Bad for SEO? (span tag within header tag)

Hi,

I have a question and since I don't know the answer it bothers me. I understand the importance of SEO in terms of ranking etc.

My question is while header tags (h1 ... h6) are important and should be used to illustrate important key words and terms, does inserting a <span> tag inside that header tag affect its effectiveness?

for example

I'm don't think it effects your SEO... but I'm not 100%

But why do you have the extra span there?
You could also give a class name to the h1-element:

I never considered applying a class to a header, the reason I include a span inside a header tag is so I can apply an underline to the text where as should the header have a "border-bottom" applied, it repeats the bottom border across the full width.

What about:

h1 {text-decoration: underline}

No It do not give any problem.

If your heading color is as same as background color,then it can be a problem and is considered black hat seo.

H1 is the most important, and widely exploited header tag. Several spammy sites have exploited H1 tag to such a great extent, that google becomes cautious, when it encounters one.

If you are using H1 make sure not to stuff to many keywords, and you should abstain from using any <SPAN>, which could get mistaken as <SPAM> .

Try using external style sheet to control H1 tag, instead of using a <SPAN> or any other within <h1> tag