/**
 * @file base.css
 * @description Shared base styles, reset, typography, and CSS variables
 * @module Base Styles
 * 
 * This file contains:
 * - CSS reset/normalize
 * - Base typography
 * - Shared CSS variables (colors, spacing, typography)
 * - Common base styles
 */

/* ============================================
   CSS Reset & Normalize
   ============================================ */

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

/* ============================================
   CSS Variables - Shared Design Tokens
   ============================================ */

:root {
    /* Color System - Primary */
    --primary-color: #1a5490;
    --secondary-color: #2c7fb8;
    --accent-color: #ff6b35;
    
    /* Color System - Text */
    --text-color: #333333;
    --text-light: #666666;
    --text-muted: #999999;
    
    /* Color System - Backgrounds */
    --bg-light: #f8f9fa;
    --white: #ffffff;
    --black: #000000;
    
    /* Color System - Borders */
    --border-color: #e0e0e0;
    --border-light: rgba(0, 0, 0, 0.05);
    
    /* Color System - Shadows */
    --shadow-light: 0 2px 4px rgba(0, 0, 0, 0.08);
    --shadow-medium: 0 4px 12px rgba(0, 0, 0, 0.12);
    --shadow-heavy: 0 8px 24px rgba(0, 0, 0, 0.16);
    
    /* Typography */
    --font-primary: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    --font-size-base: 16px;
    --line-height-base: 1.6;
    
    /* Spacing System */
    --spacing-xs: 0.5rem;    /* 8px */
    --spacing-sm: 0.75rem;    /* 12px */
    --spacing-md: 1rem;       /* 16px */
    --spacing-lg: 1.5rem;     /* 24px */
    --spacing-xl: 2rem;       /* 32px */
    --spacing-2xl: 3rem;      /* 48px */
    --spacing-3xl: 4rem;      /* 64px */
    
    /* Border Radius */
    --radius-sm: 4px;
    --radius-md: 8px;
    --radius-lg: 12px;
    
    /* Transitions */
    --transition-fast: 0.15s ease;
    --transition-base: 0.3s ease;
    --transition-slow: 0.5s ease;
}

/* ============================================
   Base Typography
   ============================================ */

body {
    font-family: var(--font-primary);
    font-size: var(--font-size-base);
    line-height: var(--line-height-base);
    color: var(--text-color);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* Headings */
h1, h2, h3, h4, h5, h6 {
    font-weight: 700;
    line-height: 1.2;
    margin-bottom: var(--spacing-md);
    color: var(--text-color);
}

h1 {
    font-size: 3.5rem;
    letter-spacing: -0.02em;
}

h2 {
    font-size: 2.75rem;
    letter-spacing: -0.02em;
}

h3 {
    font-size: 1.5rem;
}

h4 {
    font-size: 1.25rem;
}

h5 {
    font-size: 1.1rem;
}

h6 {
    font-size: 1rem;
}

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

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

a:hover {
    color: var(--secondary-color);
}

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

li {
    margin-bottom: var(--spacing-xs);
}

/* Images */
img {
    max-width: 100%;
    height: auto;
    display: block;
}

/* Code */
code {
    font-family: 'Courier New', Courier, monospace;
    background: var(--bg-light);
    padding: 0.2em 0.4em;
    border-radius: var(--radius-sm);
    font-size: 0.9em;
}

/* ============================================
   Base Utilities
   ============================================ */

/* Container */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-lg);
}

/* Screen Reader Only */
.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border-width: 0;
}