diff --git a/doc/source/whatsnew/v1.3.0.rst b/doc/source/whatsnew/v1.3.0.rst
index 17d8c79994dbe..895c21e79886f 100644
--- a/doc/source/whatsnew/v1.3.0.rst
+++ b/doc/source/whatsnew/v1.3.0.rst
@@ -448,7 +448,7 @@ Other
 - :meth:`Index.where` behavior now mirrors :meth:`Index.putmask` behavior, i.e. ``index.where(mask, other)`` matches ``index.putmask(~mask, other)`` (:issue:`39412`)
 - Bug in :func:`pandas.testing.assert_series_equal`, :func:`pandas.testing.assert_frame_equal`, :func:`pandas.testing.assert_index_equal` and :func:`pandas.testing.assert_extension_array_equal` incorrectly raising when an attribute has an unrecognized NA type (:issue:`39461`)
 - Bug in :class:`Styler` where ``subset`` arg in methods raised an error for some valid multiindex slices (:issue:`33562`)
--
+- :class:`Styler` rendered HTML output minor alterations to support w3 good code standard (:issue:`39626`)
 -
 
 .. ---------------------------------------------------------------------------
diff --git a/pandas/io/formats/templates/html.tpl b/pandas/io/formats/templates/html.tpl
index 97bfda9af089d..b315c57a65cdf 100644
--- a/pandas/io/formats/templates/html.tpl
+++ b/pandas/io/formats/templates/html.tpl
@@ -1,70 +1,70 @@
 {# Update the template_structure.html document too #}
 {%- block before_style -%}{%- endblock before_style -%}
 {% block style %}
-<style  type="text/css" >
+<style type="text/css">
 {% block table_styles %}
 {% for s in table_styles %}
-    #T_{{uuid}} {{s.selector}} {
-    {% for p,val in s.props %}
-      {{p}}: {{val}};
-    {% endfor -%}
-    }
-{%- endfor -%}
+#T_{{uuid}} {{s.selector}} {
+{% for p,val in s.props %}
+  {{p}}: {{val}};
+{% endfor %}
+}
+{% endfor %}
 {% endblock table_styles %}
 {% block before_cellstyle %}{% endblock before_cellstyle %}
 {% block cellstyle %}
-{%- for s in cellstyle %}
-    {%- for selector in s.selectors -%}{%- if not loop.first -%},{%- endif -%}#T_{{uuid}}{{selector}}{%- endfor -%} {
-    {% for p,val in s.props %}
-        {{p}}: {{val}};
-    {% endfor %}
-    }
-{%- endfor -%}
-{%- endblock cellstyle %}
+{% for s in cellstyle %}
+{% for selector in s.selectors %}{% if not loop.first %}, {% endif %}#T_{{uuid}}{{selector}}{% endfor %} {
+{% for p,val in s.props %}
+  {{p}}: {{val}};
+{% endfor %}
+}
+{% endfor %}
+{% endblock cellstyle %}
 </style>
-{%- endblock style %}
-{%- block before_table %}{% endblock before_table %}
-{%- block table %}
-<table id="T_{{uuid}}" {% if table_attributes %}{{ table_attributes }}{% endif %}>
-{%- block caption %}
-{%- if caption -%}
-    <caption>{{caption}}</caption>
-{%- endif -%}
-{%- endblock caption %}
-{%- block thead %}
-<thead>
-    {%- block before_head_rows %}{% endblock %}
-    {%- for r in head %}
-    {%- block head_tr scoped %}
+{% endblock style %}
+{% block before_table %}{% endblock before_table %}
+{% block table %}
+<table id="T_{{uuid}}"{% if table_attributes %} {{table_attributes}}{% endif %}>
+{% block caption %}
+{% if caption %}
+  <caption>{{caption}}</caption>
+{% endif %}
+{% endblock caption %}
+{% block thead %}
+  <thead>
+{% block before_head_rows %}{% endblock %}
+{% for r in head %}
+{% block head_tr scoped %}
     <tr>
-        {%- for c in r %}
-        {%- if c.is_visible != False %}
-        <{{ c.type }} class="{{c.class}}" {{ c.attributes|join(" ") }}>{{c.value}}</{{ c.type }}>
-        {%- endif %}
-        {%- endfor %}
+{% for c in r %}
+{% if c.is_visible != False %}
+      <{{c.type}} class="{{c.class}}" {{c.attributes|join(" ")}}>{{c.value}}</{{c.type}}>
+{% endif %}
+{% endfor %}
     </tr>
-    {%- endblock head_tr %}
-    {%- endfor %}
-    {%- block after_head_rows %}{% endblock %}
-</thead>
-{%- endblock thead %}
-{%- block tbody %}
-<tbody>
-    {% block before_rows %}{% endblock before_rows %}
-    {% for r in body %}
-    {% block tr scoped %}
+{% endblock head_tr %}
+{% endfor %}
+{% block after_head_rows %}{% endblock %}
+  </thead>
+{% endblock thead %}
+{% block tbody %}
+  <tbody>
+{% block before_rows %}{% endblock before_rows %}
+{% for r in body %}
+{% block tr scoped %}
     <tr>
-        {% for c in r %}
-        {% if c.is_visible != False %}
-        <{{ c.type }} {% if c.id is defined -%} id="T_{{ uuid }}{{ c.id }}" {%- endif %} class="{{ c.class }}" {{ c.attributes|join(" ") }}>{{ c.display_value }}</{{ c.type }}>
-        {% endif %}
-        {%- endfor %}
+{% for c in r %}
+{% if c.is_visible != False %}
+      <{{c.type}} {% if c.id is defined -%} id="T_{{uuid}}{{c.id}}" {%- endif %} class="{{c.class}}" {{c.attributes|join(" ")}}>{{c.display_value}}</{{c.type}}>
+{% endif %}
+{% endfor %}
     </tr>
-    {% endblock tr %}
-    {%- endfor %}
-    {%- block after_rows %}{%- endblock after_rows %}
-</tbody>
-{%- endblock tbody %}
+{% endblock tr %}
+{% endfor %}
+{% block after_rows %}{% endblock after_rows %}
+  </tbody>
+{% endblock tbody %}
 </table>
-{%- endblock table %}
-{%- block after_table %}{% endblock after_table %}
+{% endblock table %}
+{% block after_table %}{% endblock after_table %}
diff --git a/pandas/tests/io/formats/test_style.py b/pandas/tests/io/formats/test_style.py
index d2c5b5b9d0b2c..0bd0c5bd87761 100644
--- a/pandas/tests/io/formats/test_style.py
+++ b/pandas/tests/io/formats/test_style.py
@@ -140,8 +140,8 @@ def test_multiple_render(self):
         s = Styler(self.df, uuid_len=0).applymap(lambda x: "color: red;", subset=["A"])
         s.render()  # do 2 renders to ensure css styles not duplicated
         assert (
-            '<style  type="text/css" >\n#T__row0_col0,#T__row1_col0{\n            '
-            "color:  red;\n        }</style>" in s.render()
+            '<style type="text/css">\n#T__row0_col0, #T__row1_col0 {\n'
+            "  color:  red;\n}\n</style>" in s.render()
         )
 
