:root {
  --brand-blue: #015283;
  --brand-yellow: #ffbd59;
  --brand-red: #ff5959;
  --surface: #f5f5f5;
  --ink: #333333;
  --white: #ffffff;
  --font-gothic: "Yu Gothic", "YuGothic", "Yu Gothic Medium",
    "Hiragino Kaku Gothic ProN", "Hiragino Sans", "Noto Sans JP", system-ui,
    sans-serif;
  --font-heiti: "STHeiti Light", "STHeiti", "Hiragino Kaku Gothic ProN",
    "Hiragino Sans", "Noto Sans JP", system-ui, sans-serif;
}

.site-header {
  overflow: visible;
}

.site-header__home {
  display: block;
  flex: 0 0 auto;
}

.site-header__nav {
  gap: clamp(0.05rem, 0.35vw, 0.35rem);
}

body:not(.subpage) .site-header__nav {
  color: var(--white);
}

body:not(.subpage).is-after-firstview .site-header__nav {
  color: var(--brand-blue);
}

body:not(.subpage).is-dark-surface .site-header__nav {
  color: var(--white);
}

.site-header__nav > a,
.site-header__nav > button,
.site-header__nav .nav-group__trigger {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 3rem;
  padding: 0.4rem clamp(0.65rem, 1vw, 1.1rem);
  border: 0;
  border-radius: 1rem;
  background: transparent;
  color: inherit;
  font: inherit;
  font-size: clamp(0.7rem, 0.82vw, 0.9rem);
  font-weight: 700;
  letter-spacing: 0.07em;
  line-height: 1;
  text-decoration: none;
  white-space: nowrap;
  cursor: pointer;
  transition:
    color 300ms ease,
    background-color 220ms ease,
    opacity 220ms ease;
}

.site-header__nav > button[disabled],
.nav-dropdown button[disabled] {
  cursor: default;
  opacity: 0.52;
}

.site-header__nav > a:hover,
.site-header__nav > a:focus-visible,
.site-header__nav > button:not([disabled]):hover,
.site-header__nav > button:not([disabled]):focus-visible,
.nav-group__trigger:hover,
.nav-group__trigger:focus-visible,
.nav-group:focus-within .nav-group__trigger {
  outline: none;
  background: rgba(255, 255, 255, 0.13);
}

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

.nav-group__trigger::after {
  width: 0.35rem;
  height: 0.35rem;
  margin: -0.2rem 0 0 0.55rem;
  border-right: 1px solid currentColor;
  border-bottom: 1px solid currentColor;
  content: "";
  transform: rotate(45deg);
  transition: transform 240ms ease;
}

.nav-dropdown {
  position: absolute;
  top: calc(100% + 0.55rem);
  left: 50%;
  width: max-content;
  min-width: 13.25rem;
  padding: 0.55rem;
  border: 1px solid rgba(1, 82, 131, 0.1);
  border-radius: 1.15rem;
  background: rgba(245, 245, 245, 0.96);
  box-shadow: 0 1.1rem 3.5rem rgba(0, 31, 49, 0.13);
  opacity: 0;
  visibility: hidden;
  transform: translate(-50%, -0.65rem) scale(0.97);
  transform-origin: center top;
  transition:
    opacity 220ms ease,
    visibility 220ms ease,
    transform 280ms cubic-bezier(0.22, 1, 0.36, 1);
}

.nav-dropdown::before {
  position: absolute;
  right: 0;
  bottom: 100%;
  left: 0;
  height: 0.7rem;
  content: "";
}

.nav-dropdown a,
.nav-dropdown button {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1.5rem;
  width: 100%;
  min-height: 2.85rem;
  padding: 0.65rem 0.85rem;
  border: 0;
  border-radius: 0.8rem;
  background: transparent;
  color: var(--ink);
  font: inherit;
  font-size: 0.78rem;
  font-weight: 700;
  letter-spacing: 0.065em;
  text-align: left;
  text-decoration: none;
  white-space: nowrap;
  transition:
    background-color 180ms ease,
    color 180ms ease,
    transform 180ms ease;
}

