/* 
 * aheart4math.com - Main Stylesheet
 * Responsive design for mobile and desktop
 */

/* ===== CSS Variables ===== */
:root {
    --color-primary: #2c3e50;
    --color-secondary: #3498db;
    --color-accent: #e74c3c;
    --color-light: #ecf0f1;
    --color-dark: #1a252f;
    --color-text: #333;
    --color-text-light: #666;
    --color-white: #fff;
    --color-border: #ddd;
    
    --font-primary: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, sans-serif;
    --font-mono: 'Consolas', 'Monaco', 'Courier New', monospace;
    
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-xxl: 3rem;
    
    --border-radius: 8px;
    --border-radius-sm: 4px;
    --shadow-sm: 0 2px 4px rgba(0, 0, 0, 0.1);
    --shadow-md: 0 4px 8px rgba(0, 0, 0, 0.15);
    --shadow-lg: 0 8px 16px rgba(0, 0, 0, 0.2);
    
    --transition-fast: 0.2s ease;
    --transition-normal: 0.3s ease;
    
    --max-width: 1200px;
    --header-height: 70px;
}

/* ===== Reset & Base ===== */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

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

body {
    font-family: var(--font-primary);
    line-height: 1.6;
    color: var(--color-text);
    background-color: var(--color-white);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

/* ===== Typography ===== */
h1, h2, h3, h4, h5, h6 {
    color: var(--color-primary);
    line-height: 1.3;
    margin-bottom: var(--spacing-md);
}

h1 { font-size: 2rem; }
h2 { font-size: 1.5rem; }
h3 { font-size: 1.25rem; }

p {
    margin-bottom: var(--spacing-md);
}

a {
    color: var(--color-secondary);
    text-decoration: none;
    transition: color var(--transition-fast);
}

a:hover {
    color: var(--color-primary);
    text-decoration: underline;
}

/* ===== Layout ===== */
main {
    flex: 1;
    width: 100%;
    max-width: var(--max-width);
    margin: 0 auto;
    padding: var(--spacing-md);
}

.container {
    width: 100%;
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 var(--spacing-md);
}

/* ===== Header & Navigation ===== */
.site-header {
    background-color: var(--color-white);
    box-shadow: var(--shadow-sm);
    position: sticky;
    top: 0;
    z-index: 1000;
}

.main-nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    max-width: var(--max-width);
    margin: 0 auto;
    padding: var(--spacing-md);
    height: var(--header-height);
}

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

.logo:hover {
    color: var(--color-secondary);
    text-decoration: none;
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: var(--spacing-lg);
}

.nav-menu a {
    color: var(--color-text);
    font-weight: 500;
    padding: var(--spacing-sm) var(--spacing-md);
    border-radius: var(--border-radius-sm);
    transition: all var(--transition-fast);
}

.nav-menu a:hover,
.nav-menu a.active {
    color: var(--color-secondary);
    background-color: var(--color-light);
    text-decoration: none;
}

/* Mobile Navigation Toggle */
.nav-toggle {
    display: none;
    flex-direction: column;
    gap: 5px;
    background: none;
    border: none;
    cursor: pointer;
    padding: var(--spacing-sm);
}

.nav-toggle span {
    display: block;
    width: 25px;
    height: 3px;
    background-color: var(--color-primary);
    border-radius: 2px;
    transition: all var(--transition-fast);
}

/* ===== Hero Section ===== */
.hero {
    text-align: center;
    padding: var(--spacing-xxl) var(--spacing-md);
    background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-dark) 100%);
    color: var(--color-white);
    border-radius: var(--border-radius);
    margin-bottom: var(--spacing-xl);
}

.hero-content h1 {
    color: var(--color-white);
    font-size: 2.5rem;
    margin-bottom: var(--spacing-md);
}

.tagline {
    font-size: 1.25rem;
    opacity: 0.9;
    margin-bottom: var(--spacing-xl);
}

.hero-cta {
    display: flex;
    gap: var(--spacing-md);
    justify-content: center;
    flex-wrap: wrap;
}

/* ===== Buttons ===== */
.btn {
    display: inline-block;
    padding: var(--spacing-md) var(--spacing-xl);
    border-radius: var(--border-radius);
    font-weight: 600;
    text-decoration: none;
    transition: all var(--transition-normal);
    cursor: pointer;
    border: 2px solid transparent;
}

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

.btn-primary:hover {
    background-color: var(--color-primary);
    color: var(--color-white);
    text-decoration: none;
}

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

.btn-secondary:hover {
    background-color: var(--color-white);
    color: var(--color-primary);
    text-decoration: none;
}

/* ===== Features Grid ===== */
.features {
    padding: var(--spacing-xl) 0;
}

.features h2 {
    text-align: center;
    margin-bottom: var(--spacing-xl);
}

.feature-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: var(--spacing-lg);
}

