diff -up evolution-3.28.5/data/webview.css.frame-flattenning evolution-3.28.5/data/webview.css

--- evolution-3.28.5/data/webview.css.frame-flattenning	2018-07-30 15:37:05.000000000 +0200

+++ evolution-3.28.5/data/webview.css	2022-09-14 11:12:42.996943588 +0200

@@ -8,8 +8,8 @@ img {

 }

 body {

-  /* Use margin so that children can safely use width=100% */

-  margin: 5px 10px 5px 10px;

+  /* Use padding so that children can safely use width=100% */

+  padding: 8px;

 }

 th {

@@ -30,21 +30,21 @@ img#__evo-contact-photo {

 img.navigable {

   cursor: pointer;

-  margin-right: 4px;

+  padding-right: 4px;

 }

 .attachments {

   background: #FFF;

   border: 1px solid silver;

-  margin: 10px 10px 10px 10px;

+  padding: 10px 10px 10px 10px;

   border-left: 0;

   border-right: 0;

   border-bottom: 0;

 }

 .attachment {

-  margin-left: 8px;

-  margin-right: 0px;

+  padding-left: 8px;

+  padding-right: 0px;

 }

 .attachment td {

@@ -58,21 +58,21 @@ iframe:not([id$=".itip"]) {

 .part-container {

   height: 100%;

-  margin-top: 2px;

-  margin-bottom: 2px;

+  padding: 0px;

 }

 .part-container-nostyle iframe {

-  margin-right: 10px;

+  margin: 0px;

+  padding: 0px;

 }

 .part-container-inner-margin {

-  margin: 8px;

+  padding: 0px;

 }

 object { /* GtkWidgets */

-  margin-top: 2px;

-  margin-bottom: 2px;

+  padding-top: 2px;

+  padding-bottom: 2px;

 }

 .__evo-highlight {

@@ -139,7 +139,7 @@ th.rtl {

 /***** PRINTING *******/

 .printing-header {

-  margin-bottom: 20px;

+  padding-bottom: 20px;

 }

 .printing-header h1,

@@ -159,7 +159,7 @@ th.rtl {

 /******* ITIP *********/

 .itip.icon {

   float: left;

-  margin-right: 5px;

+  padding-right: 5px;

 }

 .itip.content {

@@ -168,7 +168,7 @@ th.rtl {

 }

 .itip.description {

-  margin: 5px;

+  padding: 5px;

 }

 .itip tr {

@@ -192,7 +192,7 @@ th.rtl {

 }

 #table_row_buttons img {

-  margin-right: 5px;

+  padding-right: 5px;

   vertical-align: middle;

 }

diff -up evolution-3.28.5/src/em-format/e-mail-formatter-text-plain.c.frame-flattenning evolution-3.28.5/src/em-format/e-mail-formatter-text-plain.c

--- evolution-3.28.5/src/em-format/e-mail-formatter-text-plain.c.frame-flattenning	2018-07-30 15:37:05.000000000 +0200

+++ evolution-3.28.5/src/em-format/e-mail-formatter-text-plain.c	2022-09-14 11:12:42.996943588 +0200

@@ -111,7 +111,7 @@ emfe_text_plain_format (EMailFormatterEx

 		string =

 			"

 			"-e-web-view-background-color -e-web-view-text-color\" "

-			"style=\"border: none; padding: 8px; margin: 0;\">";

+			"style=\"border: none; padding: 0px; margin: 0;\">";

 		g_output_stream_write_all (

 			stream, string, strlen (string),

diff -up evolution-3.28.5/src/mail/e-mail-display.c.frame-flattenning evolution-3.28.5/src/mail/e-mail-display.c

--- evolution-3.28.5/src/mail/e-mail-display.c.frame-flattenning	2018-07-30 15:37:05.000000000 +0200

+++ evolution-3.28.5/src/mail/e-mail-display.c	2022-09-14 11:12:42.997943589 +0200

@@ -1529,6 +1529,19 @@ mail_display_set_fonts (EWebView *web_vi

 	mail_display_get_font_settings (display->priv->settings, monospace, variable);

 }

+static gboolean

+mail_display_can_use_frame_flattening (void)

