[9.0] [SB] Fix graph layout stories (#217766) (#218476)

# Backport

This will backport the following commits from `main` to `9.0`:
- [[SB] Fix graph layout stories
(#217766)](#217766)

<!--- Backport version: 9.6.6 -->

### Questions ?
Please refer to the [Backport tool
documentation](https://github.com/sorenlouv/backport)

<!--BACKPORT [{"author":{"name":"Brad
White","email":"[email protected]"},"sourceCommit":{"committedDate":"2025-04-16T16:59:08Z","message":"[SB]
Fix graph layout stories (#217766)\n\n## Summary\n\nThis fixes the graph
layout stories not rendering properly after\n#214684. Open to a better
or preferred fix as I'm not familiar with\nthese components.\n\nThere
was a console warning:\n```js\n[React Flow]: The React Flow parent
container needs a width and a height to render the graph. Help:
https://reactflow.dev/error#004\n```\n\n[Storybook
preview\nlink](https://ci-artifacts.kibana.dev/storybooks/pr-217766/cloud_security_posture_graph/index.html?path=/story/components-graph-components-graph-layout--simple-api-mock)\n\n---------\n\nCo-authored-by:
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Fix graph layout
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Fix graph layout stories (#217766)\n\n## Summary\n\nThis fixes the graph
layout stories not rendering properly after\n#214684. Open to a better
or preferred fix as I'm not familiar with\nthese components.\n\nThere
was a console warning:\n```js\n[React Flow]: The React Flow parent
container needs a width and a height to render the graph. Help:
https://reactflow.dev/error#004\n```\n\n[Storybook
preview\nlink](https://ci-artifacts.kibana.dev/storybooks/pr-217766/cloud_security_posture_graph/index.html?path=/story/components-graph-components-graph-layout--simple-api-mock)\n\n---------\n\nCo-authored-by:
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Fix graph layout stories (#217766)\n\n## Summary\n\nThis fixes the graph
layout stories not rendering properly after\n#214684. Open to a better
or preferred fix as I'm not familiar with\nthese components.\n\nThere
was a console warning:\n```js\n[React Flow]: The React Flow parent
container needs a width and a height to render the graph. Help:
https://reactflow.dev/error#004\n```\n\n[Storybook
preview\nlink](https://ci-artifacts.kibana.dev/storybooks/pr-217766/cloud_security_posture_graph/index.html?path=/story/components-graph-components-graph-layout--simple-api-mock)\n\n---------\n\nCo-authored-by:
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BACKPORT-->

Co-authored-by: Brad White <[email protected]>

Author: kibanamachine

x-pack/solutions/security/packages/kbn-cloud-security-posture/graph/.storybook/decorators/global_styles_decorator.tsx

@@ -10,7 +10,7 @@ import { Global, css } from '@emotion/react';
 const globalStyles = css`
   html,
   body,
-  #root {
+  #storybook-root {
     width: 100%;
     height: 100%;
     margin: 0;