STEP-3: Specify image dimensions and serve scaled images
Specifying a width and height for all images allows for faster rendering by eliminating the need for unnecessary reflows and repaints.
Don’t use width and height specifications to scale images on the fly. If an image file is actually 60 x 60 pixels, don’t set the dimensions to 30 x 30 in the HTML or CSS. If the image needs to be smaller, scale it in an image editor and set its dimensions to match.