/* ==========================================
   TFI RETRO LIBRARY - Modern Archive System
   ========================================== */

@import url('https://fonts.googleapis.com/css2?family=IBM+Plex+Sans:wght@200;400;500;600;700&family=JetBrains+Mono:wght@300;400;500&display=swap');

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

:root {
  /* Typography Scale */
  --font-sans: 'IBM Plex Sans', system-ui, -apple-system, sans-serif;
  --font-mono: 'JetBrains Mono', 'Courier New', monospace;

  --text-xs: 0.6875rem;    /* 11px */
  --text-sm: 0.8125rem;    /* 13px */
  --text-base: 0.9375rem;  /* 15px */
  --text-lg: 1.125rem;     /* 18px */
  --text-xl: 1.5rem;       /* 24px */
  --text-2xl: 2rem;        /* 32px */
  --text-3xl: 2.75rem;     /* 44px */
  --text-4xl: 3.5rem;      /* 56px */

  /* Color System - OKLCH for rich gradients */
  --color-bg: oklch(98% 0.005 280);
  --color-surface: oklch(100% 0 0);
  --color-surface-elevated: oklch(99% 0.002 280);

  --color-text-primary: oklch(18% 0.01 280);
  --color-text-secondary: oklch(45% 0.01 280);
  --color-text-tertiary: oklch(62% 0.01 280);

  --color-accent: oklch(35% 0.08 260);
  --color-accent-bright: oklch(55% 0.12 260);
  --color-accent-subtle: oklch(92% 0.02 260);

  --color-border: oklch(88% 0.005 280);
  --color-border-strong: oklch(75% 0.01 280);

  /* Spacing Scale (8px base) */
  --space-1: 0.25rem;   /* 4px */
  --space-2: 0.5rem;    /* 8px */
  --space-3: 0.75rem;   /* 12px */
  --space-4: 1rem;      /* 16px */
  --space-6: 1.5rem;    /* 24px */
  --space-8: 2rem;      /* 32px */
  --space-12: 3rem;     /* 48px */
  --space-16: 4rem;     /* 64px */
  --space-24: 6rem;     /* 96px */
  --space-32: 8rem;     /* 128px */

  /* Layout */
  --content-max: 1280px;
  --content-narrow: 720px;
  --grid-gap: var(--space-6);

  /* Effects */
  --shadow-sm: 0 1px 2px 0 oklch(0% 0 0 / 0.03),
               0 1px 3px 0 oklch(0% 0 0 / 0.05);
  --shadow-md: 0 2px 4px -1px oklch(0% 0 0 / 0.04),
               0 4px 6px -1px oklch(0% 0 0 / 0.06);
  --shadow-lg: 0 4px 6px -2px oklch(0% 0 0 / 0.04),
               0 10px 15px -3px oklch(0% 0 0 / 0.08);
  --shadow-xl: 0 10px 25px -5px oklch(0% 0 0 / 0.08),
               0 20px 40px -10px oklch(0% 0 0 / 0.12);

  --radius-sm: 2px;
  --radius-md: 4px;
  --radius-lg: 8px;

  --transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-base: 250ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-slow: 350ms cubic-bezier(0.4, 0, 0.2, 1);
}

/* ==========================================
   Reset & Base Styles
   ========================================== */

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

html {
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  font-family: var(--font-sans);
  font-size: var(--text-base);
  line-height: 1.6;
  color: var(--color-text-primary);
  background: var(--color-bg);
  position: relative;
}

/* Subtle noise texture overlay */
body::before {
  content: '';
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  opacity: 0.03;
  pointer-events: none;
  z-index: 9999;
  background-image: url("data:image/svg+xml,%3Csvg viewBox='0 0 256 256' xmlns='http://www.w3.org/2000/svg'%3E%3Cfilter id='noise'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.9' numOctaves='4' /%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23noise)' /%3E%3C/svg%3E");
}

::selection {
  background: var(--color-accent-subtle);
  color: var(--color-text-primary);
}

/* ==========================================
   Typography System
   ========================================== */

h1, h2, h3, h4, h5, h6 {
  font-weight: 600;
  line-height: 1.2;
  letter-spacing: -0.02em;
  color: var(--color-text-primary);
}

h1 {
  font-size: var(--text-4xl);
  font-weight: 700;
  letter-spacing: -0.04em;
}

h2 {
  font-size: var(--text-3xl);
  font-weight: 600;
}

h3 {
  font-size: var(--text-2xl);
}

h4 {
  font-size: var(--text-xl);
}

p {
  line-height: 1.7;
}

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

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

.mono {
  font-family: var(--font-mono);
  letter-spacing: -0.01em;
}

.text-secondary {
  color: var(--color-text-secondary);
}

.text-tertiary {
  color: var(--color-text-tertiary);
}

.text-accent {
  color: var(--color-accent);
}

/* ==========================================
   Layout Components
   ========================================== */

.container {
  max-width: var(--content-max);
  margin: 0 auto;
  padding: 0 var(--space-6);
}

