/* ===================================
   BASE LAYOUT & TYPOGRAPHY
   =================================== */

/* CSS Variables */
:root {
    /* Colors */
    --color-primary: #39b7ff;
    --color-primary-dark: #1a9eff;
    --color-primary-light: #6cc7ff;
    --color-secondary: #2c3e50;
    --color-text-primary: #1a202c;
    --color-text-secondary: #4a5568;
    --color-text-muted: #718096;
    --color-background: #ffffff;
    --color-background-light: #f7fafc;
    --color-border: #e2e8f0;
    --color-border-light: #e9ecef;
    
    /* Typography */
    --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    --font-serif: 'Source Serif Pro', Georgia, 'Times New Roman', serif;
    --font-weight-light: 300;
    --font-weight-regular: 400;
    --font-weight-medium: 500;
    --font-weight-semibold: 600;
    --font-weight-bold: 700;
    
    /* Spacing */
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-2xl: 3rem;
    
    /* Border Radius */
    --border-radius-sm: 4px;
    --border-radius-md: 8px;
    --border-radius-lg: 12px;
    
    /* 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 15px rgba(0, 0, 0, 0.1);
    --shadow-xl: 0 20px 25px rgba(0, 0, 0, 0.1);
}

/* Reset & Base Styles */
* {
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-sans);
    font-weight: var(--font-weight-regular);
    line-height: 1.6;
    color: var(--color-text-primary);
    background-color: var(--color-background);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
    font-family: var(--font-serif);
    font-weight: var(--font-weight-semibold);
    line-height: 1.3;
    color: var(--color-text-primary);
    margin-bottom: var(--spacing-md);
}

h1 {
    font-size: 2.5rem;
    font-weight: var(--font-weight-bold);
    letter-spacing: -0.02em;
}

h2 {
    font-size: 2rem;
    font-weight: var(--font-weight-semibold);
    letter-spacing: -0.01em;
}

h3 {
    font-size: 1.5rem;
    font-weight: var(--font-weight-semibold);
}

h4 {
    font-size: 1.25rem;
    font-weight: var(--font-weight-semibold);
}

h5 {
    font-size: 1.1rem;
    font-weight: var(--font-weight-medium);
}

h6 {
    font-size: 1rem;
    font-weight: var(--font-weight-medium);
}

p {
    margin-bottom: var(--spacing-lg);
    color: var(--color-text-secondary);
}

.lead {
    font-family: var(--font-serif);
    font-size: 1.25rem;
    font-weight: var(--font-weight-regular);
    line-height: 1.7;
    color: var(--color-text-secondary);
}

.display-4 {
    font-family: var(--font-serif);
    font-weight: var(--font-weight-bold);
    letter-spacing: -0.03em;
}

.display-5 {
    font-family: var(--font-serif);
    font-weight: var(--font-weight-semibold);
    letter-spacing: -0.02em;
}

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

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

/* Lists */
ul, ol {
    margin-bottom: var(--spacing-lg);
    padding-left: var(--spacing-xl);
}

li {
    margin-bottom: var(--spacing-sm);
    line-height: 1.7;
}

/* Utility Classes */
.text-primary {
    color: var(--color-primary) !important;
}

.text-muted {
    color: var(--color-text-muted) !important;
}

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

.border {
    border: 1px solid var(--color-border) !important;
}

/* Responsive Typography */
@media (max-width: 768px) {
    h1 {
        font-size: 2rem;
    }
    
    h2 {
        font-size: 1.75rem;
    }
    
    .lead {
        font-size: 1.1rem;
    }
}