Delete `border-color : $border-color ;`.

src/client/styles/scss/_override-bootstrap-variables.scss

@@ -25,8 +25,6 @@ $gray-900: darken($dark, 5%) !default;
 $grays: ("50": $gray-50) !default;
 $red: #ff0a54 !default;
 
-
-
 //== Typography
 //
 //## Font, line-height, and color for body text, headings, and more.

src/client/styles/scss/theme/_apply-colors-dark.scss

@@ -14,7 +14,7 @@ $bgcolor-table-hover: lighten($bgcolor-table, 7.5%) !default;
 $bgcolor-sidebar-list-group: $bgcolor-list !default;
 $color-tags: #949494 !default;
 $bgcolor-tags: $dark !default;
-$border-color-toc: $gray-300 !default;
+$border-color-toc: $gray-500 !default;
 
 // override bootstrap variables
 $border-color: $gray-500;
@@ -38,7 +38,6 @@ select.form-control,
 textarea.form-control {
   color: lighten($color-global, 30%);
   background-color: darken($bgcolor-global, 5%);
-  border-color: $border-color;
   &:focus {
     background-color: $bgcolor-global;
   }
@@ -66,7 +65,7 @@ textarea.form-control {
 }
 
 .input-group input {
-  border-color: $border-color;
+  border-color: $secondary;
 }
 
 /*
@@ -355,13 +354,6 @@ ul.pagination {
   }
 }
 
-/*
- * admin settings
- */
-.admin-setting-header {
-  border-color: $border-color;
-}
-
 /*
 * grw-side-contents
 */
@@ -375,13 +367,6 @@ ul.pagination {
   }
 }
 
-/*
- * modal
- */
-.grw-modal-head {
-  border-color: $border-color;
-}
-
 /*
  * GROWI user page
  */

src/client/styles/scss/theme/_apply-colors-light.scss

@@ -314,13 +314,6 @@ $table-hover-bg: $bgcolor-table-hover;
   border-color: $border-color;
 }
 
-/*
- * modal
- */
-.grw-modal-head {
-  border-color: $border-color;
-}
-
 /*
  * GROWI user page
  */

src/client/styles/scss/theme/mixins/_list-group.scss

@@ -3,7 +3,6 @@
     .list-group-item {
       color: $color;
       background-color: $bgcolor;
-      border-color: $border-color;
 
       &.list-group-item-action {
         &:hover {