diff --git a/plugins/ui/src/deephaven/ui/components/spectrum/flex.py b/plugins/ui/src/deephaven/ui/components/spectrum/flex.py
index 7634ebab0..91f5f2f69 100644
--- a/plugins/ui/src/deephaven/ui/components/spectrum/flex.py
+++ b/plugins/ui/src/deephaven/ui/components/spectrum/flex.py
@@ -18,7 +18,7 @@ def flex(
     justify_content: JustifyContent | None = None,
     align_content: AlignContent | None = None,
     align_items: AlignItems | None = None,
-    gap: DimensionValue | None = None,
+    gap: DimensionValue | None = "size-100",
     column_gap: DimensionValue | None = None,
     row_gap: DimensionValue | None = None,
     **props: Any,
diff --git a/tests/ui.spec.ts-snapshots/UI-loads-1-chromium-linux.png b/tests/ui.spec.ts-snapshots/UI-loads-1-chromium-linux.png
index 3886c4dc6..30c17ce6c 100644
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diff --git a/tests/ui.spec.ts-snapshots/UI-loads-1-firefox-linux.png b/tests/ui.spec.ts-snapshots/UI-loads-1-firefox-linux.png
index 2f9c74f20..a6bf6f6df 100644
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diff --git a/tests/ui.spec.ts-snapshots/UI-loads-1-webkit-linux.png b/tests/ui.spec.ts-snapshots/UI-loads-1-webkit-linux.png
index 2434db2b4..183a38341 100644
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