* {
    box-sizing: border-box;
    font-size: 18px;
    font-family: Arial, Helvetica, sans-serif;
    letter-spacing: 0.05rem;
    margin: 0;
}

html, body {
    height: 100%;

    --height-hf: 3rem;
}

nav{
    background-image: linear-gradient(to right, #610766, #600078, #58008c, #4500a2, #050bba);

    color: #fefdff;
    height: var(--height-hf);
    text-align: end;
    padding-top: 1rem;
    padding-right: 0.5rem;
}

nav {
    position: fixed;
    top: 0;
    width: 100%;
}

nav  li {
    display: inline;
    padding: 2ch;
    color: white;
    text-decoration: none;
}

h1 {
    font-size: 3rem;
    text-align: center;
    font-variant: small-caps;
    color: #600078;
    margin-bottom: 3rem;
}

h2 {
    font-size: 2rem;
    padding: 0.5rem;
    text-align: center;
}

main {
    padding: 0.25rem 0.5rem;
    margin-top: var(--height-hf);
    margin-bottom: calc(var(--height-hf) * - 1);
}

body {
    min-height: 100svh;
    background-color: #fefdff;
    color: #030703;
    display: flex;
    flex-direction: column;
 } 

 footer {
    margin-top: auto;
    align-self: flex-end;
 }

 .flex-container {
    display: flex;
    justify-content: center;
    gap: 20%;
 }

 iframe {
    height: 75vh;
    width: 100%;
 }
 
 code {
    background-color: lightgrey;
 }

 .lists {
    color: inherit;
    background-color: aqua;
 }

 .exercise  a{
    display: block;

 }