In CSS, inherit, initial, revert, unset, and all are global property values that can be applied to any CSS property, and they control how the value of that property is computed. Let's break them down:

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🔹 inherit

• Definition: The property value is explicitly inherited from the parent element.
• Use Case: Useful when the property is not normally inherited by default, but you want it to be.
• Example:

  p {
    color: inherit;
  }

• If the parent has color: red, then the <p> will also have red text.

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🔹 initial

• Definition: Resets the property to its default value as defined by the CSS specification (not the browser's stylesheet).
• Use Case: When you want to override styles and reset them to the standard default.
• Example:

  div {
    display: initial; /* Resets to 'inline' for most elements */
  }

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🔹 unset

• Definition: Acts like:
  • inherit if the property is normally inherited (e.g., color, font-family)
  • initial if it is not normally inherited (e.g., display, margin)
• Use Case: A smart reset when you're not sure if the property is inherited by default.
• Example:

  span {
    all: unset;
  }

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🔹 revert

• Definition: Reverts the property to the default value from the user-agent (browser stylesheet), user stylesheets, or author stylesheets, depending on the cascade order.
• Use Case: Useful when you're overriding some framework or third-party styles and want to go back to the browser default.
• Example:

  button {
    all: revert; /* Removes framework styles and uses browser styles */
  }

• Note: Supported in modern browsers, but not in Internet Explorer.

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🔹 all

• Definition: A shorthand that applies a global keyword (inherit, initial, unset, revert) to all properties (except unicode-bidi and direction).
• Use Case: Reset or override all styles at once.
• Example:

  * {
    all: unset;
  }

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🧠 Summary Table:

Keyword	Meaning	Inherits?	Resets to spec?	Reverts to browser/user style?
inherit	Inherit value from parent	✅ Yes	❌ No	❌ No
initial	Reset to CSS spec-defined default	❌ No	✅ Yes	❌ No
unset	inherit if inherited, else initial	✅/❌ Smart	✅/❌ Smart	❌ No
revert	Revert to browser/user/author stylesheet	Depends	Depends	✅ Yes
all	Applies one of the above to all properties	Depends	Depends	Depends

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📌 More questions:

Q: How is revert different from initial?
A: initial sets the value to the CSS spec default, whereas revert goes back to the value defined by the user-agent stylesheet or previously declared styles, following the normal CSS cascade.

Q: What does all: unset do?
A: It removes all styles, including margin, padding, borders, and resets the element to a "bare" state. It’s a handy way to eliminate default and framework styles.

Q: Why not always use unset instead of initial or inherit?
A: While unset is flexible, it may not be ideal when you want precise control—like explicitly inheriting or resetting a specific non-inherited property.

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💡 Real-world Example:

button {
  all: unset;
  background-color: blue;
  color: white;
  padding: 0.5rem 1rem;
  border-radius: 5px;
}

This is common in design systems or resets where you remove all browser default styles from a button before styling it from scratch.

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✅ Pro Tip:

Always test revert for browser compatibility, especially if you are supporting legacy browsers like Internet Explorer.

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