.mobile-menu-btn { display: none; }
.mobile-nav { display: none; }
@media (max-width: 860px) {
  .mobile-menu-btn {
    display: inline-flex;
    align-items: center; justify-content: center;
    width: 44px; height: 44px;
    border: 0; background: transparent;
    color: var(--ink);
    position: fixed;
    top: max(10px, env(safe-area-inset-top));
    right: max(12px, env(safe-area-inset-right));
    z-index: 9999;
    padding: 0;
    -webkit-tap-highlight-color: transparent;
  }
  body.menu-open .mobile-menu-btn { color: var(--ink); }
  .mobile-menu-btn span,
  .mobile-menu-btn span::before,
  .mobile-menu-btn span::after {
    display: block;
    width: 22px; height: 2px;
    background: currentColor;
    transition: transform .35s cubic-bezier(.7,0,.2,1), opacity .2s ease;
  }
  .mobile-menu-btn span { position: relative; }
  .mobile-menu-btn span::before,
  .mobile-menu-btn span::after { content: ""; position: absolute; left: 0; }
  .mobile-menu-btn span::before { top: -7px; }
  .mobile-menu-btn span::after  { top:  7px; }
  body.menu-open .mobile-menu-btn span { background: transparent; }
  body.menu-open .mobile-menu-btn span::before { transform: translateY(7px) rotate(45deg); }
  body.menu-open .mobile-menu-btn span::after  { transform: translateY(-7px) rotate(-45deg); }

  .mobile-nav {
    display: flex;
    position: fixed;
    top: 0; left: 0; right: 0; bottom: 0;
    width: 100vw;
    height: 100vh;
    height: 100dvh;
    max-width: 100vw;
    max-height: 100vh;
    max-height: 100dvh;
    background: #fff;
    z-index: 9990;
    padding: 96px 28px max(40px, env(safe-area-inset-bottom)) 28px;
    flex-direction: column;
    gap: 0;
    overflow-y: auto;
    overscroll-behavior: contain;
    transform: translateY(-100%);
    transition: transform .55s cubic-bezier(.7,0,.2,1);
  }
  body.menu-open .mobile-nav { transform: translateY(0); }
  body.menu-open { overflow: hidden; }
  .mobile-nav a {
    font-family: var(--font-display);
    font-weight: 800;
    font-size: clamp(36px, 10vw, 52px);
    letter-spacing: 0.02em;
    color: var(--ink);
    padding: 20px 4px;
    border-bottom: 1px solid var(--line);
    display: block;
    line-height: 1.05;
    opacity: 0;
    transform: translateY(24px);
    transition: opacity .55s ease, transform .55s cubic-bezier(.2,.7,.2,1);
  }
  body.menu-open .mobile-nav a { opacity: 1; transform: none; }
  body.menu-open .mobile-nav > a:nth-child(1) { transition-delay: 0.15s; }
  body.menu-open .mobile-nav > a:nth-child(2) { transition-delay: 0.22s; }
  body.menu-open .mobile-nav > a:nth-child(3) { transition-delay: 0.29s; }
  body.menu-open .mobile-nav > a:nth-child(4) { transition-delay: 0.36s; }
  .mobile-nav a.btn {
    margin-top: 32px;
    background: var(--blue);
    color: #fff;
    border: 0;
    border-radius: 999px;
    font-family: var(--font-jp);
    font-size: 16px;
    padding: 22px 28px;
    text-align: center;
    letter-spacing: 0.04em;
    border-bottom: 0;
    line-height: 1.4;
    box-shadow: 0 10px 28px -10px rgba(31,31,232,.55);
  }
  .mobile-nav-foot {
    margin-top: auto;
    padding-top: 36px;
    display: flex;
    gap: 10px;
    align-items: center;
    justify-content: center;
    flex-wrap: wrap;
    color: var(--muted);
    font-family: var(--font-display);
    font-size: 11px;
    letter-spacing: .18em;
    opacity: 0;
    transition: opacity .55s ease .5s;
  }
  body.menu-open .mobile-nav-foot { opacity: 1; }
  .mobile-close-btn {
    position: absolute;
    top: max(18px, env(safe-area-inset-top));
    right: max(20px, env(safe-area-inset-right));
    display: inline-flex;
    align-items: center;
    gap: 10px;
    background: transparent;
    border: 0;
    padding: 10px 12px;
    color: var(--ink);
    font-family: var(--font-display);
    font-weight: 800;
    font-size: 12px;
    letter-spacing: 0.22em;
    cursor: pointer;
    -webkit-tap-highlight-color: transparent;
    z-index: 2;
    opacity: 0;
    transform: translateY(-8px);
    transition: opacity .35s ease, transform .35s cubic-bezier(.2,.7,.2,1);
  }
  .mobile-close-btn span { display: none; }
  .mobile-close-btn svg { display: block; }
  body.menu-open .mobile-close-btn { opacity: 1; transform: translateY(0); transition-delay: .1s; }
  body.menu-open .mobile-menu-btn { display: none; }
}