/* ---------------------------------------------------------------
   Blockchain Explained — Acetate Manual Presentation
   Following the acetate technical manual direction: color-coded
   divider boards, milk acetate content leaves, stepped tab rail
   --------------------------------------------------------------- */

:root {
  /* Base colors */
  --charcoal: #2C2C2C;
  --milk-acetate: rgba(255, 255, 255, 0.92);
  --milk-acetate-opaque: #FFFFFF;

  /* Board colors for each slide */
  --oxide-orange: #D97706;
  --chrome-yellow: #EAB308;
  --grass-green: #16A34A;
  --teal: #0D9488;
  --ultramarine: #2563EB;
  --violet: #7C3AED;
  --sienna: #92400E;
  --coral: #F87171;
  --amber: #F59E0B;
  --jade: #059669;

  /* Neutral tones */
  --ink-muted: #57636F;
  --rule: #D1D5DB;

  /* Board saturation for progression */
  --board-saturation: 1;

  /* Spacing */
  --measure: 62ch;

  /* Typography scales */
  --heading-size: 34px;
  --body-size: 17px;
  --label-size: 11px;
  --mono-size: 14px;

  /* Surfaces */
  scrollbar-color: var(--rule) transparent;
  caret-color: var(--charcoal);
  color-scheme: light dark;
}

@media (prefers-color-scheme: dark) {
  :root {
    --charcoal: #E5E7EB;
    --milk-acetate: rgba(29, 32, 38, 0.92);
    --milk-acetate-opaque: #1D2026;
    --ink-muted: #9CA3AF;
    --rule: #374151;

    /* Brighter board colors for dark mode */
    --oxide-orange: #FB923C;
    --chrome-yellow: #FCD34D;
    --grass-green: #4ADE80;
    --teal: #2DD4BF;
    --ultramarine: #60A5FA;
    --violet: #A78BFA;
    --sienna: #D97706;
    --coral: #FCA5A5;
    --amber: #FBBF24;
    --jade: #34D399;
  }
}

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

html {
  overflow-x: clip;
}

body {
  margin: 0;
  font-family: 'Iowan Old Style', 'Palatino Linotype', 'URW Palladio L', P052, serif;
  -webkit-font-smoothing: antialiased;
  line-height: 1.6;
  color: var(--charcoal);
  background: var(--milk-acetate-opaque);
  overflow: hidden;
  height: 100vh;
}

::selection {
  background: var(--oxide-orange);
  color: white;
}

:focus-visible {
  outline: 2px solid var(--oxide-orange);
  outline-offset: 3px;
}

/* ---------------------------------------------------------------
   Tab Rail — Stepped navigation on right edge
   --------------------------------------------------------------- */

.tab-rail {
  position: fixed;
  right: 0;
  top: 0;
  bottom: 0;
  width: 64px;
  display: flex;
  flex-direction: column;
  justify-content: flex-start;
  padding: 0;
  z-index: 100;
  background: transparent;
}

.tab {
  width: 48px;
  height: 10%;
  border: none;
  background: transparent;
  color: var(--charcoal);
  font-family: 'Univers', 'Helvetica Neue', 'Arial Narrow', sans-serif;
  font-size: var(--label-size);
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  cursor: pointer;
  padding: 0;
  position: relative;
  transition: all 90ms steps(2);
  display: flex;
  align-items: center;
  justify-content: center;
  border-left: 1px solid var(--rule);
}

.tab::before {
  content: '';
  position: absolute;
  left: 0;
  top: 0;
  bottom: 0;
  width: 100%;
  opacity: 0.2;
  transition: opacity 90ms steps(2);
}

.tab:nth-child(1)::before { background: var(--oxide-orange); }
.tab:nth-child(2)::before { background: var(--chrome-yellow); }
.tab:nth-child(3)::before { background: var(--grass-green); }
.tab:nth-child(4)::before { background: var(--teal); }
.tab:nth-child(5)::before { background: var(--ultramarine); }
.tab:nth-child(6)::before { background: var(--violet); }
.tab:nth-child(7)::before { background: var(--sienna); }
.tab:nth-child(8)::before { background: var(--coral); }
.tab:nth-child(9)::before { background: var(--amber); }
.tab:nth-child(10)::before { background: var(--jade); }

.tab.active {
  width: 64px;
}

.tab.active::before {
  opacity: 1;
}

.tab-number {
  position: relative;
  z-index: 1;
}

.tab:hover:not(.active)::before {
  opacity: 0.4;
}

/* ---------------------------------------------------------------
   Slides Container
   --------------------------------------------------------------- */

