.theme-toggle-btn {
  background: none;
  border: none;
  cursor: pointer;
  padding: 0 16px;
  display: flex;
  align-items: center;
  height: 40px;
}

.theme-switch {
  position: relative;
  display: inline-block;
  width: 52px;
  height: 28px;
  vertical-align: middle;
}

.theme-switch input {
  opacity: 0;
  width: 0;
  height: 0;
}

.theme-slider {
  position: absolute;
  cursor: pointer;
  top: 0; left: 0; right: 0; bottom: 0;
  background-color: #e0e0e0;
  transition: background 0.4s;
  border-radius: 34px;
  box-shadow: 0 2px 8px rgba(0,0,0,0.08);
}

.theme-slider:before {
  position: absolute;
  content: "";
  height: 22px;
  width: 22px;
  left: 3px;
  bottom: 3px;
  background-color: #fff;
  transition: .4s;
  border-radius: 50%;
  box-shadow: 0 1px 4px rgba(0,0,0,0.15);
}

.theme-switch input:checked + .theme-slider {
  background-color: #222;
}

.theme-switch input:checked + .theme-slider:before {
  transform: translateX(24px);
  background-color: #ffd600;
}

.theme-slider .slider-icon {
  position: absolute;
  top: 4px;
  font-size: 18px;
  z-index: 2;
  transition: opacity 0.3s;
  pointer-events: none;
}
.theme-slider .slider-sun {
  left: 8px;
  color: #ffd600;
  opacity: 1;
}
.theme-switch input:checked + .theme-slider .slider-sun {
  opacity: 0.3;
}
.theme-slider .slider-moon {
  right: 8px;
  color: #fff;
  opacity: 0.3;
}
.theme-switch input:checked + .theme-slider .slider-moon {
  opacity: 1;
}

body.dark-mode {
  background: #181818 !important;
  color: #eee !important;
}
body.dark-mode .u-header,
body.dark-mode .u-footer {
  background: #23272f !important;
}
body.dark-mode .u-nav-link {
  color: #eee !important;
}
body.dark-mode .theme-slider {
  background-color: #444 !important;
  box-shadow: 0 2px 8px rgba(0,0,0,0.25);
}
body.dark-mode .theme-slider:before {
  background-color: #222 !important;
  box-shadow: 0 1px 4px rgba(255,255,255,0.08);
}