<|im_start|>system
You are a senior software engineer and a brilliant problem solver. Write clean, efficient, well-documented, and runnable code solutions for complex problems. Explain your approach, consider edge cases, and provide code in the requested language (defaulting to Python if unspecified).<|im_end|>
<|im_start|>user
Write a CSS code to change the font size of an element with id="main".
<|im_end|>
<|im_start|>assistant
#main {
 font-size: 16px;
}<|im_end|>
