css {
    margin: 0;  
    padding: 0; 
}
body{
      background-color: white;
    }
header {
    display: flex;
    justify-content: center;
}
.Logo, .Top_menu {
    margin-right: 20px;
    display: inline-block;
    vertical-align: middle;
}
.Top_menu li {
    margin-right: 20px;
    display: inline-block;
    vertical-align: middle;
}
.Top_menu a {
    font-family: "Courier New", Courier, monospace;
    font-size: 25px;
    color: blue;
    vertical-align: middle;
    text-decoration: none;
    transition: color 0.5s, background-color 0.5s;
}

@keyframes colorChange {
    0% { color: blue; }
    25% { color: red; }
    50% { color: green; }
    75% { color: purple; }
    100% { color: blue; }
}
.Logo {
    font-family: "Courier New", Courier, monospace;
    font-size: 40px; 
    color: black;
    vertical-align: middle;  
}
.It_by {
    font-family: Arial;
    font-size: 40px;
}
.content {
    margin-left: 20px;
}
pre {
    text-align: left;