/* ==========================================================================
   Editorial Love Letter — CSS Reset & Typography System
   ========================================================================== */

/* CSS Reset & Base Styles */
*,
*::before,
*::after {
    box-sizing: border-box;
}

* {
    margin: 0;
    padding: 0;
}

html {
    hanging-punctuation: first last;
    scroll-behavior: smooth;
}

body {
    line-height: 1.5;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    text-rendering: optimizeLegibility;
}

img,
picture,
video,
canvas,
svg {
    display: block;
    max-width: 100%;
}

input,
button,
textarea,
select {
    font: inherit;
}

p,
h1,
h2,
h3,
h4,
h5,
h6 {
    overflow-wrap: break-word;
}

/* ==========================================================================
   CSS Custom Properties (Design Tokens)
   ========================================================================== */

:root {
    /* Typography Scale - Fluid Responsive */
    --text-xs: clamp(0.75rem, 0.7rem + 0.25vw, 0.875rem);
    --text-sm: clamp(0.875rem, 0.8rem + 0.375vw, 1rem);
    --text-base: clamp(1rem, 0.95rem + 0.25vw, 1.125rem);
    --text-lg: clamp(1.125rem, 1.05rem + 0.375vw, 1.25rem);
    --text-xl: clamp(1.25rem, 1.15rem + 0.5vw, 1.5rem);
    --text-2xl: clamp(1.5rem, 1.35rem + 0.75vw, 2rem);
    --text-3xl: clamp(1.875rem, 1.65rem + 1.125vw, 2.5rem);
    --text-4xl: clamp(2.25rem, 1.95rem + 1.5vw, 3.5rem);
    --text-5xl: clamp(3rem, 2.5rem + 2.5vw, 4.5rem);

    /* Line Heights */
    --leading-tight: 1.25;
    --leading-snug: 1.375;
    --leading-normal: 1.5;
    --leading-relaxed: 1.625;
    --leading-loose: 1.7;

    /* Font Families */
    --font-display: 'Playfair Display', Georgia, 'Times New Roman', serif;
    --font-serif: 'PT Serif', Georgia, 'Times New Roman', serif;
    --font-sans: 'Inter', system-ui, -apple-system, sans-serif;

    /* Spacing Scale - Based on 1.5rem baseline */
    --space-1: 0.375rem;   /* 6px */
    --space-2: 0.75rem;    /* 12px */
    --space-3: 1.125rem;   /* 18px */
    --space-4: 1.5rem;     /* 24px - baseline */
    --space-5: 2.25rem;    /* 36px */
    --space-6: 3rem;       /* 48px */
    --space-8: 4.5rem;     /* 72px */
    --space-10: 6rem;      /* 96px */
    --space-12: 9rem;      /* 144px */
    --space-16: 12rem;     /* 192px */

    /* Content Widths */
    --content-narrow: 45ch;
    --content-wide: 70ch;
    --content-max: 85ch;

    /* Animation */
    --transition-fast: 0.15s ease-out;
    --transition-base: 0.25s ease-out;
    --transition-slow: 0.4s ease-out;
    --reveal-distance: 30px;

    /* Shadows */
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-base: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
}

/* Light Theme (Default) */
:root {
    --color-canvas: #1a1915;
    --color-paper: #faf9f7;
    --color-paper-elevated: #ffffff;
    --color-ink-primary: #2b2a27;
    --color-ink-secondary: #5a5853;
    --color-ink-tertiary: #8e8c85;
    --color-border: #e8e6e1;
    --color-accent: #c4a574;
    --color-accent-subtle: #f4f1ea;
}

/* Dark Theme */
[data-theme="dark"] {
    --color-canvas: #0a0a08;
    --color-paper: #1c1b18;
    --color-paper-elevated: #252420;
    --color-ink-primary: #f5f4f1;
    --color-ink-secondary: #c8c6c0;
    --color-ink-tertiary: #8e8c85;
    --color-border: #2d2c28;
    --color-accent: #d4b58a;
    --color-accent-subtle: #252420;
}

/* ==========================================================================
   Base Typography & Layout
   ========================================================================== */

body {
    font-family: var(--font-serif);
    font-size: var(--text-lg);
    line-height: var(--leading-loose);
    color: var(--color-ink-primary);
    background-color: var(--color-canvas);
    overflow-x: hidden;
}

/* Canvas - Full viewport background */
.canvas {
    min-height: 100vh;
    padding: var(--space-4) var(--space-2);
    display: flex;
    align-items: center;
    justify-content: center;
}

@media (min-width: 48rem) {
    .canvas {
        padding: var(--space-8) var(--space-4);
    }
}

/* Editorial Spread - The "paper" */
.spread {
    background-color: var(--color-paper);
    border-radius: 2px;
    box-shadow: var(--shadow-xl);
    max-width: 60rem;
    width: 100%;
    padding: var(--space-8) var(--space-6);
    margin: 0 auto;
    position: relative;
}

@media (min-width: 48rem) {
    .spread {
        padding: var(--space-12) var(--space-10);
    }
}

@media (min-width: 80rem) {
    .spread {
        padding: var(--space-16) var(--space-12);
    }
}

/* ==========================================================================
   Section Layout & Spacing
   ========================================================================== */

