.nav-button {
    position: fixed;
    width: 40px;
    height: 50px;
    background-color: transparent;
    color: Lime;
    font-weight: bold;
    text-align: center;
    line-height: 30px;
    font-size: 28px;
    border-radius: 50%;
    cursor: pointer;
    z-index: 1000;
    text-decoration: none;
    border: none;
}
.nav-button-left {
    left: 0;
    top: 40px;
}
.nav-button-right {
    right: 0;
    top: 40px;
}
.nav-button-up {
    top: 0;
    left: 50%;
    transform: translateX(-50%);
}
header {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    background-color: black;
}
h1 {
    color: Lime;
    width: 100%;
    margin-top: 30px;
    background-color: black;
    text-align: center;
}
body {
    font-family: Arial, sans-serif;
    line-height: 1.6;
    margin-left: 40px;
    margin-right: 40px;
    margin-top: 90px;
    text-align: left;
}
h2 {
    color: LimeGreen;
}
img {
    display: block;
    margin: 20px auto;
    width: 250px;
}
ul {
    list-style-type: disc;
    margin-left: 20px;
    text-align: left;
}
.section {
    margin-bottom: 20px;
}
main {
    text-align: left;
    display: inline-block;
}