header nav { position: relative; }
.menu-toggle {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 5px;
  width: 48px;
  height: 48px;
  padding: 0;
  color: #f0f4fa;
  background: transparent;
  border: 1px solid #23adf2;
  border-radius: 12px;
  cursor: pointer;
}
.menu-toggle span { display: block; width: 24px; height: 2px; background: currentColor; border-radius: 2px; }
.menu-toggle:hover, .menu-toggle[aria-expanded="true"] { background: #102638; }
.site-menu {
  position: absolute;
  z-index: 20;
  right: 0;
  top: calc(100% - 1px);
  display: grid;
  gap: 2px;
  width: min(300px, 100%);
  max-height: calc(100dvh - 150px);
  overflow-y: auto;
  margin: 0;
  padding: 10px;
  list-style: none;
  background: #0c141e;
  border: 1px solid #2c4359;
  border-radius: 14px;
  box-shadow: 0 16px 38px rgb(0 0 0 / 40%);
}
.site-menu[hidden] { display: none; }
.site-menu a {
  display: block;
  padding: 12px 15px;
  color: #f0f4fa;
  border-radius: 8px;
  font-size: 1rem;
  line-height: 1.5;
}
.site-menu a:hover, .site-menu a:focus-visible { color: #65c7ff; background: #142b3d; }
@media (max-width: 540px) {
  .site-menu { max-height: calc(100dvh - 122px); }
}