CSS Rule Conflicts: Which Rule Takes Precedence?

In CSS, multiple rules can apply to the same element, leading to conflicts. When two or more CSS rules target the same element with different styles, the browser must determine which rule overrides the other.

In this blog, you’ll learn:

✅ How CSS specificity affects conflicts
✅ How source order impacts which rule wins
✅ The role of !important in overriding styles
✅ How inheritance influences styles
✅ Best practices for resolving CSS conflicts

1. Specificity: The Most Important Factor

CSS specificity determines which rule wins when multiple rules apply to the same element.

How Specificity Works

Each CSS selector is assigned a specificity score based on the type of selector used:

Selector Type	Example	Specificity Score
Inline Styles	<p style="color: red;">	1000
ID Selector	#heading {}	100
Class, Attribute, or Pseudo-class	.title {}, [type="text"] {}, :hover	10
Element Selector	p {}, h1 {}	1
Universal Selector (*)	* {}	0

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Example 1: Specificity in Action

p { color: blue; }            /* Specificity: 1 */
#special { color: green; }    /* Specificity: 100 */
.special-class { color: red; } /* Specificity: 10 */

<p id="special" class="special-class">Which color will I be?</p>

✅ The ID selector (#special) wins because it has a higher specificity (100) than the class selector (10) and the element selector (1).

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2. Source Order: The Last Rule Wins (If Specificity is the Same)

If two CSS rules have the same specificity, the last rule in the CSS file takes precedence.

Example 2: Source Order Conflict

p {
    color: blue;
}

p {
    color: red;
}

<p>This text will be red.</p>

✅ The second p { color: red; } rule overrides the first rule because it appears later in the CSS file.

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3. The Power of !important (Overrides Everything)

The !important declaration forces a CSS rule to take precedence over all other rules, regardless of specificity.

Example 3: !important Overriding Other Rules

p {
    color: blue !important;
}

p {
    color: red;
}

<p>This text will be blue.</p>

✅ The !important rule wins, even though p { color: red; } is written later.

🔴 Use !important sparingly because it can make debugging harder and override other styles unexpectedly.

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4. Inheritance: How Parent Elements Affect Child Elements

Some CSS properties inherit values from parent elements, while others do not.

Example 4: Inherited vs. Non-Inherited Properties

body {
    color: blue; /* Inherited */
}

p {
    background-color: yellow; /* Not inherited */
}

✅ The <p> text will be blue (inherits from body), but the background-color will not inherit.

Force Inheritance with inherit

p {
    color: inherit; /* Takes the parent's color */
}

Reset Inherited Styles with initial

p {
    color: initial; /* Resets to the default browser style */
}

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5. Best Practices for Handling CSS Conflicts

✅ Use specificity wisely—prefer classes over IDs for styling.
✅ Follow a structured CSS order—write general rules first, then more specific ones.
✅ Minimize !important usage—use it only when necessary.
✅ Group related styles together—keep your CSS organized to avoid confusion.
✅ Use CSS variables (--primary-color: blue;) to maintain consistency.

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Conclusion

When two CSS rules conflict, specificity is the main deciding factor. If specificity is the same, source order determines which rule wins. The !important declaration can override everything, but should be used sparingly. Understanding these principles ensures clean, maintainable, and bug-free CSS.