body {
  margin: 0;
  font-family: Arial, sans-serif;
  background: #f4f4f4;
}
.header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 10px;
  background: #000;
  color: #fff;
}
.logo { height: 40px; }
.search { width: 60%; padding: 8px; }

.carousel img {
  width: 100%;
  display: block;
}

.announcement {
  background: yellow;
  padding: 8px;
  text-align: center;
}

.platforms {
  padding: 10px;
}
.platform h2 {
  background: #222;
  color: #fff;
  padding: 10px;
  cursor: pointer;
  user-select: none;
}
ul.collapsed {
  display: none;
  list-style: none;
  padding-left: 15px;
  margin-top: 0;
}
ul li a {
  display: block;
  padding: 6px;
  color: #333;
  text-decoration: none;
  border-bottom: 1px solid #ddd;
}
footer {
  position: fixed;
  bottom: 0;
  width: 100%;
  background: #111;
  color: #fff;
  display: flex;
  justify-content: space-around;
  padding: 10px 0;
}
footer a {
  color: gold;
  text-decoration: none;
}