Mastering Angular Component Styles with Scoping

Angular's component-based architecture allows for modularity and reusability. A key aspect of this is managing styles effectively to prevent conflicts between components. This challenge focuses on understanding and implementing scoped styles within Angular components, a fundamental technique for building maintainable and robust applications.

Problem Description

Your task is to create an Angular component that demonstrates the concept of scoped styles. This means that the styles defined within the component should only apply to the elements within that specific component's template and should not "leak" out to affect other parts of the application.

Key Requirements:

1. Create an Angular Component: Develop a new Angular component.
2. Define Scoped Styles: Implement styles within the component's stylesheet (e.g., .scss or .css file) that are specific to this component.
3. Demonstrate Isolation: Ensure that these styles do not affect elements outside of the component's template.
4. Use a Global Style for Contrast: Include a global style rule (e.g., in styles.scss) that targets an element that also exists within your component's template, to visually prove that your component's styles are indeed scoped.

Expected Behavior:

When the component is rendered in the application, the elements within its template should be styled according to the component's specific styles. Any global styles targeting similar elements should not override or interfere with the component's scoped styles.

Edge Cases to Consider:

• What happens if an element with the same selector exists in a parent or sibling component? (It should not be affected by the child component's styles).
• How do you ensure styles don't affect child components rendered within your component? (This is the default behavior of Angular's View Encapsulation, which you'll be leveraging).

Examples

Example 1: Basic Scoped Styling

Component: my-card.component.ts

import { Component } from '@angular/core';

@Component({
  selector: 'app-my-card',
  templateUrl: './my-card.component.html',
  styleUrls: ['./my-card.component.scss'] // This is where your scoped styles will go
})
export class MyCardComponent {
  title = 'Awesome Card';
  content = 'This is some descriptive content for the card.';
}

Component Template: my-card.component.html

<div class="card-container">
  <h2>{{ title }}</h2>
  <p>{{ content }}</p>
  <button class="card-button">Click Me</button>
</div>

Component Styles: my-card.component.scss

.card-container {
  border: 1px solid #ccc;
  padding: 16px;
  margin: 8px;
  background-color: #f9f9f9;
  border-radius: 5px;
}

h2 {
  color: steelblue;
  font-size: 1.5em;
}

.card-button {
  background-color: dodgerblue;
  color: white;
  padding: 10px 15px;
  border: none;
  border-radius: 3px;
  cursor: pointer;
}

Global Styles: styles.scss

/* Global style that might unintentionally clash */
h2 {
  color: red !important; /* Intended to show it won't affect the scoped h2 */
  font-size: 2em;
}

button {
  background-color: lightgray; /* Intended to show it won't affect the scoped button */
}

Application Usage in app.component.html:

<h1>My Application</h1>
<app-my-card></app-my-card>
<p>This is some text outside the card.</p>
<h2>This is a global H2</h2>
<button>This is a global button</button>

Expected Output:

The app-my-card component will display a card with a blue title, a gray border, and a blue button. The global h2 and button elements outside the card will be styled with red and light gray respectively, demonstrating that the component's styles are indeed scoped and do not affect global elements. The h2 and button inside the card will retain their steelblue and dodgerblue colors.

Constraints

• You must use Angular's default View Encapsulation mechanism (Emulated) to achieve scoped styles. Do not manually add attributes or use techniques that bypass Angular's built-in scoping.
• The solution should be implemented using TypeScript.
• The component should be functional and render correctly in an Angular application.
• The global stylesheet (styles.scss or equivalent) should contain at least one rule that would affect the target elements if styles were not scoped.

Notes

• Angular's default ViewEncapsulation.Emulated works by adding unique attributes to the component's elements and modifying the CSS to target those attributes, effectively scoping the styles.
• Consider how :host and :host-context() can be used for styling the component itself or elements within it based on its context. For this challenge, focus on styling elements within the component.
• Success is measured by the clear visual distinction between the component's styled elements and global elements that share similar selectors, proving style isolation.