added text preprocessor

Author: khan4019

css.html

@@ -316,8 +316,9 @@ <h2>7. specificity </h2>
 
 <div id="mark">
   <h2>8. box model</h2>
-  <p><strong>Question:</strong> Why you should care aobut css box model?</p>
-  <p><strong>Answer:</strong> everything in a web page is a box where you can control size, position, background, etc. Each box/content area is optionally surrounded by padding, border and margin. When you set height and widht of an element, you set content height and width</p>
+  <p><strong>Question:</strong> What is css box model?</p>
+  <p><strong>Answer:</strong> everything in a web page is a box where you can control size, position, background, etc. Each box/content area is optionally surrounded by padding, border and margin. When you set height and widht of an element, you set content height and width.</p>
+  <p>Technically, height, width, padding and border are part of box model and margin is related to it.</p>
   <p>ref: <a href="http://www.w3.org/TR/CSS21/box.html">W3: box model</a>, <a href="http://css-tricks.com/the-css-box-model/">css box model</a></p>
   <div>
     <button id = "boxModel" type="button" class="toggleExample btn btn-primary">show example</button>
@@ -480,10 +481,10 @@ <h2>18. sprite</h2>
 </div>
 <div id="mtuli_lang">
   <h2>19. pre processor</h2>
-  <p><strong>Question:</strong> Have you used any preprocessor? What are the reasons to use preprocessor?</p>
-  <p><strong>Answer:</strong> learn sass or pass away.</p>
+  <p><strong>Question:</strong> What are the reasons to use preprocessor?</p>
+  <p><strong>Answer:</strong> you write css in high level with some special syntax (declaring variable, nested syntax, mathmetical operations, etc.) and that is compiled to css. Preprocessor helps you to speed up develop, maintain, ensure best practices and also confirms concatenation, compression, etc.</p>
 
-  ref: <a href="http://www.frontendjournal.com/most-common-technical-interview-question-for-frontend-developers/">most common interview questions</a>
+  ref: <a href="http://css-tricks.com/musings-on-preprocessing/">css preprocessor</a>, <a href="https://developers.google.com/chrome-developer-tools/docs/css-preprocessors">working with preprocessor</a>
 </div>
 <div id="download_order">
   <h2>20. show & tell</h2>