simplex/static/main.css

.collapsible {
  width: 100%;
  text-align: left;
  cursor: pointer;
}

.content {
  padding: 1rem;
  background-color: #eee;
  display: none;
  overflow: hidden;
}

.delete, .error {
  background-color: red;
  border-color: red;
  color: white;
}

h1 {
  text-align: center;
}

.btns {
  justify-content: center;
}