fix: scss warning

Author: Chasen-Zhang

src/css/theme.scss

@@ -63,15 +63,7 @@
   --breadcrumbs-item-active: rgb(55 65 81);
   --doc-index-list-icon-bg: rgb(248 250 252);
   --card-hover-color: rgb(59 130 246);
-  
-  // mark
-  // ::selection {
-  //   color: #fff;
-  //   background: var(--color-primary);
-  //   cursor: none;
-  //   outline: none;
-  // }
-  // --ifm-font-family-base: 'Poppins', ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, Segoe UI, Roboto, Helvetica Neue, Arial, Noto Sans, sans-serif, Apple Color Emoji, Segoe UI Emoji, Segoe UI Symbol, Noto Color Emoji;
+  --ifm-font-family-base: 'Poppins', ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, Segoe UI, Roboto, Helvetica Neue, Arial, Noto Sans, sans-serif, Apple Color Emoji, Segoe UI Emoji, Segoe UI Symbol, Noto Color Emoji;
   --color-bg-0 : rgba(247,248,250,1.00);
   --color-bg-1 : rgba(255,255,255,1.00);
   --color-bg-2 : rgba(255,255,255,1.00);
@@ -215,7 +207,13 @@
   --blue-5: #0176F8;
   --indigo-5: rgb(94, 110, 195);
   --prism-color2: #393A34;
-  --prism-background-color2: #fff;;
+  --prism-background-color2: #fff;
+  ::selection {
+    color: #fff;
+    background: var(--color-primary);
+    cursor: none;
+    outline: none;
+  }
 }
 
 /* For readability concerns, you should choose a lighter palette in dark mode. */