/* The Perceptron (2014 archive): a declassified 1950s technical report. */

html:has(.arc-perceptron),
body:has(.arc-perceptron) {
  background: #cdbb8f;
  color: #2b2620;
}

.arc-perceptron {
  --arc-p-paper: #f3ead3;
  --arc-p-paper-deep: #e9dcbc;
  --arc-p-ink: #2b2620;
  --arc-p-ink-soft: #5d5446;
  --arc-p-rule: #b9a985;
  --arc-p-red: #a3352b;
  --arc-p-plate: #171613;
  --arc-p-type: "American Typewriter", "Courier Prime", Courier, "Courier New", ui-monospace, monospace;
  --arc-p-serif: Charter, "Iowan Old Style", "Palatino Linotype", Georgia, ui-serif, serif;

  display: block;
  min-height: 100svh;
  padding: 40px 24px 56px;
  background:
    radial-gradient(ellipse at 20% 0%, rgba(255, 248, 225, 0.35), transparent 60%),
    #cdbb8f;
  color: var(--arc-p-ink);
  font-family: var(--arc-p-serif);
  font-size: 18px;
  line-height: 1.65;
}

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

.arc-perceptron a {
  color: inherit;
  text-decoration: underline;
  text-decoration-thickness: 1px;
  text-underline-offset: 3px;
}

.arc-perceptron a:hover {
  color: var(--arc-p-red);
}

.arc-perceptron :focus-visible {
  outline: 2px solid var(--arc-p-red);
  outline-offset: 3px;
  border-radius: 1px;
}

/* The sheet of paper */

.arc-p-sheet {
  max-width: 960px;
  margin: 0 auto;
  padding: 28px 56px 40px;
  background:
    linear-gradient(180deg, rgba(255, 255, 255, 0.35), rgba(255, 255, 255, 0) 30%),
    var(--arc-p-paper);
  box-shadow:
    0 1px 0 rgba(0, 0, 0, 0.05),
    0 18px 40px -18px rgba(60, 45, 15, 0.45),
    0 2px 6px rgba(60, 45, 15, 0.12);
}

/* Top line: home link and file mark */

.arc-p-topbar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 16px;
  font-family: var(--arc-p-type);
  font-size: 13px;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--arc-p-ink-soft);
}

.arc-perceptron .arc-p-home {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  min-height: 44px;
  text-decoration: none;
  color: var(--arc-p-ink);
}

.arc-perceptron .arc-p-home:hover {
  color: var(--arc-p-red);
  text-decoration: underline;
}

.arc-p-file {
  text-align: right;
}

/* Report header block */

.arc-p-report {
  margin-top: 12px;
  border: 2px solid var(--arc-p-ink);
}

.arc-p-report-head {
  display: flex;
  justify-content: space-between;
  align-items: stretch;
  border-bottom: 1px solid var(--arc-p-ink);
  font-family: var(--arc-p-type);
  text-transform: uppercase;
}

.arc-p-org {
  margin: 0;
  padding: 12px 18px;
  font-size: 14px;
  line-height: 1.4;
  letter-spacing: 0.14em;
}

.arc-p-org span {
  color: var(--arc-p-ink-soft);
  font-size: 12px;
}

.arc-p-report-no {
  margin: 0;
  padding: 12px 18px;
  border-left: 1px solid var(--arc-p-ink);
  text-align: right;
}

.arc-p-report-no dt {
  font-size: 11px;
  letter-spacing: 0.14em;
  color: var(--arc-p-ink-soft);
}

.arc-p-report-no dd {
  margin: 0;
  font-size: 20px;
  letter-spacing: 0.08em;
}

.arc-p-title-block {
  position: relative;
  padding: 62px 18px 30px;
  text-align: center;
  border-bottom: 1px solid var(--arc-p-ink);
}

.arc-p-kicker {
  margin: 0 0 6px;
  font-family: var(--arc-p-type);
  font-size: 13px;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--arc-p-ink-soft);
}

