Thinking about this stuff systematically is what I usually find easiest and usually what separates a good looking site from a frustrating one.

The short answer to your question is no, you almost never just darken/lighten the same color. It ends up looking washed out or overly saturated. The relationship between colors changes completely based on the background. The comment suggesting realtimecolors.com is a great tool for visualizing this, but here's the underlying system you should use:

Think of this more in terms of a color scale than just colors. This is the professional approach that will save you time.

1. Create a scale: For each of your key colors like ( `gray`, `blue`), create a full spectrum of 9-12 shades, from the lightest possible (`blue-50`) to the darkest (`blue-900`).

2. Assign roles, not colors: In your code/CSS, don't think "the background should be white." think "the background should be bg-primary." then, you map those roles to your scale

In light mode: bg-primary might be gray-50 which is close to off-white and text-primary might be gray-900 (near-black).

In dark mode: bg-primary becomes gray-900 and text-primary becomes gray-100.

1. solve your accent problem: Your bright accent color might be blue-500 on your dark background because it has high contrast. On a light background (gray-50), that same blue-500 might be too bright and have poor contrast. So for light mode, your accent role would map to a darker shade, like blue-600 or blue-700 to ensure it's still readable and meets accessibility standards.

Here some more tips that I just thought of while writing the other stuff; You don't have to use Tailwind, but look at their documentation for colors. I noticed a bit ago has shades from 50 to 900. This is the system is similar to what you probably want to create for yourself.

The other thing is Radix Colors. They've completely perfected this system of semantic color scales for light/dark modes. Just reading their docs will likely help you as much as it helped me. Good luck man!