:root {
  --forge-ink: #09224f;
  --forge-muted: #50627e;
  --forge-line: #cddff4;
  --forge-white: #fff;
  --forge-orange: #ff6200;
  --forge-orange-ink: #a24600;
  --forge-shadow: 0 18px 44px rgb(10 48 99 / 13%);
  --forge-shell: 1180px;
}

* { box-sizing: border-box; }

.skip-link {
  position: fixed;
  z-index: 100;
  top: 12px;
  left: 12px;
  padding: 10px 16px;
  border-radius: 8px;
  color: var(--forge-white);
  background: var(--forge-ink);
  transform: translateY(-160%);
}

.skip-link:focus { transform: translateY(0); }

.page-shell {
  width: min(calc(100% - 48px), var(--forge-shell));
  margin-inline: auto;
}

.site-header {
  position: sticky;
  z-index: 50;
  top: 0;
  border-bottom: 2px solid rgb(205 223 244 / 88%);
  background: rgb(255 255 255 / 94%);
  backdrop-filter: blur(14px);
  color: var(--forge-ink);
  font-family: Inter, "Yu Gothic UI", "Hiragino Sans", Meiryo, system-ui, sans-serif;
  line-height: 1.7;
}

.site-header__inner {
  display: grid;
  grid-template-columns: auto 1fr auto;
  align-items: center;
  min-height: 80px;
  gap: 30px;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 11px;
  width: max-content;
  color: var(--forge-ink);
  font-weight: 760;
  letter-spacing: -0.02em;
  text-decoration: none;
}

.brand-mark {
  display: grid;
  place-items: center;
  width: 40px;
  height: 40px;
  border: 2px solid var(--forge-ink);
  border-radius: 13px;
  color: var(--forge-ink);
  background: linear-gradient(145deg, #ff9d16, var(--forge-orange));
  box-shadow: 4px 4px 0 #a9d3ff;
  transform: rotate(-3deg);
}

.brand-mark span {
  font-size: 19px;
  font-weight: 900;
  transform: rotate(3deg);
}

.brand-name { font-size: 1.1rem; font-weight: 900; }
.brand-name strong { color: var(--forge-orange-ink); }

.desktop-nav {
  display: flex;
  justify-content: flex-end;
  align-items: center;
  gap: clamp(18px, 3vw, 38px);
}

.desktop-nav a {
  position: relative;
  padding: 25px 0 22px;
  color: #30384a;
  font-size: .94rem;
  font-weight: 650;
  text-decoration: none;
}

.desktop-nav a::after {
  position: absolute;
  right: 0;
  bottom: 15px;
  left: 0;
  height: 4px;
  border-radius: 999px;
  background: var(--forge-orange);
  content: "";
  opacity: 0;
  transform: scaleX(.4);
  transition: 160ms ease;
}

.desktop-nav a:hover::after,
.desktop-nav a[aria-current="page"]::after { opacity: 1; transform: scaleX(1); }

.site-header__actions { display: flex; align-items: center; gap: 12px; }

.language-switcher {
  display: inline-flex;
  padding: 3px;
  border: 2px solid #b9d6f5;
  border-radius: 999px;
  background: #f4f9ff;
}

.language-switcher a,
.language-switcher span {
  display: grid;
  place-items: center;
  min-width: 34px;
  min-height: 30px;
  padding: 2px 7px;
  border-radius: 999px;
  color: #41516a;
  font-size: .75rem;
  font-weight: 850;
  line-height: 1;
  text-decoration: none;
}

.language-switcher a[aria-current="page"] {
  color: var(--forge-white);
  background: var(--forge-ink);
  box-shadow: 0 2px 0 #ffb34e;
}

.language-switcher span[aria-disabled="true"],
.mobile-language-switcher span[aria-disabled="true"] { opacity: .42; }

.github-button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 44px;
  padding: 8px 18px;
  gap: 8px;
  border: 2px solid var(--forge-ink);
  border-radius: 999px;
  color: var(--forge-ink);
  background: var(--forge-white);
  box-shadow: 0 4px 0 #bdd9f7;
  font-weight: 750;
  text-decoration: none;
}

