html {
    overflow-y: scroll;
}

main {
    display: grid;
}

body {
    background: #fff;
    font-family: 'Courier New';
    margin: 0;
    padding: 0;
    -webkit-animation: random 60s infinite;
    animation: random 60s infinite;
}

@keyframes  random {
    12.5% { background: red; } 
    25% { background: orangered; }
    37.5% { background: yellow; } 
    50% { background: green; } 
    62.5% { background: blue; }
    75% { background: indigo; }
    87.5% { background: violet; }
    100% { background: white; }      
}

header {
    background: black;
    border-bottom: 1px solid white;
    padding: 20px;
}

section {
    color: white;
    font-size: 2.5em;
    text-align: center;
    float: top;
}

nav {
    text-align: center;
    position: sticky;
    top: 0px;
}

ul {
    margin: 1em 0 1em 0;
    font-size: 25px;
    list-style-type: none;
    padding-left: 0;
}

li {
    border: solid 1px white;
    margin-left: 2em;
    padding: 0.3em 1em 0.3em 1em;
    text-align: center;
    display: inline;
}

footer {
    text-align: center;
    color: white;
}

/* NADPISY */

h1 {
    text-align: center;
    font-weight: normal;
    font-size: 50px;
    letter-spacing: 60px;
    margin-left: 4%;
}

h2 {
    text-align: center;
    font-weight: normal;
    font-size: 50px;
    margin-top: 2.5%;
    margin-right: 25%;
    margin-left: 25%;
    padding-top: 2%;
    padding-bottom: 2%;
    letter-spacing: 5px;
    border: 1px solid white;
    background-color: black;
}

h3 {
    text-align: center;
    font-weight: normal;
    font-size: 1.2em;
    margin-top: 2.5%;
    margin-right: 35%;
    margin-left: 35%;
    padding: 2%;
    letter-spacing: 5px;
    border: 1px solid white;
    background-color: black;
}

/* OBRAZKY */

img {
    width: 33%;
}

/* ODKAZY */

a {
    text-decoration: none;
}

a, a:visited  {
    color: white;
}

a:hover {
    color: lightgrey;
}

a:active {
    color: #424949;
}

/* TEXT NA INDEXU */

.about {
    font-size: 25px;
    letter-spacing: 2px;
    border: 1px solid white;
    background-color: black;
    padding: 1em;
    margin: 4em 6em 2em 6em;
}

/* ENERGY DRINKY */

.item {
    width: 10em;
    border: 1px solid white;
    background-color: black;
    display: inline-block;
    padding: 1em;
    margin: 1em;    
}
.title {
    font-size: 1.2em;
}
.thumb {
    width: 100px;
    padding: 1em 0 1em 0;
}
.score {
    font-size: 1.2em;
}

/* TISK */

@media only print {
    nav, aside, header, footer {
        display: none;    
    }

    body {
        font-family: 'Times New Roman';
    }

    h2, h3 {
        margin: 0;
        color: black;
    }

    .about {
        margin: 1em;
        color: black;
    }

    .thumb {
        width: 65px;
    }

    .title {
        font-size: 20px;
        color: black;
    }

    .score {
        font-size: 20px;
        color: black;
    }

    .item {
        width: 4em;
        border: 1px solid black;
        margin: 1em;
    }
    
}

/* RESPONZIVITA */

@media only screen and (max-width: 600px) {
    li {
        margin-left: 20%;
        margin-right: 20%;
    }

    h2 {
        font-size: 1em;
        margin-top: 0.5em;
    }
        
    h3 {
        margin-top: 0.5em;
        font-size: 0.7em;
        margin-left: 4em;
        margin-right: 4em;
    }

    .item {
        width: 5em;
    }

    .title {
        font-size: 1em;
    }

}

@media only screen and (max-width: 960px) and (min-width: 601px) {
    li {
        margin-left: 35%;
        margin-right: 35%;
    }

    h2 {
        letter-spacing: 0;
        font-size: 0.9em;
        margin-top: 0.5em;
    }

    h3 {
        letter-spacing: 0;
        font-size: 0.9em;
        margin-top: 0.5em;
        margin-left: 5em;
        margin-right: 5em;
    }

}

@media only screen and (max-width: 960px) {

    h1 {
        letter-spacing: 0;
    }

    h2 {
        letter-spacing: 0;
    }

    h3 {
        letter-spacing: 0;
    }

    ul {
        padding: 0;
        margin: 0;
    }

    li {
        display: block;
        text-align: center;
        border: 1px solid white;
        padding: 0.5em 0.5em 0.5em 0.5em;
    }

    .about {
        letter-spacing: 0;
        font-size: 0.5em;
        margin: 1em 2.5em 1em 2.5em;
    }

}