.container-narrow {
  max-width: var(--content-narrow);
  margin: 0 auto;
  padding: 0 var(--space-6);
}

.section {
  padding: var(--space-16) 0;
}

.grid {
  display: grid;
  gap: var(--grid-gap);
}

.grid-2 {
  grid-template-columns: repeat(2, 1fr);
}

.grid-3 {
  grid-template-columns: repeat(3, 1fr);
}

.grid-4 {
  grid-template-columns: repeat(4, 1fr);
}

@media (max-width: 1024px) {
  .grid-4 { grid-template-columns: repeat(2, 1fr); }
  .grid-3 { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 640px) {
  .grid-4,
  .grid-3,
  .grid-2 {
    grid-template-columns: 1fr;
  }
}

/* ==========================================
   Header
   ========================================== */

.site-header {
  padding: var(--space-8) 0 var(--space-6) 0;
  border-bottom: 1px solid var(--color-border);
  background: var(--color-surface);
  position: sticky;
  top: 0;
  z-index: 100;
  backdrop-filter: blur(12px);
  background: oklch(100% 0 0 / 0.92);
}

.site-header .container {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: var(--space-8);
}

.site-title {
  flex: 1;
}

.site-title h1 {
  font-size: var(--text-2xl);
  font-weight: 700;
  letter-spacing: -0.03em;
  margin-bottom: var(--space-1);
}

.site-subtitle {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  color: var(--color-text-tertiary);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.site-nav {
  display: flex;
  gap: var(--space-4);
  align-items: center;
}

.nav-link {
  font-size: var(--text-sm);
  font-weight: 500;
  padding: var(--space-2) var(--space-3);
  border-radius: var(--radius-sm);
  transition: all var(--transition-fast);
  position: relative;
}

.nav-link::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: var(--space-3);
  right: var(--space-3);
  height: 1px;
  background: var(--color-accent);
  transform: scaleX(0);
  transition: transform var(--transition-base);
}

.nav-link:hover::after,
.nav-link.active::after {
  transform: scaleX(1);
}

.nav-link:hover {
  color: var(--color-accent);
}

.nav-link.active {
  color: var(--color-accent);
  font-weight: 600;
}

/* ==========================================
   Cards & Surfaces
   ========================================== */

.card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: var(--space-6);
  transition: all var(--transition-base);
}

.card:hover {
  border-color: var(--color-border-strong);
  box-shadow: var(--shadow-md);
}

.card-interactive {
  cursor: pointer;
}

.card-interactive:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-lg);
}

.surface-elevated {
  background: var(--color-surface-elevated);
  box-shadow: var(--shadow-sm);
}

/* ==========================================
   Buttons & Interactive Elements
   ========================================== */

.btn {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  padding: var(--space-3) var(--space-6);
  font-family: var(--font-sans);
  font-size: var(--text-sm);
  font-weight: 500;
  border: 1px solid;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: all var(--transition-fast);
  text-decoration: none;
  white-space: nowrap;
}

.btn-primary {
  background: var(--color-accent);
  border-color: var(--color-accent);
  color: var(--color-surface);
}

.btn-primary:hover {
  background: var(--color-accent-bright);
  border-color: var(--color-accent-bright);
  color: var(--color-surface);
  box-shadow: var(--shadow-md);
}

.btn-secondary {
  background: transparent;
  border-color: var(--color-border-strong);
  color: var(--color-text-primary);
}

.btn-secondary:hover {
  background: var(--color-surface-elevated);
  border-color: var(--color-accent);
  color: var(--color-accent);
}

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

.btn-ghost:hover {
  background: var(--color-surface-elevated);
  color: var(--color-text-primary);
}

/* ==========================================
   Form Elements
   ========================================== */

input[type="text"],
input[type="search"],
textarea {
  width: 100%;
  padding: var(--space-3) var(--space-4);
  font-family: var(--font-sans);
  font-size: var(--text-sm);
  color: var(--color-text-primary);
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  transition: all var(--transition-fast);
}

input:focus,
textarea:focus {
  outline: none;
  border-color: var(--color-accent);
  box-shadow: 0 0 0 3px var(--color-accent-subtle);
}

/* ==========================================
   Archive Grid (Book Shelf Reimagined)
   ========================================== */

.archive-section {
  margin-bottom: var(--space-16);
}

.archive-year {
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  font-weight: 500;
  color: var(--color-text-tertiary);
  text-transform: uppercase;
  letter-spacing: 0.1em;
  margin-bottom: var(--space-6);
  padding-bottom: var(--space-2);
  border-bottom: 1px solid var(--color-border);
}

.archive-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: var(--space-4);
}

.archive-item {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-left: 3px solid var(--color-accent);
  padding: var(--space-6);
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: all var(--transition-base);
  position: relative;
  overflow: hidden;
}

.archive-item::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: linear-gradient(135deg,
    var(--color-accent-subtle) 0%,
    transparent 50%);
  opacity: 0;
  transition: opacity var(--transition-base);
}

.archive-item:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
  border-left-width: 4px;
}