     def test_render_empty_dfs(self):
@@ -1794,11 +1794,11 @@ def test_column_and_row_styling(self):
         df = DataFrame(data=[[0, 1], [1, 2]], columns=["A", "B"])
         s = Styler(df, uuid_len=0)
         s = s.set_table_styles({"A": [{"selector": "", "props": [("color", "blue")]}]})
-        assert "#T__ .col0 {\n          color: blue;\n    }" in s.render()
+        assert "#T__ .col0 {\n  color: blue;\n}" in s.render()
         s = s.set_table_styles(
             {0: [{"selector": "", "props": [("color", "blue")]}]}, axis=1
         )
-        assert "#T__ .row0 {\n          color: blue;\n    }" in s.render()
+        assert "#T__ .row0 {\n  color: blue;\n}" in s.render()
 
     def test_colspan_w3(self):
         # GH 36223
@@ -1855,12 +1855,12 @@ def test_tooltip_render(self, ttips):
         s = Styler(df, uuid_len=0).set_tooltips(ttips).render()
 
         # test tooltip table level class
-        assert "#T__ .pd-t {\n          visibility: hidden;\n" in s
+        assert "#T__ .pd-t {\n  visibility: hidden;\n" in s
 
         # test 'Min' tooltip added
         assert (
-            "#T__ #T__row0_col0:hover .pd-t {\n          visibility: visible;\n    }  "
-            + '  #T__ #T__row0_col0 .pd-t::after {\n          content: "Min";\n    }'
+            "#T__ #T__row0_col0:hover .pd-t {\n  visibility: visible;\n}\n"
+            + '#T__ #T__row0_col0 .pd-t::after {\n  content: "Min";\n}'
             in s
         )
         assert (
@@ -1871,8 +1871,8 @@ def test_tooltip_render(self, ttips):
 
