:root {
    --primary-color: #3b82f6;
    --secondary-color: #3498DB;
    --accent-color: #004aad;
    --success-color: #10b981;
    --warning-color: #f59e0b;
    --error-color: #ef4444;
    --light-green: #E8F8F5;
    --light-blue: #EBF3FF;
    --text-dark: #1f2937;
    --text-light: #6b7280;
    --white: #FFFFFF;
    --gray-light: #f9fafb;
    --gray-medium: #e5e7eb;
    --shadow: 0 10px 30px rgba(0,0,0,0.08); 
    --shadow-hover: 0 20px 40px rgba(0,0,0,0.12); 
    --shadow-lg: 0 25px 50px rgba(0,0,0,0.15); 
    --border-radius: 20px; 
    --border-radius-lg: 24px; 
    --transition: all 0.4s cubic-bezier(0.4, 0, 0.2, 1); 
    --blur: blur(10px); 
}

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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: linear-gradient(135deg, var(--light-blue), var(--white));
    min-height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    padding: 20px;
    color: var(--text-dark);
}

.container {
    width: 100%;
    max-width: 450px;
}

.card {
    background: var(--white);
    border-radius: var(--border-radius-lg);
    box-shadow: var(--shadow-lg);
    overflow: hidden;
    transition: var(--transition);
}

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

.header {
    padding: 30px 30px 20px;
    text-align: center;
    background: var(--light-blue);
    border-bottom: 1px solid var(--gray-medium);
}

.logo {
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 15px;
}

.logo-icon {
    font-size: 2.5rem;
    color: var(--primary-color);
    margin-right: 15px;
}

.logo-text {
    font-size: 2rem;
    font-weight: 700;
    color: var(--accent-color);
}

.tagline {
    font-size: 1rem;
    color: var(--text-light);
    font-weight: 500;
}

.tabs {
    display: flex;
    background: var(--gray-light);
    position: relative;
}

.tab {
    flex: 1;
    padding: 18px 0;
    text-align: center;
    font-weight: 600;
    color: var(--text-light);
    cursor: pointer;
    transition: var(--transition);
    position: relative;
    z-index: 1;
}

.tab.active {
    color: var(--primary-color);
}

.tab-slider {
    position: absolute;
    bottom: 0;
    left: 0;
    width: 50%;
    height: 100%;
    background: var(--white);
    transition: var(--transition);
    z-index: 0;
    border-bottom: 3px solid var(--primary-color);
}

.form-container {
    padding: 30px;
}

.form {
    display: none;
    animation: fadeIn 0.5s ease;
}

.form.active {
    display: block;
}

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

.form-title {
    text-align: center;
    margin-bottom: 25px;
    color: var(--accent-color);
    font-size: 1.8rem;
    font-weight: 700;
}

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

.input-group label {
    display: block;
    margin-bottom: 8px;
    color: var(--text-dark);
    font-weight: 500;
}

.input-group input,
.input-group select {
    width: 100%;
    padding: 14px 16px 14px 45px;
    border: 1px solid var(--gray-medium);
    border-radius: 12px;
    background: var(--white);
    color: var(--text-dark);
    font-size: 1rem;
    transition: var(--transition);
    outline: none;
}

.input-group input::placeholder {
    color: var(--text-light);
}

.input-group input:focus,
.input-group select:focus {
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.2);
}

.input-group i {
    position: absolute;
    left: 16px;
    top: 50%;
    transform: translateY(-50%);
    color: var(--text-light);
    transition: var(--transition);
}

.input-group input:focus + i {
    color: var(--primary-color);
}

.password-toggle {
    position: absolute;
    right: 16px;
    top: 50%;
    transform: translateY(-50%);
    color: var(--text-light);
    cursor: pointer;
    transition: var(--transition);
}

.password-toggle:hover {
    color: var(--primary-color);
}

.error-message {
    color: var(--error-color);
    font-size: 0.85rem;
    margin-top: 5px;
    display: none;
    align-items: center;
    gap: 5px;
}

.btn {
    width: 100%;
    padding: 14px;
    border: none;
    border-radius: 12px;
    background: var(--primary-color);
    color: var(--white);
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    margin-top: 10px;
}

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

.btn:active {
    transform: translateY(0);
}

.success-message {
    background: var(--light-green);
    color: var(--success-color);
    padding: 12px;
    border-radius: 8px;
    margin-top: 15px;
    text-align: center;
    display: none;
    align-items: center;
    justify-content: center;
    gap: 10px;
    border: 1px solid rgba(16, 185, 129, 0.3);
}

.divider {
    display: flex;
    align-items: center;
    margin: 25px 0;
    color: var(--text-light);
}

.divider::before,
.divider::after {
    content: '';
    flex: 1;
    height: 1px;
    background: var(--gray-medium);
}

.divider span {
    padding: 0 15px;
    font-size: 0.9rem;
}

.social-login {
    display: flex;
    gap: 15px;
    margin-top: 20px;
}

.social-btn {
    flex: 1;
    padding: 12px;
    border-radius: 10px;
    background: var(--white);
    border: 1px solid var(--gray-medium);
    color: var(--text-dark);
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 10px;
    cursor: pointer;
    transition: var(--transition);
    font-weight: 500;
}

.social-btn:hover {
    background: var(--gray-light);
    transform: translateY(-2px);
}

.footer {
    text-align: center;
    margin-top: 25px;
    color: var(--text-light);
    font-size: 0.9rem;
}

.footer a {
    color: var(--primary-color);
    text-decoration: none;
    transition: var(--transition);
}

.footer a:hover {
    color: var(--accent-color);
    text-decoration: underline;
}

/* Responsive Design */
@media (max-width: 480px) {
    .container {
        max-width: 100%;
    }
    
    .form-container {
        padding: 20px;
    }
    
    .form-title {
        font-size: 1.5rem;
    }
    
    .logo-text {
        font-size: 1.8rem;
    }
    
    .social-login {
        flex-direction: column;
    }
}