.nav-link {
    font-size: 18px;
    color: #000;
}
.nav-link:hover {
    color: #f58432;
}

.navbar-nav .nav-link.active {
    text-decoration: underline;
}

.header {
  position: sticky;
  top: 0;
  z-index: 100;
}

.img {
    background: url("../media/frack.jpeg") no-repeat;
    background-size: cover;
    background-position: center;
    height: 500px;
}

.grad {
    height: 500px;
    background-image: linear-gradient(to right, rgba(255,255,255,0), rgba(0,0,0,100));
    opacity: 0;
    animation: show 3s 1;
    animation-fill-mode: forwards;
    animation-delay: 0s;
}

@keyframes show{
    0%{
        opacity:0;
    }
    100% {
        opacity:1;
    }
}

.img1 {
    background: url("../media/import.jpeg") no-repeat;
    background-size: cover;
    background-position: center;
    height: 300px;
}

.img2 {
    background: url("../media/device1.png") no-repeat;
    background-size: contain;
    background-position: center;
    height: 800px;
}

.img3 {
    background: url("../media/device2.png") no-repeat;
    background-size: contain;
    background-position: center;
    height: 800px;
}

.up_btn {
    display:inline-block;
    position:fixed;
    bottom:30px;right:30px;
    padding:5px 10px;
    font-size:16px;
    text-decoration: none;
    color: #666;
    background:#ddd;
    border-radius:15px
}