.section {
    margin-bottom: var(--space-10);
}

.section:last-child {
    margin-bottom: 0;
}

@media (min-width: 48rem) {
    .section {
        margin-bottom: var(--space-12);
    }
}

/* ==========================================================================
   Typography Hierarchy
   ========================================================================== */

/* Meta Title - Small caps header */
.meta-title {
    font-family: var(--font-sans);
    font-size: var(--text-sm);
    font-weight: 500;
    letter-spacing: 0.15em;
    text-transform: uppercase;
    color: var(--color-ink-tertiary);
    margin-bottom: var(--space-2);
    line-height: var(--leading-normal);
}

/* Main Title */
.main-title {
    font-family: var(--font-display);
    font-size: var(--text-5xl);
    font-weight: 600;
    line-height: var(--leading-tight);
    color: var(--color-ink-primary);
    margin-bottom: var(--space-2);
    max-width: var(--content-wide);
}

/* Letter Body */
.letter-body {
    max-width: var(--content-wide);
}

.letter-paragraph {
    font-size: var(--text-lg);
    line-height: var(--leading-loose);
    color: var(--color-ink-primary);
    margin-bottom: var(--space-5);
    max-width: var(--content-wide);
}

.letter-paragraph:last-child {
    margin-bottom: 0;
}

/* Pull Quote */
.pull-quote {
    font-family: var(--font-display);
    font-size: var(--text-2xl);
    font-style: italic;
    line-height: var(--leading-snug);
    color: var(--color-ink-secondary);
    margin: var(--space-8) 0;
    padding: var(--space-6) 0;
    border-top: 1px solid var(--color-border);
    border-bottom: 1px solid var(--color-border);
    text-align: center;
    position: relative;
    max-width: var(--content-narrow);
    margin-left: auto;
    margin-right: auto;
}


/* Signature Section */
.signature-container {
    margin-top: var(--space-8);
    max-width: var(--content-narrow);
}

.closing {
    font-size: var(--text-base);
    color: var(--color-ink-secondary);
    margin-bottom: var(--space-3);
    line-height: var(--leading-relaxed);
}

.signature {
    font-family: var(--font-display);
    font-size: var(--text-2xl);
    font-style: italic;
    color: var(--color-ink-primary);
    margin-bottom: var(--space-2);
    line-height: var(--leading-snug);
}

.date {
    font-family: var(--font-sans);
    font-size: var(--text-sm);
    color: var(--color-ink-tertiary);
    font-weight: 400;
    line-height: var(--leading-normal);
}

/* ==========================================================================
   Theme Toggle
   ========================================================================== */

.theme-toggle {
    position: fixed;
    top: var(--space-4);
    right: var(--space-4);
    z-index: 1000;
    background: var(--color-paper-elevated);
    border: 1px solid var(--color-border);
    border-radius: 50%;
    width: 3rem;
    height: 3rem;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: all var(--transition-base);
    box-shadow: var(--shadow-base);
    font-size: var(--text-lg);
}

.theme-toggle:hover {
    transform: translateY(-1px);
    box-shadow: var(--shadow-lg);
}

.theme-toggle:focus {
    outline: 2px solid var(--color-accent);
    outline-offset: 2px;
}

.theme-icon {
    transition: opacity var(--transition-base);
    position: absolute;
}

.theme-icon--dark {
    opacity: 0;
}

[data-theme="dark"] .theme-icon--light {
    opacity: 0;
}

[data-theme="dark"] .theme-icon--dark {
    opacity: 1;
}

/* ==========================================================================
   Scroll Reveal Animations
   ========================================================================== */

[data-reveal] {
    opacity: 0;
    transform: translateY(var(--reveal-distance));
    transition: opacity var(--transition-slow), transform var(--transition-slow);
}

[data-reveal].is-revealed {
    opacity: 1;
    transform: translateY(0);
}

/* Stagger delay for multiple elements */
[data-reveal]:nth-child(1) { transition-delay: 0ms; }
[data-reveal]:nth-child(2) { transition-delay: 100ms; }
[data-reveal]:nth-child(3) { transition-delay: 200ms; }
[data-reveal]:nth-child(4) { transition-delay: 300ms; }

/* ==========================================================================
   Accessibility & Reduced Motion
   ========================================================================== */

@media (prefers-reduced-motion: reduce) {
    *,
    *::before,
    *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
    
    [data-reveal] {
        opacity: 1;
        transform: none;
        transition: none;
    }
    
    html {
        scroll-behavior: auto;
    }
}

/* High contrast mode support */
@media (prefers-contrast: high) {
    :root {
        --color-ink-primary: #000000;
        --color-ink-secondary: #2d2d2d;
        --color-paper: #ffffff;
        --color-border: #666666;
    }
    
    [data-theme="dark"] {
        --color-ink-primary: #ffffff;
        --color-paper: #000000;
        --color-border: #999999;
    }
}

/* Focus management */
:focus-visible {
    outline: 2px solid var(--color-accent);
    outline-offset: 2px;
    border-radius: 2px;
}

/* Print styles */
@media print {
    .theme-toggle {
        display: none;
    }
    
    .canvas {
        padding: 0;
    }
    
    .spread {
        box-shadow: none;
        max-width: none;
        margin: 0;
        padding: 2rem;
    }
    
    [data-reveal] {
        opacity: 1;
        transform: none;
    }
}