* {
    padding: 0px;
    margin: 0px;
    box-sizing: border-box;
}

header>h1,
header>h2 {
    background-color: brown;
    color: lightgreen;
    text-align: center;
    font-family: 'Courier New', Courier, monospace;
    padding: 5px 20px;
}

header>h1 {
    font-size: 3rem;
}

header>h2 {
    font-size: 2, 2rem;
}

nav>ul {
    margin: 10px;
    list-style-type: none;
    display: flex;
    flex-direction: column;
}

nav>ul>li {
    width: 100%;
}

nav>ul>li>a {
    display: block;
    text-align: center;
    background-color: lightgray;
    padding: 10px 0px;
    border: black solid 1px;
}

nav>ul>li>a:active {
    background-color: darkgrey;
}


main {
    margin: 10px;
    min-height: 500px;
    background-color: aquamarine;
}

main>table {
    width: 100%;

}

main>table>tbody>tr>th {
    width: 33.33%;
}

main>table>thead>tr>th {
    background-color: rgb(228, 228, 228);
}

main>table>tbody>tr:nth-child(odd) {
    background-color: white;
}

main>table>tbody>tr:nth-child(even) {
    background-color: rgb(228, 228, 228);
}

main>table,
main>table>tbody>tr>th,
main>table>tbody>tr>td {
    border: black solid 3px;
    border-collapse: collapse;
}

main>section>table {
    border-spacing: 0px;
    padding: 10px
}

main>section>table>tbody>tr>td.small_red {
    width: 300px;
    height: 250px;
    background-color: red;
}

main>section>table>tbody>tr>td.big_red {
    width: 450px;
    height: 250px;
    background-color: red;
}

main>section>table>tbody>tr>td.cross {
    width: 100px;
    height: 100px;
    background-color: yellow;
}


footer {
    background-color: lightcyan;
}

/* surfplatta */
@media screen and (min-width: 600px) {

    header>h1,
    header>h2 {
        background-color: blueviolet;
    }

    main {
        max-width: 700px;
        margin: auto;
    }
}

/* dator */
@media screen and (min-width: 1000px) {

    header>h1,
    header>h2 {
        background-color: aqua;
    }

    nav>ul {
        flex-direction: row;
    }

}