--- a/mail/base/content/systemIntegrationDialog.xhtml
+++ b/mail/base/content/systemIntegrationDialog.xhtml
@@ -5,17 +5,18 @@
 
 <?xml-stylesheet href="chrome://global/skin/global.css"?>
 
 <!DOCTYPE window>
 
 <window xmlns:html="http://www.w3.org/1999/xhtml"
         xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
         onload="gSystemIntegrationDialog.onLoad();"
-        data-l10n-id="system-integration-title">
+        data-l10n-id="system-integration-title"
+        style="min-width: 33em;">
 <dialog id="systemIntegrationDialog"
         buttons="accept,cancel"
         data-l10n-id="system-integration-dialog"
         data-l10n-attrs="buttonlabelaccept, buttonlabelcancel, buttonlabelcancel2">
 
   <script src="chrome://messenger/content/systemIntegrationDialog.js"/>
 
   <linkset>

--- a/mail/components/preferences/applicationManager.xhtml
+++ b/mail/components/preferences/applicationManager.xhtml
@@ -8,17 +8,17 @@
 <?xml-stylesheet href="chrome://messenger/skin/preferences/applications.css"?>
 
 <!DOCTYPE window>
 
 <window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
         xmlns:html="http://www.w3.org/1999/xhtml"
         onload="gAppManagerDialog.init();"
         data-l10n-id="app-manager-window-dialog"
-        data-l10n-attrs="style">
+        style="min-width: 30em;">
 <dialog id="appManager"
         buttons="accept,cancel">
 
   <script src="chrome://global/content/preferencesBindings.js"/>
   <script src="chrome://messenger/content/preferences/general.js"/>
   <script src="chrome://messenger/content/preferences/applicationManager.js"/>
 
   <commandset id="appManagerCommandSet">

--- a/mail/components/preferences/attachmentReminder.xhtml
+++ b/mail/components/preferences/attachmentReminder.xhtml
@@ -7,17 +7,17 @@
 
 <!DOCTYPE window>
 
 <window type="child"
         xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
         xmlns:html="http://www.w3.org/1999/xhtml"
         data-l10n-id="attachment-reminder-window"
         onload="gAttachmentReminderOptionsDialog.init();"
-        style="width:38em;">
+        style="min-width: 38em;">
   <dialog id="attachmentReminderOptionsDialog"
           dlgbuttons="accept,cancel">
     <script src="chrome://messenger/content/preferences/attachmentReminder.js"/>
 
     <linkset>
       <html:link rel="localization" href="branding/brand.ftl"/>
       <html:link rel="localization" href="messenger/preferences/attachment-reminder.ftl"/>
     </linkset>

--- a/mail/components/preferences/colors.xhtml
+++ b/mail/components/preferences/colors.xhtml
@@ -5,18 +5,17 @@
 
 <?xml-stylesheet href="chrome://global/skin/global.css"?>
 
 <!DOCTYPE window>
 
 <window type="child"
         xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
         xmlns:html="http://www.w3.org/1999/xhtml"
-        data-l10n-id="colors-dialog-window"
-        data-l10n-attrs="style">
+        data-l10n-id="colors-dialog-window">
   <dialog id="ColorsDialog"
           dlgbuttons="accept,cancel">
 
     <linkset>
       <html:link rel="localization" href="messenger/preferences/colors.ftl"/>
     </linkset>
 
     <hbox>

--- a/mail/components/preferences/connection.xhtml
+++ b/mail/components/preferences/connection.xhtml
@@ -7,17 +7,17 @@
 
 <?xml-stylesheet href="chrome://global/skin/global.css"?>
 <?xml-stylesheet href="chrome://messenger/skin/input-fields.css"?>
 
 <window type="child"
         xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
         xmlns:html="http://www.w3.org/1999/xhtml"
         data-l10n-id="connection-dialog-window"
-        data-l10n-attrs="style"
+        style="min-width: 49em;"
         onload="gConnectionsDialog.checkForSystemProxy();">
 <dialog id="ConnectionsDialog"
         dlgbuttons="accept,cancel">
 
   <linkset>
     <html:link rel="localization" href="messenger/preferences/connection.ftl"/>
     <html:link rel="localization" href="messenger/preferences/preferences.ftl"/>
     <html:link rel="localization" href="branding/brand.ftl"/>

--- a/mail/components/preferences/cookies.xhtml
+++ b/mail/components/preferences/cookies.xhtml
@@ -8,17 +8,16 @@
 
