* {
  font-family: system-ui, "Helvetica Neue", sans-serif;
}

#boxes {
  display: flex;
  justify-content: center;
  margin: 10vh 0;
}
#boxes .box {
  width: 500px;
  height: 100%;
  max-height: 650px;
  border: 1px solid #ddd;
  padding: 10px 10px 0 10px;
  margin-right: 2.5%;
  overflow: auto;
}
#boxes .box:last-child {
  margin: 0;
}
#boxes .box > * {
  width: 100%;
  text-align: left;
}
#boxes .box li {
  margin-left: 20px;
}

main {
  padding: 15px;
}

li {
  margin-bottom: 10px;
  font-size: 14px;
}

h1, h2, h3,
h4, h5, h6 {
  margin: 0 0 15px 0;
}

ul {
  margin: 0;
  padding: 0;
}

button {
  color: #000;
  background: #eee;
  display: block;
  font-size: 13.5px;
  border: 1px solid #ddd;
  padding: 5px;
  margin-bottom: 10px;
}

button[disabled] {
  color: #999;
  cursor: not-allowed;
}

button:not([disabled]) {
  cursor: pointer;
}
button:not([disabled]):hover {
  background: #ddd;
}
button:not([disabled]):active {
  background: #ccc;
}