body {
  font-family: sans-serif;
  background: #1a1a1a;
  color: #eee;
  display: flex;
  justify-content: center;
  padding: 20px;
}
.card {
  background: #2d2d2d;
  padding: 25px;
  border-radius: 16px;
  width: 75%;
  box-shadow: 0 8px 20px rgba(0,0,0,0.4);
}
h1 {
  color: #4db8ff;
  margin-top: 0;
  text-align: center;
}
h4 {
  text-align: center;
  font-size: 0.85em;
}
.setting {
  margin-bottom: 20px;
}
a {
  color: #488;
}

label {
  display: block;
  font-size: 11px;
  color: #888;
  margin-bottom: 8px;
  text-transform: uppercase;
  font-weight: bold;
}
input[type="range"] {
  width: 100%;
  cursor: pointer;
  color: #488;
}
input[type="number"] {
  width: 100%;
  padding: 12px;
  background: #3d3d3d;
  border: 1px solid #555;
  color: white;
  border-radius: 8px;
  box-sizing: border-box;
}
.btn-box {
  display: flex;
  gap: 10px;
  margin-top: 25px;
}
button {
  flex: 1;
  padding: 15px;
  border: none;
  border-radius: 8px;
  font-weight: bold;
  cursor: pointer;
  transition: 0.2s;
}
#start {
  background: #00c853;
  color: white;
}
#stop {
  background: #d50000;
  color: white;
}
#status {
  margin-top: 20px;
  font-size: 13px;
  color: #4db8ff;
  text-align: center;
  min-height: 50px;
  padding: 10px;
  border-top: 1px solid #444;
}