I'm a front end web developer and currently I'm in the process of redoing my online portfolio.
When I had graduated from my Web Development course it was highly recommended we all make ourselves a portfolio, showcasing our work from our studies.

I have since graduated and have been working in Web for a few years now so I'm curious to know what employers look for in a portfolio when they are looking to hire a front end developer. I've been through a few interviews in my time and some employers don't even bother to check my portfolio, where as some have looked at every inch of my site right down to the code, to even giving me suggestions on how I could have done something better.

I've also switched jobs recently and work for a much bigger company, I do a lot of HTML/CSS as part of my role, but most of the time its just styling small bits and bobs here and there, is that worthy to even mention that on my portfolio? or as a front end dev should you only show full sites you've built? - what if I don't get to create a full site, how do I tell people I've worked on aspects or portions of a website?

I guess my question is how do I let prospective employers know what work is mine, how I code and what it looks like?
I'm not too flashy on the jQuery (I know and I call myself a front end dev!) and I'm currently learning and want to put up a blog of things that I have learned, do you think this will negatively impact me in some way?

Any suggestions/advice/help on this topic would be greatly appreciated.
Would love to hear what you put on your portfolio and what you think may also be good ideas.