:root {
  --paper: #f8f7f3;
  --surface: #ffffff;
  --ink: #242629;
  --muted: #616b70;
  --line: #d9dfdd;
  --waseda-red: #8a0024;
  --teal: #0f6f72;
  --max-width: 880px;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: Inter, "Noto Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  font-size: 16px;
  line-height: 1.65;
}

a {
  color: var(--teal);
  text-underline-offset: 0.2em;
}

.skip-link {
  position: absolute;
  left: 1rem;
  top: -4rem;
  z-index: 10;
  padding: 0.65rem 0.85rem;
  background: var(--ink);
  color: #ffffff;
  border-radius: 4px;
}

.skip-link:focus {
  top: 1rem;
}

.page-shell {
  width: min(var(--max-width), calc(100% - 2rem));
  margin: 0 auto;
  padding: 5rem 0 3rem;
}

.top-action {
  display: flex;
  justify-content: flex-end;
  margin-bottom: 3.2rem;
}

.hero {
  padding: 0 0 4rem;
  border-bottom: 1px solid var(--line);
}

.eyebrow {
  margin: 0 0 0.7rem;
  color: var(--waseda-red);
  font-size: 0.78rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

h1,
h2,
h3,
p {
  overflow-wrap: anywhere;
}

h1 {
  margin: 0;
  color: var(--ink);
  font-size: clamp(3.4rem, 12vw, 6.5rem);
  line-height: 0.98;
  font-weight: 760;
  letter-spacing: 0;
}

h2 {
  margin: 0;
  color: var(--ink);
  font-size: clamp(1.7rem, 4vw, 2.6rem);
  line-height: 1.15;
  letter-spacing: 0;
}

h3 {
  margin: 0;
  color: var(--ink);
  font-size: 1.08rem;
  line-height: 1.35;
  letter-spacing: 0;
}

.role {
  margin: 1.15rem 0 0;
  color: var(--muted);
  font-size: 1.05rem;
}

.lead {
  max-width: 44rem;
  margin: 1.35rem 0 0;
  color: var(--ink);
  font-size: clamp(1.15rem, 2vw, 1.42rem);
  line-height: 1.45;
}

.section-block {
  padding: 3.8rem 0;
  border-bottom: 1px solid var(--line);
}

.section-intro {
  max-width: 720px;
}

.section-intro p:last-child {
  margin: 1rem 0 0;
  color: var(--muted);
  font-size: 1.03rem;
}

.teaching-link-button {
  min-height: 44px;
  padding: 0.72rem 1rem;
  border: 1px solid var(--line);
  border-left: 4px solid var(--waseda-red);
  border-radius: 4px;
  background: var(--surface);
  color: var(--ink);
  font: inherit;
  font-weight: 700;
  cursor: default;
}

.teaching-link-button:disabled {
  opacity: 1;
}

.research-list {
  display: grid;
  gap: 1.1rem;
  margin-top: 2rem;
}

.research-list article {
  padding: 0 0 1.1rem;
  border-bottom: 1px solid var(--line);
}

.research-list article:last-child {
  padding-bottom: 0;
  border-bottom: 0;
}

.research-list p {
  margin: 0.35rem 0 0;
  color: var(--muted);
}

.quiet-actions {
  padding-top: 2rem;
}

.contact-disclosure {
  max-width: 560px;
  color: var(--muted);
}

.contact-disclosure summary {
  display: inline-flex;
  min-height: 40px;
  align-items: center;
  padding: 0.5rem 0.85rem;
  border: 1px solid var(--line);
  border-radius: 4px;
  background: var(--surface);
  color: var(--ink);
  font-weight: 700;
  cursor: pointer;
  list-style: none;
}

.contact-disclosure summary::-webkit-details-marker {
  display: none;
}

.contact-disclosure summary::after {
  content: "+";
  margin-left: 0.65rem;
  color: var(--waseda-red);
}

.contact-disclosure[open] summary::after {
  content: "-";
}

address {
  font-style: normal;
}

.contact-disclosure address {
  margin-top: 1rem;
}

.contact-disclosure span {
  display: block;
}

.contact-disclosure p {
  margin: 1rem 0 0;
}

@media (max-width: 640px) {
  .page-shell {
    padding: 3rem 0 2rem;
  }

  .hero {
    padding-bottom: 3rem;
  }

  .section-block {
    padding: 3rem 0;
  }

  .top-action {
    justify-content: flex-start;
    margin-bottom: 2.4rem;
  }

  .teaching-link-button {
    width: 100%;
  }
}