diff --git a/res/css/views/dialogs/_CompoundDialog.pcss b/res/css/views/dialogs/_CompoundDialog.pcss
index b20c17cd2af..15df4f39511 100644
--- a/res/css/views/dialogs/_CompoundDialog.pcss
+++ b/res/css/views/dialogs/_CompoundDialog.pcss
@@ -27,6 +27,11 @@ limitations under the License.
 }
 
 .mx_CompoundDialog {
+    .mx_Dialog {
+        display: flex;
+        flex-direction: column;
+    }
+
     .mx_CompoundDialog_header {
         padding: 32px 32px 16px 32px;
 
@@ -49,6 +54,13 @@ limitations under the License.
         }
     }
 
+    .mx_CompoundDialog_form {
+        display: flex;
+        flex-direction: column;
+        min-height: 0;
+        max-height: 100%;
+    }
+
     .mx_CompoundDialog_content {
         overflow: auto;
         padding: 8px 32px;
@@ -57,10 +69,6 @@ limitations under the License.
     .mx_CompoundDialog_footer {
         padding: 20px 32px;
         text-align: right;
-        position: absolute;
-        bottom: 0;
-        left: 0;
-        right: 0;
 
         .mx_AccessibleButton {
             margin-left: 24px;
@@ -69,14 +77,17 @@ limitations under the License.
 }
 
 .mx_ScrollableBaseDialog {
+    display: flex;
+    flex-direction: column;
+
     width: 544px; /* fixed */
     height: 516px; /* fixed */
-
-    .mx_CompoundDialog_content {
-        height: 349px; /* dialogHeight - header - footer */
-    }
+    max-width: 100%;
+    min-height: 0;
+    max-height: 80%;
 
     .mx_CompoundDialog_footer {
         box-shadow: 0px -4px 4px rgba(0, 0, 0, 0.05); /* hardcoded colour for both themes */
+        z-index: 1; /* needed to make footer & shadow appear above dialog content */
     }
 }
diff --git a/src/components/views/dialogs/ScrollableBaseModal.tsx b/src/components/views/dialogs/ScrollableBaseModal.tsx
index 32975c6833a..97ddbda2c98 100644
--- a/src/components/views/dialogs/ScrollableBaseModal.tsx
+++ b/src/components/views/dialogs/ScrollableBaseModal.tsx
@@ -96,7 +96,7 @@ export default abstract class ScrollableBaseModal<
                             aria-label={_t("Close dialog")}
                         />
                     </div>
-                    <form onSubmit={this.onSubmit}>
+                    <form onSubmit={this.onSubmit} className="mx_CompoundDialog_form">
                         <div className="mx_CompoundDialog_content">{this.renderContent()}</div>
                         <div className="mx_CompoundDialog_footer">
                             <AccessibleButton onClick={this.onCancel} kind="primary_outline">
diff --git a/test/components/views/elements/__snapshots__/PollCreateDialog-test.tsx.snap b/test/components/views/elements/__snapshots__/PollCreateDialog-test.tsx.snap
index 1bcf17dcd42..7e60d633599 100644
--- a/test/components/views/elements/__snapshots__/PollCreateDialog-test.tsx.snap
+++ b/test/components/views/elements/__snapshots__/PollCreateDialog-test.tsx.snap
@@ -1,7 +1,7 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP
 
-exports[`PollCreateDialog renders a blank poll 1`] = `"<div data-focus-guard="true" tabindex="0" style="width: 1px; height: 0px; padding: 0px; overflow: hidden; position: fixed; top: 1px; left: 1px;"></div><div data-focus-lock-disabled="false" role="dialog" aria-labelledby="mx_CompoundDialog_title" aria-describedby="mx_CompoundDialog_content" class="mx_CompoundDialog mx_ScrollableBaseDialog"><div class="mx_CompoundDialog_header"><h1>Create poll</h1><div aria-label="Close dialog" role="button" tabindex="0" class="mx_AccessibleButton mx_CompoundDialog_cancelButton"></div></div><form><div class="mx_CompoundDialog_content"><div class="mx_PollCreateDialog"><h2>Poll type</h2><div class="mx_Field mx_Field_select"><select type="text" id="mx_Field_1"><option value="org.matrix.msc3381.poll.disclosed">Open poll</option><option value="org.matrix.msc3381.poll.undisclosed">Closed poll</option></select><label for="mx_Field_1"></label></div><p>Voters see results as soon as they have voted</p><h2>What is your poll question or topic?