:root {
  --a4-ink: #102a43;
  --a4-muted: #526b80;
  --a4-paper: #f5fbff;
  --a4-surface: #ffffff;
  --a4-line: #cfe4f6;
  --a4-blue: #2f9fe8;
  --a4-blue-dark: #0967a8;
  --a4-blue-soft: #daf2ff;
  --a4-gold: #b76e18;
}

body {
  color: var(--a4-ink);
  background: var(--a4-paper);
  font-family: Inter, ui-sans-serif, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

body > header {
  min-height: 3.7rem;
  color: white;
  background: linear-gradient(110deg, #075b9a, var(--a4-blue));
  text-shadow: none;
  box-shadow: 0 1px 0 rgba(0, 0, 0, 0.15);
}

h1#doc_title {
  color: white;
  font-family: Georgia, "Times New Roman", serif;
  font-size: clamp(1rem, 2vw, 1.35rem);
  letter-spacing: -0.015em;
}

#doc_title a,
#doc_title a:visited {
  color: white;
  text-shadow: none;
}

nav.toc,
.toc ul li {
  background: #0b3a5d;
}

.toc ul li.current {
  background: var(--a4-blue-dark);
}

.toc ul a {
  color: rgba(255, 255, 255, 0.88);
  font-size: 0.93rem;
  text-shadow: none;
}

.toc ul a:hover,
.toc ul a:focus-visible {
  background: #125d8d;
}

.content {
  background:
    radial-gradient(circle at 100% 0%, rgba(204, 237, 255, 0.72), transparent 28rem),
    var(--a4-paper);
}

div.content-wrapper {
  width: 100%;
  max-width: 78ch;
}

.main-text {
  margin: 0.5rem 0 3rem;
  padding: clamp(1.1rem, 3vw, 2.4rem);
  border: 1px solid var(--a4-line);
  border-radius: 0.9rem;
  background: rgba(255, 255, 255, 0.92);
  box-shadow: 0 18px 48px rgba(19, 105, 166, 0.08);
}

.main-text > h1:first-child,
.titlepage h1,
h1,
h2 {
  color: var(--a4-ink);
  font-family: Georgia, "Times New Roman", serif;
  font-weight: 500;
  letter-spacing: -0.025em;
}

.main-text > h1:first-child {
  margin-bottom: 1.2rem;
  padding-bottom: 0.8rem;
  border-bottom: 3px solid var(--a4-blue);
}

a {
  color: var(--a4-blue-dark);
  text-underline-offset: 0.16em;
}

a:hover,
a:focus-visible {
  color: #075483;
}

div[class$="_thmwrapper"] {
  margin: 1.6rem 0;
  padding: 1.05rem 1.15rem;
  border: 1px solid var(--a4-line);
  border-radius: 0.7rem;
  background: var(--a4-surface);
  box-shadow: 0 5px 20px rgba(19, 105, 166, 0.05);
}

div[class$="_thmwrapper"]:target {
  border-color: var(--a4-gold);
  box-shadow: 0 0 0 4px rgba(185, 137, 47, 0.16);
}

div[class$="_thmheading"] {
  color: var(--a4-blue-dark);
  flex-wrap: wrap;
  gap: 0.16rem;
}

div.theorem_thmcontent,
div.proposition_thmcontent {
  border-left: 0.2rem solid var(--a4-blue);
}

div.lemma_thmcontent,
div.corollary_thmcontent,
div.definition_thmcontent,
div.thm_thmcontent {
  border-left: 0.13rem solid #86b8d8;
}

div[class$="_thmcontent"] {
  margin-left: 0.2rem;
  padding: 0.55rem 0 0.2rem 1rem;
}

div.proof_wrapper {
  margin: 0.7rem 0 1.2rem;
  padding: 0.8rem 1rem;
  border-radius: 0.55rem;
  background: #edf7fd;
}

div.proof_content {
  margin-left: 0;
  border-left: 0.1rem solid #9abdd3;
}

a.lean_decl,
a.lean_link,
a.github_link,
a.latex_link {
  display: inline-block;
  max-width: 100%;
  overflow-wrap: anywhere;
  margin: 0.16rem 0;
  padding: 0.22rem 0.48rem;
  border: 1px solid #b5d9ef;
  border-radius: 0.38rem;
  color: var(--a4-blue-dark);
  background: var(--a4-blue-soft);
  font-family: ui-monospace, SFMono-Regular, Menlo, monospace;
  font-size: 0.8rem;
  font-weight: 650;
  text-decoration: none;
}

a.lean_decl:hover,
a.lean_decl:focus-visible,
a.lean_link:hover,
a.lean_link:focus-visible,
a.github_link:hover,
a.github_link:focus-visible,
a.latex_link:hover,
a.latex_link:focus-visible {
  border-color: var(--a4-blue);
  background: #c9ebff;
}

nav.prev_up_next {
  background: #0b3a5d;
}

nav.prev_up_next a {
  color: white;
  text-shadow: none;
}

div.modal-content {
  border-color: var(--a4-blue);
  border-radius: 0.7rem;
}

div.modal-content header {
  color: white;
  background: var(--a4-blue-dark);
  text-shadow: none;
}

table {
  overflow: hidden;
  border: 1px solid var(--a4-line);
  border-radius: 0.5rem;
  background: var(--a4-surface);
}

pre.verbatim {
  overflow-x: auto;
  border: 1px solid var(--a4-line);
  border-radius: 0.5rem;
  background: #eef7fc;
}

::selection {
  color: white;
  background: var(--a4-blue-dark);
}

@media (max-width: 1023px) {
  .main-text {
    border-radius: 0.65rem;
  }

  nav.toc.active {
    max-width: 22rem;
  }
}

@media (max-width: 620px) {
  body > header {
    min-height: 3.3rem;
  }

  h1#doc_title {
    padding-right: 2.3rem;
    font-size: 0.92rem;
    line-height: 1.15;
  }

  div.content {
    padding: 0.45rem;
  }

  .main-text {
    padding: 1rem 0.85rem;
  }

  div[class$="_thmwrapper"] {
    padding: 0.85rem;
  }

  div[class$="_thmcontent"] {
    padding-left: 0.7rem;
  }
}