feat(ui): improve visibility of inline code (cotes2020#1831)

Author: cotes2020

_sass/addon/syntax.scss

@@ -102,7 +102,7 @@ code {
 
   &.highlighter-rouge {
     font-size: $code-font-size;
-    padding: 3px 5px;
+    padding: 3px 6px;
     word-break: break-word;
     border-radius: 4px;
     background-color: var(--inline-code-bg);

_sass/colors/syntax-dark.scss

@@ -7,7 +7,7 @@
   --highlight-bg-color: #151515;
   --highlighter-rouge-color: #c9def1;
   --highlight-lineno-color: #808080;
-  --inline-code-bg: #323238;
+  --inline-code-bg: rgba(255, 255, 255, 0.05);
   --code-color: #b0b0b0;
   --code-header-text-color: #6a6a6a;
   --code-header-muted-color: #353535;

_sass/colors/syntax-light.scss

@@ -8,17 +8,13 @@
   --highlight-bg-color: #f6f8fa;
   --highlighter-rouge-color: #3f596f;
   --highlight-lineno-color: #9e9e9e;
-  --inline-code-bg: #f6f6f7;
+  --inline-code-bg: rgba(25, 25, 28, 0.05);
   --code-color: #3a3a3a;
   --code-header-text-color: #a3a3a3;
   --code-header-muted-color: #e5e5e5;
   --code-header-icon-color: #c9c8c8;
   --clipboard-checked-color: #43c743;
 
-  [class^='prompt-'] {
-    --inline-code-bg: #fbfafa;
-  }
-
   /* --- Syntax highlight theme from `rougify style github` --- */
 
   .highlight table td {