* {
  box-sizing: border-box;
}

body {
  margin: 0;
  background: #0b1729;
  color: white;
  font-family: Arial, sans-serif;
}

main {
  max-width: 440px;
  margin: 40px auto;
  padding: 20px;
}

h1 {
  color: #60c5ff;
}

.panel {
  background: #17283d;
  padding: 24px;
  border-radius: 16px;
  margin: 25px 0;
}

.panel p {
  line-height: 1.8;
}

button {
  display: block;
  width: 100%;
  padding: 17px;
  margin-top: 12px;
  border: none;
  border-radius: 10px;
  font-size: 16px;
  font-weight: bold;
  cursor: pointer;
}

#startBtn {
  background: #22c55e;
  color: #061b0e;
}

#stopBtn {
  background: #ef4444;
  color: white;
}

#syncBtn {
  background: #38bdf8;
  color: #081525;
}

button:disabled {
  opacity: 0.4;
  cursor: not-allowed;
}