In CSS, how to write media queries to make the form:
1. 600px wide when the screen is greater than or equal to 600px wide,
2. use grid layout to layout labels and form elements when the screen is greater than or equal to 600px wide,
3. the width of the screen when the screen is less than 600px wide,
4. lay out the labels and form elements as full width when the screen is less than 600px wide.