h1{
    background-color: chartreuse;
    text-align: center;
    width: 800px;
    margin: 10px auto;
    border: 4px solid black;
    height: 100px;
    line-height: 100px;
    transition: 3s;
}
h1:hover{
    background-color: red;
    font-size: 500%;
    transition: 3s;
}
ul{
    margin: 10px auto;
    width: 800px;
    padding: 0;
}
li{
    width: 154px;
    float: left;
    list-style: none;
    border: 3px solid black;
}
.ds {
    background-color: cyan;
}
.ds2 {
    background-color: lightblue;
}
.ds:hover {
    border-radius: 50px;
    transition: 3s;
}
.ds2:hover {
    border-radius: 50px;
    transition: 3s;
}
video{
    display: block;
    margin: 10px auto;
    width: 800px;
    border: 3px solid black;
}