It looked like your .main-f1 class was the container for the lights?
If so, you can set the width and height to the window height/width to keep the aspect ratio by using calc.
What I wrote below will give an aspect ratio of 2:1.
You will run into other problems if you try to make the window very narrow, so some additional code would be needed to keep the div from being larger than the window. I would probably incorporate a max-width, max-height as well. Hopefully this gets you moving in the right direction, though.
.main-f1{
height: 70vh;
width: calc(70vh * 2);
border: 2px solid red;
display: flex;
flex-direction: row;
}