Many H3 headings

https://developer.mozilla.org/en-us/mozilla/firefox/experimental_features : 34
https://developer.mozilla.org/en-us/web/svg/attribute : 30
https://developer.mozilla.org/en-us/web/svg/element : 42
https://developer.mozilla.org/en-us/web/guide/audio_and_video_delivery/cross-browser_audio_basics : 22
https://developer.mozilla.org/en-us/web/mathml/element : 22
https://developer.mozilla.org/en-us/web/css/css_images/using_css_gradients : 25
https://developer.mozilla.org/en-us/web/css/webkit_extensions : 30
https://developer.mozilla.org/en-us/web/css/mozilla_extensions : 36
https://developer.mozilla.org/en-us/web/css/css_columns/using_multi-column_layouts : 21
https://developer.mozilla.org/en-us/web/html/element/input/search : 21
https://developer.mozilla.org/en-us/web/http/proxy_servers_and_tunneling/proxy_auto-configuration_pac_file : 22
https://developer.mozilla.org/en-us/web/api/webgl_api/constants : 53
https://developer.mozilla.org/en-us/web/api/url_pattern_api : 26
https://developer.mozilla.org/en-us/web/api/canvasrenderingcontext2d : 21
https://developer.mozilla.org/en-us/web/javascript/reference : 32
https://developer.mozilla.org/en-us/web/javascript/reference/global_objects/array : 24
https://developer.mozilla.org/en-us/web/accessibility/cognitive_accessibility : 26
https://developer.mozilla.org/en-us/web/accessibility/understanding_colors_and_luminance : 22
https://developer.mozilla.org/en-us/web/media/formats/video_codecs : 25
https://developer.mozilla.org/en-us/mdn/at_ten/history_of_mdn : 22
https://developer.mozilla.org/en-us/mdn/contribute/howto/write_an_api_reference/information_contained_in_a_webidl_file : 30
https://developer.mozilla.org/en-us/mdn/guidelines/writing_style_guide : 21