#theme-toggle-btn {
  position: fixed;
  top: max(14px, env(safe-area-inset-top, 0px));
  right: max(14px, env(safe-area-inset-right, 0px));
  z-index: 9999;
  box-sizing: border-box;
  width: 42px;
  height: 42px;
  padding: 0;
  margin: 0;
  border: 0.75px solid rgba(0, 0, 0, 0.12);
  border-radius: 8px;
  background-color: rgba(255, 255, 255, 0.85);
  color: #043361;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.15rem;
  line-height: 1;
  transition: background-color 0.15s ease, border-color 0.15s ease, color 0.15s ease;
  -webkit-tap-highlight-color: transparent;
}

#theme-toggle-btn:hover {
  background-color: #c2efff;
  border-color: rgba(0, 0, 0, 0.18);
}

#theme-toggle-btn:focus-visible {
  outline: 2px solid #39c;
  outline-offset: 2px;
}

@media (prefers-color-scheme: dark) {
  html:not([data-theme="light"]) #theme-toggle-btn {
    border-color: rgba(255, 255, 255, 0.2);
    background-color: rgba(32, 33, 43, 0.92);
    color: #ffffff;
  }

  html:not([data-theme="light"]) #theme-toggle-btn:hover {
    background-color: rgba(62, 183, 240, 0.15);
    border-color: rgba(62, 183, 240, 0.45);
  }
}

html[data-theme="dark"] #theme-toggle-btn {
  border-color: rgba(255, 255, 255, 0.2);
  background-color: rgba(32, 33, 43, 0.92);
  color: #ffffff;
}

html[data-theme="dark"] #theme-toggle-btn:hover {
  background-color: rgba(62, 183, 240, 0.15);
  border-color: rgba(62, 183, 240, 0.45);
}

html[data-theme="light"] #theme-toggle-btn {
  border-color: rgba(0, 0, 0, 0.12);
  background-color: rgba(255, 255, 255, 0.85);
  color: #043361;
}

html[data-theme="light"] #theme-toggle-btn:hover {
  background-color: #c2efff;
}

/* Icon reflects effective theme (CSS-only); click switches to the other mode */
#theme-toggle-btn .theme-toggle-icon--sun {
  display: none;
}
#theme-toggle-btn .theme-toggle-icon--moon {
  display: inline-block;
}

/* Make FA moon match the 18x18 sun SVG */
#theme-toggle-btn .theme-toggle-icon--moon i {
  display: block;
  font-size: 15px;
  line-height: 15px;
}

@media (prefers-color-scheme: dark) {
  html:not([data-theme="light"]) #theme-toggle-btn .theme-toggle-icon--sun {
    display: inline-block;
  }
  html:not([data-theme="light"]) #theme-toggle-btn .theme-toggle-icon--moon {
    display: none;
  }
}

html[data-theme="dark"] #theme-toggle-btn .theme-toggle-icon--sun {
  display: inline-block;
}
html[data-theme="dark"] #theme-toggle-btn .theme-toggle-icon--moon {
  display: none;
}

html[data-theme="light"] #theme-toggle-btn .theme-toggle-icon--sun {
  display: none;
}
html[data-theme="light"] #theme-toggle-btn .theme-toggle-icon--moon {
  display: inline-block;
}