Update files/en-us/web/accessibility/understanding_colors_and_luminan…

…ce/index.html

Co-authored-by: Eric Bailey <ericwbailey@users.noreply.github.com>

files/en-us/web/accessibility/understanding_colors_and_luminance/index.html

@@ -163,7 +163,7 @@ <h3 id="CSS_Color_Level_3_notations">CSS Color Level 3 notations:</h3>
 
 <p>Shown after that, we can use a hex value. Hex value means "hexadecimal," where the 0-255 integer is represented by two digits that each range from 0-15. As there are no Arabic numerals above 9, we use the letters a-f to represent 10-15. We add the '#' symbol to indicate the value is hex. Thus, #ff = 255.
 
-<p>In some of the examples above, you'll notice that some have a fourth value which is called “alpha”, the A in RGBA. The alpha channel is not a color channel, but defines transparency in terms of the opacity value of the color. A higher value means the color is more opaque therefore less transparent. In the examples above, the alpha value is set to half or 50% opaque.</p>
+<p>In some of the previous examples, you'll notice that some have a fourth value which is called “alpha”, the A in RGBA. The alpha channel is not a color channel, but defines transparency in terms of the opacity value of the color. A higher value means the color is more opaque therefore less transparent. In the examples above, the alpha value is set to half or 50% opaque.</p>
 
 
 <h3 id="sRGB_the_accessible_colorspace">sRGB: the accessible colorspace </h3>