:root {
  --header-height: 128px;
  --content-width: 1080px;
  --radius: 20px;
  --bg-overlay: rgba(255, 255, 255, 0.2);
  --muted: #444f5e;
  --accent: #0f766e;
  --accent-2: #2563eb;
  --card-bg: rgba(255, 255, 255, 0.78);
  --card-border: rgba(255, 255, 255, 0.64);
  --shadow: 0 14px 32px rgba(15, 23, 42, 0.14);
}

header {
  position: relative;
  min-height: var(--header-height);
  display: grid;
  grid-template-rows: auto auto;
  align-content: center;
  row-gap: 10px;
  padding: 16px 24px 12px;
}

.logo {
  grid-row: 1;
  justify-self: center;
}

.menu-toggle-input {
  position: absolute;
  width: 1px;
  height: 1px;
  opacity: 0;
  pointer-events: none;
}

.header-nav {
  grid-row: 2;
  position: static;
  justify-self: end;
  display: flex;
  align-items: center;
  justify-content: flex-end;
  flex-wrap: wrap;
  gap: 8px;
  max-width: 100%;
}

.header-nav a {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 38px;
  padding: 8px 10px;
  color: #1f2937;
  font-size: 0.9rem;
  font-weight: 700;
  text-decoration: none;
  text-shadow: 0 1px 10px rgba(255, 255, 255, 0.72);
  transition: color 180ms ease, transform 180ms ease;
}

.header-nav a:hover,
.header-nav a:focus-visible {
  color: var(--accent);
  transform: translateY(-1px);
  outline: none;
}

.nav-accordion {
  position: relative;
  display: inline-flex;
  align-items: center;
}

.nav-accordion summary {
  display: inline-flex;
  align-items: center;
  min-height: 38px;
  padding: 8px 10px;
  color: #1f2937;
  font-size: 0.9rem;
  font-weight: 700;
  text-decoration: none;
  text-shadow: 0 1px 10px rgba(255, 255, 255, 0.72);
  cursor: pointer;
  list-style: none;
  transition: color 180ms ease, transform 180ms ease;
}

.nav-accordion summary::-webkit-details-marker {
  display: none;
}

.nav-accordion summary::after {
  content: "▾";
  margin-left: 6px;
  font-size: 1.5em;
  transition: transform 180ms ease;
}

.nav-accordion[open] summary::after {
  transform: rotate(180deg);
}

.nav-accordion summary:hover,
.nav-accordion summary:focus-visible {
  color: #0f766e;
  transform: translateY(-1px);
  outline: none;
}

.nav-accordion-panel {
  position: absolute;
  top: calc(100% + 6px);
  right: 0;
  min-width: 160px;
  padding: 8px 0;
  border-radius: 14px;
  background: rgba(17, 24, 39, 0.88);
  backdrop-filter: blur(12px);
  box-shadow: 0 14px 32px rgba(15, 23, 42, 0.22);
  z-index: 30;
}

.nav-accordion-panel a {
  width: 100%;
  min-height: 38px;
  justify-content: flex-start;
  padding: 8px 14px;
  color: #ffffff;
  text-shadow: none;
}

.nav-accordion-panel a:hover,
.nav-accordion-panel a:focus-visible {
  color: #ffffff;
  background: rgba(255, 255, 255, 0.12);
  transform: none;
}

.hamburger {
  position: absolute;
  right: 24px;
  top: 50%;
  transform: translateY(-50%);
  display: none;
  width: 44px;
  height: 44px;
  align-items: center;
  justify-content: center;
  flex-direction: column;
  gap: 5px;
  border-radius: 999px;
  cursor: pointer;
  background: rgba(17, 24, 39, 0.68);
  backdrop-filter: blur(8px);
}

.hamburger span {
  width: 20px;
  height: 2px;
  border-radius: 999px;
  background: #ffffff;
  transition: transform 180ms ease, opacity 180ms ease;
}

