Css

Align center:
.button{
display: inline-flex;
align-items:center;
}
or:

section {
display: grid;
place-items: center;
}

Text centered:
ul{
width: max-content;
margin: 0 auto;
text-align: left;
}

Video Aspect Ratio:

aspect-ratio:16/9;

div{ /* for video YouTube Keep the same shape */

aspect-ratio:16/9;

}

100 CSS tricks with code here:

1linelayouts.glitch.me