File: example/style.css

.text-half{
  background-color: rgba(255, 255, 255, 0.63);
}
.masthead, .mastfoot{
  position: inherit !important;
}
.collapse{
  opacity: 0;
  transition: opacity 0.35s ease;
}
.collapsing, .collapse.show{
  opacity: 1;
  transition: opacity 0.35s ease;
}
.list-group-item{
  text-shadow: 0 0 0 rgba(0,0,0,0);
  color: #333 !important;
  background-color: #fff !important;
}

a,
a:focus,
a:hover {
  color: #fff;
}

.btn-secondary,
.btn-secondary:hover,
.btn-secondary:focus {
  color: #333 !important;
  text-shadow: none;
  background-color: #fff;
  border: 1px solid transparent;
  margin: 2px;
}

html,
body {
  height: 100%;
  background-color: #333;
  -webkit-box-shadow: inset 0 0 5rem rgba(0,0,0,.5);
          box-shadow: inset 0 0 5rem rgba(0,0,0,.5);
}
body {
  color: #fff;
  text-align: center;
  text-shadow: 0 .05rem .1rem rgba(0,0,0,.5);
}

.site-wrapper {
  width: 100%;
}
.site-wrapper-inner {
  vertical-align: top;
}
.cover-container {
  margin-right: auto;
  margin-left: auto;
}

.inner {
  padding: 2rem;
}

.masthead {
  margin-bottom: 2rem;
}

.masthead-brand {
  margin-bottom: 0;
}

.mb-1{
  margin: 0 auto;
}

.nav-masthead .nav-link {
  padding: .25rem 0;
  font-weight: bold;
  color: rgba(255,255,255,.5);
  background-color: transparent;
  border-bottom: .25rem solid transparent;
}

.nav-masthead .nav-link:hover,
.nav-masthead .nav-link:focus {
  border-bottom-color: rgba(255,255,255,.25);
}

.nav-masthead .nav-link + .nav-link {
  margin-left: 1rem;
}

.nav-masthead .active {
  color: #fff;
  border-bottom-color: #fff;
}

@media (min-width: 48em) {
  .masthead-brand {
    float: left;
  }
  .nav-masthead {
    float: right;
  }
}

.cover {
  padding: 0 1.5rem;
}
.cover .btn-lg {
  padding: .75rem 1.25rem;
  font-weight: bold;
}

.mastfoot {
  color: rgba(255,255,255,.5);
}


@media (min-width: 40em) {
  .masthead {
    position: fixed;
    top: 0;
  }
  .mastfoot {
    position: fixed;
    bottom: 0;
  }
  .site-wrapper-inner {
    vertical-align: middle;
  }
  .masthead,
  .mastfoot,
  .cover-container {
    width: 100%;
  }
}