.slides-container {
  position: fixed;
  left: 0;
  right: 64px;
  top: 0;
  bottom: 80px;
  overflow: hidden;
}

.slide {
  position: absolute;
  left: 0;
  right: 0;
  top: 0;
  bottom: 0;
  opacity: 1;
  visibility: visible;
  transition: opacity 90ms steps(2), visibility 0ms;
  display: flex;
}

.slide:not(.active) {
  opacity: 0;
  visibility: hidden;
  transition: opacity 90ms steps(2), visibility 0ms 90ms;
}

/* Board — Colored vertical band on left */

.board {
  width: 288px;
  height: 100%;
  flex-shrink: 0;
  filter: saturate(var(--board-saturation));
}

.slide[data-color="oxide-orange"] .board { background: var(--oxide-orange); }
.slide[data-color="chrome-yellow"] .board { background: var(--chrome-yellow); }
.slide[data-color="grass-green"] .board { background: var(--grass-green); }
.slide[data-color="teal"] .board { background: var(--teal); }
.slide[data-color="ultramarine"] .board { background: var(--ultramarine); }
.slide[data-color="violet"] .board { background: var(--violet); }
.slide[data-color="sienna"] .board { background: var(--sienna); }
.slide[data-color="coral"] .board { background: var(--coral); }
.slide[data-color="amber"] .board { background: var(--amber); }
.slide[data-color="jade"] .board { background: var(--jade); }

/* Acetate Leaf — Floating content panel */

.acetate-leaf {
  flex: 1;
  background: var(--milk-acetate);
  box-shadow: 2px 2px 0 rgba(0, 0, 0, 0.15);
  padding: 48px 64px 48px 56px;
  overflow-y: auto;
  overflow-x: hidden;
}

.slide-heading {
  font-family: 'Univers', 'Helvetica Neue', 'Arial Narrow', sans-serif;
  font-size: var(--heading-size);
  font-weight: 500;
  line-height: 1.2;
  color: var(--charcoal);
  margin: 0 0 24px -200px;
  padding-left: 200px;
}

.content {
  max-width: var(--measure);
}

.content p {
  font-size: var(--body-size);
  line-height: 1.6;
  margin: 0 0 16px 0;
  text-wrap: pretty;
}

.content p:last-of-type {
  margin-bottom: 32px;
}

/* Diagrams */

.diagram {
  margin: 32px 0 0 0;
  padding: 0;
}

.diagram svg {
  max-width: 100%;
  height: auto;
  display: block;
}

.diagram figcaption {
  font-family: 'Univers', 'Helvetica Neue', 'Arial Narrow', sans-serif;
  font-size: 13px;
  line-height: 1.4;
  color: var(--ink-muted);
  margin-top: 12px;
  font-style: italic;
}

/* ---------------------------------------------------------------
   Navigation Controls
   --------------------------------------------------------------- */

.controls {
  position: fixed;
  left: 0;
  right: 64px;
  bottom: 0;
  height: 80px;
  background: var(--milk-acetate);
  border-top: 1px solid var(--rule);
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 32px;
  padding: 0 64px;
  z-index: 100;
}

.control-btn {
  min-width: 120px;
  min-height: 44px;
  border: 2px solid var(--charcoal);
  background: transparent;
  color: var(--charcoal);
  font-family: 'Univers', 'Helvetica Neue', 'Arial Narrow', sans-serif;
  font-size: 14px;
  font-weight: 500;
  cursor: pointer;
  padding: 12px 24px;
  transition: all 90ms steps(2);
  border-radius: 3px;
}

.control-btn:hover:not(:disabled) {
  background: var(--charcoal);
  color: var(--milk-acetate-opaque);
}

.control-btn:disabled {
  opacity: 0.3;
  cursor: not-allowed;
}

.progress-indicator {
  font-family: 'Univers', 'Helvetica Neue', 'Arial Narrow', sans-serif;
  font-size: 17px;
  font-weight: 600;
  color: var(--charcoal);
  display: flex;
  align-items: baseline;
  gap: 4px;
}

.current-slide {
  font-size: 24px;
}

.divider {
  opacity: 0.5;
}

.total-slides {
  opacity: 0.6;
}

.keyboard-hint {
  font-family: 'IBM Plex Mono', 'Menlo', 'Monaco', 'Courier New', monospace;
  font-size: 12px;
  color: var(--ink-muted);
  letter-spacing: 0.1em;
}

/* ---------------------------------------------------------------
   Responsive — Mobile and tablet
   --------------------------------------------------------------- */

@media (max-width: 900px) {
  :root {
    --heading-size: 28px;
    --body-size: 16px;
  }

