/* Halvern for btcsite.org
   Palette, four colors, hue 105:
   paper #ebf3e8, ink #12290a, moss #2b6219, lime #92f472
   Text pairs: ink on paper 13.7:1, paper on moss 6.5:1, ink on lime 11.4:1, lime on moss 5.4:1,
   paper on ink 13.7:1, lime on ink 11.4:1. Focus rings use ink on paper and lime, lime on moss. */

:root {
  --paper: #ebf3e8;
  --ink: #12290a;
  --moss: #2b6219;
  --lime: #92f472;

  --font-display: Rockwell, Cambria, Georgia, serif;
  --font-body: -apple-system, BlinkMacSystemFont, "Segoe UI", system-ui, Roboto, "Helvetica Neue", Arial, sans-serif;

  --gutter: 16px;
  --rule: clamp(8px, 1.2vw, 14px);
  --measure: 66ch;
}

@media (min-width: 768px) {
  :root {
    --gutter: clamp(24px, 4vw, 64px);
  }
}

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

html {
  -webkit-text-size-adjust: 100%;
  text-size-adjust: 100%;
}

body {
  margin: 0;
  background-color: var(--paper);
  color: var(--ink);
  font-family: var(--font-body);
  font-size: clamp(1rem, 0.96rem + 0.2vw, 1.125rem);
  line-height: 1.6;
  overflow-wrap: break-word;
  -webkit-font-smoothing: antialiased;
}

h1,
h2,
h3 {
  font-family: var(--font-display);
  font-weight: 700;
  line-height: 1.04;
  letter-spacing: -0.01em;
  margin: 0 0 0.5em;
  overflow-wrap: break-word;
}

p {
  margin: 0 0 1em;
  max-width: var(--measure);
}

ul,
ol {
  margin: 0;
  padding: 0;
}

a {
  color: inherit;
  text-decoration-line: underline;
  text-decoration-thickness: 0.1em;
  text-underline-offset: 0.18em;
}

a:hover {
  text-decoration-thickness: 0.22em;
}

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

:focus-visible {
  outline: 4px solid var(--ink);
  outline-offset: 4px;
}

.band--moss :focus-visible,
.site-footer :focus-visible {
  outline-color: var(--lime);
}

.band--lime :focus-visible {
  outline-color: var(--ink);
}

/* Skip link */

.skip-link {
  position: absolute;
  top: 0;
  left: var(--gutter);
  z-index: 10;
  padding: 12px 16px;
  background-color: var(--lime);
  color: var(--ink);
  font-weight: 700;
  transform: translateY(-150%);
}

.skip-link:focus {
  transform: translateY(12px);
}

/* Header and navigation */

.site-header {
  background-color: var(--paper);
  border-bottom: var(--rule) solid var(--ink);
}

.header-inner,
.footer-inner {
  width: 100%;
  max-width: 1200px;
  margin-inline: auto;
  padding-inline: var(--gutter);
}

.header-inner {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 14px 24px;
  padding-block: 18px;
}

.wordmark {
  display: flex;
  flex-direction: column;
  text-decoration: none;
}

.wordmark-name {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: clamp(1.9rem, 1.5rem + 1.4vw, 2.75rem);
  line-height: 1;
  letter-spacing: -0.02em;
}

.wordmark-sub {
  margin-top: 4px;
  font-size: 0.72rem;
  font-weight: 700;
  letter-spacing: 0.16em;
  text-transform: uppercase;
}

.site-nav ul {
  display: flex;
  flex-wrap: wrap;
  gap: 8px 22px;
  list-style: none;
}

.site-nav a {
  display: inline-block;
  padding-block: 4px;
  font-size: 0.95rem;
  font-weight: 700;
  text-decoration: none;
  border-bottom: 3px solid transparent;
}

.site-nav a:hover,
.site-nav a[aria-current="page"] {
  border-bottom-color: var(--ink);
}