.arc-perceptron h1 {
  margin: 0;
  font-family: var(--arc-p-type);
  font-size: clamp(34px, 6vw, 60px);
  font-weight: 400;
  line-height: 1.05;
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

.arc-p-dek {
  max-width: 34em;
  margin: 14px auto 0;
  font-style: italic;
  font-size: 19px;
  line-height: 1.5;
  color: var(--arc-p-ink-soft);
}

/* The one bold gesture: a rubber stamp */

.arc-p-stamp {
  position: absolute;
  top: 16px;
  right: 22px;
  margin: 0;
  padding: 6px 12px 4px;
  border: 3px double var(--arc-p-red);
  border-radius: 3px;
  color: var(--arc-p-red);
  font-family: var(--arc-p-type);
  font-size: 14px;
  font-weight: 700;
  line-height: 1.1;
  letter-spacing: 0.22em;
  text-align: center;
  text-transform: uppercase;
  transform: rotate(-7deg);
  opacity: 0.82;
  mix-blend-mode: multiply;
}

.arc-p-stamp span {
  display: block;
  font-size: 22px;
  letter-spacing: 0.3em;
  margin-right: -0.3em;
}

.arc-p-fields {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  margin: 0;
}

.arc-p-fields > div {
  padding: 10px 14px 12px;
  border-left: 1px solid var(--arc-p-ink);
}

.arc-p-fields > div:first-child {
  border-left: 0;
}

.arc-p-fields dt {
  font-family: var(--arc-p-type);
  font-size: 11px;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--arc-p-ink-soft);
}

.arc-p-fields dd {
  margin: 2px 0 0;
  font-family: var(--arc-p-type);
  font-size: 14px;
  line-height: 1.35;
}

/* Figure 1. The canvas width is the figure's own width (read by the controller), so
   the figure carries no padding; insets live on its children. */

.arc-p-figure {
  margin: 44px 0 0;
  padding: 0;
}

.arc-p-plate {
  position: relative;
  cursor: crosshair;
  background: var(--arc-p-plate);
  box-shadow: 0 0 0 1px var(--arc-p-ink), 0 0 0 7px #fbf6e8, 0 0 0 8px var(--arc-p-rule);
}

.arc-p-canvas {
  display: block;
  width: 100%;
  height: auto;
  background-color: var(--arc-p-plate);
  background-image:
    linear-gradient(rgba(231, 222, 196, 0.06) 1px, transparent 1px),
    linear-gradient(90deg, rgba(231, 222, 196, 0.06) 1px, transparent 1px),
    radial-gradient(ellipse at center, rgba(255, 245, 215, 0.07), transparent 70%);
  background-size: 40px 40px, 40px 40px, 100% 100%;
  background-position: center center;
}

.arc-p-notice {
  position: absolute;
  left: 50%;
  bottom: 14px;
  transform: translateX(-50%);
  width: max-content;
  max-width: calc(100% - 24px);
  padding: 6px 12px;
  background: rgba(23, 22, 19, 0.85);
  border: 1px solid rgba(231, 222, 196, 0.25);
  color: #d8cfb6;
  font-family: var(--arc-p-type);
  font-size: 12px;
  letter-spacing: 0.08em;
  text-align: center;
  text-transform: uppercase;
  pointer-events: none;
  user-select: none;
}

.arc-p-caption {
  margin-top: 22px;
  padding: 0 4px;
  font-size: 16px;
  line-height: 1.55;
}

.arc-p-caption p {
  margin: 0;
}

.arc-p-caption strong {
  font-family: var(--arc-p-type);
  font-weight: 400;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

.arc-p-legend {
  display: flex;
  flex-wrap: wrap;
  gap: 6px 24px;
  margin: 8px 0 0;
  padding: 0;
  list-style: none;
  font-family: var(--arc-p-type);
  font-size: 13px;
  color: var(--arc-p-ink-soft);
}

.arc-p-legend li {
  display: flex;
  align-items: center;
  gap: 8px;
}

.arc-p-key {
  display: inline-block;
  flex-shrink: 0;
  width: 26px;
  height: 0;
}