</h2><div class="mx_Field mx_Field_input mx_Field_labelAlwaysTopLeft mx_Field_placeholderIsHint"><input id="poll-topic-input" maxlength="340" label="Question or topic" placeholder="Write something..." type="text" value=""><label for="poll-topic-input">Question or topic</label></div><h2>Create options</h2><div class="mx_PollCreateDialog_option"><div class="mx_Field mx_Field_input mx_Field_labelAlwaysTopLeft mx_Field_placeholderIsHint"><input id="pollcreate_option_0" maxlength="340" label="Option 1" placeholder="Write an option" type="text" value=""><label for="pollcreate_option_0">Option 1</label></div><div role="button" tabindex="0" class="mx_AccessibleButton mx_PollCreateDialog_removeOption"></div></div><div class="mx_PollCreateDialog_option"><div class="mx_Field mx_Field_input mx_Field_labelAlwaysTopLeft mx_Field_placeholderIsHint"><input id="pollcreate_option_1" maxlength="340" label="Option 2" placeholder="Write an option" type="text" value=""><label for="pollcreate_option_1">Option 2</label></div><div role="button" tabindex="0" class="mx_AccessibleButton mx_PollCreateDialog_removeOption"></div></div><div role="button" tabindex="0" class="mx_AccessibleButton mx_PollCreateDialog_addOption mx_AccessibleButton_hasKind mx_AccessibleButton_kind_secondary">Add option</div></div></div><div class="mx_CompoundDialog_footer"><div role="button" tabindex="0" class="mx_AccessibleButton mx_AccessibleButton_hasKind mx_AccessibleButton_kind_primary_outline">Cancel</div><button type="submit" role="button" tabindex="0" aria-disabled="true" disabled="" class="mx_AccessibleButton mx_Dialog_nonDialogButton mx_AccessibleButton_hasKind mx_AccessibleButton_kind_primary mx_AccessibleButton_disabled">Create Poll</button></div></form></div><div data-focus-guard="true" tabindex="0" style="width: 1px; height: 0px; padding: 0px; overflow: hidden; position: fixed; top: 1px; left: 1px;"></div>"`;
+exports[`PollCreateDialog renders a blank poll 1`] = `"<div data-focus-guard="true" tabindex="0" style="width: 1px; height: 0px; padding: 0px; overflow: hidden; position: fixed; top: 1px; left: 1px;"></div><div data-focus-lock-disabled="false" role="dialog" aria-labelledby="mx_CompoundDialog_title" aria-describedby="mx_CompoundDialog_content" class="mx_CompoundDialog mx_ScrollableBaseDialog"><div class="mx_CompoundDialog_header"><h1>Create poll</h1><div aria-label="Close dialog" role="button" tabindex="0" class="mx_AccessibleButton mx_CompoundDialog_cancelButton"></div></div><form class="mx_CompoundDialog_form"><div class="mx_CompoundDialog_content"><div class="mx_PollCreateDialog"><h2>Poll type</h2><div class="mx_Field mx_Field_select"><select type="text" id="mx_Field_1"><option value="org.matrix.msc3381.poll.disclosed">Open poll</option><option value="org.matrix.msc3381.poll.undisclosed">Closed poll</option></select><label for="mx_Field_1"></label></div><p>Voters see results as soon as they have voted</p><h2>What is your poll question or topic?