         # test 'Max' tooltip added
         assert (
-            "#T__ #T__row0_col1:hover .pd-t {\n          visibility: visible;\n    }  "
-            + '  #T__ #T__row0_col1 .pd-t::after {\n          content: "Max";\n    }'
+            "#T__ #T__row0_col1:hover .pd-t {\n  visibility: visible;\n}\n"
+            + '#T__ #T__row0_col1 .pd-t::after {\n  content: "Max";\n}'
             in s
         )
         assert (
@@ -1892,16 +1892,16 @@ def test_tooltip_reindex(self):
             index=[0, 2],
         )
         s = Styler(df, uuid_len=0).set_tooltips(DataFrame(ttips)).render()
-        assert '#T__ #T__row0_col0 .pd-t::after {\n          content: "Mi";\n    }' in s
-        assert '#T__ #T__row0_col2 .pd-t::after {\n          content: "Ma";\n    }' in s
-        assert '#T__ #T__row2_col0 .pd-t::after {\n          content: "Mu";\n    }' in s
-        assert '#T__ #T__row2_col2 .pd-t::after {\n          content: "Mo";\n    }' in s
+        assert '#T__ #T__row0_col0 .pd-t::after {\n  content: "Mi";\n}' in s
+        assert '#T__ #T__row0_col2 .pd-t::after {\n  content: "Ma";\n}' in s
+        assert '#T__ #T__row2_col0 .pd-t::after {\n  content: "Mu";\n}' in s
+        assert '#T__ #T__row2_col2 .pd-t::after {\n  content: "Mo";\n}' in s
 
     def test_tooltip_ignored(self):
         # GH 21266
         df = DataFrame(data=[[0, 1], [2, 3]])
         s = Styler(df).set_tooltips_class("pd-t").render()  # no set_tooltips()
-        assert '<style  type="text/css" >\n</style>' in s
+        assert '<style type="text/css">\n</style>' in s
         assert '<span class="pd-t"></span>' not in s
 
     def test_tooltip_class(self):
@@ -1913,11 +1913,8 @@ def test_tooltip_class(self):
             .set_tooltips_class(name="other-class", properties=[("color", "green")])
             .render()
         )
-        assert "#T__ .other-class {\n          color: green;\n" in s
-        assert (
-            '#T__ #T__row0_col0 .other-class::after {\n          content: "tooltip";\n'
-            in s
-        )
+        assert "#T__ .other-class {\n  color: green;\n" in s
+        assert '#T__ #T__row0_col0 .other-class::after {\n  content: "tooltip";\n' in s
 
         # GH 39563
         s = (
@@ -1926,10 +1923,50 @@ def test_tooltip_class(self):
             .set_tooltips_class(name="other-class", properties="color:green;color:red;")
             .render()
         )
-        assert (
-            "#T__ .other-class {\n          color: green;\n          color: red;\n "
-            in s
+        assert "#T__ .other-class {\n  color: green;\n  color: red;\n}" in s
+
+    def test_w3_html_format(self):
+        s = (
+            Styler(
+                DataFrame([[2.61], [2.69]], index=["a", "b"], columns=["A"]),
+                uuid_len=0,
+            )
+            .set_table_styles([{"selector": "th", "props": "att2:v2;"}])
+            .applymap(lambda x: "att1:v1;")
+            .set_table_attributes('class="my-cls1" style="attr3:v3;"')
+            .set_td_classes(DataFrame(["my-cls2"], index=["a"], columns=["A"]))
+            .format("{:.1f}")
+            .set_caption("A comprehensive test")
         )
+        expected = """<style type="text/css">
+#T__ th {
+  att2: v2;
+}
+#T__row0_col0, #T__row1_col0 {
+  att1: v1;
+}
+</style>
+<table id="T__" class="my-cls1" style="attr3:v3;">
+  <caption>A comprehensive test</caption>
+  <thead>
+    <tr>
+      <th class="blank level0" ></th>
+      <th class="col_heading level0 col0" >A</th>
+    </tr>
+  </thead>
+  <tbody>
+    <tr>
+      <th id="T__level0_row0" class="row_heading level0 row0" >a</th>
+      <td id="T__row0_col0" class="data row0 col0 my-cls2" >2.6</td>
+    </tr>
+    <tr>
+      <th id="T__level0_row1" class="row_heading level0 row1" >b</th>
+      <td id="T__row1_col0" class="data row1 col0" >2.7</td>
+    </tr>
+  </tbody>
+</table>
+"""
+        assert expected == s.render()
 
 
 @td.skip_if_no_mpl