.header {
  position: fixed;
  top: 3rem;
  left: 50%;
  transform: translateX(-50%);
  z-index: 999;
}
.header__inner {
  width: 116rem;
  padding: 1.5rem 3rem;
  background-color: rgba(0, 0, 0, 0.4);
  -webkit-backdrop-filter: blur(3px);
  backdrop-filter: blur(3px);
  border-radius: 8px;
  box-shadow: 0 1.388vw 1.736vw -1.389vw rgba(13, 14, 15, .8);
}
.header__main {
  display: flex;
  justify-content: space-between;
  align-items: center;
}
.header__logo {
  display: block;
  width: 16rem;
}
.header__buttons {
  display: flex;
  align-items: center;
  gap: 3rem;
}
.header__entry {
  display: block;
  color: var(--c-white);
  padding: 0.2rem 0.8rem;
  box-sizing: border-box;

  position: relative;
}
.header__entry::after {
  display: block;
  content: "";
  position: absolute;
  bottom: 0.3rem;
  left: 48%;
  transform: translateX(-50%);
  width: 88%;
  height: 1px;
  background-color: var(--c-white);
}
.header__entry-inner {
  display: flex;
  align-items: center;
  justify-content: flex-start;
  gap: 0.3rem;
  position: relative;
}
.header__button .header__line:nth-child(1) {
  transform-origin: top left;
}
.header__button .header__line:nth-child(3) {
  transform-origin: bottom left;
}
.header__button.is-open {
  opacity: 0.5;
}
.header__button.is-open .header__line:nth-child(1) {
  transform: rotate(36deg);
}
.header__button.is-open .header__line:nth-child(2) {
  transform: scaleX(0);
}
.header__button.is-open .header__line:nth-child(3) {
  transform: rotate(-36deg);
}
.btn__arrow--header {
  position: relative;
  width: 2.4rem;
  height: 2.4rem;
}
.header__lines {
  display: flex;
  flex-direction: column;
  gap: 0.8rem;
}
.header__line {
  width: 3.5rem;
  height: 2px;
  background-color: var(--c-white);
  transition: transform 650ms var(--transition-easeOutExpo);
}
@media (max-width: 767px) {
  .header {
    top: 2rem;
  }
  .header__inner {
    width: 34.5rem;
    padding: 1.4rem 1.5rem;
  }
  .header__logo {
    width: 12rem;
  }
  .header__buttons {
    gap: 1rem;
  }
  .header__entry {
    padding: 0.2rem 0.8rem;
  }
  .header__button.is-open .header__line:nth-child(1) {
    transform: rotate(36deg);
  }
  .header__button.is-open .header__line:nth-child(3) {
    transform: rotate(-36deg);
  }
  .btn__arrow--header {
    width: 2rem;
    height: 2rem;
  }
  .header__lines {
    gap: 0.6rem;
  }
  .header__line {
    width: 2.8rem;
  }
}

@media (min-width: 768px) {
  .header__entry:hover {
    opacity: 0.6;
  }
  .btn__hover:hover .btn__arrow-img {
    transform: scale(0);
  }
  .btn__hover:hover .btn__arrow-img--hover {
    transform: scale(1);
  }
  .header__button:hover .header__line:nth-child(2) {
    transform: scaleX(0);
  }
  .header__menu-link:hover {
    color: var(--c-black);
  }
  .header__menu-link:hover::after {
    transform-origin: top;
    transform: scaleY(1);
  }
}

