:root {
  --ink: #1f2933;
  --muted: #667085;
  --blue: #245b8f;
  --paper: #fffdf9;
  --line: #e5e0d8;
}

* {
  box-sizing: border-box;
}

body {
  max-width: 1150px;
  margin: 0 auto;
  padding: 0 2rem;
  color: var(--ink);
  background: var(--paper);
  font-family: Georgia, "Times New Roman", serif;
  font-size: 18px;
  line-height: 1.75;
}

@media (max-width: 700px) {
  body {
    padding: 0 1rem;
    font-size: 17px;
  }
}

header {
  padding: 2rem 0 1rem;
  border-bottom: 1px solid var(--line);
}

nav a {
  margin-right: 1.5rem;
  color: var(--blue);
  font-family: system-ui, sans-serif;
  font-size: 0.95rem;
  text-decoration: none;
}

nav a:hover {
  text-decoration: underline;
}

main {
  padding: 3rem 0;
}

h1,
h2,
h3 {
  color: #172b4d;
  line-height: 1.25;
}

h1 {
  margin-bottom: 1.5rem;
  font-size: 2.7rem;
}

h2 {
  margin-top: 2.5rem;
  font-size: 1.8rem;
}

a {
  color: var(--blue);
}

blockquote {
  margin: 2rem 0;
  padding: 0.5rem 1.5rem;
  border-left: 4px solid var(--blue);
  color: var(--muted);
  font-style: italic;
}

pre {
  overflow-x: auto;
  padding: 1rem;
  border-radius: 6px;
  background: #f1f3f5;
  font-size: 0.85rem;
}

code {
  padding: 0.15rem 0.3rem;
  border-radius: 4px;
  background: #f1f3f5;
  font-size: 0.9em;
}

footer {
  padding: 1.5rem 0 3rem;
  border-top: 1px solid var(--line);
  color: var(--muted);
  font-family: system-ui, sans-serif;
  font-size: 0.85rem;
}









.profile-photo {
  width: 180px;
  height: 180px;
  object-fit: cover;
  border-radius: 50%;
  display: block;
  margin: 1.5rem 0;
}




.theorem,
.lemma,
.proposition,
.corollary,
.definition,
.remark {
  margin: 2rem 0;
  padding: 1rem 1.4rem;
  border-left: 5px solid #245b8f;
  border-radius: 6px;
  background: #eef5fb;
}

.theorem::before {
  content: "Theorem";
}

.lemma::before {
  content: "Lemma";
}

.proposition::before {
  content: "Proposition";
}

.corollary::before {
  content: "Corollary";
}

.definition::before {
  content: "Definition";
}

.remark::before {
  content: "Remark";
}

.theorem::before,
.lemma::before,
.proposition::before,
.corollary::before,
.definition::before,
.remark::before {
  display: block;
  margin-bottom: 0.5rem;
  color: #174a7e;
  font-weight: bold;
  font-style: italic;
}

.proof {
  margin: 1.5rem 0 2rem;
  padding-left: 1.4rem;
  border-left: 3px solid #999;
}

.proof-title {
  font-weight: bold;
  font-style: italic;
}

.qed {
  float: right;
  font-size: 1.2rem;
}