you should not leave your job.
Teaching is a most comfortable profession and you have lot of time to prepare for css in this profession. You have lot of holidays in this profession.
You can never get too much holidays in shape of summer vacation in any other field. You can cover a lot of your css syllabus in summer vacations.

In the current scenario of unemployment leaving a job would not be a good decision. As a bird in hand is worth than two in the bush.

I am also doing job as a teacher and will appear in 2014. In this profession I have witnessed that a lot of things of css are automatically prepared especially the objective portion. All the other jobs have a hectic schedule and you would not get such a comfortable schedule as in this profession.

Now decision is yours.

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Success is never achieved by the size of our brain but it is always achieved by the quality of our thoughts.