.menu-toggle-input:checked ~ .hamburger span:nth-child(1) {
  transform: translateY(7px) rotate(45deg);
}

.menu-toggle-input:checked ~ .hamburger span:nth-child(2) {
  opacity: 0;
}

.menu-toggle-input:checked ~ .hamburger span:nth-child(3) {
  transform: translateY(-7px) rotate(-45deg);
}

main {
  min-height: calc(100vh - var(--header-height) - var(--footer-height));
  padding: 48px 20px 40px;
}

.page {
  width: min(100%, var(--content-width));
  margin: 0 auto;
}

.breadcrumb {
  margin: 0 0 18px;
  font-size: 0.88rem;
  color: var(--muted);
}

.breadcrumb a {
  text-decoration: none;
}

.breadcrumb a:hover,
.breadcrumb a:focus-visible {
  text-decoration: underline;
}

.hero {
  padding: 40px;
  border: 1px solid var(--card-border);
  border-radius: var(--radius);
  background: var(--card-bg);
  backdrop-filter: blur(14px);
  box-shadow: var(--shadow);
}

.hero-label {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 12px;
  font-size: 0.82rem;
  font-weight: 700;
  letter-spacing: 0.12em;
  color: var(--accent);
  text-transform: uppercase;
}

.hero-label::before {
  content: "";
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
}

h1 {
  margin: 0;
  font-size: clamp(2rem, 5vw, 3.4rem);
  line-height: 1.12;
  letter-spacing: 0.04em;
}

.lead {
  /* max-width: 760px; */
  margin: 20px 0 0;
  font-size: clamp(1rem, 2vw, 1.12rem);
  line-height: 1.9;
  color: var(--muted);
}

.section {
  margin-top: 34px;
  padding: 32px;
  border: 1px solid var(--card-border);
  border-radius: var(--radius);
  background: var(--card-bg);
  backdrop-filter: blur(14px);
  box-shadow: var(--shadow);
}

.section h2 {
  margin: 0 0 18px;
  font-size: clamp(1.35rem, 3vw, 2rem);
  line-height: 1.35;
  letter-spacing: 0.04em;
}

.section p {
  margin: 0;
  line-height: 1.9;
  color: var(--muted);
}

.section figure {
  margin: 24px 0 0;
  overflow: hidden;
}

.section figure img {
  display: block;
  width: 100%;
  max-width: 100%;
  height: auto;
  object-fit: contain;
  border-radius: 16px;
}

.section figcaption {
  margin-top: 10px;
  font-size: 0.88rem;
  line-height: 1.7;
  color: var(--muted);
}

.research-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 20px;
  margin-top: 22px;
}

.research-card {
  padding: 24px;
  border-radius: 18px;
  background: rgba(255, 255, 255, 0.68);
  border: 1px solid rgba(255, 255, 255, 0.7);
  box-shadow: 0 8px 18px rgba(15, 23, 42, 0.08);
}

.research-card h3 {
  margin: 0 0 10px;
  font-size: 1.12rem;
  line-height: 1.45;
  color: #12313f;
}

.research-card p {
  font-size: 0.96rem;
}

.tag-list {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin: 24px 0 0;
  padding: 0;
  list-style: none;
}

.tag-list li {
  padding: 7px 12px;
  border-radius: 999px;
  font-size: 0.86rem;
  font-weight: 700;
  color: #0f3d46;
  background: rgba(236, 253, 245, 0.82);
  border: 1px solid rgba(20, 184, 166, 0.24);
}

.flow-list {
  display: grid;
  gap: 14px;
  margin: 22px 0 0;
  padding: 0;
  list-style: none;
  counter-reset: flow;
}

.flow-list li {
  position: relative;
  padding: 18px 18px 18px 62px;
  border-radius: 16px;
  background: rgba(255, 255, 255, 0.68);
  border: 1px solid rgba(255, 255, 255, 0.7);
  line-height: 1.8;
  color: var(--muted);
}