  .board {
    width: 80px;
  }

  .acetate-leaf {
    padding: 32px 24px;
  }

  .slide-heading {
    margin-left: 0;
    padding-left: 0;
  }

  .tab-rail {
    width: 48px;
  }

  .tab {
    width: 36px;
  }

  .tab.active {
    width: 48px;
  }

  .slides-container {
    right: 48px;
  }

  .controls {
    right: 48px;
    padding: 0 24px;
    gap: 16px;
  }

  .control-btn {
    min-width: 100px;
    font-size: 13px;
  }
}

@media (max-width: 640px) {
  :root {
    --heading-size: 24px;
    --body-size: 15px;
  }

  .board {
    width: 48px;
  }

  .acetate-leaf {
    padding: 24px 20px;
  }

  .tab-rail {
    width: 40px;
  }

  .tab {
    width: 32px;
    font-size: 9px;
  }

  .tab.active {
    width: 40px;
  }

  .slides-container {
    right: 40px;
    bottom: 72px;
  }

  .controls {
    right: 40px;
    height: 72px;
    padding: 0 16px;
    gap: 12px;
  }

  .control-btn {
    min-width: 80px;
    font-size: 12px;
    padding: 10px 16px;
  }

  .btn-label {
    display: none;
  }

  .control-btn::after {
    font-family: monospace;
  }

  #prev-btn::after {
    content: '←';
  }

  #next-btn::after {
    content: '→';
  }

  .keyboard-hint {
    display: none;
  }

  .progress-indicator {
    font-size: 15px;
  }

  .current-slide {
    font-size: 20px;
  }
}

/* ---------------------------------------------------------------
   Motion — Respect reduced motion preference
   --------------------------------------------------------------- */

@media (prefers-reduced-motion: no-preference) {
  .slide,
  .tab {
    transition: all 90ms steps(2);
  }

  .control-btn {
    transition: all 90ms steps(2);
  }
}

@media (prefers-reduced-motion: reduce) {
  .slide,
  .tab,
  .control-btn {
    transition: none;
  }
}

/* ---------------------------------------------------------------
   Print Stylesheet
   --------------------------------------------------------------- */

@media print {
  @page {
    margin: 0.75in;
  }

  body {
    background: white;
    color: black;
    overflow: visible;
    height: auto;
  }

  .tab-rail,
  .controls {
    display: none;
  }

  .slides-container {
    position: static;
    right: auto;
    bottom: auto;
  }

  .slide {
    position: static;
    opacity: 1 !important;
    visibility: visible !important;
    page-break-after: always;
    display: flex;
    min-height: 8in;
  }

  .slide:last-child {
    page-break-after: auto;
  }

  .board {
    width: 1.5in;
    print-color-adjust: exact;
    -webkit-print-color-adjust: exact;
  }

  .acetate-leaf {
    background: white;
    box-shadow: none;
    padding: 0.5in;
    overflow: visible;
  }

  .slide-heading {
    margin-left: 0;
    padding-left: 0;
  }

  .diagram svg {
    max-width: 6in;
  }
}

/* ---------------------------------------------------------------
   Accessibility — Enhanced focus and contrast
   --------------------------------------------------------------- */

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

button {
  font: inherit;
}

button:focus-visible,
.tab:focus-visible {
  outline: 2px solid var(--oxide-orange);
  outline-offset: 3px;
  z-index: 1;
}

/* Ensure diagrams are accessible */
.diagram svg {
  role: img;
}

/* ---------------------------------------------------------------
   Progressive atmospheric shifts (raised from cyclorama-dawn)
   --------------------------------------------------------------- */

.slide[data-slide="0"] { --board-saturation: 1; }
.slide[data-slide="1"] { --board-saturation: 1; }
.slide[data-slide="2"] { --board-saturation: 0.95; }
.slide[data-slide="3"] { --board-saturation: 0.92; }
.slide[data-slide="4"] { --board-saturation: 0.90; }
.slide[data-slide="5"] { --board-saturation: 0.88; }
.slide[data-slide="6"] { --board-saturation: 0.86; }
.slide[data-slide="7"] { --board-saturation: 0.92; }
.slide[data-slide="8"] { --board-saturation: 0.95; }
.slide[data-slide="9"] { --board-saturation: 1; }
@media (max-width: 480px) {
  /* --impeccable-mobile-pad */
  body { padding-inline: max(1rem, 16px); }
  .container, [class*="container"], section, header, footer, nav, main, article {
    padding-inline: max(1rem, 16px);
  }
}
/* --impeccable-measure */
p, li, dt, dd, blockquote, figcaption, td, th { max-width: min(75ch, 100%); }