style: optimize gitalk plugin dark mode style

source/css/layout/_partial/comment/gitalk.styl

@@ -174,11 +174,10 @@ $gt-size-avatar-mobi := em(32px)
       &-login
         margin-right: 0
       &-preview
-        background-color: $gt-color-btn
+        background-color: var(--background-color)
         color: $gt-color-main
         &:hover
-          background-color: darken($gt-color-btn, 5%)
-          border-color: lighten($gt-color-main, 20%)
+          background-color: var(--magic-background-color)
       &-public
         &:hover
           background-color: lighten($gt-color-main, 20%)
@@ -298,20 +297,21 @@ $gt-size-avatar-mobi := em(32px)
       min-height: em(82px)
       max-height: em(240px)
       border-radius: $gt-size-border-radius
-      border: 1px solid $gt-color-input-border
+      border: 1px solid var(--border-color)
       font-size: em(14px)
       word-wrap: break-word
       resize: vertical
-      background-color: $gt-color-input-bg
+      color: var(--normal-text-color)
+      background-color: var(--fourth-text-color)
       outline: none
       transition: all 0.25s ease
       &:hover
-        background-color: lighten($gt-color-input-bg, 50%)
+        background-color: var(--background-color)
     &-preview
       padding: em(12px)
       border-radius: $gt-size-border-radius
-      border: 1px solid $gt-color-input-border
-      background-color: $gt-color-input-bg
+      border: 1px solid var(--border-color)
+      background-color: var(--background-color)
     &-controls
       position: relative
       margin: em(12px) 0 0
@@ -419,7 +419,8 @@ $gt-size-avatar-mobi := em(32px)
       top: 0
       right: 0
     &-body
-      color: $gt-color-comment-txt !important
+      //color: $gt-color-comment-txt !important
+      color: var(--second-text-color) !important
       .email-hidden-toggle a
         display: inline-block;
         height: 12px;
@@ -446,7 +447,7 @@ $gt-size-avatar-mobi := em(32px)
         display: block
     &-admin
       .gt-comment-content
-        background-color: $gt-color-comment-adminbg
+        background-color: var(--fourth-text-color)
 
   @keyframes gt-kf-rotate
     0%

source/css/layout/common/variables.styl

@@ -97,9 +97,9 @@ $default-font-weight = 400;
   --magic-background-color: $magic-background-color;
   --primary-color: $primary-color;
   --first-text-color: $first-text-color;
-  --fourth-text-color: $fourth-text-color;
   --second-text-color: $second-text-color;
   --third-text-color: $third-text-color;
+  --fourth-text-color: $fourth-text-color;
   --normal-text-color: $normal-text-color;
   --border-color: $border-color;
   --selection-color: $selection-color;