/* Poster bands */

.band {
  position: relative;
  display: flex;
  align-items: center;
  min-height: 100vh;
  min-height: 100svh;
  padding-block: clamp(56px, 9vw, 128px);
  border-top: var(--rule) solid var(--ink);
}

main > .band:first-child {
  border-top: 0;
}

.band-inner {
  width: 100%;
  max-width: 1200px;
  margin-inline: auto;
  padding-inline: var(--gutter);
}

.band--paper {
  background-color: var(--paper);
  color: var(--ink);
}

.band--lime {
  background-color: var(--lime);
  color: var(--ink);
}

.band--moss {
  background-color: var(--moss);
  color: var(--paper);
}

.band--moss a {
  color: var(--lime);
}

.band--moss .kicker {
  color: var(--lime);
}

.band--moss .note {
  border-left-color: var(--lime);
}

/* Typography */

.kicker {
  margin: 0 0 1.25rem;
  font-size: 0.8rem;
  font-weight: 700;
  letter-spacing: 0.16em;
  text-transform: uppercase;
}

.display {
  margin: 0 0 0.35em;
  font-size: clamp(2.5rem, 1rem + 7.6vw, 9.5rem);
  line-height: 0.94;
  letter-spacing: -0.03em;
}

.heading {
  font-size: clamp(2rem, 1.2rem + 3.4vw, 4.5rem);
  line-height: 1.02;
}

.subhead {
  font-size: clamp(1.35rem, 1.1rem + 1vw, 2rem);
  line-height: 1.15;
}

.lede {
  max-width: 36ch;
  font-size: clamp(1.15rem, 1rem + 0.7vw, 1.5rem);
  line-height: 1.5;
}

.numeral {
  max-width: none;
  margin: 0;
  font-family: var(--font-display);
  font-size: clamp(5rem, 3rem + 12vw, 14rem);
  font-weight: 700;
  line-height: 0.82;
  letter-spacing: -0.05em;
}

.split {
  display: grid;
  gap: clamp(28px, 4vw, 72px);
  align-items: center;
}

@media (min-width: 900px) {
  .split {
    grid-template-columns: minmax(0, 1fr) minmax(0, 1.25fr);
  }
}

.note {
  margin: 2rem 0 0;
  padding: 14px 18px;
  border-left: 10px solid currentColor;
  font-weight: 700;
}

.status {
  margin: 0 0 24px;
  max-width: none;
  padding: 14px 18px;
  border-left: 10px solid var(--ink);
  background-color: var(--lime);
  color: var(--ink);
  font-weight: 700;
}

/* Buttons and links */

.actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 2rem;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 48px;
  padding: 0.7rem 1.25rem;
  border: 3px solid var(--ink);
  border-radius: 0;
  background-color: transparent;
  color: var(--ink);
  font-family: var(--font-body);
  font-size: 1rem;
  font-weight: 700;
  line-height: 1.2;
  text-decoration: none;
  cursor: pointer;
  transition: background-color 150ms ease, color 150ms ease;
}

.btn:hover {
  background-color: var(--ink);
  color: var(--paper);
}

.btn--solid {
  background-color: var(--ink);
  color: var(--paper);
}

.btn--solid:hover {
  background-color: var(--paper);
  color: var(--ink);
}

.btn--small {
  min-height: 44px;
  padding: 0.5rem 0.9rem;
  font-size: 0.95rem;
}

.band--moss .btn {
  color: var(--lime);
  border-color: var(--lime);
  background-color: transparent;
}

.band--moss .btn:hover {
  background-color: var(--lime);
  color: var(--ink);
}

.band--moss .btn--solid {
  background-color: var(--lime);
  color: var(--ink);
}

.band--moss .btn--solid:hover {
  background-color: var(--paper);
  color: var(--ink);
  border-color: var(--paper);
}

/* Lists used as rules */

.facts {
  list-style: none;
  border-top: 4px solid currentColor;
}

.facts li {
  padding: 18px 0;
  border-bottom: 4px solid currentColor;
}

.facts li strong {
  display: block;
  margin-bottom: 4px;
  font-family: var(--font-display);
  font-size: clamp(1.35rem, 1.1rem + 0.8vw, 1.85rem);
}

