diff --git a/static/js/markdown.js b/static/js/markdown.js
index 8735b83e7f..3eb2e36930 100644
--- a/static/js/markdown.js
+++ b/static/js/markdown.js
@@ -682,10 +682,24 @@ export function mdToHtml(src, opts) {
     const rows = table.trim().split('\n');
     if (rows.length < 2) return table;
 
+    // Per-column text alignment from the GFM separator row (row index 1):
+    //   :--- -> left   :---: -> center   ---: -> right   --- -> default (left,
+    // matching the previous behaviour). Columns without a spec stay left.
+    const hasSeparator = /^[\s|:\-]+$/.test(rows[1]);
+    const aligns = hasSeparator
+      ? splitTableRow(rows[1]).map((spec) => {
+          const left = spec.startsWith(':');
+          const right = spec.endsWith(':');
+          if (left && right) return 'center';
+          if (right) return 'right';
+          return 'left';
+        })
+      : [];
+
     let html = '<table style="border-collapse: collapse; width: 100%; margin: 10px 0;">';
 
     rows.forEach((row, idx) => {
-      if (idx === 1 && /^[\s|:\-]+$/.test(row)) {
+      if (idx === 1 && hasSeparator) {
         html += '<tbody>';
         return;
       }
@@ -694,9 +708,10 @@ export function mdToHtml(src, opts) {
 
       html += '<tr>';
 
-      cells.forEach(cell => {
+      cells.forEach((cell, i) => {
         const tag = idx === 0 ? 'th' : 'td';
-        html += `<${tag} style="padding: 8px; text-align: left; border-bottom: 1px solid var(--border);">${cell.trim()}</${tag}>`;
+        const align = aligns[i] || 'left';
+        html += `<${tag} style="padding: 8px; text-align: ${align}; border-bottom: 1px solid var(--border);">${cell.trim()}</${tag}>`;
       });
 
       html += '</tr>';
diff --git a/tests/test_markdown_rendering_js.py b/tests/test_markdown_rendering_js.py
index 2ffe8914f7..e9c505891d 100644
--- a/tests/test_markdown_rendering_js.py
+++ b/tests/test_markdown_rendering_js.py
@@ -136,6 +136,43 @@ def test_table_separator_row_not_rendered_as_data(node_available):
     assert "---" not in html
 
 
+def test_table_column_alignment_from_separator(node_available):
+    # GFM alignment markers in the separator row set per-column text-align:
+    #   :--- -> left   :---: -> centre   ---: -> right. It applies to the header
+    #   cells and every body cell in the column.
+    html = _run_markdown_case(
+        "| Name | Score | Amount |\n"
+        "| :--- | :---: | ---: |\n"
+        "| Alpha | 12 | 3.50 |\n"
+        "| Bravo | 7 | 128.00 |"
+    )
+
+    # Header cells carry the column's alignment.
+    assert 'text-align: left; border-bottom: 1px solid var(--border);">Name</th>' in html
+    assert 'text-align: center; border-bottom: 1px solid var(--border);">Score</th>' in html
+    assert 'text-align: right; border-bottom: 1px solid var(--border);">Amount</th>' in html
+    # Body cells inherit the same per-column alignment.
+    assert 'text-align: left; border-bottom: 1px solid var(--border);">Alpha</td>' in html
+    assert 'text-align: center; border-bottom: 1px solid var(--border);">12</td>' in html
+    assert 'text-align: right; border-bottom: 1px solid var(--border);">3.50</td>' in html
+    # One header + two body cells per column.
+    assert html.count("text-align: left") == 3
+    assert html.count("text-align: center") == 3
+    assert html.count("text-align: right") == 3
+
+
+def test_table_default_alignment_column_stays_left(node_available):
+    # A column whose separator has no colon (`---`) keeps the previous default,
+    # left alignment; a `---:` column is right-aligned; nothing becomes centre.
+    html = _run_markdown_case("| Key | Value |\n| --- | ---: |\n| id | 42 |")
+
+    assert 'text-align: left; border-bottom: 1px solid var(--border);">Key</th>' in html
+    assert 'text-align: right; border-bottom: 1px solid var(--border);">Value</th>' in html
+    assert 'text-align: left; border-bottom: 1px solid var(--border);">id</td>' in html
+    assert 'text-align: right; border-bottom: 1px solid var(--border);">42</td>' in html
+    assert "text-align: center" not in html
+
+
 def test_process_with_thinking_handles_gemma4_thought_channel(node_available):
     html = _run_markdown_case(
         "<|channel>thought\ninternal reasoning<channel|>Final answer.",