Good to see the way you coded , you have used ul and li elements where I have used buttons instead. I see one difference from the design is that the content in h2 is near to h1 tag in the design,rest is good, I learnt some thing new from this code
I see your code and few suggestions from my side , you used
{
position: absolute;
top:50% ;
left:50%;
}
Inorder to align the item in the middle we can keep
{
margin: auto;
}
it will align the item in the middle of the viewport width, Hope it helps