fix some scss issue

Author: NichtsHsu

_sass/addon/commons.scss

@@ -80,7 +80,6 @@ h5 {
 
 img {
   max-width: 100%;
-  height: auto;
   transition: all 0.35s ease-in-out;
 
   .blur & {

_sass/colors/typography-light.scss

@@ -73,6 +73,7 @@
   --footnote-target-bg: lightcyan;
   --tb-odd-bg: #fbfcfd;
   --tb-border-color: #eaeaea;
+  --tb-shade-color: 0, 0, 0;
   --dash-color: silver;
   --kbd-wrap-color: #bdbdbd;
   --kbd-text-color: var(--text-color);