.deepdoc-masthead {
  position: relative;
  overflow-x: clip;
  padding-top: clamp(66px, 9vw, 118px);
  padding-bottom: clamp(50px, 7vw, 88px);
  border-bottom: var(--line-thin) solid var(--color-border);
  background: var(--color-panel);
}

.deepdoc-masthead::before,
.deepdoc-masthead::after {
  position: absolute;
  pointer-events: none;
  content: "";
}

.deepdoc-masthead::before {
  top: 0;
  right: var(--gutter);
  width: clamp(76px, 12vw, 168px);
  height: 100%;
  border-right: var(--line-thin) solid var(--color-border);
  border-left: var(--line-thin) solid var(--color-border);
}

.deepdoc-masthead::after {
  top: clamp(28px, 5vw, 64px);
  right: calc(var(--gutter) + clamp(18px, 3vw, 42px));
  width: clamp(38px, 6vw, 84px);
  height: clamp(38px, 6vw, 84px);
  border: var(--line-strong) solid var(--color-accent);
  background: var(--color-panel-strong);
}

.deepdoc-masthead .reading-wrap {
  position: relative;
  z-index: 1;
}

.deepdoc-masthead h1 {
  max-width: 720px;
  font-size: clamp(54px, 7.2vw, 94px);
}

.deepdoc-deck {
  max-width: 720px;
  margin-top: 30px;
  color: var(--color-muted);
  font-size: clamp(17px, 1.8vw, 21px);
  line-height: 1.9;
}

.deepdoc-register {
  display: flex;
  flex-wrap: wrap;
  gap: 10px 26px;
  margin-top: 28px;
  padding-top: 14px;
  border-top: var(--line-thin) solid var(--color-border);
  color: var(--color-muted);
  font-family: var(--font-mono);
  font-size: 10px;
  letter-spacing: .07em;
}

.deepdoc-masthead .callout {
  margin-top: 38px;
  margin-bottom: 0;
}

.deepdoc-masthead .callout a {
  color: var(--color-text);
  text-decoration: underline;
  text-decoration-color: var(--color-accent);
  text-underline-offset: 4px;
}

.deepdoc-body {
  padding-top: clamp(52px, 8vw, 96px);
  padding-bottom: var(--section-space);
}

.deepdoc-chapter {
  min-width: 0;
  scroll-margin-top: 68px;
}

.deepdoc-chapter + .deepdoc-chapter {
  margin-top: clamp(70px, 10vw, 118px);
}

.deepdoc-chapter h2 {
  scroll-margin-top: 68px;
}

.chapter-mark {
  margin: 0 0 12px;
  color: var(--color-accent);
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: .13em;
}

.deepdoc-body .deepdoc-chapter > h2 {
  margin-top: 0;
}

.deepdoc-body .data-table-wrap {
  margin: 1.7rem 0;
}

.deepdoc-body .panel h3 {
  margin-top: 0;
}

.deepdoc-body .panel p:last-child {
  margin-bottom: 0;
}

.proof-sequence {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: var(--line-thin);
  margin: 2rem 0;
  border: var(--line-thin) solid var(--color-border);
  background: var(--color-border);
}

.proof-sequence > * {
  min-width: 0;
  border: 0;
  background: var(--color-panel);
}

.proof-sequence h3 {
  margin-bottom: 12px;
  font-size: 24px;
}

@media (max-width: 760px) {
  .deepdoc-masthead::before,
  .deepdoc-masthead::after {
    display: none;
  }

  .proof-sequence {
    grid-template-columns: minmax(0, 1fr);
  }
}

@media (max-width: 480px) {
  .deepdoc-register {
    align-items: flex-start;
    flex-direction: column;
  }

  .deepdoc-body {
    padding-top: 46px;
  }

  .deepdoc-chapter + .deepdoc-chapter {
    margin-top: 70px;
  }
}