
    font-size: 14px;
    border-left: 4px solid var(--error-color);
}

.error-message.show {
    display: block;
    animation: shake 0.3s;
}

@keyframes shake {
    0%, 100% { transform: translateX(0); }
    25% { transform: translateX(-5px); }
    75% { transform: translateX(5px); }
}

.warning-box {
    background: var(--warning-background);
    border: 2px solid var(--warning-border);
    border-radius: 12px;
    padding: 24px;
    margin-bottom: 24px;
    text-align: center;
}

.warning-icon {
    width: 64px;
    height: 64px;
    color: var(--warning-border);
    margin: 0 auto 16px;
}

.warning-box h2 {
    font-size: 20px;
    color: var(--text-primary);
    margin-bottom: 12px;
    line-height: 1.4;
}

.warning-text {
    font-size: 14px;
    color: var(--text-secondary);
    margin-top: 12px;
}

.success-box {
    text-align: center;
    padding: 24px;
}

.success-icon {
    width: 80px;
    height: 80px;
    color: var(--success-color);
    margin: 0 auto 24px;
}

.success-box h2 {
    font-size: 24px;
    color: var(--text-primary);
    margin-bottom: 12px;
}

.success-box p {
    font-size: 16px;
    color: var(--text-secondary);
    line-height: 1.6;
}

/* Loading state */
.btn.loading {
    position: relative;
    color: transparent;
    pointer-events: none;
}

.btn.loading::after {
    content: '';
    position: absolute;
    width: 16px;
    height: 16px;
    top: 50%;
    left: 50%;
    margin-left: -8px;
    margin-top: -8px;
    border: 2px solid rgba(255, 255, 255, 0.3);
    border-radius: 50%;
    border-top-color: white;
    animation: spin 0.6s linear infinite;
}

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

/* Responsive */
@media (max-width: 576px) {
    .card {
        padding: 24px;
    }
    
    .header h1 {
        font-size: 24px;
    }
    
    .button-group {
        flex-direction: column-reverse;
    }
}