+{

+	guint wk_major, wk_minor;

+

+	wk_major = webkit_get_major_version ();

+	wk_minor = webkit_get_minor_version ();

+

+	/* The 2.38 is the last version, which supports frame-flattening;

+	   prefer it over the manual and expensive calculations. */

+	return (wk_major < 2) || (wk_major == 2 && wk_minor <= 38);

+}

+

 static void

 mail_display_web_view_initialize (WebKitWebView *web_view)

 {

@@ -1536,9 +1549,11 @@ mail_display_web_view_initialize (WebKit

 	webkit_settings = webkit_web_view_get_settings (web_view);

-	g_object_set (webkit_settings,

-		"enable-frame-flattening", TRUE,

-		NULL);

+	if (mail_display_can_use_frame_flattening ()) {

+		g_object_set (webkit_settings,

+			"enable-frame-flattening", TRUE,

+			NULL);

+	}

 }

 static void

diff -up evolution-3.28.5/src/modules/text-highlight/e-mail-formatter-text-highlight.c.frame-flattenning evolution-3.28.5/src/modules/text-highlight/e-mail-formatter-text-highlight.c

--- evolution-3.28.5/src/modules/text-highlight/e-mail-formatter-text-highlight.c.frame-flattenning	2018-07-30 15:37:05.000000000 +0200

+++ evolution-3.28.5/src/modules/text-highlight/e-mail-formatter-text-highlight.c	2022-09-14 11:12:42.997943589 +0200

@@ -122,16 +122,26 @@ text_hightlight_read_data_thread (gpoint

 {

 	TextHighlightClosure *closure = user_data;

 	gint nbuffer = 10240;

+	gssize read;

+	gsize wrote = 0;

 	gchar *buffer;

 	g_return_val_if_fail (closure != NULL, NULL);

 	buffer = g_new (gchar, nbuffer);

+	strcpy (buffer, "<style>body{margin:0; padding:8px;}</style>");

+	read = strlen (buffer);

+

+	if (!g_output_stream_write_all (closure->output_stream, buffer, read, &wrote, closure->cancellable, &closure->error) ||

+	    (gssize) wrote != read || closure->error) {

+		g_free (buffer);

+		return NULL;

+	}

+

 	while (!camel_stream_eos (closure->read_stream) &&

 	       !g_cancellable_set_error_if_cancelled (closure->cancellable, &closure->error)) {

-		gssize read;

-		gsize wrote = 0;

+		wrote = 0;

 		read = camel_stream_read (closure->read_stream, buffer, nbuffer, closure->cancellable, &closure->error);

 		if (read < 0 || closure->error)

diff -up evolution-3.28.5/src/web-extensions/e-dom-utils.c.frame-flattenning evolution-3.28.5/src/web-extensions/e-dom-utils.c

--- evolution-3.28.5/src/web-extensions/e-dom-utils.c.frame-flattenning	2018-07-30 15:37:05.000000000 +0200

+++ evolution-3.28.5/src/web-extensions/e-dom-utils.c	2022-09-14 11:12:42.997943589 +0200

@@ -837,9 +837,8 @@ set_iframe_and_body_width (WebKitDOMDocu

 		gchar *style;

 		/* Message main body */

-		local_width -= 8; /* 8 + 8 margins of body without iframes */

-		if (level > 1)

-			local_width -= 8;

+		local_width -= level * 20; /* 10 + 10 margins of body without iframes */

+		local_width -= 4;

 		style = g_strdup_printf ("width: %" G_GINT64_FORMAT "px;", local_width);

 		e_dom_utils_add_css_rule_into_style_sheet_in_document (

@@ -867,7 +866,7 @@ set_iframe_and_body_width (WebKitDOMDocu

 			style);

 		g_free (style);

-		local_width -= 2; /* 1 + 1 frame borders */

+		local_width -= 4; /* 2 + 2 frame borders */

 		style = g_strdup_printf ("width: %" G_GINT64_FORMAT "px;", local_width);

 		e_dom_utils_add_css_rule_into_style_sheet_in_document (

@@ -891,15 +890,11 @@ set_iframe_and_body_width (WebKitDOMDocu

 	} else {

 		gchar *style;

