general.css

/* others */
body {
    background-color: #f9f9f9;
}

h1, h2 {
    color: black;
    text-align: center;
    font-size: 40px;
    font-family: 'Courier New'; /* Helvetica Neue */
    font-weight: lighter;
    letter-spacing: 3px
}

p {
    color: black;
}

code {
    background-color: cornsilk;
    color: cadetblue;
}

input[type=text] {
    user-select: none;
    background-color: #3CBC8D;
    color: white;
}

form {
    position: fixed;
    right: 5px;
    top: 5px;
}

input[type="image"] {
    border-radius: 20px;
}

input[type="image"]:hover {
    filter: brightness(80%)
}

/* menu */
.active {
    background-color: aquamarine;
    color: gray;
}

ul {
    font-family: sans-serif;
    list-style-type: none;
    margin: 0;
    padding: 0;
    overflow: hidden;
    background-color: #333;
}

li {
    float: left;
}

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

li a:hover:not(.active), .dropdown:hover .dropbtn {
    background-color: darkcyan;
}

li.dropdown {
    display: inline-block;
}

.dropdown-content {
    display: none;
    position: absolute;
    background-color: #5f5f5f;
    min-width: 160px;
    box-shadow: 0px 8px 16px 0px rgba(0,0,0,0.2);
}

.dropdown-content a {
    color: black;
    padding: 12px 16px;
    text-decoration: none;
    display: block;
    text-align: left;
}

.dropdown-content a:hover {
    background-color: #f1f1f1
}

.dropdown:hover .dropdown-content {
    display: block;
}