* modal: support for setting class to body of iframe.

lib/modal/src/component/index.ts

@@ -1 +1,2 @@
 export * from './modal-dialog';
+export * from './modal-iframe-content';

lib/modal/src/component/modal-iframe-content.tsx

@@ -3,6 +3,7 @@ import {Component, createRef} from 'preact';
 export type ModalIframeContentProps = {
     url: string;
     watchHeight?: boolean;
+    iframeBodyClass?: string;
 };
 
 export type ModalIframeContentState = {
@@ -20,6 +21,10 @@ export class ModalIframeContent extends Component<ModalIframeContentProps> {
 
     state: ModalIframeContentState = {};
 
+    get iframeDoc() {
+        return this._ref.current?.contentWindow?.document;
+    }
+
     componentDidMount() {
         if (this.props.watchHeight) {
             this._watchIframeHeight();
@@ -30,12 +35,11 @@ export class ModalIframeContent extends Component<ModalIframeContentProps> {
         this._rob?.disconnect();
     }
 
-    _watchIframeHeight = () => {
-        const iframeDoc = this._ref.current?.contentWindow?.document;
+    _watchIframeHeight() {
+        const iframeDoc = this.iframeDoc;
         if (!iframeDoc) {
             return;
         }
-
         let rob = this._rob;
         rob?.disconnect();
         rob = new ResizeObserver(() => {
@@ -47,17 +51,33 @@ export class ModalIframeContent extends Component<ModalIframeContentProps> {
         rob.observe(iframeDoc.body);
         rob.observe(iframeDoc.documentElement);
         this._rob = rob;
+    }
+
+    _handleIframeLoad = () => {
+        const iframeDoc = this.iframeDoc;
+        if (!iframeDoc) {
+            return;
+        }
+
+        const {iframeBodyClass, watchHeight} = this.props;
+
+        if (watchHeight) {
+            this._watchIframeHeight();
+        }
+
+        if (iframeBodyClass) {
+            iframeDoc.body.classList.add(iframeBodyClass);
+        }
     };
 
     render() {
-        const {url, watchHeight} = this.props;
         return (
             <iframe
                 className="modal-iframe"
                 style={this.state}
-                src={url}
+                src={this.props.url}
                 ref={this._ref}
-                onLoad={watchHeight ? this._watchIframeHeight : undefined}
+                onLoad={this._handleIframeLoad}
             />
         );
     }