style.css

html, body {
  margin: 0;
  padding: 0;
  background: #faf8ef;
  color: #776e65;
  font-family: 'Lato', 'Helvetica Neue', Arial, sans-serif;
  font-size: 18px; }

body {
  margin: 30px 0; }

.container {
  width: 500px;
  margin: 0 auto; }

.heading:after {
  content: "";
  display: block;
  clear: both; }

h1.title {
  font-size: 60px;
  font-weight: bold;
  margin: 0;
  display: block;
  float: left; }

.above-game:after {
  content: "";
  display: block;
  clear: both;
}

.game-intro {
  float: left;
  line-height: 42px;
  margin-bottom: 0;
}

p {
  margin-top: 0;
  margin-bottom: 10px;
  line-height: 1.65;
}

hr {
  border: none;
  border-bottom: 1px solid #d8d4d0;
  margin-top: 20px;
  margin-bottom: 30px;
}

.game-explanation {
  margin-top: 50px;
}

#background{
  height: 500px;
  width: 500px;
  background-image: url('images/back.jpg');
  margin: 40 auto 0;
}

.credits {
  margin-top: 30px;
}

a {
  color: #776e65;
  font-weight: bold;
  text-decoration: underline;
  cursor: pointer;
}

.sharing {
  margin-top: 20px;
}

#flappy-alert {
  position: fixed;
  top: 15px;
  right: 15px;
  padding: 10px;
  max-width: 200px;
  background-color: rgba(0, 0, 0, .35);
  color: #fff;
  border-radius: 5px;
  opacity: 0;
  transition: opacity .4s;
  pointer-events: none;
}

#flappy-alert.visible {
  opacity: 1;
}