body {
  display: grid;
  place-items: center;
  margin: 0;
  background: linear-gradient(45deg, hsl(285 100% 50%), hsl(210 100% 50%));
  background-attachment: fixed;
  font-family: 'Inter';
  color: #fff;
  box-sizing: border-box;
}

.main {
  max-width: 728px;
  margin: auto;
  font-weight: 300;
  font-size: 24px;
  text-align: center;
  padding: 30px;
  box-sizing: border-box;
}
.main a {
  color: #ffeb3b;
  text-decoration: none;
}

.main ul {
  padding-left: 0;
}
.main ul li {
  list-style: none;
  line-height: 1.5;
}
.main ul li.ttl {
  font-weight: 700;
  margin-top: 15px;
}

.live-tester {
  max-width: 666px;
  margin: auto;
  display: flex;
  flex-flow: row wrap;
  align-items: center;
  justify-content: center;
  gap: 15px;
  box-sizing: border-box;
}
.live-tester .ttl {
  width: 100%;
  text-align: center;
}
.live-tester .h2 {
  font-size: 21px;
  margin-bottom: 0;
}
.live-tester .ttl .h3 {
  font-size: 18px;
  font-weight: 300;
}
.live-tester .html {
  width: 100%;
  min-height:150px;  
  border-radius: 9px;
  padding: 15px;
  box-sizing: border-box;
}
.live-tester iframe {
  background: #fff;
  width:100%;
  min-height:150px;
  border-radius: 9px;
  border: 1px solid #fff;
}