.nav-dropdown a::after {
  color: var(--brand-blue);
  content: "↗";
  font-size: 0.78rem;
  font-weight: 400;
}

.nav-dropdown a:hover,
.nav-dropdown a:focus-visible {
  outline: none;
  background: var(--white);
  color: var(--brand-blue);
  transform: translateX(0.12rem);
}

.nav-dropdown a[aria-current="page"] {
  background: var(--white);
  color: var(--brand-blue);
}

.nav-dropdown button span:last-child {
  color: #888;
  font-family: var(--font-heiti);
  font-size: 0.58rem;
  font-weight: 300;
  letter-spacing: 0.08em;
}

@media (hover: hover) and (pointer: fine) {
  .nav-group:hover .nav-dropdown,
  .nav-group:focus-within .nav-dropdown,
  .nav-group.is-open .nav-dropdown {
    opacity: 1;
    visibility: visible;
    transform: translate(-50%, 0) scale(1);
  }

  .nav-group:hover .nav-group__trigger::after,
  .nav-group:focus-within .nav-group__trigger::after,
  .nav-group.is-open .nav-group__trigger::after {
    transform: translateY(0.18rem) rotate(225deg);
  }
}

.site-header__nav .site-header__teacher {
  min-height: 2.45rem;
  margin-left: clamp(0.1rem, 0.35vw, 0.4rem);
  padding-inline: clamp(0.8rem, 1.15vw, 1.2rem);
  border: 1px solid var(--brand-blue);
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.8);
  color: var(--brand-blue);
  text-shadow: none;
}

.site-header__nav .site-header__teacher:hover,
.site-header__nav .site-header__teacher:focus-visible {
  border-color: var(--brand-blue);
  background: var(--brand-blue);
  color: var(--white);
}

.site-header__menu-toggle {
  display: none;
}

.page-transition {
  position: fixed;
  z-index: 500;
  inset: 0;
  display: grid;
  place-items: center;
  overflow: hidden;
  background: var(--surface);
  opacity: 0;
  visibility: hidden;
  pointer-events: none;
  transition:
    opacity 480ms cubic-bezier(0.65, 0, 0.35, 1),
    visibility 480ms;
}

.page-transition__title {
  display: none;
  margin: 0;
  color: var(--ink);
  font-family: var(--font-heiti);
  font-size: clamp(1.4rem, 2.2vw, 2.4rem);
  font-weight: 300;
  letter-spacing: 0.18em;
  line-height: normal;
  opacity: 0;
  filter: blur(16px);
  transform: translateY(0.4em) scale(0.96);
  white-space: nowrap;
}

.page-transition__title[lang="ja"] {
  font-family: var(--font-gothic);
  font-weight: 500;
}

.page-transition.is-entering,
.page-transition.is-leaving {
  opacity: 1;
  visibility: visible;
  pointer-events: auto;
}

.page-transition.is-entering .page-transition__title,
.page-transition.is-leaving .page-transition__title {
  animation: page-title-reveal 900ms cubic-bezier(0.22, 1, 0.36, 1) forwards;
  animation-delay: 160ms;
}

.page-transition.is-exiting {
  opacity: 0;
  visibility: hidden;
  pointer-events: none;
}

.page-transition.is-exiting .page-transition__title {
  animation: page-title-exit 380ms ease forwards;
}

body.is-page-transitioning {
  overflow: hidden;
}

@keyframes page-title-reveal {
  to {
    opacity: 1;
    filter: blur(0);
    transform: translateY(0) scale(1);
  }
}

@keyframes page-title-exit {
  from {
    opacity: 1;
    filter: blur(0);
    transform: translateY(0) scale(1);
  }
  to {
    opacity: 0;
    filter: blur(14px);
    transform: translateY(-0.3em) scale(0.98);
  }
}

@media (width < 1200px) {
  .site-header__menu-toggle {
    position: relative;
    z-index: 2;
    display: grid;
    place-items: center;
    width: 2.8rem;
    height: 2.8rem;
    padding: 0;
    border: 0;
    border-radius: 50%;
    background: rgba(255, 255, 255, 0.14);
    color: inherit;
  }

