.theme-fab {
  position: fixed;
  right: 26px;
  bottom: 26px;
  z-index: 1000;
  background: var(--panel);
  border-radius: 50%;
  box-shadow: 0 2px 12px rgba(66,103,233,0.13);
  border: none;
  cursor: pointer;
  width: 54px;
  height: 54px;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: background 0.2s, box-shadow 0.2s, transform 0.2s;
}
.theme-fab:active {
  transform: scale(0.96);
  box-shadow: 0 2px 6px rgba(66,103,233,0.10);
}
.theme-fab .theme-icon {
  width: 32px;
  height: 32px;
  background-size: cover;
  background-repeat: no-repeat;
  transition: transform 0.3s;
}
.theme-fab .theme-icon.sun {
  background-image: url('/static/images/theme-sun.svg');
}
.theme-fab .theme-icon.moon {
  background-image: url('/static/images/theme-moon.svg');
}
.theme-fab.open .theme-icon {
  transform: scale(1.25) rotate(180deg);
}
@media (max-width: 600px) {
  .theme-fab {
    right: 12px;
    bottom: 12px;
    width: 44px;
    height: 44px;
  }
  .theme-fab .theme-icon {
    width: 24px;
    height: 24px;
  }
}