.steps {
  list-style: none;
  counter-reset: step;
  border-top: 4px solid currentColor;
}

.steps li {
  counter-increment: step;
  display: grid;
  grid-template-columns: 2.5rem minmax(0, 1fr);
  gap: 12px;
  padding: 16px 0;
  border-bottom: 4px solid currentColor;
}

.steps li::before {
  content: counter(step);
  font-family: var(--font-display);
  font-size: 1.8rem;
  font-weight: 700;
  line-height: 1;
}

.steps li p {
  margin: 0;
}

/* Diagrams and charts */

.diagram,
.chart svg {
  width: 100%;
  height: auto;
}

.diagram {
  margin: 2.5rem 0 1rem;
}

.svg-block {
  fill: var(--lime);
}

.svg-title {
  fill: var(--ink);
  font-family: var(--font-body);
  font-size: 32px;
  font-weight: 700;
}

.svg-body {
  fill: var(--ink);
  font-family: var(--font-body);
  font-size: 24px;
}

.svg-arrow {
  fill: none;
  stroke: var(--paper);
  stroke-width: 8;
  stroke-linecap: square;
  stroke-dasharray: 1;
  animation: draw-arrow 1.2s ease-out both;
}

@keyframes draw-arrow {
  from {
    stroke-dashoffset: 1;
  }
  to {
    stroke-dashoffset: 0;
  }
}

.diagram-caption {
  font-size: 0.98rem;
}

.chart {
  margin: 0;
}

.chart-bar {
  fill: var(--moss);
}

.chart-value {
  fill: var(--ink);
  font-family: var(--font-display);
  font-size: 30px;
  font-weight: 700;
  text-anchor: middle;
}

.chart-tick {
  fill: var(--ink);
  font-family: var(--font-body);
  font-size: 24px;
  font-weight: 700;
  text-anchor: middle;
}

.chart-axis {
  stroke: var(--ink);
  stroke-width: 4;
}

.chart figcaption {
  margin-top: 12px;
  font-size: 0.95rem;
  font-weight: 700;
}

/* Tables */

.data-table {
  width: 100%;
  margin: 2rem 0 0;
  border-collapse: collapse;
  font-size: 0.98rem;
}

.data-table caption {
  caption-side: top;
  margin-bottom: 12px;
  text-align: left;
  font-family: var(--font-display);
  font-size: 1.35rem;
  font-weight: 700;
}

.data-table th,
.data-table td {
  padding: 12px 12px 12px 0;
  text-align: left;
  vertical-align: top;
  border-bottom: 3px solid currentColor;
  overflow-wrap: anywhere;
}

.data-table thead th {
  font-size: 0.78rem;
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

/* Guide chapter navigation */

.chapter-nav ol {
  list-style: none;
  margin-top: 2.5rem;
  border-top: var(--rule) solid var(--ink);
}

.chapter-nav li {
  border-bottom: 4px solid var(--ink);
}

.chapter-nav a {
  display: flex;
  align-items: baseline;
  gap: 16px;
  padding: 16px 0;
  font-family: var(--font-display);
  font-size: clamp(1.4rem, 1rem + 1.6vw, 2.6rem);
  font-weight: 700;
  line-height: 1.1;
  text-decoration: none;
}

.chapter-nav a:hover {
  text-decoration: underline;
  text-decoration-thickness: 0.08em;
}

/* Progressive enhancement: JavaScript-only controls stay hidden without JavaScript */

.no-js .js-only {
  display: none;
}

.js .no-js-only {
  display: none;
}

/* Ranking (priorities page) */

.rank-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin: 0 0 24px;
}

.rank-list {
  list-style: none;
  border-top: var(--rule) solid var(--ink);
}

.rank-item {
  position: relative;
  display: grid;
  grid-template-columns: clamp(3rem, 2.4rem + 2vw, 5.5rem) minmax(0, 1fr);
  column-gap: clamp(12px, 2vw, 24px);
  align-items: start;
  padding: clamp(18px, 2.4vw, 28px) 0;
  border-bottom: 4px solid var(--ink);
  background-color: var(--paper);
}

