body {
  font-family: "Segoe UI", "Yu Gothic UI", sans-serif;
  margin: 0;
  padding: 0;
  background: #f7f8fa;
}

main {
  padding: 16px;
}

h1 {
  font-size: 18px;
  margin-top: 0;
}

button {
  background: #0078d4;
  color: #fff;
  border: none;
  border-radius: 4px;
  padding: 8px 16px;
  cursor: pointer;
  font-size: 14px;
}

button:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

label {
  display: flex;
  flex-direction: column;
  margin-bottom: 12px;
}

input[type="number"] {
  padding: 4px;
  font-size: 14px;
}

#log {
  margin-top: 16px;
  background: #fff;
  border: 1px solid #d0d7de;
  border-radius: 4px;
  padding: 8px;
  min-height: 60px;
  font-size: 12px;
  white-space: pre-wrap;
}