Small updates to intro

fixed some awkwardness and clarity of some opening statements

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

@@ -28,7 +28,7 @@
 
 <h2 id="Introduction_to_Color_and_Accessibility">Introduction to Color and Accessibility</h2>
 
-<p>When designing visual and readable content to be accessible to all sighted users, it is important to have an understanding of light, color, and perception. This page specifically discusses:</p>
+<p>When designing visual and readable content with the aim of accessibility for all sighted users, it is important to have an understanding of light, color, and perception. This page specifically discusses:</p>
 
 <ul>
   <li>luminance which is a linear measure of light</li>
@@ -37,7 +37,7 @@ <h2 id="Introduction_to_Color_and_Accessibility">Introduction to Color and Acces
   <li>how these interrelate and interact with design elements</li>
 </ul>
 
-<p>While understanding these is important for design and readability for all sighted users, it is especially true for those with reduced vision and color deficient vision, and also for those with certain neurological, cognitive, and other impairments.</p>
+<p>While understanding these concepts are important for design and readability for all sighted users, they are especially important for those with reduced vision and color deficient vision, and also for those with certain neurological, cognitive, and other impairments.</p>
 
 <h3 id="Standards_and_Guidelines">Standards and Guidelines</h3>
 
@@ -55,7 +55,8 @@ <h2 id="Color_basics">Color basics</h2>
 <p>We normally associate L, M, or S cone sensitivity with the sensation of red, green, and blue colors, respectively, the three primary colors of light. Specific red, green, and blue hues are used for the "color primaries" used in an RGB additive color model. The sRGB colorspace, the default standard colorspace for web content, is an example of an additive RGB color model.</p>
 
 <h3>RGB additive model</h4>
-<p>RGB is called an additive color model because it functions by adding light of different wavelengths in different proportions to stimulate the L, M, S cones in the eye to create a particular color perception. For instance when you see the color yellow on your monitor, the monitor is still only putting out red and green light. This stimulates the L and M cones similarly to how a "yellow" wavelength of light might. The red and green light do not "mix" in the air as if paint, they remain separate. The "mixing" happens in our vision system's neurological processing.</p>
+<p>RGB is called an additive color model because it functions by adding light of different wavelengths in different proportions to stimulate the L, M, S cones in the eye to create a particular color sensation. For instance when you see the color yellow on your monitor, the monitor is still only emitting red and green light. The separate red and green stimulate the L and M cones similarly to how a "yellow" wavelength of light might, as yellow is "in between" red and green. The red and green light do not "mix" in the air as if paint, they remain separate. The "mixing" happens in our vision system's neurological processing.</p>
+
 
 <figure>
   <img alt="An image of a block of red and of green, with a plus, over a bar of yellow with an equals sign" src="greenandredareyellow.svg">