body {
  background-color: #0f131a;
  background-image: url(../img/bg_book.jpg);
  background-size: cover;
  position: relative;
  height: calc(100vh - 72px);
}

.covered {
  z-index: -300;
  padding: 0;
  margin: 0;
  background-color: rgba(255, 255, 255, 0.6);
  position: absolute;
  top: 0;
  bottom: 0;
  right: 0;
  left: 0;
}

/* top section */
.top-section-container {
  position: relative;
  width: 80%;
}

section {
  width: 90%;
  margin: auto;
  padding-left: 60px;
}

.content-container {
  margin-top: 48px;
  color: #000;
  padding: 0;
  width: 80%;
}

.content-container p {
  text-indent: 0;
  margin: 4px 0;
  font-size: 1em;
}

/* top section */
section#top-section {
  width: 90%;
  background-color: transparent;
  height: calc(100vh - 72px);
}

.button {
  position: relative;
  height: 36px;
  background: transparent;
  border: 1px solid #0f131a;
  line-height: .9em;
  font-size: .9em;
  text-decoration: none;
  -webkit-transition: ease-in-out .3s;
  transition: ease-in-out .3s;
  -webkit-box-sizing: border-box;
  box-sizing: border-box;
  overflow: hidden;
  z-index: 1;
  color: #0f131a;
  display: inline-block;
  margin-top: 16px;
  border-radius: 3px;
  padding: 11px;
}

.button:before, .button:after {
  -webkit-transition: ease-in-out .3s;
  transition: ease-in-out .3s;
  -webkit-box-sizing: border-box;
  box-sizing: border-box;
  z-index: -1;
}

.button:before {
  position: absolute;
  top: 0;
  right: -50px;
  bottom: 0;
  left: 0;
  border-right: 50px solid transparent;
  border-bottom: 60px solid rgba(0, 0, 0, 0.8);
  -webkit-transform: translateX(-100%);
  transform: translateX(-100%);
  content: "";
}

.button:hover {
  color: #FFFEF4;
}

.button:hover:before {
  -webkit-transform: translateX(0);
  transform: translateX(0);
}