CSS Transitions

A CSS transition defines how an element changes from one style to another over a certain period. Instead of instantly changing styles, transitions animate the change smoothly, providing a polished effect.

For example, instead of a button instantly changing color on hover, a transition makes it fade gracefully from one color to another.

Key Components of a CSS Transition

Property – The CSS property to animate (width, background-color, transform, etc.).
Duration – How long the animation takes (0.5s, 1s, 2s).
Timing Function – The speed curve of the animation (ease, linear, ease-in, ease-out, ease-in-out, or cubic-bezier()).
Delay – Optional delay before the animation starts (0.5s, 1s, etc.).

Transition Property

The transition-property defines which CSS properties should be animated. You can target a single property:

    .box {
      width: 150px;
      height: 150px;
      background-color: #54a0ff;
      color: white;
      font-weight: bold;
      display: flex;
      justify-content: center;
      align-items: center;
      border-radius: 12px;

      /* Only the background-color will animate */
      transition-property: background-color;
      transition-duration: 1s;
    }

    .box:hover {
      background-color: #ff6b6b; /* Only this property will transition */
    }

<div class="box">Hover Me</div>

Or multiple properties:

transition-property: width, height, transform;

  .box {
      width: 150px;
      height: 150px;
      background-color: #54a0ff;
      color: white;
      font-weight: bold;
      display: flex;
      justify-content: center;
      align-items: center;
      border-radius: 12px;
      transition-property: width, height, background-color, transform;
      transition-duration: 0.5s, 0.7s, 1s, 0.8s;
      transition-timing-function: ease, ease-in-out, linear, ease-in;
    }

    .box:hover {
      width: 250px;
      height: 200px;
      background-color: #ff6b6b;
      transform: rotate(10deg) scale(1.1);
      cursor: pointer;
    }

<div class="box">Hover Me</div>

Transition Duration

The transition-duration specifies how long the animation lasts:

.box {
      width: 150px;
      height: 150px;
      background-color: #54a0ff;
      color: white;
      display: flex;
      justify-content: center;
      align-items: center;
      font-weight: bold;
      border-radius: 12px;

      transition-property: background-color;
      transition-duration: 2s; /* Smooth transition over 2 seconds */
    }

    .box:hover {
      background-color: #ff6b6b;
    }

<div class="box">Hover Me</div>

For multiple properties, different durations can be applied:

.box {
      width: 150px;
      height: 150px;
      background-color: #54a0ff;
      color: white;
      font-weight: bold;
      display: flex;
      justify-content: center;
      align-items: center;
      border-radius: 12px;
      transition-property: width, height, background-color;
      transition-duration: 0.5s, 1s, 1.5s; /* Each property has different duration */
    }

    .box:hover {
      width: 250px;           /* 0.5s */
      height: 200px;          /* 1s */
      background-color: #ff6b6b; /* 1.5s */
      cursor: pointer;
    }

<div class="box">Hover Me</div>

Transition Timing Function

The transition-timing-function controls how the animation progresses over time:

Function	Description
`linear`	Constant speed
`ease`	Slow start, fast middle, slow end (default)
`ease-in`	Slow start, fast end
`ease-out`	Fast start, slow end
`ease-in-out`	Slow start & end, fast middle
`cubic-bezier(n,n,n,n)`	Custom speed curve

Example:

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Transition Timing Function Example</title>
  <style>
    body {
      display: flex;
      justify-content: space-around;
      align-items: center;
      height: 100vh;
      background-color: #f4f4f9;
      font-family: Arial, sans-serif;
    }

    .box {
      width: 100px;
      height: 100px;
      background-color: #54a0ff;
      display: flex;
      justify-content: center;
      align-items: center;
      color: white;
      font-weight: bold;
      border-radius: 12px;
      transition-property: transform;
      transition-duration: 2s;
    }

    /* Different timing functions */
    .linear:hover {
      transition-timing-function: linear;
      transform: translateY(100px);
    }

    .ease:hover {
      transition-timing-function: ease;
      transform: translateY(100px);
    }

    .ease-in:hover {
      transition-timing-function: ease-in;
      transform: translateY(100px);
    }

    .ease-out:hover {
      transition-timing-function: ease-out;
      transform: translateY(100px);
    }

    .ease-in-out:hover {
      transition-timing-function: ease-in-out;
      transform: translateY(100px);
    }
  </style>
</head>
<body>
  <div class="box linear">Linear</div>
  <div class="box ease">Ease</div>
  <div class="box ease-in">Ease-In</div>
  <div class="box ease-out">Ease-Out</div>
  <div class="box ease-in-out">Ease-In-Out</div>
</body>
</html>

Transition Delay

The transition-delay sets a pause before the animation starts:

.box {
      width: 150px;
      height: 150px;
      background-color: #54a0ff;
      color: white;
      font-weight: bold;
      display: flex;
      justify-content: center;
      align-items: center;
      border-radius: 12px;
      transition: background-color 1s;
      transition-delay: 1s; /* Wait 1 second before starting */
    }

    .box:hover {
      background-color: #ff6b6b;
    }

 <div class="box">Hover Me</div>

Complete CSS Transition Example

This example combines property, duration, timing function, and delay to create a dynamic, interactive hover effect:

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>CSS Transitions Example</title>
  <style>
    body {
      display: flex;
      justify-content: center;
      align-items: center;
      height: 100vh;
      font-family: Arial, sans-serif;
      background-color: #f4f4f9;
    }

    .transition-box {
      width: 150px;
      height: 150px;
      background-color: #54a0ff;
      color: white;
      font-weight: bold;
      display: flex;
      justify-content: center;
      align-items: center;
      border-radius: 12px;
      box-shadow: 0 5px 15px rgba(0,0,0,0.1);

      /* Transition Properties */
      transition-property: width, height, background-color, transform;
      transition-duration: 0.6s, 0.8s, 1s, 0.7s;
      transition-timing-function: ease-in, ease-out, ease-in-out, linear;
      transition-delay: 0s, 0.2s, 0.4s, 0s;
    }

    .transition-box:hover {
      width: 250px;
      height: 200px;
      background-color: #ff6b6b;
      transform: scale(1.1) rotate(10deg);
      cursor: pointer;
    }
  </style>
</head>
<body>
  <div class="transition-box">Hover Me</div>
</body>
</html>