Meta: move .yesno styling to shared style sheet

See whatwg/whatwg.org#457.

Author: annevk

styles.css

@@ -1,8 +1,6 @@
 :root {
   --bad-example-text: gray;
 
-  --yesno-yes-bg: yellow;
-
   --control-glyph-text: #d50606;
 
   --img-abstract-bg: #424242;
@@ -13,8 +11,6 @@
   :root {
     --bad-example-text: gray;
 
-    --yesno-yes-bg: #004000;
-
     --control-glyph-text: #d50606;
 
     --img-abstract-bg: #424242;
@@ -26,9 +22,6 @@ iframe { border: 0; }
 
 .bad, .bad *:not(.X\58X) { color: var(--bad-example-text); }
 
-.applies .yes, .yesno .yes { background: var(--yesno-yes-bg); }
-.yesno .yes, .yesno .no { text-align: center; }
-
 .applies thead th > * { display: block; }
 .applies thead code { display: block; }
 .applies td { text-align: center; }