.theme-btn {
  background: var(--color-bg-light);
  border: 1px solid var(--color-border);
  font-size: 18px;
  color: var(--color-text-medium);
  cursor: pointer;
  transition: all 0.3s ease;
  padding: 10px;
  border-radius: 10px;
  width: 40px;
  height: 40px;
  display: flex;
  align-items: center;
  justify-content: center;
  position: relative;
  overflow: hidden;
}

.theme-btn::before {
  content: "";
  position: absolute;
  top: 50%;
  left: 50%;
  width: 0;
  height: 0;
  border-radius: 50%;
  background: var(--color-primary);
  transform: translate(-50%, -50%);
  transition: width 0.3s ease, height 0.3s ease;
}

.theme-btn:hover::before {
  width: 100%;
  height: 100%;
}

.theme-btn:hover {
  border-color: var(--color-primary);
  transform: translateY(-2px);
  box-shadow: var(--shadow-green);
}

.theme-btn:hover i {
  color: var(--color-white);
  position: relative;
  z-index: 1;
}

.theme-btn:active {
  transform: translateY(0) scale(0.95);
}

.theme-btn.switching {
  animation: themeSwitch 0.5s ease;
}

@keyframes themeSwitch {
  0% { transform: rotate(0deg); }
  50% { transform: rotate(180deg) scale(1.1); }
  100% { transform: rotate(360deg); }
}

.theme-btn .fa-sun { color: #f59e0b; }
.theme-btn .fa-moon { color: #6366f1; }

@media (max-width: 768px) {
  .theme-btn {
    width: 36px;
    height: 36px;
    font-size: 16px;
  }
}

@media (max-width: 480px) {
  .theme-btn {
    width: 34px;
    height: 34px;
    font-size: 15px;
  }
}