header {
    text-align: center;
    text-decoration: underline;
    position: fixed;
    top: 0;
    left: 0;
    background-color: white;
    width: 100%;
    height: 10em;
}

main {
    padding: 9em 5% 5% 13em;
}

aside {
    position: fixed;
    top: 30%;
    left: 0;
    width: 12em;
    height: fit-content;
}

footer {
    text-align: right;
    position: fixed;
    bottom: 0;
    right: 0;
    background-color: grey;
    padding: 0.5em 1em;
    border-radius: 1em 0 0 0;
}

section {
    margin: 3% 0;
}

section li {
    margin: 1em;
}

.aktivni {
    background:red;
    border-color: darkblue;
    color: black;
}

.pribeh {
    font-style: italic;
    display: none;
}

.popis {
    font-style: normal;
    display: none;
}

.pravidla {
    font-style: normal;
    background: lightgrey;
    border: 2px solid darkgrey;
}

.priklad {
    font-family: Arial;
    display: none;
}

.poznamky {
    background-color: yellow;
    display: none;
}

p {
    margin: 0;
    text-indent: 2em;
    text-align: justify;
}

h3 {
    margin: 2em 0;
}

table {
    margin: 1em 5em;
}

table, table td, table th {
    border-collapse: collapse;
    border: 2px solid darkblue;
    padding: 5px;
}

.jizva th, .jizva td{
    text-align: center;
}

.spalujici {
    text-decoration: line-through;
}

.skryjbox {
    display: none;
}

.podpis {
    text-align: right;
    margin-top: 1em;
}

label {
    background: darkgray;
    border: 0.2em solid darkblue;
    border-radius: 2em;
    padding: 0.5em 1em;
    font-weight: bolder;
    color: darkblue;
    transition: 1s;
    position: fixed;
}

label:hover {
    color: red;
    border-color: red;
}

#lpribeh {
    top: 7em;
    left: 14em;
}

#lpopis {
    top: 7em;
    left: 25em;
}

#lpriklad {
    top: 7em;
    left: 35.5em;
}

#lpoznamky {
    top: 7em;
    left: 47em;
}

#spribeh:checked ~ article .pribeh {
    display: block;
}

#spopis:checked ~ article .popis {
    display: block;
}

#spriklad:checked ~ article .priklad {
    display: block;
}

#spoznamky:checked ~ article .poznamky {
    display: block;
}

.skryjbox:checked + label {
    background:red;
    border-color: darkblue;
    color:darkblue;
    transition: 2s;
}

:target::before {
    content: "";
    display: block;
    height: 10em;
    margin: -10em 0 0;
}

img {
    width: 40em;
    height: auto;
    padding: 1em;
}