This is a simple little grid showing all the variations for a single primary of the R G B colors for web use. But most of these colors will not be seen. Remember the limitations of web browsers and the 216 Color Web-Safe palette. No graphics were used to create this color grid - all the colors are generated by the Hex codes used in the HTML layout.
Notice the change from solid Black at the upper left corner to only 100% Blue at the lower right of the grid. Hold your cursor over a color block to see the RGB / Hex color code. The codes are spread apart for inspection and are actually written all together. Ex: #000000