modified scroll bar position

resource/styles/scss/_layout_growi.scss

@@ -7,6 +7,7 @@
     &.affix {
       margin-top: 5px;
       top: calc(46px + 5px);
+      min-width: calc(#{100/12*2%} - #{$grid-gutter-width});  // width of 2column - padding
     }
 
     .revision-toc-content {