fix: typo of variable fg-default & make copied button active bg color as a variable (#260)

Author: lianghx-319

core/src/styles/markdown.less

@@ -44,6 +44,7 @@
     --color-accent-emphasis: #1f6feb;
     --color-attention-subtle: rgba(187, 128, 9, 0.15);
     --color-danger-fg: #f85149;
+    --color-copied-active-bg: #2e9b33;
   }
 }
 
@@ -93,6 +94,7 @@
     --color-accent-emphasis: #0969da;
     --color-attention-subtle: #fff8c5;
     --color-danger-fg: #cf222e;
+    --color-copied-active-bg: #2e9b33;
   }
 }
 
@@ -405,7 +407,14 @@ body[data-color-mode*='light'] {
   kbd {
     display: inline-block;
     padding: 3px 5px;
-    font: 11px ui-monospace, SFMono-Regular, SF Mono, Menlo, Consolas, Liberation Mono, monospace;
+    font:
+      11px ui-monospace,
+      SFMono-Regular,
+      SF Mono,
+      Menlo,
+      Consolas,
+      Liberation Mono,
+      monospace;
     line-height: 10px;
     color: var(--color-fg-default);
     vertical-align: middle;
@@ -444,7 +453,14 @@ body[data-color-mode*='light'] {
   kbd {
     display: inline-block;
     padding: 3px 5px;
-    font: 11px ui-monospace, SFMono-Regular, SF Mono, Menlo, Consolas, Liberation Mono, monospace;
+    font:
+      11px ui-monospace,
+      SFMono-Regular,
+      SF Mono,
+      Menlo,
+      Consolas,
+      Liberation Mono,
+      monospace;
     line-height: 10px;
     color: var(--color-fg-default);
     vertical-align: middle;
@@ -530,13 +546,27 @@ body[data-color-mode*='light'] {
 
   tt,
   code {
-    font-family: ui-monospace, SFMono-Regular, SF Mono, Menlo, Consolas, Liberation Mono, monospace;
+    font-family:
+      ui-monospace,
+      SFMono-Regular,
+      SF Mono,
+      Menlo,
+      Consolas,
+      Liberation Mono,
+      monospace;
     font-size: 12px;
   }
   pre {
     margin-top: 0;
     margin-bottom: 0;
-    font-family: ui-monospace, SFMono-Regular, SF Mono, Menlo, Consolas, Liberation Mono, monospace;
+    font-family:
+      ui-monospace,
+      SFMono-Regular,
+      SF Mono,
+      Menlo,
+      Consolas,
+      Liberation Mono,
+      monospace;
     font-size: 12px;
     word-wrap: normal;
   }
@@ -1008,7 +1038,7 @@ body[data-color-mode*='light'] {
       display: flex;
       position: absolute;
       cursor: pointer;
-      color: var(--color-fg-defaul);
+      color: var(--color-fg-default);
       top: 6px;
       right: 6px;
       border-radius: 5px;
@@ -1036,7 +1066,7 @@ body[data-color-mode*='light'] {
     }
     &:hover .copied:active,
     .copied.active {
-      background: #2e9b33;
+      background: var(--color-copied-active-bg);
       color: var(--color-canvas-default);
     }
     .active {