  .site-header__menu-toggle span,
  .site-header__menu-toggle::before,
  .site-header__menu-toggle::after {
    position: absolute;
    top: 50%;
    left: 50%;
    width: 1.1rem;
    height: 1px;
    background: currentColor;
    content: "";
    transition: transform 220ms ease, opacity 220ms ease;
  }

  .site-header__menu-toggle span {
    transform: translate(-50%, -50%);
  }

  .site-header__menu-toggle::before {
    transform: translate(-50%, calc(-50% - 0.32rem));
  }

  .site-header__menu-toggle::after {
    transform: translate(-50%, calc(-50% + 0.32rem));
  }

  .site-header__menu-toggle[aria-expanded="true"] span {
    opacity: 0;
  }

  .site-header__menu-toggle[aria-expanded="true"]::before {
    transform: translate(-50%, -50%) rotate(45deg);
  }

  .site-header__menu-toggle[aria-expanded="true"]::after {
    transform: translate(-50%, -50%) rotate(-45deg);
  }

  .site-header__nav {
    position: absolute;
    top: calc(100% + 0.45rem);
    right: 0.6rem;
    display: flex;
    align-items: stretch;
    flex-direction: column;
    width: min(21rem, calc(100vw - 1.2rem));
    max-height: calc(100svh - 5.25rem);
    padding: 0.65rem;
    overflow: auto;
    border: 1px solid rgba(1, 82, 131, 0.1);
    border-radius: 1.2rem;
    background: rgba(245, 245, 245, 0.98);
    box-shadow: 0 1rem 3rem rgba(0, 31, 49, 0.14);
    color: var(--ink) !important;
    opacity: 0;
    visibility: hidden;
    transform: translateY(-0.5rem) scale(0.98);
    transform-origin: right top;
    transition:
      opacity 180ms ease,
      visibility 180ms ease,
      transform 240ms cubic-bezier(0.22, 1, 0.36, 1);
  }

  .site-header__nav.is-open {
    opacity: 1;
    visibility: visible;
    transform: translateY(0) scale(1);
  }

  .site-header__nav > a,
  .site-header__nav > button,
  .site-header__nav .nav-group__trigger {
    justify-content: space-between;
    width: 100%;
    min-height: 2.8rem;
    padding-inline: 0.85rem;
    color: var(--ink) !important;
    font-size: 0.75rem;
    text-align: left;
    text-shadow: none !important;
  }

  .nav-group {
    display: block;
  }

  .nav-dropdown {
    position: static;
    display: grid;
    width: 100%;
    min-width: 0;
    max-height: 0;
    padding: 0 0.35rem;
    overflow: hidden;
    border: 0;
    border-radius: 0.7rem;
    background: rgba(1, 82, 131, 0.035);
    box-shadow: none;
    opacity: 1;
    visibility: visible;
    transform: none;
    transition:
      max-height 300ms ease,
      padding 300ms ease;
  }

  .nav-group.is-open .nav-dropdown {
    max-height: 14rem;
    padding-block: 0.35rem;
    opacity: 1;
    visibility: visible;
    transform: none;
  }

  .nav-group.is-open .nav-group__trigger::after {
    transform: translateY(0.18rem) rotate(225deg);
  }

  .site-header__nav .site-header__teacher {
    justify-content: center;
    width: auto;
    margin: 0.35rem 0 0;
    color: var(--brand-blue) !important;
  }
}

@media (width < 768px) {
  .site-header__menu-toggle {
    width: 2.5rem;
    height: 2.5rem;
  }
}

@media (width < 768px) {
  .page-transition__title {
    font-size: clamp(1.25rem, 5.7vw, 1.8rem);
    letter-spacing: 0.14em;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-transition,
  .page-transition__title,
  .nav-dropdown,
  .site-header__nav {
    animation-duration: 1ms !important;
    animation-delay: 0ms !important;
    transition-duration: 1ms !important;
  }
}