body {
    font-family: system-ui, sans-serif;
}
header, main, footer {
    max-width: 900px;
    font-size: 1em;
    padding: 1em;
    margin: 0.5em auto;
}
header, footer {
    text-align: center;
}

h1 {
    font-size: 2.5em;
    margin-top: 0;
}
h2 {
    font-size: 1.4em;
    color: #770000;
/*    text-decoration: underline solid 4px #770000;
    border-bottom-style: solid;
    border-bottom-color: black;*/
}
h3 {
    font-size: 1.2em;
}

h4 {
    font-size: 1em;
}

code {
    background-color: #eeeeee;
    padding: 0.1em;
}
pre {
    margin-bottom: 1.5em;
    padding-top: 1em;
    padding-bottom: 1em;
    background-color: #eeeeee;
    overflow-y: auto;
    border-radius: 8px;
}
blockquote {
    margin-top: 2em;
    padding-left: 1em;
    border-left: 0.3em solid  black;
}
img {
    max-width: 100%;
    border-radius: 25px;
}

section {
    display: flex;
    flex-flow: row wrap;
    align-items: start;
    justify-content: space-around;
    gap: 50px;
    padding-top: 2em;
    padding-bottom: 2em;
}

.f {
    width: 360px;
}

.b0 {
    background-color: #ffffff;
}    

.b1 {
    background: linear-gradient(#e2e2e2, #f7f7f7);
    text-align: center;
    padding-top: 20px;
    padding-bottom: 20px;
}    

.content {
    max-width: 1200px;
    margin: 0.5em auto;
}

a {
    color: #770000;
}

.pad {
    padding-left: 2em;
    padding-right: 2em;
}

h4 {
    margin-top: 10px;
    margin-bottom: 8px;
}

p {
    margin-top: 8px;
}

.rl {
    border-top: solid 1px #770000;
}
