body {
  font-family: Arial, sans-serif;
  background: #1e1e2f;
  color: white;
  text-align: center;
  padding: 20px;
}
.container {
  max-width: 500px;
  margin: auto;
  padding: 20px;
}
#speed-display {
  font-size: 100px;
  font-weight: bold;
  margin: 20px 0;
  color: #00ffcc;
  text-shadow: 0 0 10px #00ffcc;
}
.unit-toggle {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 10px;
  margin: 20px 0;
}
.switch {
  position: relative;
  display: inline-block;
  width: 50px;
  height: 24px;
}
.switch input {
  opacity: 0;
  width: 0;
  height: 0;
}
.slider {
  position: absolute;
  cursor: pointer;
  background-color: #ccc;
  transition: .4s;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  border-radius: 24px;
}
.slider:before {
  position: absolute;
  content: "";
  height: 18px;
  width: 18px;
  left: 3px;
  bottom: 3px;
  background-color: white;
  transition: .4s;
  border-radius: 50%;
}
input:checked + .slider {
  background-color: #00ffcc;
}
input:checked + .slider:before {
  transform: translateX(26px);
}
.buttons button {
  margin: 10px;
  padding: 10px 20px;
  font-size: 18px;
  background: #00ffcc;
  color: black;
  border: none;
  border-radius: 8px;
  cursor: pointer;
  transition: background 0.3s;
}
.buttons button:hover {
  background: #00e6b3;
}
#status {
  margin-top: 20px;
  font-size: 14px;
  color: #aaa;
}