diff --git a/static/index.html b/static/index.html
index 1f55169a..6ead38ac 100644
--- a/static/index.html
+++ b/static/index.html
@@ -279,7 +279,7 @@
         </div>
       </div>
       <div class="panel-head-sub" style="padding:0 12px 8px">
-        <select id="insightsPeriod" onchange="loadInsights()" style="width:100%;background:var(--input-bg);color:var(--text);border:1px solid var(--border);border-radius:6px;padding:4px 8px;font-size:12px">
+        <select id="insightsPeriod" class="insights-period-select" onchange="loadInsights()">
           <option value="7">7 days</option>
           <option value="30" selected>30 days</option>
           <option value="90">90 days</option>
diff --git a/static/style.css b/static/style.css
index 98f6b7f0..f996dcbd 100644
--- a/static/style.css
+++ b/static/style.css
@@ -2234,6 +2234,7 @@
   .notes-preview-card .memory-content{max-height:420px;overflow:auto;}
 .field-label{font-size:10px;font-weight:700;text-transform:uppercase;letter-spacing:.08em;color:var(--muted);margin-bottom:5px;opacity:.8;}
   select{width:100%;background:var(--input-bg);border:1px solid var(--border2);border-radius:8px;color:var(--text);padding:8px 28px 8px 10px;font-size:12px;outline:none;appearance:none;margin-bottom:6px;cursor:pointer;background-image:url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='10' height='6' viewBox='0 0 10 6'%3E%3Cpath d='M1 1l4 4 4-4' stroke='%238888aa' stroke-width='1.5' fill='none' stroke-linecap='round'/%3E%3C/svg%3E");background-repeat:no-repeat;background-position:right 10px center;}
+  .insights-period-select{width:auto;border-radius:6px;padding:6px 28px 6px 10px;font-size:12px;margin-bottom:0;}
   select:focus{border-color:var(--accent);box-shadow:0 0 0 2px var(--accent-bg);}
   optgroup{color:var(--muted);font-size:11px;font-weight:700;}
   option{background:var(--bg);color:var(--text);padding:6px;}
diff --git a/tests/test_insights.py b/tests/test_insights.py
index a4594db5..2a2b5d68 100644
--- a/tests/test_insights.py
+++ b/tests/test_insights.py
@@ -173,6 +173,14 @@ def test_insights_frontend_has_daily_chart_styles_and_range_switching_hooks():
     assert ".insights-model-team" not in STYLE_CSS
 
 
+def test_insights_period_select_uses_shared_chevron_styles():
+    assert 'id="insightsPeriod" class="insights-period-select"' in INDEX_HTML
+    assert 'id="insightsPeriod" onchange="loadInsights()" style=' not in INDEX_HTML
+    assert ".insights-period-select" in STYLE_CSS
+    assert "width:auto" in STYLE_CSS.split(".insights-period-select", 1)[1].split("}", 1)[0]
+    assert "padding:6px 28px 6px 10px" in STYLE_CSS
+
+
 def _make_daily_rows(n):
     rows = []
     for i in range(n):