-		local_width -= 20; /* 10 + 10 margins of body with iframes */

-		local_width -= 8; /* attachment margin */

-		local_width -= 2; /* 1 + 1 frame borders */

+		local_width -= (level - 1) * 20; /* 10 + 10 margins of body with iframes */

+		local_width -= 4; /* 2 + 2 frame borders */

+		local_width -= 10; /* attachment margin */

-		/* We need to subtract another 10 pixels from the iframe width to

-		 * have the iframe's borders on the correct place. We can't subtract

-		 * it from local_width as we don't want to propagate this change

-		 * further. */

-		style = g_strdup_printf ("width: %" G_GINT64_FORMAT "px;", local_width - 10);

+		style = g_strdup_printf ("width: %" G_GINT64_FORMAT "px;", local_width);

 		e_dom_utils_add_css_rule_into_style_sheet_in_document (

 			document,

 			"-e-mail-formatter-style-sheet",

@@ -933,7 +928,7 @@ set_iframe_and_body_width (WebKitDOMDocu

 		if (level == 0) {

 			gchar *style = NULL;

-			tmp_local_width -= 8; /* attachment's margin */

+			tmp_local_width -= 10; /* attachment's margin */

 			style = g_strdup_printf ("width: %" G_GINT64_FORMAT "px;", tmp_local_width);

 			e_dom_utils_add_css_rule_into_style_sheet_in_document (

@@ -947,9 +942,7 @@ set_iframe_and_body_width (WebKitDOMDocu

 				"-e-mail-formatter-style-sheet",

 				".attachment-wrapper iframe[src*=\"__formatas=txt\"]",

 				style);

-			g_free (style);

-			style = g_strdup_printf ("width: %" G_GINT64_FORMAT "px;", local_width);

 			e_dom_utils_add_css_rule_into_style_sheet_in_document (

 				document,

 				"-e-mail-formatter-style-sheet",

@@ -992,8 +985,10 @@ dom_window_resize_cb (WebKitDOMDOMWindow

 	document = webkit_dom_dom_window_get_document (dom_window);

-	if (document)

+	if (document) {

 		e_dom_resize_document_content_to_preview_width (document);

+		e_dom_update_iframe_height (document);

+	}

 }

 static gboolean

@@ -1106,6 +1101,7 @@ e_dom_utils_e_mail_display_bind_dom (Web

 	e_dom_wrap_long_anchors (document);

 	e_dom_resize_document_content_to_preview_width (document);

+	e_dom_update_iframe_height (document);

 }

 void

@@ -1160,6 +1156,99 @@ e_dom_utils_e_mail_display_unstyle_block

 	g_clear_object (&collection);

 }

+static void

+e_dom_update_iframe_height_recursive (WebKitDOMDocument *document)

+{

+	WebKitDOMHTMLCollection *frames = NULL;

+	WebKitDOMHTMLElement *body;

+	gulong ii, length;

+

+	frames = webkit_dom_document_get_elements_by_tag_name_as_html_collection (document, "iframe");

+	length = webkit_dom_html_collection_get_length (frames);

+	for (ii = 0; ii < length; ii++) {

+		WebKitDOMHTMLIFrameElement *iframe;

+		WebKitDOMDocument *content_document;

+

+		iframe = WEBKIT_DOM_HTML_IFRAME_ELEMENT (webkit_dom_html_collection_item (frames, ii));

+

+		content_document = webkit_dom_html_iframe_element_get_content_document (iframe);

+		if (!content_document)

+			continue;

+

+		e_dom_update_iframe_height_recursive (content_document);

+	}

+

+	body = webkit_dom_document_get_body (document);

+	if (body) {

+		WebKitDOMDOMWindow *default_view;

+

+		default_view = webkit_dom_document_get_default_view (document);

+		if (default_view) {

+			WebKitDOMElement *frame_elem;

+

+			frame_elem = webkit_dom_dom_window_get_frame_element (default_view);

+			if (frame_elem) {

+				WebKitDOMHTMLIFrameElement *iframe = WEBKIT_DOM_HTML_IFRAME_ELEMENT (frame_elem);

