Header 1 has rgba value with .5 alpha

Header 2 has a yellow background with red color text

Header 3 has background and .5 opacity

Header 4 uses hex values; 3 or 6.

RGB values can be discovered in web inspector or in Photoshop or using handy tools like http://htmlcolorcodes.com or simply google web color picker

Make gradients, too. Code can be generated on sites like: http://cssgradient.io

Make text gradients, too. Code can be generated on sites like: http://cssgradient.io