CSS coding looks great in visual code studio- but not cpanel?

[Nightmares]

So basically I have spent the last 48 hours designing and coding my layout since i am done learning front end (or most of it, anyways)... I have coded everything perfectly in visual code studio... got the visual that I liked and went to upload it to my sites cpanel. Mobile view reflects what I am seeing on visual code studio but desktop view is not reflecting anything like it...

My Site<-- for you to see yourself.

Here is the CSS code for the date/time and I don't think this would be a javascript issue? No matter what I input on cpanel, changes also do not reflect to browser..

/*Date & Time*/
.datetime{
    position: relative;
    margin-left: 100px;
    margin-right: 100px;
    color: white;
    left: 150px;
    top: 200px;
    width: 200px;
}
.time{
    position:absolute;
    top: 20px;
    font-size: 15px;
}
.date{
    position: absolute;
    top: 40px;
    font-size: 13px;

}

(also attached pictures)

 

[menator01]

I really do not know html that much but, in the past I think most would have separate css for views. One for mobile apps and one for desktop view.
Using this site for instance. My desktop view is different than the one on my phone.
Just a thought.

 

[OldMan]

menator01 is half right. Noone makes multiple sites anymore, they use responsive design https://www.w3schools.com/html/html_responsive.asp
All modern browsers have a responsive design mode where you can view the differences at different settings. Personally, I design for the smallest viewport, 320px, and 1900px for the largest - although people can watch on their 85inch TV screens
Design for the smallest screen and go from there. If you need help come on back.