/* ============================================
   BASE.CSS - Global Styles & Resets
   ============================================ */

/* CSS Variables for colors and spacing */
:root {
    /* Default (Eyecare) Theme Colors */
    --color-primary: #5bb3a8;
    --color-primary-light: #7cc4ba;
    --color-primary-lighter: #a8d5c8;
    --color-primary-lightest: #d4f1e8;
    
    --color-bg: #ffffff;
    --color-bg-secondary: #f0fdf9;
    --color-bg-tertiary: #e8f5f0;
    
    --color-text: #1a3a36;
    --color-text-secondary: #4a6b68;
    --color-text-tertiary: #7a9b98;
    
    --color-border: #c8e6e0;
    --color-border-light: #d4f1e8;
    
    --color-success: #4caf50;
    --color-warning: #ff9800;
    --color-error: #f44336;
    
    /* Spacing Scale */
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-2xl: 3rem;
    --spacing-3xl: 4rem;
    
    /* Typography */
    --font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    --font-size-xs: 0.75rem;
    --font-size-sm: 0.875rem;
    --font-size-base: 1rem;
    --font-size-lg: 1.125rem;
    --font-size-xl: 1.25rem;
    --font-size-2xl: 1.5rem;
    --font-size-3xl: 2rem;
    --font-size-4xl: 2.5rem;
    
    --font-weight-light: 300;
    --font-weight-normal: 400;
    --font-weight-medium: 500;
    --font-weight-semibold: 600;
    --font-weight-bold: 700;
    
    /* Line Heights */
    --line-height-tight: 1.25;
    --line-height-normal: 1.5;
    --line-height-relaxed: 1.75;
    
    /* Border Radius */
    --radius-sm: 0.375rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.875rem;
    --radius-xl: 1.25rem;
    --radius-2xl: 1.5rem;
    --radius-full: 9999px;
    
    /* Shadows */
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1);
    
    /* Transitions */
    --transition-fast: 150ms ease-in-out;
    --transition-base: 200ms ease-in-out;
    --transition-slow: 300ms ease-in-out;
}

/* Dark Theme Variables */
body.dark-theme {
    --color-bg: #0f1419;
    --color-bg-secondary: #1a2530;
    --color-bg-tertiary: #253541;
    
    --color-text: #e8e8e8;
    --color-text-secondary: #b3b3b3;
    --color-text-tertiary: #7f7f7f;
    
    --color-border: #2a3f5a;
    --color-border-light: #3a4f6a;
}

/* High Contrast Theme Variables */
body.high-contrast-theme {
    --color-primary: #0066cc;
    --color-primary-light: #0080ff;
    --color-primary-lighter: #4d94ff;
    --color-primary-lightest: #cce5ff;
    
    --color-text: #000000;
    --color-border: #000000;
}

/* ============================================
   Reset & Normalization
   ============================================ */

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

html {
    scroll-behavior: smooth;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

body {
    font-family: var(--font-family);
    font-size: var(--font-size-base);
    line-height: var(--line-height-normal);
    color: var(--color-text);
    background-color: var(--color-bg);
    transition: background-color var(--transition-base), color var(--transition-base);
}

/* Typography Resets */
h1, h2, h3, h4, h5, h6 {
    font-weight: var(--font-weight-bold);
    line-height: var(--line-height-tight);
    color: var(--color-text);
}

h1 { font-size: var(--font-size-4xl); }
h2 { font-size: var(--font-size-3xl); }
h3 { font-size: var(--font-size-2xl); }
h4 { font-size: var(--font-size-xl); }
h5 { font-size: var(--font-size-lg); }
h6 { font-size: var(--font-size-base); }

p {
    color: var(--color-text-secondary);
    line-height: var(--line-height-relaxed);
}

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

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

/* List Resets */
ul, ol {
    list-style: none;
}

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

/* Form Elements */
input, textarea, select, button {
    font-family: inherit;
    font-size: inherit;
}

button {
    cursor: pointer;
    border: none;
    background: none;
}

/* Focus Styles for Accessibility */
:focus-visible {
    outline: 2px solid var(--color-primary);
    outline-offset: 2px;
}

/* Selection Styling */
::selection {
    background-color: var(--color-primary-light);
    color: white;
}

::-webkit-scrollbar {
    width: 8px;
    height: 8px;
}

::-webkit-scrollbar-track {
    background: var(--color-bg-secondary);
}

::-webkit-scrollbar-thumb {
    background: var(--color-primary-lighter);
    border-radius: var(--radius-full);
}

::-webkit-scrollbar-thumb:hover {
    background: var(--color-primary-light);
}

/* ============================================
   Utility Classes
   ============================================ */

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-md);
}

@media (min-width: 768px) {
    .container {
        padding: 0 var(--spacing-xl);
    }
}

.visually-hidden {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border-width: 0;
}