.github-button:hover {
  color: var(--forge-white);
  background: var(--forge-ink);
  box-shadow: 0 5px 0 #ffbb61;
  transform: translateY(-1px);
}

.github-dot { font-size: .78rem; }
.mobile-nav { display: none; justify-self: end; }

.mobile-nav summary {
  min-height: 44px;
  padding: 9px 14px;
  border: 2px solid var(--forge-ink);
  border-radius: 999px;
  background: var(--forge-white);
  box-shadow: 0 3px 0 #bdd9f7;
  cursor: pointer;
  font-weight: 700;
  list-style: none;
}

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

.mobile-nav nav {
  position: absolute;
  top: calc(100% + 1px);
  right: 0;
  left: 0;
  display: grid;
  padding: 14px 24px 20px;
  border-bottom: 2px solid var(--forge-line);
  background: #fafdff;
  box-shadow: var(--forge-shadow);
}

.mobile-nav nav a {
  min-height: 44px;
  padding: 9px 8px;
  border-bottom: 1px solid #eff1f4;
  color: var(--forge-ink);
  font-weight: 650;
  text-decoration: none;
}

.mobile-nav nav a[aria-current="page"] { color: var(--forge-orange-ink); }

.mobile-language-switcher {
  display: grid;
  grid-template-columns: 1fr 1fr;
  margin-top: 12px;
  padding: 5px;
  gap: 6px;
  border: 2px solid #c7ddf5;
  border-radius: 14px;
  background: var(--forge-white);
}

.mobile-nav nav .mobile-language-switcher a,
.mobile-language-switcher span {
  display: grid;
  place-items: center;
  min-height: 38px;
  padding: 6px 10px;
  border: 0;
  border-radius: 10px;
  color: #41516a;
  font-size: .86rem;
  text-decoration: none;
}

.mobile-nav nav .mobile-language-switcher a[aria-current="page"] {
  color: var(--forge-white);
  background: var(--forge-ink);
}

.site-footer {
  margin-top: 48px;
  border-top: 2px solid var(--forge-line);
  color: var(--forge-ink);
  background: radial-gradient(circle at 13% 45%, rgb(255 153 19 / 10%), transparent 12rem), radial-gradient(circle at 88% 48%, rgb(42 133 231 / 10%), transparent 12rem), rgb(248 252 255 / 94%);
  font-family: Inter, "Yu Gothic UI", "Hiragino Sans", Meiryo, system-ui, sans-serif;
  line-height: 1.7;
}

.site-footer__inner {
  display: grid;
  grid-template-columns: auto 1fr auto;
  align-items: center;
  min-height: 112px;
  gap: 30px;
}

.site-footer__copy { text-align: center; }
.site-footer p { margin: 0; color: var(--forge-muted); text-align: center; }

.site-footer__copy small {
  display: block;
  margin-top: 6px;
  color: #58708e;
  font-size: .72rem;
  font-weight: 850;
  letter-spacing: .07em;
}

.site-footer nav {
  display: flex;
  justify-content: flex-end;
  flex-wrap: wrap;
  max-width: 510px;
  gap: 9px 18px;
}

.site-footer nav a {
  color: var(--forge-muted);
  font-size: .84rem;
  font-weight: 700;
  text-decoration: none;
}

@media (max-width: 1100px) {
  .desktop-nav, .desktop-github, .site-header__actions { display: none; }
  .site-header__inner { grid-template-columns: 1fr auto; }
  .mobile-nav { display: block; }
}

@media (max-width: 980px) {
  .site-footer__inner {
    grid-template-columns: 1fr;
    justify-items: center;
    padding-block: 28px;
    gap: 12px;
  }
  .site-footer nav { justify-content: center; }
}

@media (max-width: 390px) {
  .page-shell { width: min(calc(100% - 24px), var(--forge-shell)); }
  .brand-name { font-size: .9rem; }
  .mobile-nav summary { padding-inline: 11px; font-size: .86rem; }
}

@media (prefers-reduced-motion: reduce) {
  .desktop-nav a::after, .github-button { transition: none; }
}