.arc-p-key-target {
  border-top: 3px solid #e74c3c;
}

.arc-p-key-current {
  border-top: 2px solid #666;
}

.arc-p-key-dots {
  display: inline-flex;
  gap: 4px;
  width: auto;
  height: auto;
}

.arc-p-key-dots i {
  display: block;
  width: 9px;
  height: 9px;
  border: 1.5px solid #777;
  border-radius: 50%;
}

.arc-p-key-dots i:first-child {
  background: #777;
}

/* Table I: the weight readouts as a ruled form */

.arc-p-weights {
  margin-top: 36px;
  padding: 18px 20px 16px;
  border: 1px solid var(--arc-p-ink);
  background: rgba(255, 255, 255, 0.22);
}

.arc-perceptron .arc-p-weights h2 {
  margin: 0;
  padding-bottom: 10px;
  border-bottom: 1px solid var(--arc-p-ink);
  font-family: var(--arc-p-type);
  font-size: 14px;
  font-weight: 400;
  letter-spacing: 0.1em;
  text-transform: uppercase;
}

.arc-p-weights h2 span {
  margin-right: 6px;
}

.arc-p-weights-body {
  display: grid;
  grid-template-columns: minmax(0, 0.95fr) minmax(0, 1.05fr);
  gap: 28px;
  align-items: center;
  padding-top: 16px;
}

.arc-p-schematic {
  display: block;
  width: 100%;
  max-width: 380px;
  height: auto;
}

.arc-p-sch-lines line,
.arc-p-sch-lines polyline {
  fill: none;
  stroke: var(--arc-p-ink);
  stroke-width: 1.3;
}

.arc-p-sch-nodes circle,
.arc-p-sch-nodes rect {
  fill: #fbf6e8;
  stroke: var(--arc-p-ink);
  stroke-width: 1.5;
}

.arc-p-sch-nodes .arc-p-sch-step {
  fill: none;
  stroke: var(--arc-p-red);
  stroke-width: 2;
}

.arc-p-sch-text text {
  font-family: var(--arc-p-type);
  font-size: 15px;
  fill: var(--arc-p-ink);
  text-anchor: middle;
}

.arc-p-sch-text .arc-p-sch-sigma {
  font-family: var(--arc-p-serif);
  font-size: 22px;
}

.arc-p-sch-text .arc-p-sch-w {
  font-size: 13px;
  fill: var(--arc-p-red);
}

.arc-p-sch-text .arc-p-sch-small {
  font-size: 13px;
  fill: var(--arc-p-ink-soft);
}

.arc-p-form {
  margin: 0;
}

.arc-p-row {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 14px;
  padding: 10px 0 6px;
}

.arc-p-row + .arc-p-row {
  margin-top: 6px;
}

.arc-p-row dt {
  flex-shrink: 0;
  font-family: var(--arc-p-type);
  font-size: 13px;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--arc-p-ink-soft);
}

.arc-p-row dt span {
  display: inline-block;
  min-width: 2.2em;
  color: var(--arc-p-red);
  text-transform: none;
}

.arc-p-row dd {
  flex: 1 1 auto;
  min-width: 7.5em;
  margin: 0;
  padding: 0 4px 2px;
  border-bottom: 1px solid var(--arc-p-ink);
  font-family: var(--arc-p-type);
  font-size: 18px;
  text-align: right;
  font-variant-numeric: tabular-nums;
  white-space: nowrap;
}

.arc-p-note {
  margin: 14px 0 0;
  font-size: 14px;
  font-style: italic;
  color: var(--arc-p-ink-soft);
}

/* Report body */

.arc-p-body {
  max-width: 680px;
  margin: 56px auto 0;
}

.arc-p-body section + section {
  margin-top: 40px;
}

.arc-perceptron .arc-p-body h2 {
  margin: 0 0 14px;
  padding-bottom: 6px;
  border-bottom: 1px solid var(--arc-p-rule);
  font-family: var(--arc-p-type);
  font-size: 17px;
  font-weight: 400;
  letter-spacing: 0.1em;
  text-transform: uppercase;
}

