main.css

body {
    background-color: #F5EFE6;
    color: #2F2F2F;
    font-family: Georgia, "Times New Roman", serif;
    margin: 0;
    padding: 0;
}

.topnav {
    background-color: #6B4F3F;
    padding: 15px;
    text-align: center;
    overflow: hidden;
}

.topnav a {
    color: white;
    float: left;
    display: block;
    text-decoration: none;
    margin: 15px;
    font-size: 18px;
}

.topnav a:hover {
    color: #FFD27F;
}

.content {
    background-color: #FFFAF3;
    width: 80%;
    max-width: 900px;
    margin: 40px auto;
    padding: 30px;
    border: 3px solid #C89F72;
    border-radius: 18px;
    text-align: center;
}

h1 {
    color: #5A3E2B;
    font-size: 42px;
    margin-bottom: 15px;
}

p {
    font-size: 18px;
    line-height: 1.5;
}

input {
    margin: 10px;
    padding: 10px;
    font-size: 16px;
}

input[type="submit"] {
    background-color: #8A5A44;
    color: white;
    border: none;
    border-radius: 10px;
    padding: 12px 25px;
    cursor: pointer;
}

input[type="submit"]:hover {
    background-color: #5A3E2B;
}

.serval-link {
    color: #7A4E2D;
    text-decoration: none;
    font-weight: bold;
}

.serval-link:hover {
    color: #B36B2C;
    text-decoration: underline;
}

img {
    border: 4px solid #C89F72;
    border-radius: 14px;
    margin: 15px auto;
    max-width: 80%;
}

.bottomnav {
    background-color: #6B4F3F;
    color: white;
    text-align: center;
    padding: 15px;
    margin-top: 40px;
}

.bottomnav a {
    color: white;
    text-decoration: none;
}

#loader {
    position: absolute;
    left: 50%;
    top: 50%;
    z-index: 1;
    width: 120px;
    height: 120px;
    margin: -76px 0 0 -76px;
    border: 16px solid #F5EFE6;
    border-radius: 50%;
    border-top: 16px solid #8A5A44;
    -webkit-animation: spin 2s linear infinite;
    animation: spin 2s linear infinite;
}

@-webkit-keyframes spin {
    0% { -webkit-transform: rotate(0deg); }
    100% { -webkit-transform: rotate(360deg); }
}

@keyframes spin {
     0% { transform: rotate(0deg); }
     100% { transform: rotate(360deg); }
}

/* Add animation to "page content" */
.animate-bottom {
    position: relative;
    -webkit-animation-name: animatebottom;
    -webkit-animation-duration: 1s;
    animation-name: animatebottom;
    animation-duration: 1s
}

@-webkit-keyframes animatebottom {
    from { bottom:-100px; opacity:0 }
    to { bottom:0px; opacity:1 }
}

@keyframes animatebottom {
    from{ bottom:-100px; opacity:0 }
    to{ bottom:0; opacity:1 }
}

#myDiv {
    display: none;
    text-align: center;
}

/* Hide the hamburger menu icon on large screens */
.topnav .toggle {
    display: none;
}

/* Hide additional menu links on small screens. Show hamburger icon */ 
@media screen and (max-width: 600px) {
    .topnav a:not(:first-child) {
        display: none;
    }
    .topnav a.toggle {
        float: right;
        display: block;
    }
}

/* When user clicks on hamburger icon, the "responsive" class is added to topnav through JavaScript. Menu links are displayed vertically. */ 
@media screen and (max-width: 600px) {
    .topnav.responsive {
        position: relative;
    }
    .topnav.responsive a.toggle {
        position: absolute;
        right: 0;
        top: 0;
    }
    .topnav.responsive a {
        float: none;
        display: block;
        text-align: left;
    }
}