Here's my advice: use color for the elements in your website, in opposite directions of a color wheel, for contrast, but not directly opposed or complementary, and find their additive-averaged color. In case you have chosen complementary colors, this additive-averaged color will have been grey #808080, which is neutral, but not impartial, because it will strengthen some hues more than others with the same saturation.
It's their chromatic content, which varies with lightness, that makes some colors appear brighter under the same background. You can check Hue on both HSV and LCH color models, but they will vary in Saturation and Value, Lightness and Chroma. Some colors will appear to be subdued, others will vibrate with neutral grey, unless you add the color values and find their mean.
Do this exercise: use #782121 for red, #217821 for green, #212178 for blue in Photoshop or Illustrator (Gimp or Inkscape). To find the opposite cyan, magenta and yellow, use #87DEDE, #DE87DE and #DEDE87, and average these colors from their RGB values for the adjacent pairs. You will have formed a color wheel. Now that you have it, pick colors so that they're not geometrically even (in triangles, squares and hexagons), because you will have darkened the resulting grey, when it should be closer to the lightness of the closest colors.
This illustration would not have worked with a black or white background, because the colors would be either pale or blackened against it, so I chose the grey that is the end result of an additive-averaging process. Give it a try! As a bonus, and since it is for a website, try to add your colors, not as images, but as formulas or values. Good work!
EDIT: Corrected the values for cyan, magenta and yellow.