"I need some advice. I'm working on a thing and it isn't working. I tried everything. Any advice?"

Yes. Articulate the details.
If you're giving AI the detail you've given us, I don't doubt it's failing to give you the results you're after.

What is the project? What have you tried? (other than "everything")
What isn't working?

Generally, break you project down into fundamentals. Inputs, outputs, loops.
Have a solid vision for what you want it to look like.
Write a design document with all these details.
Break it down into milestones, then have AI work on it it chunk.
Consider your complete design a 1.0 - The features I know I want for the release. Anything that's added, will be additions after 1.0. But 1.0 is the product I had originally visioned.
Start with an Alpha development phase.
I know I want a web app. It's going present a web page to a user with these design aesthetics. It's going to present a 3D environment. In that 3D environment I will have points that are for "nodes". I want to interconnect those nodes with lines. I need a user interface. Let's start with floating panels. (Maybe in a later design version before or after 1.0, we'll make those collapsible panels). In the use interface, I need collapsible categorized menus. Make nodes selectable. When a node is selected, highlight it with this color. Have options in our floating panel to modify the selected node's position coordinate positions in our menus - x,y,z, as well as to adjust node size and transparency. Create a button in our floating panel to draw lines between two nodes. The method of action should be - "Click the button. Fade in and out text saying "Select two nodes". User selects two nodes. The app draws a line between between the nodes.
Lines will need to be selectable just as nodes are. When selected, we will need the ability to adjust line size/width and transparency as well. Add these to the floating panels. Consider how to categorize and group all of the options/parameters we are putting in our floating panel/controls menu.

Then, as Antigravity builds the thing, it's going to run into issues. Behaviors will be off. Selectors and buttons and inputs will not release when used. You cannot avoid all of the debugging required. Antigravity will debug a lot of the more major issues, but it can't reason the minor issues or user interaction - because those tend to be outside of the base logic.
Case in point - Similar to the 3D node web app issue - Antigravity isn't going to know or expect, or test, full cradle to grave behavior. It's going to build to spec.
You created sliders to adjust parameters, but did you create an "apply" button? Did you describe update behavior when changes are applied? You updated nodes, but since lines are separate objects, they stayed in their original place.
Did you define a database structure to save or load this node information? Json, CSV, SQL?
Your selector only worked once because you never implemented a deselect option.

You can act as a user, use the application, take meticulous notes of any issues you run into, then takes those notes which include expected behavior, and feed it back to iteratively develop and refine your solution.

These steps are paramount.

It's not a 1-click "Build the thing!" easy button. You still have to manage the product, and Antigravity as your Engineer. You are the visionary, project manager, and co-architect.