.archive-item:hover::before {
  opacity: 1;
}

.archive-item-title {
  font-size: var(--text-lg);
  font-weight: 600;
  margin-bottom: var(--space-2);
  position: relative;
  z-index: 1;
}

.archive-item-meta {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  color: var(--color-text-tertiary);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: var(--space-4);
  position: relative;
  z-index: 1;
}

.archive-item-desc {
  font-size: var(--text-sm);
  color: var(--color-text-secondary);
  line-height: 1.6;
  position: relative;
  z-index: 1;
}

/* ==========================================
   Modal
   ========================================== */

.modal {
  display: none;
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  z-index: 1000;
}

.modal.active {
  display: flex;
  align-items: center;
  justify-content: center;
}

.modal-overlay {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: oklch(0% 0 0 / 0.6);
  backdrop-filter: blur(8px);
  animation: fadeIn var(--transition-base);
}

.modal-content {
  position: relative;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  max-width: 600px;
  width: 90%;
  max-height: 85vh;
  overflow-y: auto;
  box-shadow: var(--shadow-xl);
  animation: slideUp var(--transition-slow);
  z-index: 1;
}

.modal-header {
  padding: var(--space-8);
  border-bottom: 1px solid var(--color-border);
  position: relative;
}

.modal-close {
  position: absolute;
  top: var(--space-6);
  right: var(--space-6);
  width: 32px;
  height: 32px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: transparent;
  border: 1px solid var(--color-border);
  border-radius: 50%;
  cursor: pointer;
  font-size: var(--text-lg);
  color: var(--color-text-tertiary);
  transition: all var(--transition-fast);
}

.modal-close:hover {
  background: var(--color-surface-elevated);
  border-color: var(--color-accent);
  color: var(--color-accent);
  transform: rotate(90deg);
}

.modal-body {
  padding: var(--space-8);
}

/* ==========================================
   Footer
   ========================================== */

.site-footer {
  margin-top: var(--space-24);
  padding: var(--space-12) 0 var(--space-8) 0;
  border-top: 1px solid var(--color-border);
  font-size: var(--text-sm);
  color: var(--color-text-tertiary);
  text-align: center;
}

.site-footer strong {
  display: block;
  font-weight: 600;
  color: var(--color-text-secondary);
  margin-bottom: var(--space-2);
}

/* ==========================================
   Floating Action Button (Popo)
   ========================================== */

.fab {
  position: fixed;
  bottom: var(--space-8);
  right: var(--space-8);
  width: 56px;
  height: 56px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: 50%;
  box-shadow: var(--shadow-lg);
  cursor: pointer;
  font-size: var(--text-2xl);
  transition: all var(--transition-base);
  z-index: 50;
}

.fab:hover {
  transform: scale(1.1) rotate(5deg);
  box-shadow: var(--shadow-xl);
  border-color: var(--color-accent);
}

/* ==========================================
   Animations
   ========================================== */

@keyframes fadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

@keyframes slideUp {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes slideDown {
  from {
    opacity: 0;
    transform: translateY(-20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* Stagger animation for grid items */
.archive-item {
  animation: slideUp var(--transition-slow) backwards;
}

.archive-item:nth-child(1) { animation-delay: 0ms; }
.archive-item:nth-child(2) { animation-delay: 50ms; }
.archive-item:nth-child(3) { animation-delay: 100ms; }
.archive-item:nth-child(4) { animation-delay: 150ms; }
.archive-item:nth-child(5) { animation-delay: 200ms; }
.archive-item:nth-child(6) { animation-delay: 250ms; }
.archive-item:nth-child(7) { animation-delay: 300ms; }
.archive-item:nth-child(8) { animation-delay: 350ms; }

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

.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;
}

.flex { display: flex; }
.items-center { align-items: center; }
.justify-between { justify-content: space-between; }
.gap-2 { gap: var(--space-2); }
.gap-4 { gap: var(--space-4); }
.gap-6 { gap: var(--space-6); }

.mt-2 { margin-top: var(--space-2); }
.mt-4 { margin-top: var(--space-4); }
.mt-6 { margin-top: var(--space-6); }
.mt-8 { margin-top: var(--space-8); }
.mb-2 { margin-bottom: var(--space-2); }
.mb-4 { margin-bottom: var(--space-4); }
.mb-6 { margin-bottom: var(--space-6); }
.mb-8 { margin-bottom: var(--space-8); }

/* ==========================================
   Responsive
   ========================================== */

@media (max-width: 768px) {
  :root {
    --text-4xl: 2.5rem;
    --text-3xl: 2rem;
    --text-2xl: 1.5rem;
  }

  .site-header .container {
    flex-direction: column;
    gap: var(--space-4);
  }

  .site-nav {
    width: 100%;
    justify-content: flex-start;
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
  }

  .archive-grid {
    grid-template-columns: 1fr;
  }

  .fab {
    bottom: var(--space-6);
    right: var(--space-6);
    width: 48px;
    height: 48px;
    font-size: var(--text-xl);
  }
}