[addon-design-assets] Web View in Panel is not 100% Height

[mosherc]

Describe the bug
Design Assets panel does not show the full content of the web view.

To Reproduce
Steps to reproduce the behavior:

1. Add addon design-assets
2. Add a random web page to parameters.assets array in default export
3. Go to story
4. See web view in panel is cut off

Expected behavior
Web view inside panel takes up 100% of the height.

Screenshots

Code snippets

export default {
  title: 'Molecules/Modal',
  component: Modal,
  parameters: {
    assets: [
      'https://developer.mozilla.org/en-US/docs/Web/Accessibility/ARIA/ARIA_Live_Regions', // link to a webpage
    ],
  },
} as Meta;

System
System:
OS: macOS 11.1
CPU: (8) x64 Apple M1
Binaries:
Node: 10.16.3 - ~/.nodenv/versions/10.16.3/bin/node
Yarn: 1.22.4 - ~/.nodenv/versions/10.16.3/bin/yarn
npm: 6.9.0 - ~/.nodenv/versions/10.16.3/bin/npm
Browsers:
Chrome: 88.0.4324.150
Firefox: 80.0
Safari: 14.0.2
npmPackages:
@storybook/addon-a11y: ^6.1.10 => 6.1.17
@storybook/addon-actions: ^6.1.16 => 6.1.17
@storybook/addon-design-assets: ^6.1.17 => 6.1.17
@storybook/addon-essentials: ^6.1.9 => 6.1.17
@storybook/addon-jest: ^6.1.17 => 6.1.17
@storybook/addon-storysource: ^6.1.9 => 6.1.17
@storybook/react: ^6.1.9 => 6.1.17
@storybook/source-loader: ^6.1.9 => 6.1.17
@storybook/theming: ^6.1.9 => 6.1.17

Additional context
Adding height: 100%; to this div fixes it:

[shilman]

I recommend https://github.com/pocka/storybook-addon-designs

@ndelangen @winkerVSbecks @phated should we deprecate addon-design-assets. i believe it was created as a sample addon, but this was long before the recent addons documentation overhaul. WDYT?

[mosherc]

@shilman I actually decided to do that, works pretty well so far and has a few extra things in its api.

I was surprised that I couldn't find anyone else with this bug, but I see you only have 4500 weekly downloads on npm so not a lot of usage.

[winkerVSbecks]

@shilman had a chat with @domyen and @jonniebigodes. Yea, makes sense to deprecate this. We're going to drop the chapter that references to this from the Intro to Storybook guide too.