 <!DOCTYPE dialog>
 
 <window id="CookiesDialog"
         class="windowDialog"
         xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
         xmlns:html="http://www.w3.org/1999/xhtml"
         data-l10n-id="cookies-window-dialog"
-        data-l10n-attrs="style"
         onload="gCookiesWindow.init();"
         onunload="gCookiesWindow.uninit();"
         persist="width height">
 
   <script src="chrome://global/content/globalOverlay.js"/>
   <script src="chrome://global/content/editMenuOverlay.js"/>
   <script src="chrome://messenger/content/preferences/cookies.js"/>
 

--- a/mail/components/preferences/dockoptions.xhtml
+++ b/mail/components/preferences/dockoptions.xhtml
@@ -6,17 +6,17 @@
 <?xml-stylesheet href="chrome://global/skin/global.css"?>
 
 <!DOCTYPE window>
 
 <window type="child"
         xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
         xmlns:html="http://www.w3.org/1999/xhtml"
         data-l10n-id="dock-options-window-dialog"
-        data-l10n-attrs="style">
+        style="min-width: 33em;">
   <dialog id="DockOptionsDialog"
           dlgbuttons="accept,cancel">
 
     <linkset>
       <html:link rel="localization" href="messenger/preferences/dock-options.ftl"/>
     </linkset>
     <hbox orient="vertical">
 #ifdef XP_MACOSX

--- a/mail/components/preferences/messengerLanguages.xhtml
+++ b/mail/components/preferences/messengerLanguages.xhtml
@@ -5,17 +5,16 @@
    - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
 
 <?xml-stylesheet href="chrome://global/skin/global.css"?>
 
 <window type="child"
         xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
         xmlns:html="http://www.w3.org/1999/xhtml"
         data-l10n-id="messenger-languages-window"
-        data-l10n-attrs="title, style"
         onload="gMessengerLanguagesDialog.onLoad();">
 <dialog id="MessengerLanguagesDialog"
         buttons="accept,cancel">
 
   <linkset>
     <html:link rel="localization" href="branding/brand.ftl"/>
     <html:link rel="localization" href="messenger/preferences/languages.ftl"/>
   </linkset>

--- a/mail/components/preferences/passwordManager.xhtml
+++ b/mail/components/preferences/passwordManager.xhtml
@@ -7,17 +7,16 @@
 <?xml-stylesheet href="chrome://messenger/skin/shared/preferences/passwordmgr.css"?>
 
 <window id="SignonViewerDialog"
         xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
         xmlns:html="http://www.w3.org/1999/xhtml"
         onload="Startup();"
         onunload="Shutdown();"
         data-l10n-id="saved-logins"
-        style="width: 45em;"
         persist="width height">
 
   <linkset>
     <html:link rel="localization" href="branding/brand.ftl"/>
     <html:link rel="localization" href="messenger/preferences/passwordManager.ftl"/>
   </linkset>
   <script src="chrome://global/content/globalOverlay.js"/>
   <script src="chrome://global/content/editMenuOverlay.js"/>

--- a/mail/components/preferences/permissions.xhtml
+++ b/mail/components/preferences/permissions.xhtml
@@ -6,17 +6,16 @@
 
 <?xml-stylesheet href="chrome://global/skin/global.css"?>
 <?xml-stylesheet href="chrome://messenger/skin/input-fields.css"?>
 
 <!DOCTYPE dialog>
 
 <window id="PermissionsDialog" class="windowDialog"
         data-l10n-id="permissions-reminder-window"
-        data-l10n-attrs="style"
         xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
         xmlns:html="http://www.w3.org/1999/xhtml"
         onload="gPermissionManager.onLoad();"
         onunload="gPermissionManager.uninit();"
         persist="width height"
         onkeypress="gPermissionManager.onWindowKeyPress(event);">
 
   <script src="chrome://global/content/globalOverlay.js"/>

--- a/mail/extensions/openpgp/content/ui/keyWizard.xhtml
+++ b/mail/extensions/openpgp/content/ui/keyWizard.xhtml
@@ -11,17 +11,17 @@
 
 <!DOCTYPE window>
 
 <window type="child"
         xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
         xmlns:html="http://www.w3.org/1999/xhtml"
         onload="init();"
         lightweightthemes="true"
-        style="width: 50em;">
+        style="min-width: 50em;">
 <dialog id="openPgpKeyWizardDialog"
         data-l10n-id="key-wizard-dialog"
         data-l10n-attrs="buttonlabelaccept,buttonlabelextra1"
         buttons="accept,cancel">
 
