@charset "utf-8";

body {
  font-family: Arial, Helvetica, "微軟正黑體", sans-serif;
}

ul, ol {
  list-style: none;
  margin: 0;
  padding: 0;
}

h1 {
  text-align: center;
  color: #70bbf9;
  margin: 1em;
  font-size: 3em;
}

.container {
  max-width: 800px;
}

.mx-auto {
  margin-left: auto;
  margin-right: auto;
}

.tab__nav {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  border-bottom: solid 1px #ccc;
}

.tab__btn {
  margin-bottom: -2px;
  padding: .7rem 1rem;
  font-size: 1rem;
  color: #bbb;
  border: 0;
  background-color: transparent;
}

.tab__btn:disabled {
  background-color: #eef9ff;
  color: #70bbf9;
  border-bottom: solid 4px #70bbf9;
}

.tab__link {
  text-decoration: none;
  color: #70bbf9;
  line-height: 1;
}

.tab__link:hover {
  text-decoration: underline;
}

.tab__item {
  display: none;
  padding-top: 1rem;
  padding-bottom: 1rem;
}

.tab__videos {
  padding-top: 56.25%;
  position: relative;
}

.tab__video {
  position: absolute;
  top: 0;
  width: 100%;
  height: 100%;
}