/**
 * VTNE Exam Prep - Main Stylesheet
 * Professional medical/veterinary aesthetic with clean, modern design
 */

/* ============================================
   IMPORTS & FONTS
   ============================================ */
@import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;600;700&family=JetBrains+Mono&display=swap');

/* ============================================
   CSS VARIABLES - VTNE COLOR SCHEME
   ============================================ */
:root {
    /* Primary Colors */
    --primary-blue: #1a56db;
    --primary-blue-hover: #1544b0;
    --dark-navy: #0f172a;

    /* Background Colors */
    --light-bg: #f8fafc;
    --card-white: #ffffff;

    /* Status Colors */
    --success-green: #16a34a;
    --error-red: #dc2626;
    --warning-amber: #f59e0b;

    /* Text Colors */
    --text-primary: #1e293b;
    --text-secondary: #64748b;

    /* Borders & Dividers */
    --border-gray: #e2e8f0;
    --accent-teal: #0891b2;

    /* Shadows */
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.1);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 25px rgba(0, 0, 0, 0.15);

    /* Border Radius */
    --radius-sm: 6px;
    --radius-md: 8px;
    --radius-lg: 12px;

    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;
}

/* ============================================
   RESET & BASE STYLES
   ============================================ */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    font-size: 16px;
    scroll-behavior: smooth;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    font-size: 1rem;
    line-height: 1.6;
    color: var(--text-primary);
    background-color: var(--light-bg);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* ============================================
   TYPOGRAPHY
   ============================================ */
h1, h2, h3, h4, h5, h6 {
    font-weight: 700;
    line-height: 1.2;
    margin-bottom: 1rem;
    color: var(--dark-navy);
}

h1 { font-size: 3rem; }
h2 { font-size: 2.5rem; }
h3 { font-size: 2rem; }
h4 { font-size: 1.5rem; }
h5 { font-size: 1.25rem; }
h6 { font-size: 1rem; }

p {
    margin-bottom: 1rem;
    color: var(--text-secondary);
}

a {
    color: var(--primary-blue);
    text-decoration: none;
    transition: color 0.3s ease;
}

a:hover {
    color: var(--primary-blue-hover);
}

/* ============================================
   NAVIGATION BAR
   ============================================ */
.navbar {
    background-color: var(--dark-navy);
    padding: 1rem 0;
    box-shadow: var(--shadow-md);
    position: sticky;
    top: 0;
    z-index: 1000;
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.nav-logo {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--card-white);
    text-decoration: none;
}

.nav-logo:hover {
    color: var(--card-white);
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: 2rem;
    align-items: center;
}

.nav-link {
    color: var(--card-white);
    font-weight: 500;
    padding: 0.5rem 1rem;
    border-radius: var(--radius-sm);
    transition: background-color 0.3s ease;
}

.nav-link:hover {
    background-color: rgba(255, 255, 255, 0.1);
    color: var(--card-white);
}

.nav-link.active {
    background-color: var(--primary-blue);
}

/* Mobile Menu Toggle */
.nav-toggle {
    display: none;
    background: none;
    border: none;
    color: var(--card-white);
    font-size: 1.5rem;
    cursor: pointer;
}

/* ============================================
   BUTTONS
   ============================================ */
.btn {
    display: inline-block;
    padding: 0.75rem 1.5rem;
    font-size: 1rem;
    font-weight: 600;
    text-align: center;
    border: none;
    border-radius: var(--radius-sm);
    cursor: pointer;
    transition: all 0.3s ease;
    text-decoration: none;
}

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

.btn-primary:hover {
    background-color: var(--primary-blue-hover);
    color: var(--card-white);
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.btn-secondary {
    background-color: transparent;
    color: var(--primary-blue);
    border: 2px solid var(--primary-blue);
}

.btn-secondary:hover {
    background-color: var(--primary-blue);
    color: var(--card-white);
}

.btn-success {
    background-color: var(--success-green);
    color: var(--card-white);
}

.btn-success:hover {
    background-color: #15803d;
    color: var(--card-white);
}