     <script src="chrome://openpgp/content/ui/enigmailCommon.js"/>
     <script src="chrome://openpgp/content/ui/keyWizard.js"/>
     <script src="chrome://messenger/content/dialogShadowDom.js"/>

--- a/mail/locales/en-US/messenger/preferences/application-manager.ftl
+++ b/mail/locales/en-US/messenger/preferences/application-manager.ftl
@@ -1,11 +1,10 @@
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
 app-manager-window-dialog =
     .title = Application Details
-    .style = width: 30em; min-height: 20em;
 
 remove-app-button =
     .label = Remove
     .accesskey = R

--- a/mail/locales/en-US/messenger/preferences/colors.ftl
+++ b/mail/locales/en-US/messenger/preferences/colors.ftl
@@ -1,18 +1,14 @@
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
 colors-dialog-window =
     .title = Colors
-    .style = { PLATFORM() ->
-        [macos] width: 41em !important
-        *[other] width: 38em !important
-    }
 
 colors-dialog-legend = Text and Background
 
 text-color-label =
     .value = Text:
     .accesskey = T
 
 background-color-label =

--- a/mail/locales/en-US/messenger/preferences/connection.ftl
+++ b/mail/locales/en-US/messenger/preferences/connection.ftl
@@ -15,20 +15,16 @@ connection-dns-over-https-url-custom =
     .label = Custom
     .accesskey = C
     .tooltiptext = Enter your preferred URL for resolving DNS over HTTPS
 
 connection-dns-over-https-custom-label = Custom
 
 connection-dialog-window =
     .title = Connection Settings
-    .style = { PLATFORM() ->
-        [macos] width: 44em !important
-        *[other] width: 49em !important
-    }
 
 disable-extension-button = Disable Extension
 
 # Variables:
 #   $name (String) - The extension that is controlling the proxy settings.
 #
 # The extension-icon is the extension's icon, or a fallback image. It should be
 # purely decoration for the actual extension name, with alt="".

--- a/mail/locales/en-US/messenger/preferences/cookies.ftl
+++ b/mail/locales/en-US/messenger/preferences/cookies.ftl
@@ -1,15 +1,14 @@
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
 cookies-window-dialog =
     .title = Cookies
-    .style = width: 36em;
 
 window-close-key =
     .key = w
 
 window-focus-search-key =
     .key = f
 
 window-focus-search-alt-key =

--- a/mail/locales/en-US/messenger/preferences/dock-options.ftl
+++ b/mail/locales/en-US/messenger/preferences/dock-options.ftl
@@ -1,15 +1,14 @@
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
 dock-options-window-dialog =
     .title = App icon options
-    .style = width: 35em;
 
 dock-options-show-badge =
     .label = Show badge icon
     .accesskey = b
 
 bounce-system-dock-icon =
     .label = Animate the app icon when a new message arrives
     .accesskey = i

--- a/mail/locales/en-US/messenger/preferences/languages.ftl
+++ b/mail/locales/en-US/messenger/preferences/languages.ftl
@@ -18,17 +18,16 @@ languages-customize-select-language =
     .placeholder = Select a language to add…
 
 languages-customize-add =
     .label = Add
     .accesskey = A
 
 messenger-languages-window =
     .title = { -brand-short-name } Language Settings
-    .style = width: 40em
 
 messenger-languages-description = { -brand-short-name } will display the first language as your default and will display alternate languages if necessary in the order they appear.
 
 messenger-languages-search = Search for more languages…
 
 messenger-languages-searching =
     .label = Searching for languages…
 

--- a/mail/locales/en-US/messenger/preferences/permissions.ftl
+++ b/mail/locales/en-US/messenger/preferences/permissions.ftl
@@ -1,15 +1,14 @@
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
 permissions-reminder-window =
     .title = Exceptions
-    .style = width: 45em;
 
 permission-preferences-close-window =
     .key = w
 
 website-address-label =
     .value = Address of website:
     .accesskey = d
 

--- a/mail/themes/shared/mail/preferences/subdialog.css
+++ b/mail/themes/shared/mail/preferences/subdialog.css
@@ -64,15 +64,15 @@ xul|window > :is(xul|dialog, xul|hbox, x
   display: none;
 }
 
 .dialogFrame {
   margin: 10px;
   -moz-box-flex: 1;
   /* Default dialog dimensions */
   height: 12em;
-  width: 40ch;
+  min-width: 40ch;
 }
 
 .largeDialogContainer.doScroll {
   overflow-y: auto;
   -moz-box-flex: 1;
 }