+				WebKitDOMElement *body_elem = WEBKIT_DOM_ELEMENT (body);

+				glong scroll_height;

+				gchar *height;

+

+				scroll_height = webkit_dom_element_get_scroll_height (body_elem);

+				height = webkit_dom_html_iframe_element_get_height (iframe);

+				if (!height || scroll_height != (glong) g_ascii_strtoll (height, NULL, 10))

+					webkit_dom_html_iframe_element_set_height (iframe, "10");

+				g_free (height);

+

+				height = g_strdup_printf ("%" G_GINT64_FORMAT, (gint64) (scroll_height + 2 +

+					(webkit_dom_element_get_scroll_width (body_elem) > webkit_dom_element_get_client_width (body_elem) ? 20 : 0)));

+				webkit_dom_html_iframe_element_set_height (iframe, height);

+				g_free (height);

+			}

+		}

+

+		g_clear_object (&default_view);

+	}

+

+	g_clear_object (&frames);

+}

+

+static gboolean

+mail_display_can_use_frame_flattening (void)

+{

+	guint wk_major, wk_minor;

+

+	wk_major = webkit_get_major_version ();

+	wk_minor = webkit_get_minor_version ();

+

+	/* The 2.38 is the last version, which supports frame-flattening;

+	   prefer it over the manual and expensive calculations. */

+	return (wk_major < 2) || (wk_major == 2 && wk_minor <= 38);

+}

+

+void

+e_dom_update_iframe_height (WebKitDOMDocument *document)

+{

+	WebKitDOMDOMWindow *default_view;

+

+	if (mail_display_can_use_frame_flattening ())

+		return;

+

+	default_view = webkit_dom_document_get_default_view (document);

+	if (default_view) {

+		glong scroll_x, scroll_y;

+

+		scroll_x = webkit_dom_dom_window_get_scroll_x (default_view);

+		scroll_y = webkit_dom_dom_window_get_scroll_y (default_view);

+

+		e_dom_update_iframe_height_recursive (document);

+

+		if (scroll_y != webkit_dom_dom_window_get_scroll_y (default_view))

+			webkit_dom_dom_window_scroll_to (default_view, scroll_x, scroll_y);

+	}

+

+	g_clear_object (&default_view);

+}

+

 void

 e_dom_utils_eab_contact_formatter_bind_dom (WebKitDOMDocument *document)

 {

diff -up evolution-3.28.5/src/web-extensions/e-dom-utils.h.frame-flattenning evolution-3.28.5/src/web-extensions/e-dom-utils.h

--- evolution-3.28.5/src/web-extensions/e-dom-utils.h.frame-flattenning	2018-07-30 15:37:05.000000000 +0200

+++ evolution-3.28.5/src/web-extensions/e-dom-utils.h	2022-09-14 11:12:42.997943589 +0200

@@ -69,6 +69,7 @@ void		e_dom_utils_e_mail_display_bind_do

 						 GDBusConnection *connection);

 void		e_dom_utils_e_mail_display_unstyle_blockquotes

 						(WebKitDOMDocument *document);

+void		e_dom_update_iframe_height	(WebKitDOMDocument *document);

 WebKitDOMElement *

 		e_dom_utils_find_element_by_selector

 						(WebKitDOMDocument *document,

diff -up evolution-3.28.5/src/web-extensions/e-web-extension.c.frame-flattenning evolution-3.28.5/src/web-extensions/e-web-extension.c

--- evolution-3.28.5/src/web-extensions/e-web-extension.c.frame-flattenning	2018-07-30 15:37:05.000000000 +0200

+++ evolution-3.28.5/src/web-extensions/e-web-extension.c	2022-09-14 11:12:42.997943589 +0200

@@ -613,8 +613,10 @@ handle_method_call (GDBusConnection *con

 			e_dom_utils_hide_element (document, element_id, hidden);

-			if (expand_inner_data)

+			if (expand_inner_data) {

 				e_dom_resize_document_content_to_preview_width (document);

+				e_dom_update_iframe_height (document);

+			}

 		}

 		g_dbus_method_invocation_return_value (invocation, NULL);