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

body {
    width: 100vw;
    background-color: seagreen;
}

header {
    width: 100%;
    margin: auto;
}

nav {
    width: 100%;
    margin: auto;
    height: 50px;
    background-color: red;
}

ul {
    display: flex;
    flex-direction: row;
    margin: 0px auto;
    justify-content: center;
    background-color: blue;
    height: 100%;
    width: 100%;
}

.navigation {
    list-style-type: none;
    width: 120px;
    padding: 5px;
    background-color: fuchsia;
    text-align: center;
    text-decoration: none;
    border: 2px solid black;
    margin: 0 10px;
    height: 100%;
    text-decoration: none;
    font-weight: bold;
    font-size: 1.1em;
}

a:hover {
    background-color: rgb(117, 0, 117);
    color: #FFF;
}

.container {
    padding:20px 0;
    margin: 0px auto;
    width: 60%;
    background-color: purple;
    margin: 0 auto;
    display: flex;
    flex-flow: row wrap;
    gap: 20px;
    justify-content: center;
}

.block {
    width: 400px;
    height: 400px;
    background-color: yellow;
    border: 4px solid orangered;
    box-shadow: 8px 8px rgb(95, 45, 22);
    text-align: center;
    padding-top:10%;
    font-size: 30pt;
}

.transparent {
    width: 400px;
    height: 400px;
    background-color: rgba(187, 255, 248, 0.199);
}

footer{
    height:100px;
    background-color: aqua;
}

@media screen and (max-width:900px) {

    body {
        width: auto;
    }

    .container {
        flex-wrap: wrap;
        flex-direction: column;
        width: 80%;
    }

    .transparent {
        display: none;
    }

    ul {
        flex-direction: row;
        flex-wrap: wrap;
        width: 80%;
    }

    li {
        margin: 0;
    }

    nav {
        height: auto;
    }

    .block {
        width: 250px;
        height: 250px;
        margin: 20px auto 20px auto;
    }

    .block:nth-child(even) {
        background-color: chartreuse;
        border-color: blue;
        box-shadow: 8px 8px black;
    }

    .desktop {
        display: none;
    }

    .navigation {
        width:100%;
        margin:2px auto;
    }

}

@media screen and (max-width: 1300px) {
    .transparent {
        display: none;
    }
}