/* ===== ハンバーガーメニュー / Concept B — In the Background ===== */
/* 編集的デザインに合わせ、枠を持たない素の三本線にしています */

.hamburger {
  display: none;
  position: relative;
  z-index: 1300;
  width: 40px;
  height: 40px;
  padding: 0;
  border: 0;
  background: transparent;
  cursor: pointer;
  margin-left: auto;
  justify-self: end;
  align-items: center;
  justify-content: center;
}

.hamburger:focus-visible { outline: 1px solid var(--accent); outline-offset: 4px; }

.hamburger span {
  position: absolute;
  left: 50%;
  width: 22px;
  height: 1.5px;
  background: var(--ink);
  transform: translateX(-50%);
  transition: transform .4s var(--ease), opacity .2s var(--ease), background .35s var(--ease);
}

.hamburger span:nth-child(1) { top: 13px; }
.hamburger span:nth-child(2) { top: 19px; }
.hamburger span:nth-child(3) { top: 25px; }

.hamburger:hover span { background: var(--accent); }

.hamburger[aria-expanded="true"] span:nth-child(1) {
  transform: translateX(-50%) translateY(6px) rotate(45deg);
  background: var(--accent);
}
.hamburger[aria-expanded="true"] span:nth-child(2) { opacity: 0; }
.hamburger[aria-expanded="true"] span:nth-child(3) {
  transform: translateX(-50%) translateY(-6px) rotate(-45deg);
  background: var(--accent);
}

.mobile-menu {
  position: fixed;
  inset: 0;
  z-index: 1200;
  display: grid;
  align-content: center;
  justify-items: start;
  gap: 20px;
  padding: 0 clamp(24px, 8vw, 72px);
  background: var(--paper);
  transform: translateY(-105%);
  visibility: hidden;
  transition: transform .65s var(--ease), visibility 0s linear .65s;
}

.mobile-menu.is-open {
  transform: none;
  visibility: visible;
  transition: transform .65s var(--ease), visibility 0s;
}

.mobile-menu nav {
  display: grid;
  justify-items: start;
  text-align: left;
  gap: 18px;
}

.mobile-menu a {
  position: relative;
  font-size: clamp(32px, 10vw, 56px);
  line-height: 1.05;
  letter-spacing: -.05em;
  color: var(--ink);
  transition: color .3s var(--ease);
}

.mobile-menu a::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: 2px;
  width: 100%;
  height: 2px;
  background: var(--accent);
  transform: scaleX(0);
  transform-origin: right;
  transition: transform .45s var(--ease);
}

.mobile-menu a:hover { color: var(--accent); }
.mobile-menu a:hover::after { transform: scaleX(1); transform-origin: left; }

.mobile-menu small {
  position: absolute;
  left: clamp(24px, 8vw, 72px);
  bottom: 30px;
  font-size: 10px;
  letter-spacing: .2em;
  text-transform: uppercase;
  color: var(--muted);
}

body.menu-open { overflow: hidden; }

@media (max-width: 980px) {
  .nav { display: none; }
  .hamburger { display: flex; }
  /* 開いている間もブランドと閉じるボタンを前面に保つ */
  header { z-index: 1400; }
}

@media (prefers-reduced-motion: reduce) {
  .mobile-menu, .hamburger span, .mobile-menu a::after { transition-duration: .01ms; }
}