fix:[Lightbox] Increase z-index

[Xapphire13]

to: @williaster @alecklandgraf

Description

This change increases the z-index of lightbox so that it appears on top of application chrome (headers etc). The lightbox is a full screen image viewer and if things appear on top of it, and block the lightbox controls.

Motivation and Context

A recent change in a product using lunar caused the lightbox controls to be covered and unusable.

Testing

• [x] Storybook (looks the same as before, and DOM element has the correct z-index)

Screenshots

n/a (no visual change)

Checklist

• My code follows the style guide of this project.
• I have updated or added documentation accordingly.
• I have read the CONTRIBUTING document.

[airbnb-bot]

Size Changes

Package	Diff	ESM	Prev ESM	CJS	Prev CJS
core	+0.1%	570.69 KB	570.22 KB	715.76 KB	715.13 KB

Compared to master. File sizes are unminified and ungzipped.

View raw build stats

Previous (master)

{
  "apollo": {
    "esm": 10832,
    "lib": 14147
  },
  "app-shell": {
    "esm": 12906,
    "lib": 19874
  },
  "composer": {
    "esm": 68247,
    "lib": 101805
  },
  "core": {
    "esm": 583901,
    "lib": 732297
  },
  "forms": {
    "esm": 37350,
    "lib": 49298
  },
  "icons": {
    "esm": 156355,
    "lib": 205626
  },
  "layouts": {
    "esm": 15298,
    "lib": 20770
  },
  "metrics": {
    "esm": 5467,
    "lib": 7729
  },
  "test-utils": {
    "esm": 4279,
    "lib": 5937
  }
}

Current

{
  "apollo": {
    "esm": 10832,
    "lib": 14147
  },
  "app-shell": {
    "esm": 12906,
    "lib": 19874
  },
  "composer": {
    "esm": 68247,
    "lib": 101805
  },
  "core": {
    "esm": 584388,
    "lib": 732939
  },
  "forms": {
    "esm": 37350,
    "lib": 49298
  },
  "icons": {
    "esm": 156355,
    "lib": 205626
  },
  "layouts": {
    "esm": 15298,
    "lib": 20770
  },
  "metrics": {
    "esm": 5467,
    "lib": 7729
  },
  "test-utils": {
    "esm": 4279,
    "lib": 5937
  }
}