🔥 Use CSS object-fit: contain; and object-fit: cover; to scale 100% width and 100% height images as large as they will go without messing up aspect ratios.
Works with <video> in most browsers except IE+Edge
🔥 With CSS variables, you can overwrite values when authoring HTML with an inline style attribute
🔥 You can set and use variables inside a CSS declaration. Handy for when you need the same value more than once!