You receive feedback on your mockup design that the accessibility is not good due to the lack of contrast. Which element do you need to adjust to address this issue?

To address the issue of poor accessibility due to lack of contrast in your mockup design, you need to adjust the color scheme of your design. This includes the colors of your text, background, buttons, and other interactive elements.

Here are the steps you can follow:

1. Identify the elements with low contrast: Look at your design and identify which elements are hard to see or read due to lack of contrast. This could be text that's too light on a light background, or elements that blend into the background.

2. Use a contrast checker: There are many online tools available that can check the contrast of your colors to ensure they meet accessibility standards. You simply input your foreground and background colors and the tool will tell you if the contrast is sufficient.

3. Adjust your colors: If your colors don't pass the contrast check, you'll need to adjust them. This could mean making your text darker, or your background lighter, for example. The goal is to make sure there's enough difference between the two that the text is easy to read.

4. Test your changes: After you've made changes, use the contrast checker again to make sure your new colors pass. It's also a good idea to get feedback from others, as they might spot issues you've missed.

5. Implement the changes: Once you're happy with your new color scheme, implement it in your design.

Remember, good contrast is not just about making your design look good, it's also about making it accessible to as many people as possible, including those with visual impairments.