.menu {
  padding: 14rem 8rem 5rem;
  position: fixed;
  top: 2rem;
  left: 50%;
  width: 118rem;
  height: auto;
  background-color: rgba(0, 0, 0, 0.7);
  -webkit-backdrop-filter: blur(5px);
  backdrop-filter: blur(3px);
  border-radius: 8px;
  box-shadow: 0 1.388vw 1.736vw -1.389vw rgba(13, 14, 15, .8);
  transform: translateX(-50%);
  z-index: 900;
  -webkit-clip-path: inset(0 0 100% 0);
  clip-path: inset(0 0 100% 0);
  opacity: 0;
  transition: all 950ms var(--transition-easeOutExpo), opacity 1200ms var(--transition-easeOutExpo);
}
.menu.is-open {
  opacity: 1;
  -webkit-clip-path: inset(0 0 0 0);
  clip-path: inset(0 0 0 0);
}
.menu__main {
  display: grid;
  justify-content: space-between;
  grid-template-columns: repeat(3, max-content);
  row-gap: 3rem;
}
.menu__main-link {
  font-size: 1.4rem;
  color: var(--c-gray);
  display: block;
  margin-bottom: 2rem;
}
.menu__main-link:last-child {
  margin-bottom: 0;
}
.menu__main-link:first-child {
  font-size: 1.6rem;
  font-weight: 700;
  color: var(--c-white);
}
.menu__bottom {
  display: flex;
  justify-content: flex-end;
  margin-top: 3rem;
  /* align-items: flex-end; */
}
.menu__bottom-links {
  display: flex;
  align-items: center;
  gap: 1rem;
  color: var(--c-gray);
}
.menu__bottom-link {
  font-size: 1.4rem;
  color: var(--c-gray);
  display: inline-block;
  position: relative;
}
@media (max-width: 767px) {
  .menu {
    padding: 10rem 2rem 8rem;
    top: 1rem;
    width: 36.5rem;
    border-radius: 8px;
    height: 95vh;     /* 古いブラウザ用 */
    height: 95svh;    /* iOS 15+ 一部 */
    height: 95dvh;    /* iOS 16.4+ 推奨：見えている高さに追従 */
    overflow-y: scroll;
  }
  .menu__main {
    grid-template-columns: 1fr;
  }
  .menu__bottom {
    flex-direction: column-reverse;
    align-items: flex-start;
    gap: 2rem;
  }
}
@media (min-width: 768px) {
  .menu__main-link:hover {
    opacity: 1;
    text-decoration: underline;
    color: var(--c-white);
  }
  .menu__bottom-link:hover {
    opacity: 1;
    text-decoration: underline;
    color: var(--c-white);
  }
}

.scroll-top {
  position: fixed;
  bottom: 3rem;
  /* 右からの距離を「最小3rem、最大でコンテナ右端と揃う位置」にする */
  inset-inline-end: max(3rem, calc((100vw - var(--max-width)) / 2 - 1rem));
  z-index: 800;

  opacity: 0;
  pointer-events: none;
  transform: translateY(2px);
  transition:
    opacity 650ms var(--transition-easeOutExpo),
    transform 650ms var(--transition-easeOutExpo);
}
.scroll-top.is-visible {
  opacity: 1;
  pointer-events: auto;
  transform: translateY(0);
}
.scroll-top__link {
  display: block;
  width: 6rem;
  height: 6rem;
  border-radius: 50%;
  border: 1px solid var(--c-white);
  background-color: rgba(0, 0, 0, 0.4);
  -webkit-backdrop-filter: blur(3px);
  backdrop-filter: blur(3px);
  box-shadow: 0 1.388vw 1.736vw -1.389vw rgba(13, 14, 15, .8);
  display: flex;
  align-items: center;
  justify-content: center;
  position: relative;
  isolation: isolate;
}
.scroll-top__link::before {
  content: "";
  position: absolute;
  inset: 0;
  transform: scale(0);
  background-color: rgba(255, 255, 255, 1);
  border-radius: 50%;
  transition: transform 650ms var(--transition-easeOutExpo);
}
.scroll-top__img {
  display: block;
  position: relative;
  z-index: 1;
  mix-blend-mode: difference;
  width: 3rem;
  height: 3rem;
  transform: translateY(0);
  transition: transform 650ms 150ms var(--transition-easeOutExpo);
}

@media (max-width: 767px) {
  .scroll-top__link {
    width: 4rem;
    height: 4rem;
  }
  .scroll-top__img {
    width: 2rem;
    height: 2rem;
  }
  .scroll-top {
    inset-inline-end: 1.5rem;
    bottom: 2rem; /* 好みで調整 */
  }
}

@media (min-width: 768px) {
  .scroll-top__link:hover .scroll-top__img {
    transform: translateY(-3px);
  }
  .scroll-top__link:hover::before {
    transition: transform 350ms var(--transition-easeOutExpo);
    transform: scale(1);
  }
}