move css about icon

src/client/styles/scss/_layout.scss

@@ -88,6 +88,12 @@ body {
   }
 }
 
+// page preview button in link form
+.btn-page-preview svg {
+  width: 18px;
+  height: 18px;
+}
+
 // printable style
 @media print {
   padding: 30px;

src/client/styles/scss/atoms/_buttons.scss

@@ -85,10 +85,3 @@
     }
   }
 }
-
-// page preview button in link form
-.btn-page-preview svg {
-  width: 18px;
-  height: 18px;
-  fill: white;
-}

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

@@ -233,6 +233,11 @@ pre:not(.hljs):not(.CodeMirror-line) {
   fill: $color-editor-icons;
 }
 
+// page preview button in link form
+.btn-page-preview svg {
+  fill: white;
+}
+
 /*
  * Modal
  */