CSS: update comments for sphinx_immaterial special cases

Author: mgeier

src/nbsphinx/_static/nbsphinx-code-cells.css_t

@@ -63,12 +63,14 @@ div.nblast.container {
 
 /* input prompt */
 div.nbinput.container div.prompt pre,
+/* for sphinx_immaterial theme: */
 div.nbinput.container div.prompt pre > code {
     color: #307FC1;
 }
 
 /* output prompt */
 div.nboutput.container div.prompt pre,
+/* for sphinx_immaterial theme: */
 div.nboutput.container div.prompt pre > code {
     color: #BF5B3D;
 }
@@ -206,8 +208,9 @@ div.nboutput.container div.output_area > div[class^='highlight']{
     overflow-y: hidden;
 }
 
-/* hide copybtn icon on prompts (needed for 'sphinx_copybutton' ext and `sphinx_immaterial` theme) */
+/* hide copy button on prompts for 'sphinx_copybutton' extension ... */
 .prompt .copybtn,
+/* ... and 'sphinx_immaterial' theme */
 .prompt .md-clipboard.md-icon {
     display: none;
 }