main.css

html {
    overflow-x: hidden;
    overflow-y: auto;
}

body {
    background-color: #18191c;
}

ul li {
    position: relative;
    top: 300px;
    left: 110px;
    display: inline;
    padding: 10px 10px
}

.inner {
    position: relative;
    left: 45%;
    top: -55px;
}

h1 {
    position: relative;
    top: 270px;
    left: 230px;
    color: #ffffff;
    font-family: Arial;
    font-size: 60px;
}

.ButtonC {
    background: linear-gradient(to bottom, #ffffff 5%, #ffffff 100%);
    background-color: #ffffff;
    border-radius: 4px;
    border: 2px solid #ffffff;
    display: inline-block;
    cursor: pointer;
    color: #000000;
    font-family: Arial;
    font-size: 20px;
    font-weight: bold;
    padding: 8px 20px;
    text-decoration: none;
}

.ButtonC:hover {
    background: linear-gradient(to bottom, #ffffff 5%, #ffffff 100%);
    background-color: #ffffff;
}

.ButtonC:active {
    position: relative;
    top: 1px;
}

.ButtonS {
    background: linear-gradient(to bottom, #18191c 5%, #18191c 100%);
    background-color: #18191c;
    border-radius: 4px;
    border: 2px solid #525355;
    display: inline-block;
    cursor: pointer;
    color: #ffffff;
    font-family: Arial;
    font-size: 20px;
    font-weight: bold;
    padding: 8px 20px;
    text-decoration: none;
}

.ButtonS:hover {
    background: linear-gradient(to bottom, #292a2d 5%, #292a2d 100%);
    background-color: #292a2d;
}

.ButtonS:active {
    position: relative;
    top: 1px;
}

.star {
    background: grey;
    position: absolute;
    width: 5px;
    height: 5px;
    content: '';
    border-radius: 100%;
    transform: rotate(250deg);
    opacity: 0.4;
    animation-name: shimmer;
    animation-duration: 1.5s;
    animation-iteration-count: infinite;
    animation-direction: alternate;
}

@keyframes shimmer {
    from {
        opacity: 0;
    }
    to {
        opacity: 0.7;
    }
}

.star1 {
    top: 40%;
    left: 10%;
    animation-delay: 1s;
}

.star2 {
    top: 60%;
    left: 20%;
    animation-delay: 3s;
}

.star3 {
    top: 10%;
    left: 30%;
    animation-delay: 2s;
}

.star4 {
    top: 90%;
    left: 40%;
}

.star5 {
    top: 20%;
    left: 50%;
    animation-delay: 0.5s;
}

@media (max-width: 768px) {
    .inner {
        display: none;
    }
    ul li {
        display: inline-block;
        justify-content: center;
        position: relative;
        top: 220px;
        left: 60px;
        padding: 10px, 10px;
    }
    html {
        overflow-x: hidden;
        overflow-y: auto;
    }
    .ButtonC {
        background: linear-gradient(to bottom, #ffffff 5%, #ffffff 100%);
        background-color: #ffffff;
        border-radius: 4px;
        border: 2px solid #ffffff;
        display: inline-block;
        cursor: pointer;
        color: #000000;
        font-family: Arial;
        font-size: 13px;
        font-weight: bold;
        padding: 8px 20px;
        text-decoration: none;
    }
    .ButtonC:hover {
        background: linear-gradient(to bottom, #ffffff 5%, #ffffff 100%);
        background-color: #ffffff;
    }
    .ButtonC:active {
        position: relative;
        top: 1px;
    }
    .ButtonS {
        background: linear-gradient(to bottom, #18191c 5%, #18191c 100%);
        background-color: #18191c;
        border-radius: 4px;
        border: 2px solid #525355;
        display: inline-block;
        cursor: pointer;
        color: #ffffff;
        font-family: Arial;
        font-size: 13px;
        font-weight: bold;
        padding: 8px 20px;
        text-decoration: none;
    }
    .ButtonS:hover {
        background: linear-gradient(to bottom, #292a2d 5%, #292a2d 100%);
        background-color: #292a2d;
    }
    .ButtonS:active {
        position: relative;
        top: 1px;
    }
    h1 {
        position: relative;
        top: 220px;
        left: 130px;
        color: #ffffff;
        font-family: Arial;
        font-size: 65px;
    }
}