body {
  margin: 0;
  font-family: sans-serif;
  background: #000;
  color: #fff;
}
.container {
  max-width: 500px;
  padding: 1rem;
  margin: auto;
}
.header {
  text-align: center;
}
.tooltip {
  position: relative;
  display: inline-block;
  cursor: pointer;
}
.tooltiptext {
  visibility: hidden;
  width: 250px;
  background-color: #fff;
  color: #000;
  padding: 5px;
  position: absolute;
  z-index: 1;
  top: -150px;
  left: 110%;
  opacity: 0;
  transition: opacity 0.5s;
}
.tooltip:hover {
  color: #669999;
  text-decoration: underline;
}
.tooltip:hover .tooltiptext {
  visibility: visible;
  opacity: .98;
}
h1 {
  font-size: 2.5rem;
  font-face: bold;
  text-align: center;
}
h2 {
  font-size: 1.5rem;
}
a {
  color: #fff;
  text-decoration: none;
  font-weight: bold;
}
a:hover {
  color: #669999;
  text-decoration: underline;
}
@media (max-width: 600px) {
  h1 {
    font-size: 1.6rem;
  }
  h2 {
    font-size: 1.2rem;
  }
  body {
    font-size: 0.95rem;
  }
  .container {
    width: 95%;
  }
}