.btn-lg {
    padding: 1rem 2rem;
    font-size: 1.125rem;
}

.btn-sm {
    padding: 0.5rem 1rem;
    font-size: 0.875rem;
}

.btn-block {
    display: block;
    width: 100%;
}

/* ============================================
   FORMS
   ============================================ */
.form-group {
    margin-bottom: 1.5rem;
}

.form-label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 600;
    color: var(--text-primary);
}

.form-control {
    width: 100%;
    padding: 0.75rem 1rem;
    font-size: 1rem;
    font-family: inherit;
    color: var(--text-primary);
    background-color: var(--card-white);
    border: 1px solid var(--border-gray);
    border-radius: var(--radius-sm);
    transition: border-color 0.3s ease, box-shadow 0.3s ease;
}

.form-control:focus {
    outline: none;
    border-color: var(--primary-blue);
    box-shadow: 0 0 0 3px rgba(26, 86, 219, 0.1);
}

.form-control::placeholder {
    color: var(--text-secondary);
}

.form-error {
    color: var(--error-red);
    font-size: 0.875rem;
    margin-top: 0.25rem;
}

.form-success {
    color: var(--success-green);
    font-size: 0.875rem;
    margin-top: 0.25rem;
}

.form-text {
    font-size: 0.875rem;
    color: var(--text-secondary);
    margin-top: 0.25rem;
}

textarea.form-control {
    min-height: 120px;
    resize: vertical;
}

select.form-control {
    cursor: pointer;
}

.form-check {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    margin-bottom: 1rem;
}

.form-check-input {
    width: 1.25rem;
    height: 1.25rem;
    cursor: pointer;
}

.form-check-label {
    cursor: pointer;
    user-select: none;
}

/* ============================================
   CARDS
   ============================================ */
.card {
    background-color: var(--card-white);
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-sm);
    overflow: hidden;
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
}

.card-header {
    padding: 1.5rem;
    border-bottom: 1px solid var(--border-gray);
}

.card-body {
    padding: 1.5rem;
}

.card-footer {
    padding: 1.5rem;
    border-top: 1px solid var(--border-gray);
    background-color: var(--light-bg);
}

.card-title {
    font-size: 1.5rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
}

.card-subtitle {
    font-size: 1rem;
    color: var(--text-secondary);
    margin-bottom: 1rem;
}

/* ============================================
   ALERTS
   ============================================ */
.alert {
    padding: 1rem 1.5rem;
    border-radius: var(--radius-sm);
    margin-bottom: 1.5rem;
    border-left: 4px solid;
}

.alert-success {
    background-color: #dcfce7;
    color: #166534;
    border-left-color: var(--success-green);
}

.alert-error {
    background-color: #fee2e2;
    color: #991b1b;
    border-left-color: var(--error-red);
}

.alert-warning {
    background-color: #fef3c7;
    color: #92400e;
    border-left-color: var(--warning-amber);
}

.alert-info {
    background-color: #dbeafe;
    color: #1e40af;
    border-left-color: var(--primary-blue);
}

/* ============================================
   CONTAINERS & LAYOUT
   ============================================ */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
}

.container-sm {
    max-width: 800px;
}

.section {
    padding: 4rem 0;
}

.section-dark {
    background-color: var(--dark-navy);
    color: var(--card-white);
}

.section-light {
    background-color: var(--light-bg);
}

.text-center {
    text-align: center;
}

.text-left {
    text-align: left;
}

.text-right {
    text-align: right;
}

/* ============================================
   GRID SYSTEM
   ============================================ */
.grid {
    display: grid;
    gap: 2rem;
}

.grid-2 {
    grid-template-columns: repeat(2, 1fr);
}

.grid-3 {
    grid-template-columns: repeat(3, 1fr);
}

.grid-4 {
    grid-template-columns: repeat(4, 1fr);
}

/* ============================================
   FLEXBOX UTILITIES
   ============================================ */
.flex {
    display: flex;
}

.flex-center {
    display: flex;
    justify-content: center;
    align-items: center;
}

.flex-between {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.flex-column {
    flex-direction: column;
}

.gap-1 { gap: 1rem; }
.gap-2 { gap: 2rem; }
.gap-3 { gap: 3rem; }

/* ============================================
   HERO SECTION
   ============================================ */
.hero {
    background: linear-gradient(135deg, var(--dark-navy) 0%, var(--primary-blue) 100%);
    color: var(--card-white);
    padding: 6rem 0;
    text-align: center;
}