.feature-card {
    background: var(--color-white);
    border: 1px solid var(--color-border);
    border-radius: var(--border-radius);
    padding: var(--spacing-xl);
    text-align: center;
    transition: all var(--transition-normal);
}

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

.feature-card h3 {
    margin-bottom: var(--spacing-md);
}

/* ===== Page Header ===== */
.page-header {
    text-align: center;
    padding: var(--spacing-xl) 0;
    border-bottom: 1px solid var(--color-border);
    margin-bottom: var(--spacing-xl);
}

/* ===== Content Sections ===== */
.content-section {
    margin-bottom: var(--spacing-xl);
}

.content-section h2 {
    margin-bottom: var(--spacing-md);
}

.content-section ul {
    list-style: disc;
    padding-left: var(--spacing-xl);
}

.content-section li {
    margin-bottom: var(--spacing-sm);
}

/* ===== Links List ===== */
.links-list {
    list-style: none;
    padding: 0;
}

.links-list li {
    padding: var(--spacing-md);
    border-bottom: 1px solid var(--color-border);
}

.links-list li:last-child {
    border-bottom: none;
}

/* ===== Forms ===== */
.schedule-form {
    max-width: 600px;
    margin: 0 auto;
}

.form-group {
    margin-bottom: var(--spacing-lg);
}

.form-group label {
    display: block;
    margin-bottom: var(--spacing-sm);
    font-weight: 600;
    color: var(--color-primary);
}

.form-group input,
.form-group select,
.form-group textarea {
    width: 100%;
    padding: var(--spacing-md);
    border: 1px solid var(--color-border);
    border-radius: var(--border-radius-sm);
    font-family: var(--font-primary);
    font-size: 1rem;
    transition: border-color var(--transition-fast);
}

.form-group input:focus,
.form-group select:focus,
.form-group textarea:focus {
    outline: none;
    border-color: var(--color-secondary);
    box-shadow: 0 0 0 3px rgba(52, 152, 219, 0.2);
}

.form-message {
    margin-top: var(--spacing-lg);
    padding: var(--spacing-md);
    border-radius: var(--border-radius-sm);
    display: none;
}

.form-message.success {
    display: block;
    background-color: #d4edda;
    color: #155724;
    border: 1px solid #c3e6cb;
}

.form-message.error {
    display: block;
    background-color: #f8d7da;
    color: #721c24;
    border: 1px solid #f5c6cb;
}

/* ===== Footer ===== */
.site-footer {
    background-color: var(--color-primary);
    color: var(--color-white);
    text-align: center;
    padding: var(--spacing-lg);
    margin-top: auto;
}

.site-footer p {
    margin: 0;
    font-size: 0.875rem;
}

/* ===== Responsive Design ===== */
@media (max-width: 768px) {
    :root {
        --header-height: 60px;
    }
    
    h1 { font-size: 1.75rem; }
    h2 { font-size: 1.375rem; }
    
    .hero-content h1 {
        font-size: 1.75rem;
    }
    
    .tagline {
        font-size: 1rem;
    }
    
    .nav-toggle {
        display: flex;
    }
    
    .nav-menu {
        display: none;
        position: absolute;
        top: var(--header-height);
        left: 0;
        right: 0;
        background-color: var(--color-white);
        flex-direction: column;
        padding: var(--spacing-md);
        box-shadow: var(--shadow-md);
    }
    
    .nav-menu.active {
        display: flex;
    }
    
    .nav-menu li {
        text-align: center;
    }
    
    .nav-menu a {
        display: block;
        padding: var(--spacing-md);
    }
    
    .hero-cta {
        flex-direction: column;
    }
    
    .btn {
        width: 100%;
        text-align: center;
    }
    
    .feature-grid {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 480px) {
    html {
        font-size: 14px;
    }
    
    .main-nav {
        padding: var(--spacing-sm) var(--spacing-md);
    }
    
    .hero {
        padding: var(--spacing-xl) var(--spacing-md);
    }
    
    .feature-card {
        padding: var(--spacing-lg);
    }
}

/* ===== Accessibility ===== */
@media (prefers-reduced-motion: reduce) {
    html {
        scroll-behavior: auto;
    }
    
    *, *::before, *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}

/* Focus visible for keyboard navigation */
:focus-visible {
    outline: 3px solid var(--color-secondary);
    outline-offset: 2px;
}

/* Skip to main content link */
.skip-link {
    position: absolute;
    top: -40px;
    left: 0;
    background: var(--color-primary);
    color: var(--color-white);
    padding: var(--spacing-sm) var(--spacing-md);
    z-index: 1001;
    transition: top var(--transition-fast);
}

.skip-link:focus {
    top: 0;
}