:root {
  --sea-deep: #0b3d59;
  --sea-mid: #12608c;
  --sea-light: #e8f3f8;
  --accent: #ff8c42;
  --text-main: #1f2d33;
  --text-sub: #4d5f68;
  --card-bg: #ffffff;
  --border-soft: #d8e6ec;
}

* {
  box-sizing: border-box;
}

html {
  -webkit-text-size-adjust: 100%;
}

body {
  margin: 0;
  padding: 0;
  font-family: "Hiragino Kaku Gothic ProN", "Hiragino Sans", "Yu Gothic", Meiryo, sans-serif;
  background: linear-gradient(180deg, var(--sea-light) 0%, #ffffff 320px);
  color: var(--text-main);
  line-height: 1.8;
}

.page {
  max-width: 720px;
  margin: 0 auto;
  padding: 24px 16px 48px;
}

header.hero {
  text-align: center;
  padding: 16px 0 8px;
}

header.hero img.title-logo {
  max-width: 260px;
  width: 70%;
  height: auto;
}

.site-title {
  margin: 0;
  font-size: 1rem;
  font-weight: normal;
  line-height: normal;
}

.tagline {
  margin: 12px 0 0;
  font-size: 0.85rem;
  color: var(--text-sub);
}

.update-badge {
  display: inline-block;
  margin-top: 16px;
  padding: 6px 18px;
  background: var(--accent);
  color: #fff;
  font-size: 0.85rem;
  font-weight: bold;
  border-radius: 999px;
  letter-spacing: 0.02em;
  box-shadow: 0 2px 6px rgba(255, 140, 66, 0.35);
}

.intro {
  background: var(--card-bg);
  border: 1px solid var(--border-soft);
  border-radius: 16px;
  padding: 20px 22px;
  margin-top: 24px;
  font-size: 0.95rem;
  color: var(--text-sub);
  box-shadow: 0 4px 14px rgba(11, 61, 89, 0.06);
}

.intro p {
  margin: 0 0 10px;
}

.intro p:last-child {
  margin-bottom: 0;
}

nav.board-list {
  margin-top: 32px;
}

nav.board-list h2 {
  font-size: 1rem;
  color: var(--sea-deep);
  margin: 0 0 14px;
  border-left: 4px solid var(--accent);
  padding-left: 10px;
}

.board-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 12px;
}

.board-card {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  background: var(--card-bg);
  border: 1px solid var(--border-soft);
  border-radius: 14px;
  padding: 16px 20px;
  text-decoration: none;
  color: var(--text-main);
  transition: transform 0.15s ease, box-shadow 0.15s ease, background 0.15s ease;
  box-shadow: 0 2px 8px rgba(11, 61, 89, 0.05);
}

.board-card:hover,
.board-card:focus-visible {
  background: var(--sea-light);
  box-shadow: 0 6px 16px rgba(11, 61, 89, 0.12);
  transform: translateY(-2px);
}

.board-card .label {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 1rem;
  font-weight: bold;
}

.board-card .emoji {
  font-size: 1.3rem;
}

.board-card .arrow {
  color: var(--sea-mid);
  font-size: 1.1rem;
}

.board-card.readonly {
  opacity: 0.85;
}

.board-card .sub {
  display: block;
  font-weight: normal;
  font-size: 0.75rem;
  color: var(--text-sub);
  margin-top: 2px;
}

.board-card.external {
  border-color: #ffd6cf;
}

.board-card.external .arrow {
  color: #ff5a3c;
}

.board-card.external:hover,
.board-card.external:focus-visible {
  background: #fff3f0;
}

footer {
  margin-top: 40px;
  text-align: center;
  padding-top: 24px;
  border-top: 1px solid var(--border-soft);
  font-size: 0.85rem;
  color: var(--text-sub);
}

footer .operator-label {
  display: block;
  margin-bottom: 6px;
}

footer a {
  color: var(--sea-mid);
  text-decoration: none;
  font-weight: bold;
}

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

/* タブレット以上 */
@media (min-width: 600px) {
  .page {
    padding: 40px 24px 64px;
  }

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

  .intro {
    padding: 24px 32px;
    font-size: 1rem;
  }
}

/* PC */
@media (min-width: 900px) {
  .page {
    max-width: 860px;
  }

  header.hero img.title-logo {
    max-width: 320px;
  }

  .board-card {
    padding: 20px 24px;
  }
}