diff --git a/muxplex/frontend/style.css b/muxplex/frontend/style.css
index a56861b..24cc1d0 100644
--- a/muxplex/frontend/style.css
+++ b/muxplex/frontend/style.css
@@ -469,6 +469,7 @@ body {
 
 .sidebar-item {
   height: 120px;
+  flex-shrink: 0;          /* prevent flex from compressing cards to fit */
   background: var(--bg-secondary);
   cursor: pointer;
   overflow: hidden;
diff --git a/muxplex/tests/test_frontend_css.py b/muxplex/tests/test_frontend_css.py
index f92d81b..f5aba74 100644
--- a/muxplex/tests/test_frontend_css.py
+++ b/muxplex/tests/test_frontend_css.py
@@ -604,3 +604,12 @@ def test_sidebar_list_has_touch_action_pan_y():
     assert "overscroll-behavior: contain" in block, (
         ".sidebar-list must have overscroll-behavior:contain to prevent scroll chaining"
     )
+
+
+def test_sidebar_item_has_flex_shrink_zero():
+    """Regression: without flex-shrink:0 cards shrink to fit, eliminating scroll overflow."""
+    css = read_css()
+    block = _extract_rule_block(css, ".sidebar-item {")
+    assert "flex-shrink: 0" in block, (
+        ".sidebar-item must have flex-shrink:0 to prevent compression"
+    )