</h2><div class="mx_Field mx_Field_input mx_Field_labelAlwaysTopLeft mx_Field_placeholderIsHint"><input id="poll-topic-input" maxlength="340" label="Question or topic" placeholder="Write something..." type="text" value=""><label for="poll-topic-input">Question or topic</label></div><h2>Create options</h2><div class="mx_PollCreateDialog_option"><div class="mx_Field mx_Field_input mx_Field_labelAlwaysTopLeft mx_Field_placeholderIsHint"><input id="pollcreate_option_0" maxlength="340" label="Option 1" placeholder="Write an option" type="text" value=""><label for="pollcreate_option_0">Option 1</label></div><div role="button" tabindex="0" class="mx_AccessibleButton mx_PollCreateDialog_removeOption"></div></div><div class="mx_PollCreateDialog_option"><div class="mx_Field mx_Field_input mx_Field_labelAlwaysTopLeft mx_Field_placeholderIsHint"><input id="pollcreate_option_1" maxlength="340" label="Option 2" placeholder="Write an option" type="text" value=""><label for="pollcreate_option_1">Option 2</label></div><div role="button" tabindex="0" class="mx_AccessibleButton mx_PollCreateDialog_removeOption"></div></div><div role="button" tabindex="0" class="mx_AccessibleButton mx_PollCreateDialog_addOption mx_AccessibleButton_hasKind mx_AccessibleButton_kind_secondary">Add option</div></div></div><div class="mx_CompoundDialog_footer"><div role="button" tabindex="0" class="mx_AccessibleButton mx_AccessibleButton_hasKind mx_AccessibleButton_kind_primary_outline">Cancel</div><button type="submit" role="button" tabindex="0" aria-disabled="true" disabled="" class="mx_AccessibleButton mx_Dialog_nonDialogButton mx_AccessibleButton_hasKind mx_AccessibleButton_kind_primary mx_AccessibleButton_disabled">Create Poll</button></div></form></div><div data-focus-guard="true" tabindex="0" style="width: 1px; height: 0px; padding: 0px; overflow: hidden; position: fixed; top: 1px; left: 1px;"></div>"`;
 
-exports[`PollCreateDialog renders a question and some options 1`] = `"<div data-focus-guard="true" tabindex="0" style="width: 1px; height: 0px; padding: 0px; overflow: hidden; position: fixed; top: 1px; left: 1px;"></div><div data-focus-lock-disabled="false" role="dialog" aria-labelledby="mx_CompoundDialog_title" aria-describedby="mx_CompoundDialog_content" class="mx_CompoundDialog mx_ScrollableBaseDialog"><div class="mx_CompoundDialog_header"><h1>Create poll</h1><div aria-label="Close dialog" role="button" tabindex="0" class="mx_AccessibleButton mx_CompoundDialog_cancelButton"></div></div><form><div class="mx_CompoundDialog_content"><div class="mx_PollCreateDialog"><h2>Poll type</h2><div class="mx_Field mx_Field_select"><select type="text" id="mx_Field_4"><option value="org.matrix.msc3381.poll.disclosed">Open poll</option><option value="org.matrix.msc3381.poll.undisclosed">Closed poll</option></select><label for="mx_Field_4"></label></div><p>Voters see results as soon as they have voted</p><h2>What is your poll question or topic?</h2><div class="mx_Field mx_Field_input mx_Field_labelAlwaysTopLeft mx_Field_placeholderIsHint"><input id="poll-topic-input" maxlength="340" label="Question or topic" placeholder="Write something..." type="text" value="How many turnips is the optimal number?"><label for="poll-topic-input">Question or topic</label></div><h2>Create options</h2><div class="mx_PollCreateDialog_option"><div class="mx_Field mx_Field_input mx_Field_labelAlwaysTopLeft mx_Field_placeholderIsHint"><input id="pollcreate_option_0" maxlength="340" label="Option 1" placeholder="Write an option" type="text" value="As many as my neighbour"><label for="pollcreate_option_0">Option 1</label></div><div role="button" tabindex="0" class="mx_AccessibleButton mx_PollCreateDialog_removeOption"></div></div><div class="mx_PollCreateDialog_option"><div class="mx_Field