🔄 CSS Transitions – Master Smooth Effects with Duration, Delay & Timing

Smooth user interactions can dramatically improve a website’s user experience—and CSS Transitions play a key role in achieving that. Whether it’s hovering over a button or focusing on a form input, transitions help you animate CSS property changes smoothly and naturally.

In this guide, we’ll explore everything about CSS Transitions: their properties, how to set durations and delays, and how to control their pacing using timing functions.

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🔰 Introduction – Why CSS Transitions Matter

✨ Imagine hovering over a button and it suddenly changes color with no warning—it feels abrupt. Now imagine it smoothly fades into the new color. That’s the power of CSS transitions.

CSS transitions allow property changes in CSS values to occur over a specified duration, rather than instantly. This enhances visual continuity and provides users with intuitive feedback.

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⏱️ Transition Properties

The foundation of any transition lies in declaring which properties should animate. This is controlled using the transition-property.

✅ Syntax

element {
  transition-property: background-color, transform;
}

💡 Explanation:

• transition-property lets you define which CSS properties will animate.
• You can list one or more properties separated by commas.
• Use all to transition all animatable properties.

🧪 Example:

.box {
  width: 100px;
  height: 100px;
  background-color: steelblue;
  transition-property: background-color, transform;
}

.box:hover {
  background-color: tomato;
  transform: rotate(10deg);
}

🎯 What happens?
On hover, the box smoothly changes color and rotates, thanks to the declared transition-property.

🔒 Pro Tip:

Not all CSS properties can be transitioned. Refer to MDN’s list of animatable properties.

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⏳ Duration & Delay

Transitions need timing—how long they should last and when they should start. Two properties handle this:

• transition-duration
• transition-delay

✅ Syntax

element {
  transition-duration: 0.5s;
  transition-delay: 0.2s;
}

💡 Explanation:

• transition-duration: Sets how long the transition takes (in seconds s or milliseconds ms).
• transition-delay: Adds a delay before the transition starts.

🧪 Example:

.card {
  background-color: lightblue;
  transition-property: background-color;
  transition-duration: 1s;
  transition-delay: 0.3s;
}

.card:hover {
  background-color: darkblue;
}

⏳ What happens?
When hovered, the color transition starts after a 0.3-second delay and completes in 1 second.

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⌛ Timing Functions

Timing functions define how the transition progresses over time. They create effects like acceleration, deceleration, or custom motion curves.

✅ Common Functions

Function	Behavior
ease	Starts slow, speeds up, then slows down (default)
linear	Constant speed from start to end
ease-in	Starts slowly
ease-out	Ends slowly
ease-in-out	Starts and ends slowly
cubic-bezier(n,n,n,n)	Custom acceleration curve

✅ Syntax

element {
  transition-timing-function: ease-in-out;
}

🧪 Example:

.button {
  padding: 10px 20px;
  background-color: teal;
  transition: background-color 0.5s ease-in-out;
}

.button:hover {
  background-color: orange;
}

⌛ What happens?
The background color change will start and end slowly, creating a smooth, natural feel.

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🧩 Shorthand Property

You can combine all transition properties into one line using the transition shorthand:

element {
  transition: background-color 0.4s ease-in 0.2s;
}

Order of values:

1. transition-property
2. transition-duration
3. transition-timing-function (optional)
4. transition-delay (optional)

🧪 Example:

nav a {
  color: black;
  transition: color 0.3s ease;
}

nav a:hover {
  color: crimson;
}

✅ The color change on hover is now animated smoothly in 0.3 seconds.

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📋 CSS Transition Property Table

Property	Description	Example
transition-property	Defines the CSS property to animate	transition-property: width
transition-duration	Sets how long the transition lasts	transition-duration: 1s
transition-delay	Sets a delay before starting	transition-delay: 0.2s
transition-timing-function	Controls speed curve	transition-timing-function: ease-out
transition	Shorthand for all	transition: all 0.5s ease

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⚠️ Notes & Best Practices

• ✅ Keep transitions subtle—too many can become distracting.
• ✅ Combine transitions with accessibility best practices (don’t hide important content with them).
• 🚫 Avoid animating expensive properties like width or height on large DOM elements. Prefer transform and opacity for performance.

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🌐 Accessibility Consideration

📣 Users with motion sensitivity may prefer reduced motion. Respect that with media queries:

@media (prefers-reduced-motion: reduce) {
  * {
    transition: none !important;
  }
}

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🧠 Summary – CSS Transitions

• CSS transitions let you animate property changes smoothly.
• Use transition-property to target specific properties.
• Control timing using transition-duration and transition-delay.
• Fine-tune the animation feel using transition-timing-function.
• Prefer animating properties like transform and opacity for better performance.

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❓FAQs – CSS Transitions

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