body,
ul,
li,
p {
  padding: 0;
  margin: 0;
}

body {
  padding: 100px 0;
  background: #ccc;
  font-family: Arial;
  color: #333;
}

p {
  line-height: 1.5em;
  margin-bottom: 1em;
}

#tabs {
  width: 400px;
  margin: auto;
}
#tabs > ul {
  list-style-type: none;
  display: flex;
}
#tabs > ul > li > a {
  display: block;
  height: 30px;
  line-height: 30px;
  margin-right: 2px;
  background: #a2a2a2;
  color: #cecece;
  text-decoration: none;
  padding: 0 15px;
  border-top-left-radius: 3px;
  border-top-right-radius: 3px;
}
#tabs > div {
  padding: 15px;
  background: #eaeaea;
  transition: opacity 200ms linear;
}
#tabs .active {
  background: #eaeaea;
  color: #333;
}
#tabs .hidden {
  display: none;
}
#tabs .visible {
  display: block;
}
#tabs .visuallyhidden {
  opacity: 0;
}