* {
    box-sizing: border-box;
}

:root {
    --linguify-primary: #2D5BBA;
    --linguify-secondary: #8B5CF6;
    --linguify-accent: #00D4AA;
    --primary: var(--linguify-primary);
    --primary-light: var(--linguify-accent);
    --primary-dark: #1E3A8A;
    --background: linear-gradient(135deg, var(--linguify-primary) 0%, var(--linguify-accent) 100%);
    --white: #ffffff;
    --gray-50: #f9fafb;
    --gray-100: #f3f4f6;
    --gray-200: #e5e7eb;
    --gray-300: #d1d5db;
    --gray-400: #9ca3af;
    --gray-500: #6b7280;
    --gray-600: #4b5563;
    --gray-700: #374151;
    --gray-800: #1f2937;
    --gray-900: #111827;
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
    --radius-lg: 0.75rem;
    --radius-xl: 1rem;
    --success: #10b981;
    --error: #ef4444;
    --warning: #f59e0b;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    background: var(--background);
    margin: 0;
    padding: 0;
    min-height: 100vh;
    line-height: 1.6;
    color: var(--gray-800);
    overflow-x: hidden;
}

.page-container {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 1rem;
}

.form-wrapper {
    width: 100%;
    max-width: 720px;
    background: var(--white);
    border-radius: 1rem;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.1);
    overflow: hidden;
    position: relative;
}

.form-container {
    padding: 1.5rem 2rem;
}

@media (min-width: 768px) {
    .form-container {
        padding: 2rem 2.5rem;
    }
}

@media (min-width: 1024px) {
    .form-container {
        padding: 2.5rem 3rem;
    }
}

.form-header {
    text-align: center;
    margin-bottom: 1.5rem;
}

.form-title {
    font-size: 1.75rem;
    font-weight: 800;
    color: var(--primary);
    margin-bottom: 0.5rem;
    line-height: 1.2;
}

@media (min-width: 768px) {
    .form-title {
        font-size: 2rem;
    }
}

.form-subtitle {
    font-size: 1rem;
    color: var(--gray-500);
    margin: 0;
}

.form-group {
    margin-bottom: 1rem;
}

.form-row {
    display: grid;
    grid-template-columns: 1fr;
    gap: 1rem;
    margin-bottom: 1rem;
}

@media (min-width: 768px) {
    .form-row {
        grid-template-columns: 1fr 1fr;
    }
}

.form-label {
    display: block;
    font-size: 0.85rem;
    font-weight: 600;
    color: var(--gray-700);
    margin-bottom: 0.25rem;
    letter-spacing: 0.025em;
}

.form-input {
    width: 100%;
    padding: 0.6rem 0.8rem;
    font-size: 0.9rem;
    line-height: 1.3;
    color: var(--gray-800);
    background: var(--white);
    border: 1px solid var(--gray-300);
    border-radius: 0.4rem;
    transition: all 0.2s ease-in-out;
    font-family: inherit;
}

.form-input:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(45, 91, 186, 0.1);
}

.form-input:hover:not(:focus) {
    border-color: var(--gray-300);
}

.form-select {
    width: 100%;
    padding: 0.6rem 0.8rem;
    font-size: 0.9rem;
    line-height: 1.3;
    color: var(--gray-800);
    background: var(--white);
    border: 1px solid var(--gray-300);
    border-radius: 0.4rem;
    transition: all 0.2s ease-in-out;
    font-family: inherit;
    cursor: pointer;
}

.form-select:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(45, 91, 186, 0.1);
}

.form-checkbox {
    margin-right: 0.75rem;
    transform: scale(1.1);
}

.form-text {
    font-size: 0.8rem;
    color: var(--gray-500);
    margin-top: 0.25rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.password-strength-container {
    margin-top: 0.5rem;
}

.password-strength-bar {
    height: 4px;
    border-radius: 2px;
    background: var(--gray-200);
    transition: all 0.3s ease;
    margin-bottom: 0.25rem;
}

.password-strength-text {
    font-size: 0.8rem;
    color: var(--gray-500);
}

.submit-button {
    width: 100%;
    padding: 0.8rem 2rem;
    font-size: 0.95rem;
    font-weight: 600;
    color: var(--white);
    background: linear-gradient(135deg, var(--linguify-primary) 0%, var(--linguify-accent) 100%);
    border: none;
    border-radius: 0.4rem;
    cursor: pointer;
    transition: all 0.3s ease;
    margin-top: 0.5rem;
    letter-spacing: 0.025em;
    position: relative;
    overflow: hidden;
}

.submit-button:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

.submit-button:active {
    transform: translateY(-1px);
}

.form-footer {
    margin-top: 2rem;
    padding-top: 2rem;
    border-top: 1px solid var(--gray-200);
    text-align: center;
}

.form-footer p {
    color: var(--gray-500);
    margin: 0.5rem 0;
}

.form-footer a {
    color: var(--primary);
    text-decoration: none;
    font-weight: 600;
    transition: color 0.2s ease;
}

.form-footer a:hover {
    color: var(--primary-dark);
}

.back-home-link {
    position: absolute;
    top: 2rem;
    left: 2rem;
    color: var(--white);
    text-decoration: none;
    font-weight: 500;
    font-size: 1rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
    transition: all 0.2s ease;
    padding: 0.5rem 1rem;
    border-radius: var(--radius-lg);
    background: rgba(255, 255, 255, 0.1);
    backdrop-filter: blur(10px);
}

.back-home-link:hover {
    background: rgba(255, 255, 255, 0.2);
    color: var(--white);
}

.checkbox-group {
    display: flex;
    align-items: flex-start;
    gap: 0.5rem;
    margin-bottom: 1rem;
}

.checkbox-label {
    font-size: 0.85rem;
    color: var(--gray-600);
    line-height: 1.4;
    margin: 0;
}

.error-message {
    color: #dc2626;
    font-size: 0.8rem;
    margin-top: 0.25rem;
}

.icon {
    width: 1.25rem;
    height: 1.25rem;
}

/* Username validation feedback */
.username-feedback {
    display: flex;
    align-items: center;
    gap: 0.375rem;
    font-size: 0.875rem;
    margin-top: 0.5rem;
    padding: 0.5rem 0.75rem;
    border-radius: 0.375rem;
    animation: fadeIn 0.2s ease-in-out;
}

.username-feedback.success {
    color: var(--success);
    background-color: rgba(16, 185, 129, 0.1);
    border: 1px solid rgba(16, 185, 129, 0.2);
}

.username-feedback.error {
    color: var(--error);
    background-color: rgba(239, 68, 68, 0.1);
    border: 1px solid rgba(239, 68, 68, 0.2);
}

.username-feedback.loading {
    color: var(--gray-600);
    background-color: var(--gray-100);
    border: 1px solid var(--gray-200);
}

.username-feedback i {
    font-size: 1rem;
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(-0.25rem);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}