mx_Field_input mx_Field_labelAlwaysTopLeft mx_Field_placeholderIsHint"><input id="pollcreate_option_1" maxlength="340" label="Option 2" placeholder="Write an option" type="text" value="The question is meaningless"><label for="pollcreate_option_1">Option 2</label></div><div role="button" tabindex="0" class="mx_AccessibleButton mx_PollCreateDialog_removeOption"></div></div><div class="mx_PollCreateDialog_option"><div class="mx_Field mx_Field_input mx_Field_labelAlwaysTopLeft mx_Field_placeholderIsHint"><input id="pollcreate_option_2" maxlength="340" label="Option 3" placeholder="Write an option" type="text" value="Mu"><label for="pollcreate_option_2">Option 3</label></div><div role="button" tabindex="0" class="mx_AccessibleButton mx_PollCreateDialog_removeOption"></div></div><div role="button" tabindex="0" class="mx_AccessibleButton mx_PollCreateDialog_addOption mx_AccessibleButton_hasKind mx_AccessibleButton_kind_secondary">Add option</div></div></div><div class="mx_CompoundDialog_footer"><div role="button" tabindex="0" class="mx_AccessibleButton mx_AccessibleButton_hasKind mx_AccessibleButton_kind_primary_outline">Cancel</div><button type="submit" role="button" tabindex="0" class="mx_AccessibleButton mx_Dialog_nonDialogButton mx_AccessibleButton_hasKind mx_AccessibleButton_kind_primary">Create Poll</button></div></form></div><div data-focus-guard="true" tabindex="0" style="width: 1px; height: 0px; padding: 0px; overflow: hidden; position: fixed; top: 1px; left: 1px;"></div>"`;
+exports[`PollCreateDialog renders a question and some options 1`] = `"<div data-focus-guard="true" tabindex="0" style="width: 1px; height: 0px; padding: 0px; overflow: hidden; position: fixed; top: 1px; left: 1px;"></div><div data-focus-lock-disabled="false" role="dialog" aria-labelledby="mx_CompoundDialog_title" aria-describedby="mx_CompoundDialog_content" class="mx_CompoundDialog mx_ScrollableBaseDialog"><div class="mx_CompoundDialog_header"><h1>Create poll</h1><div aria-label="Close dialog" role="button" tabindex="0" class="mx_AccessibleButton mx_CompoundDialog_cancelButton"></div></div><form class="mx_CompoundDialog_form"><div class="mx_CompoundDialog_content"><div class="mx_PollCreateDialog"><h2>Poll type</h2><div class="mx_Field mx_Field_select"><select type="text" id="mx_Field_4"><option value="org.matrix.msc3381.poll.disclosed">Open poll</option><option value="org.matrix.msc3381.poll.undisclosed">Closed poll</option></select><label for="mx_Field_4"></label></div><p>Voters see results as soon as they have voted</p><h2>What is your poll question or topic?</h2><div class="mx_Field mx_Field_input mx_Field_labelAlwaysTopLeft mx_Field_placeholderIsHint"><input id="poll-topic-input" maxlength="340" label="Question or topic" placeholder="Write something..." type="text" value="How many turnips is the optimal number?"><label for="poll-topic-input">Question or topic</label></div><h2>Create options</h2><div class="mx_PollCreateDialog_option"><div class="mx_Field mx_Field_input mx_Field_labelAlwaysTopLeft mx_Field_placeholderIsHint"><input id="pollcreate_option_0" maxlength="340" label="Option 1" placeholder="Write an option" type="text" value="As many as my neighbour"><label for="pollcreate_option_0">Option 1</label></div><div role="button" tabindex="0" class="mx_AccessibleButton mx_PollCreateDialog_removeOption"></div></div><div class="mx_PollCreateDialog_option"><div class="mx_Field mx_Field_input mx_Field_labelAlwaysTopLeft mx_Field_placeholderIsHint"><input id="pollcreate_option_1" maxlength="340" label="Option 2" placeholder="Write an