.ileri{
  float: right;
  padding-right: 200px;
  color: black;
}
.geri{
  float: left;
  padding-left: 200px;
  color: black;
}
.shadow{
    position: relative;
    margin: 40px auto;
    width: 400px;
    height: auto;
    background: #eeecef;
    border-radius: 25px;
     }.shadow:before,
   .shadow:after{
    content: '';
    position: absolute;
    top: -2px;
    left: -2px;
    background: linear-gradient(45deg,#f255b1,#0000ff,#00ff00,#ffff00,#a22424,#fb0094,#0000ff,#00ff00,#ffff00,#f3146d);
    background-size: 400% 400%;
    width: calc(100% + 6px);
    height: calc(100% + 6px);
    border-radius: 20px;
    z-index: -1;
    animation: animate 3s ease alternate infinite;
   }
   .shadow:after{
    filter: blur(20px);
   }
   @keyframes animate{
    0%{
      background-position: 0 50%;
    }
    50%{
      background-position: 100% 50%;
    }
    100%{
      background-position: 0% 50%;
    }
   }
   
ul {
  list-style-type: none;
  margin: 0;
  padding: 0;
  overflow: hidden;
  background-color: #282828;
  position: fixed;
  top: 0;
  width: 100%;
}

li {
  float: left;
}

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

li a:hover:not(.active) {
  background-color: #111;

}

.active {
  font-weight: 500;
}