.rank-item.is-dragging {
  background-color: var(--lime);
  outline: 4px solid var(--ink);
  outline-offset: -4px;
}

.rank-num {
  grid-column: 1;
  grid-row: 1 / span 2;
  font-family: var(--font-display);
  font-size: clamp(2.5rem, 1.8rem + 3vw, 5rem);
  font-weight: 700;
  line-height: 0.9;
  letter-spacing: -0.03em;
}

.rank-body {
  grid-column: 2;
  grid-row: 1;
  min-width: 0;
}

.rank-body h3 {
  margin-bottom: 0.35em;
  font-size: clamp(1.35rem, 1.1rem + 1vw, 2.1rem);
}

.rank-body p {
  margin: 0;
}

.rank-tools {
  grid-column: 2;
  grid-row: 2;
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-top: 16px;
}

.rank-drag {
  cursor: grab;
  touch-action: none;
  user-select: none;
  -webkit-user-select: none;
  background-color: var(--ink);
  color: var(--paper);
}

.rank-drag:hover {
  background-color: var(--paper);
  color: var(--ink);
}

.rank-item.is-dragging .rank-drag {
  cursor: grabbing;
}

/* Glossary */

.letter-nav ul {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  list-style: none;
  margin-top: 2rem;
}

.letter-nav a {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 48px;
  min-height: 48px;
  padding: 0 12px;
  border: 3px solid var(--ink);
  color: var(--ink);
  font-family: var(--font-display);
  font-size: 1.25rem;
  font-weight: 700;
  text-decoration: none;
}

.letter-nav a:hover {
  background-color: var(--ink);
  color: var(--lime);
}

.glossary-group {
  margin-top: clamp(40px, 6vw, 72px);
  padding-top: 24px;
  border-top: var(--rule) solid var(--ink);
}

.glossary-group h2 {
  font-size: clamp(3.5rem, 2rem + 6vw, 7rem);
  line-height: 0.9;
}

.glossary dt {
  margin-top: 28px;
  font-family: var(--font-display);
  font-size: clamp(1.35rem, 1.1rem + 0.9vw, 1.9rem);
  font-weight: 700;
  line-height: 1.15;
}

.glossary dd {
  margin: 6px 0 0;
  max-width: var(--measure);
}

/* Contact */

.mail-link {
  display: inline-block;
  max-width: 100%;
  padding-bottom: 8px;
  border-bottom: 8px solid var(--ink);
  color: var(--ink);
  font-family: var(--font-display);
  font-size: clamp(1.6rem, 0.9rem + 3.6vw, 4.5rem);
  font-weight: 700;
  line-height: 1.1;
  overflow-wrap: anywhere;
  text-decoration: none;
}

.mail-link:hover {
  background-color: var(--ink);
  color: var(--lime);
}

.plain-list {
  list-style: none;
  border-top: 4px solid currentColor;
}

.plain-list li {
  padding: 16px 0;
  border-bottom: 4px solid currentColor;
}

/* Footer */

.site-footer {
  padding-block: 56px 40px;
  background-color: var(--ink);
  color: var(--paper);
}

.site-footer a {
  color: var(--lime);
}

.footer-inner p {
  max-width: 62ch;
}

.footer-name {
  font-family: var(--font-display);
  font-size: 1.6rem;
  font-weight: 700;
}

.site-footer ul {
  display: flex;
  flex-wrap: wrap;
  gap: 8px 20px;
  margin-top: 16px;
  list-style: none;
}

/* Motion: every animation and transition has a static form */

@media (prefers-reduced-motion: reduce) {
  .svg-arrow {
    animation: none;
    stroke-dasharray: none;
  }

  .btn {
    transition: none;
  }
}