option" type="text" value="The question is meaningless"><label for="pollcreate_option_1">Option 2</label></div><div role="button" tabindex="0" class="mx_AccessibleButton mx_PollCreateDialog_removeOption"></div></div><div class="mx_PollCreateDialog_option"><div class="mx_Field mx_Field_input mx_Field_labelAlwaysTopLeft mx_Field_placeholderIsHint"><input id="pollcreate_option_2" maxlength="340" label="Option 3" placeholder="Write an option" type="text" value="Mu"><label for="pollcreate_option_2">Option 3</label></div><div role="button" tabindex="0" class="mx_AccessibleButton mx_PollCreateDialog_removeOption"></div></div><div role="button" tabindex="0" class="mx_AccessibleButton mx_PollCreateDialog_addOption mx_AccessibleButton_hasKind mx_AccessibleButton_kind_secondary">Add option</div></div></div><div class="mx_CompoundDialog_footer"><div role="button" tabindex="0" class="mx_AccessibleButton mx_AccessibleButton_hasKind mx_AccessibleButton_kind_primary_outline">Cancel</div><button type="submit" role="button" tabindex="0" class="mx_AccessibleButton mx_Dialog_nonDialogButton mx_AccessibleButton_hasKind mx_AccessibleButton_kind_primary">Create Poll</button></div></form></div><div data-focus-guard="true" tabindex="0" style="width: 1px; height: 0px; padding: 0px; overflow: hidden; position: fixed; top: 1px; left: 1px;"></div>"`;
 
-exports[`PollCreateDialog renders info from a previous event 1`] = `"<div data-focus-guard="true" tabindex="0" style="width: 1px; height: 0px; padding: 0px; overflow: hidden; position: fixed; top: 1px; left: 1px;"></div><div data-focus-lock-disabled="false" role="dialog" aria-labelledby="mx_CompoundDialog_title" aria-describedby="mx_CompoundDialog_content" class="mx_CompoundDialog mx_ScrollableBaseDialog"><div class="mx_CompoundDialog_header"><h1>Edit poll</h1><div aria-label="Close dialog" role="button" tabindex="0" class="mx_AccessibleButton mx_CompoundDialog_cancelButton"></div></div><form><div class="mx_CompoundDialog_content"><div class="mx_PollCreateDialog"><h2>Poll type</h2><div class="mx_Field mx_Field_select"><select type="text" id="mx_Field_5"><option value="org.matrix.msc3381.poll.disclosed">Open poll</option><option value="org.matrix.msc3381.poll.undisclosed">Closed poll</option></select><label for="mx_Field_5"></label></div><p>Voters see results as soon as they have voted</p><h2>What is your poll question or topic?</h2><div class="mx_Field mx_Field_input mx_Field_labelAlwaysTopLeft mx_Field_placeholderIsHint"><input id="poll-topic-input" maxlength="340" label="Question or topic" placeholder="Write something..." type="text" value="Poll Q"><label for="poll-topic-input">Question or topic</label></div><h2>Create options</h2><div class="mx_PollCreateDialog_option"><div class="mx_Field mx_Field_input mx_Field_labelAlwaysTopLeft mx_Field_placeholderIsHint"><input id="pollcreate_option_0" maxlength="340" label="Option 1" placeholder="Write an option" type="text" value="Answer 1"><label for="pollcreate_option_0">Option 1</label></div><div role="button" tabindex="0" class="mx_AccessibleButton mx_PollCreateDialog_removeOption"></div></div><div class="mx_PollCreateDialog_option"><div class="mx_Field mx_Field_input mx_Field_labelAlwaysTopLeft mx_Field_placeholderIsHint"><input id="pollcreate_option_1" maxlength="340" label="Option 2" placeholder="Write an option" type="text" value="Answer 2"><label for="pollcreate_option_1">Option 2</label></div><div role="button" tabindex="0" class="mx_AccessibleButton mx_PollCreateDialog_removeOption"></div></div><div role="button" tabindex="0" class="mx_AccessibleButton