Span element in Markdown

Question

I wrote a markdown.md with the following lines of code.

<span style="font-family: Open Sans; font-weight: 300; font-size: 16px; font-style: normal">300 Light normal hamburgefonstiv</span>
<br /> <span style="font-family: Open Sans; font-weight: 300; font-size: 16px;font-style: italic">300 Light italic hamburgefonstiv</span>
<br /> <span style="font-family: Open Sans; font-weight: 400; font-size: 16px; font-style: normal">400 Regular normal hamburgefonstiv</span>
<br /> <span style="font-family: Open Sans; font-weight: 400; font-size: 16px;font-style: italic">400 Regular italic hamburgefonstiv</span>
<br /> <span style="font-family: Open Sans; font-weight: 600; font-size: 16px; font-style: normal">600 Semibold normal hamburgefonstiv</span>
<br /> <span style="font-family: Open Sans; font-weight: 600; font-size: 16px;font-style: italic">600 Semibold italic hamburgefonstiv</span>
<br /> <span style="font-family: Open Sans; font-weight: 700; font-size: 16px; font-style: normal">700 Bold normal hamburgefonstiv</span>
<br /> <span style="font-family: Open Sans; font-weight: 700; font-size: 16px;font-style: italic">700 Bold italic hamburgefonstiv</span>
<br /> <span style="font-family: Open Sans; font-weight: 800; font-size: 16px; font-style: normal">800 ExtraBold normal hamburgefonstiv</span>
<br /> <span style="font-family: Open Sans; font-weight: 800; font-size: 16px;font-style: italic">800 ExtraBold italic hamburgefonstiv</span>

When I open the browser I see this. It works fine. When I open the the markdown.md on Github I see only the textlines as normal text. What is wrong? Is the idea with a span element the right one?

Answer 1

Although GitHub's markdown spec supports some HTML, CSS is not supported at all at this time. See here:

GitHub strips style tags and attributes preventing you from changing the style on their pages. This is probably for security reasons. If you could inject css into GitHub pages, you could easily launch a phishing attack.