Every web designer is taught to enter colors in hexadecimal values like #47B56C, but hex code can be like an alien language compared to the traditional RGB and CMYK color values that are familiar to photographers, videographers, and print designers. Luckily, entering colors using simpler RGB values is allowed in CSS, and it’s easy to do.
How big is a pixel? It’s widely thought that a pixel is the smallest dot that screen hardware can physically display: One pixel is one pixel. That was safe to assume for over a quarter century because the pixel density of most of our screens was stuck between 72 and 120 pixels per inch (ppi) during that era, even while everything else about our computers got exponentially faster and bigger. But screens would finally make their move, and for designers that would change how a pixel is defined.