mx_PollCreateDialog_addOption mx_AccessibleButton_hasKind mx_AccessibleButton_kind_secondary">Add option</div></div></div><div class="mx_CompoundDialog_footer"><div role="button" tabindex="0" class="mx_AccessibleButton mx_AccessibleButton_hasKind mx_AccessibleButton_kind_primary_outline">Cancel</div><button type="submit" role="button" tabindex="0" class="mx_AccessibleButton mx_Dialog_nonDialogButton mx_AccessibleButton_hasKind mx_AccessibleButton_kind_primary">Done</button></div></form></div><div data-focus-guard="true" tabindex="0" style="width: 1px; height: 0px; padding: 0px; overflow: hidden; position: fixed; top: 1px; left: 1px;"></div>"`;
+exports[`PollCreateDialog renders info from a previous event 1`] = `"<div data-focus-guard="true" tabindex="0" style="width: 1px; height: 0px; padding: 0px; overflow: hidden; position: fixed; top: 1px; left: 1px;"></div><div data-focus-lock-disabled="false" role="dialog" aria-labelledby="mx_CompoundDialog_title" aria-describedby="mx_CompoundDialog_content" class="mx_CompoundDialog mx_ScrollableBaseDialog"><div class="mx_CompoundDialog_header"><h1>Edit poll</h1><div aria-label="Close dialog" role="button" tabindex="0" class="mx_AccessibleButton mx_CompoundDialog_cancelButton"></div></div><form class="mx_CompoundDialog_form"><div class="mx_CompoundDialog_content"><div class="mx_PollCreateDialog"><h2>Poll type</h2><div class="mx_Field mx_Field_select"><select type="text" id="mx_Field_5"><option value="org.matrix.msc3381.poll.disclosed">Open poll</option><option value="org.matrix.msc3381.poll.undisclosed">Closed poll</option></select><label for="mx_Field_5"></label></div><p>Voters see results as soon as they have voted</p><h2>What is your poll question or topic?</h2><div class="mx_Field mx_Field_input mx_Field_labelAlwaysTopLeft mx_Field_placeholderIsHint"><input id="poll-topic-input" maxlength="340" label="Question or topic" placeholder="Write something..." type="text" value="Poll Q"><label for="poll-topic-input">Question or topic</label></div><h2>Create options</h2><div class="mx_PollCreateDialog_option"><div class="mx_Field mx_Field_input mx_Field_labelAlwaysTopLeft mx_Field_placeholderIsHint"><input id="pollcreate_option_0" maxlength="340" label="Option 1" placeholder="Write an option" type="text" value="Answer 1"><label for="pollcreate_option_0">Option 1</label></div><div role="button" tabindex="0" class="mx_AccessibleButton mx_PollCreateDialog_removeOption"></div></div><div class="mx_PollCreateDialog_option"><div class="mx_Field mx_Field_input mx_Field_labelAlwaysTopLeft mx_Field_placeholderIsHint"><input id="pollcreate_option_1" maxlength="340" label="Option 2" placeholder="Write an option" type="text" value="Answer 2"><label for="pollcreate_option_1">Option 2</label></div><div role="button" tabindex="0" class="mx_AccessibleButton mx_PollCreateDialog_removeOption"></div></div><div role="button" tabindex="0" class="mx_AccessibleButton mx_PollCreateDialog_addOption mx_AccessibleButton_hasKind mx_AccessibleButton_kind_secondary">Add option</div></div></div><div class="mx_CompoundDialog_footer"><div role="button" tabindex="0" class="mx_AccessibleButton mx_AccessibleButton_hasKind mx_AccessibleButton_kind_primary_outline">Cancel</div><button type="submit" role="button" tabindex="0" class="mx_AccessibleButton mx_Dialog_nonDialogButton mx_AccessibleButton_hasKind mx_AccessibleButton_kind_primary">Done</button></div></form></div><div data-focus-guard="true" tabindex="0" style="width: 1px; height: 0px; padding: 0px; overflow: hidden; position: fixed; top: 1px; left: 1px;"></div>"`;