Is parent styles leaked into child components in scoped css?111

 Is parent styles leaked into child components in scoped css?

No, parent styles are not leaked into child components when using scoped CSS in Vue.js. Scoped CSS is designed to isolate styles within a component, preventing them from affecting other components in the hierarchy.

Here's how scoped CSS works to ensure this encapsulation:

1. Unique Attribute: Vue adds a unique attribute (e.g., data-v-f3f3eg9) to the root element of a component using scoped styles.

2. Style Rewriting: The scoped styles within the component are rewritten to target only elements within that component's scope. This is done by prefixing selectors with the unique attribute.

For example:

Code snippet

<template>
  <div class="parent">
    <child-component />
  </div>
</template>

<style scoped>
  .parent {
    color: red; /* Only applies to elements within this component */
  }
</style>

The rewritten styles would look like this:

CSS

[data-v-f3f3eg9] .parent {
  color: red;
}

As a result:

• The .parent class in the parent component's scoped styles won't affect elements within the child component.

• The child component's scoped styles will also be isolated from the parent's styles.

However, there's a caveat:

• Root Element of Child Component: While scoped styles don't leak into child components, the root element of a child component is still affected by the parent's scoped styles. This is because the unique attribute is applied to the root element itself.

To illustrate:

Code snippet

<template>
  <div class="parent">
    <child-component class="child" />
  </div>
</template>

<style scoped>
  .parent {
    background-color: lightblue;
  }
</style>

In this case:

• The child component's root element would inherit the lightblue background color from the parent's scoped styles.

• However, any other elements within the child component would not be affected.

Key points to remember:

• Scoped CSS effectively isolates styles within components, preventing leakage between parent and child components.

• The root element of a child component is the only exception, as it inherits styles from the parent's scoped styles.

• Be mindful of this behavior when designing your component structure and styling.

• If you need complete isolation for the child component's root element, consider using CSS Modules or other techniques that offer stricter style encapsulation.