.arc-p-body h2 span {
  display: inline-block;
  min-width: 1.8em;
  color: var(--arc-p-red);
}

.arc-p-body p {
  margin: 0 0 1em;
}

.arc-p-abstract {
  padding: 22px 26px 8px;
  background: var(--arc-p-paper-deep);
  border-left: 3px solid var(--arc-p-ink);
}

.arc-p-abstract p {
  font-size: 17px;
}

.arc-p-steps {
  margin: 0 0 1.1em;
  padding: 0;
  list-style: none;
  counter-reset: arc-p-step;
}

.arc-p-steps li {
  position: relative;
  margin: 0 0 10px;
  padding-left: 46px;
  counter-increment: arc-p-step;
}

.arc-p-steps li::before {
  content: "(" counter(arc-p-step, lower-alpha) ")";
  position: absolute;
  left: 4px;
  top: 0;
  font-family: var(--arc-p-type);
  color: var(--arc-p-red);
}

.arc-perceptron cite {
  font-style: italic;
}

/* Footer */

.arc-p-footer {
  max-width: 680px;
  margin: 56px auto 0;
  padding-top: 18px;
  border-top: 2px solid var(--arc-p-ink);
  font-family: var(--arc-p-type);
  font-size: 13px;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--arc-p-ink-soft);
}

.arc-p-footer p {
  margin: 0;
}

.arc-p-origin a {
  display: inline-flex;
  align-items: center;
  min-height: 40px;
}

.arc-p-footer-meta {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 4px 22px;
  margin-top: 6px;
}

.arc-p-footer-meta a {
  display: inline-flex;
  align-items: center;
  min-height: 40px;
  margin-left: auto;
  color: var(--arc-p-ink);
}

/* Narrow screens */

@media (max-width: 760px) {
  .arc-perceptron {
    padding: 12px 10px 32px;
    font-size: 17px;
  }

  .arc-p-sheet {
    padding: 8px 16px 28px;
  }

  .arc-p-topbar {
    font-size: 12px;
  }

  .arc-p-file {
    display: none;
  }

  .arc-p-org {
    padding: 10px 12px;
    font-size: 11px;
    letter-spacing: 0.08em;
  }

  .arc-p-org span {
    font-size: 11px;
  }

  .arc-p-report-no {
    padding: 10px 12px;
  }

  .arc-p-report-no dt {
    font-size: 10px;
  }

  .arc-p-report-no dd {
    font-size: 14px;
    letter-spacing: 0.02em;
    white-space: nowrap;
  }

  .arc-p-title-block {
    padding: 64px 14px 24px;
  }

  .arc-p-stamp {
    top: 12px;
    right: 12px;
    font-size: 11px;
  }

  .arc-p-stamp span {
    font-size: 16px;
  }

  .arc-p-dek {
    font-size: 17px;
  }

  .arc-p-fields {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .arc-p-fields > div:nth-child(3) {
    border-left: 0;
  }

  .arc-p-fields > div:nth-child(n + 3) {
    border-top: 1px solid var(--arc-p-ink);
  }

  .arc-p-figure {
    margin-top: 32px;
  }

  .arc-p-weights {
    padding: 14px 14px 12px;
  }

  .arc-p-weights-body {
    grid-template-columns: minmax(0, 1fr);
    gap: 12px;
  }

  .arc-p-schematic {
    max-width: 300px;
    margin: 0 auto;
  }

  .arc-p-row dt {
    font-size: 12px;
  }

  .arc-p-row dd {
    min-width: 6em;
    font-size: 16px;
  }

  .arc-p-body {
    margin-top: 40px;
  }

  .arc-p-abstract {
    padding: 16px 16px 4px;
  }

  .arc-p-footer-meta a {
    margin-left: 0;
  }
}

@media (prefers-reduced-motion: reduce) {
  .arc-perceptron * {
    transition: none !important;
  }
}