.theme-toggle-btn {
  position: fixed;
  bottom: 28px;
  right: 28px;
  z-index: 999;
  display: flex;
  gap: 6px;
  align-items: center;
  padding: 6px;
  border: 1px solid var(--line);
  border-radius: 10px;
  background: color-mix(in srgb, var(--surface) 92%, var(--bg) 8%);
  box-shadow: var(--shadow);
  backdrop-filter: blur(10px);
}

.theme-btn {
  width: 36px;
  height: 36px;
  border: 1px solid transparent;
  border-radius: 8px;
  background: transparent;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: background 180ms ease-out, border-color 180ms ease-out;
  padding: 0;
}

.theme-btn:hover {
  background: color-mix(in srgb, var(--badge-bg) 70%, transparent 30%);
}

.theme-btn.active {
  background: color-mix(in srgb, var(--accent) 14%, transparent 86%);
  border-color: color-mix(in srgb, var(--accent) 35%, var(--line) 65%);
}

.theme-btn img {
  width: 18px;
  height: 18px;
  display: block;
  pointer-events: none;
  opacity: 0.78;
}

.theme-btn.active img {
  opacity: 1;
}

@media (max-width: 640px) {
  .theme-toggle-btn {
    bottom: 20px;
    right: 20px;
    padding: 6px;
    gap: 6px;
  }

  .theme-btn {
    width: 34px;
    height: 34px;
  }

  .theme-btn img {
    width: 17px;
    height: 17px;
  }
}