.flow-list li::before {
  counter-increment: flow;
  content: counter(flow, decimal-leading-zero);
  position: absolute;
  left: 18px;
  top: 18px;
  width: 32px;
  height: 32px;
  display: grid;
  place-items: center;
  border-radius: 50%;
  font-size: 0.78rem;
  font-weight: 800;
  color: #ffffff;
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
}

ul li {
  color: var(--muted);
}

.back-link {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  margin-top: 28px;
  padding: 12px 18px;
  border-radius: 999px;
  color: #ffffff;
  font-weight: 700;
  text-decoration: none;
  background: rgba(17, 24, 39, 0.78);
  box-shadow: 0 10px 20px rgba(15, 23, 42, 0.16);
  transition: transform 180ms ease, box-shadow 180ms ease;
}

.back-link:hover,
.back-link:focus-visible {
  transform: translateY(-2px);
  box-shadow: 0 14px 28px rgba(15, 23, 42, 0.22);
  outline: none;
}

.section-link {
  display: block;
  color: inherit;
  text-decoration: none;
}

.section-link .section {
  cursor: pointer;
}



@media (max-width: 767px) {
  main {
    padding: 28px 16px 34px;
  }

  .hero,
  .section {
    padding: 24px;
  }

  .research-grid {
    grid-template-columns: 1fr;
  }
}

/* 縦長表示：トップページの4リンクをハンバーガーメニューにする */
@media (orientation: portrait) {
  header {
    display: flex;
    align-items: center;
    justify-content: center;
  }

  .hamburger {
    display: inline-flex;
  }

  .header-nav {
    position: absolute;
    bottom: auto;
    top: calc(100% + 8px);
    left: auto;
    right: max(16px, env(safe-area-inset-right));
    width: min(320px, calc(100vw - 32px));
    display: grid;
    grid-template-columns: 1fr;
    gap: 0;
    padding: 12px;
    border-radius: 18px;
    background: rgba(17, 24, 39, 0.88);
    backdrop-filter: blur(12px);
    box-shadow: 0 14px 32px rgba(15, 23, 42, 0.22);
    opacity: 0;
    pointer-events: none;
    transform: translateY(-8px);
    transition: opacity 180ms ease, transform 180ms ease;
    z-index: 20;
  }

  .header-nav a {
    width: 100%;
    min-height: 44px;
    justify-content: flex-start;
    color: #ffffff;
    text-shadow: none;
    border-bottom: 1px solid rgba(255, 255, 255, 0.18);
  }

  .header-nav a:last-child {
    border-bottom: 0;
  }

    .nav-accordion {
    display: block;
    width: 100%;
  }

  .nav-accordion summary {
    width: 100%;
    min-height: 44px;
    justify-content: flex-start;
    color: #ffffff;
    text-shadow: none;
    border-bottom: 1px solid rgba(255, 255, 255, 0.18);
  }

  .nav-accordion-panel {
    position: static;
    min-width: 0;
    padding: 0 0 0 16px;
    border-radius: 0;
    background: transparent;
    box-shadow: none;
    backdrop-filter: none;
  }

  .nav-accordion-panel a {
    min-height: 40px;
    padding: 8px 14px;
    border-bottom: 1px solid rgba(255, 255, 255, 0.12);
  }

  .menu-toggle-input:checked ~ .header-nav {
    opacity: 1;
    pointer-events: auto;
    transform: translateY(0);
  }
}

@media (max-width: 767px) and (orientation: portrait) {
  :root {
    --header-height: 124px;
  }
}

@media (max-width: 950px) and (max-height: 520px) and (orientation: landscape) {
  :root {
    --header-height: 104px;
  }

  header {
    display: grid;
    grid-template-rows: auto auto;
    align-content: center;
    row-gap: 6px;
    padding: 10px 16px 8px;
  }

  main {
    padding: 24px 16px 28px;
  }
}