app.css

body{
  height:100%;
  width:100%;
  padding:0;
  margin:0;
}

.cover-background {
height:650px;
 background: linear-gradient(
  to top left,
  rgba(225,0,0,0.5),
  rgba(255,0,0,0.5) 50%,
  rgba(12,10,54,0.7) 50%,
  rgba(12,10,54,0.7)),url('library.jpg') no-repeat ;
 /* background-image: url('background.png');*/
background-size: cover;
position: relative;
}

.cover-text {
  text-align: center;
  position: absolute;
  top: 40%;
  left: 50%;
  transform: translate(-50%, -50%);
  color: white;
}

.navbar {
   z-index: 10000;
   position: sticky !important;
   top: 0px;
   width: 100%;
}​

h1{
  font-size: 250px;
}
h3 {
  font-size: 20px;
}
h5 {
  font-size: 15px;
}

ul {
  list-style-type: none;
  margin: 0;
  padding: 0;
  overflow: hidden;
  background-color: #333;
}

li {
  float:left;
}

i{

  float:right;
  display: block;
  color: white;
  text-align: center;
  padding: 14px 16px;
  font-size:20px;
  text-decoration: none;
}

li a {
  display: block;
  color: white;
  text-align: center;
  padding: 14px 16px;
  text-decoration: none;
}

li a:hover {
  background-color: #111;
}

.text-gradient{
  text-align:center;
  background:linear-gradient(to bottom right ,white ,#D35400    );
  -webkit-background-clip:text;
  -webkit-text-fill-color:transparent;
}


:after,
:before {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

section {
  height: 100%;
  width: 100%;
  display: table;

}
section.ok{
  background-color: #555;
}

.scroll-down {
  opacity: 1;
  -webkit-transition: all .5s ease-in 3s;
  transition: all .5s ease-in 3s;
}

.scroll-down {
  position: absolute;
  bottom: 30px;
  left: 50%;
  margin-left: -16px;
  display: block;
  width: 32px;
  height: 32px;
  border: 2px solid #FFF;
  background-size: 14px auto;
  border-radius: 50%;
  z-index: 2;
  -webkit-animation: bounce 2s infinite 2s;
  animation: bounce 2s infinite 2s;
  -webkit-transition: all .2s ease-in;
  transition: all .2s ease-in;
}

.scroll-down:before {
    position: absolute;
    top: calc(50% - 8px);
    left: calc(50% - 6px);
    transform: rotate(-45deg);
    display: block;
    width: 12px;
    height: 12px;
    content: "";
    border: 2px solid white;
    border-width: 0px 0 2px 2px;
}

@keyframes bounce {
  0%,
  100%,
  20%,
  50%,
  80% {
    -webkit-transform: translateY(0);
    -ms-transform: translateY(0);
    transform: translateY(0);
  }
  40% {
    -webkit-transform: translateY(-10px);
    -ms-transform: translateY(-10px);
    transform: translateY(-10px);
  }
  60% {
    -webkit-transform: translateY(-5px);
    -ms-transform: translateY(-5px);
    transform: translateY(-5px);
  }
}
img{
  width:30%;
  margin:2px;
}