.hero h1 {
    color: var(--card-white);
    font-size: 3.5rem;
    margin-bottom: 1.5rem;
}

.hero p {
    color: rgba(255, 255, 255, 0.9);
    font-size: 1.25rem;
    margin-bottom: 2rem;
}

/* ============================================
   FOOTER
   ============================================ */
.footer {
    background-color: var(--dark-navy);
    color: var(--card-white);
    padding: 3rem 0 1.5rem;
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
    margin-bottom: 2rem;
}

.footer-section h4 {
    color: var(--card-white);
    margin-bottom: 1rem;
}

.footer-section ul {
    list-style: none;
}

.footer-section ul li {
    margin-bottom: 0.5rem;
}

.footer-section a {
    color: rgba(255, 255, 255, 0.8);
}

.footer-section a:hover {
    color: var(--card-white);
}

.footer-bottom {
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    padding-top: 1.5rem;
    text-align: center;
    color: rgba(255, 255, 255, 0.6);
}

/* ============================================
   BADGES
   ============================================ */
.badge {
    display: inline-block;
    padding: 0.25rem 0.75rem;
    font-size: 0.875rem;
    font-weight: 600;
    border-radius: 999px;
}

.badge-success {
    background-color: var(--success-green);
    color: var(--card-white);
}

.badge-error {
    background-color: var(--error-red);
    color: var(--card-white);
}

.badge-warning {
    background-color: var(--warning-amber);
    color: var(--dark-navy);
}

.badge-primary {
    background-color: var(--primary-blue);
    color: var(--card-white);
}

/* ============================================
   UTILITY CLASSES
   ============================================ */
.mt-1 { margin-top: var(--spacing-sm); }
.mt-2 { margin-top: var(--spacing-md); }
.mt-3 { margin-top: var(--spacing-lg); }
.mt-4 { margin-top: var(--spacing-xl); }

.mb-1 { margin-bottom: var(--spacing-sm); }
.mb-2 { margin-bottom: var(--spacing-md); }
.mb-3 { margin-bottom: var(--spacing-lg); }
.mb-4 { margin-bottom: var(--spacing-xl); }

.pt-1 { padding-top: var(--spacing-sm); }
.pt-2 { padding-top: var(--spacing-md); }
.pt-3 { padding-top: var(--spacing-lg); }
.pt-4 { padding-top: var(--spacing-xl); }

.pb-1 { padding-bottom: var(--spacing-sm); }
.pb-2 { padding-bottom: var(--spacing-md); }
.pb-3 { padding-bottom: var(--spacing-lg); }
.pb-4 { padding-bottom: var(--spacing-xl); }

/* ============================================
   RESPONSIVE DESIGN
   ============================================ */
@media (max-width: 1024px) {
    .grid-4 {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (max-width: 768px) {
    html {
        font-size: 14px;
    }

    .nav-menu {
        display: none;
    }

    .nav-toggle {
        display: block;
    }

    .nav-menu.active {
        display: flex;
        flex-direction: column;
        position: absolute;
        top: 100%;
        left: 0;
        right: 0;
        background-color: var(--dark-navy);
        padding: 1rem;
        gap: 0.5rem;
    }

    .grid-2,
    .grid-3,
    .grid-4 {
        grid-template-columns: 1fr;
    }

    .hero h1 {
        font-size: 2.5rem;
    }

    h1 { font-size: 2.5rem; }
    h2 { font-size: 2rem; }
    h3 { font-size: 1.75rem; }
}

@media (max-width: 480px) {
    .container {
        padding: 0 1rem;
    }

    .hero {
        padding: 4rem 0;
    }

    .section {
        padding: 3rem 0;
    }
}

/* ============================================
   LOADING & ANIMATIONS
   ============================================ */
@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.fade-in {
    animation: fadeIn 0.6s ease-out;
}

.spinner {
    width: 40px;
    height: 40px;
    border: 4px solid var(--border-gray);
    border-top-color: var(--primary-blue);
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
}

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