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How do you apply a linear gradient to an image?

Published in CSS Gradients 6 mins read

To apply a linear gradient, you primarily use the linear-gradient() CSS function, which sets a linear gradient as the background-image for an HTML element. This allows you to create visually appealing transitions between colors, effectively making the gradient itself an "image" for the background. You can also layer a linear-gradient() over an existing image using CSS to achieve an overlay effect.

Understanding the linear-gradient() Function

The core of applying a linear gradient lies with the linear-gradient() function. As per the reference, "The linear-gradient() function sets a linear gradient as the background image." This powerful function allows you to define a smooth progression of colors along a straight line.

To create a linear gradient, you must define at least two color stops. Color stops are the colors you want to render smooth transitions among. You can also set a starting point and a direction (or an angle) along with the gradient effect.

Basic Syntax and Parameters

The fundamental syntax for linear-gradient() is:

background-image: linear-gradient([direction | angle,] color-stop1, color-stop2, ...);

Let's break down the parameters:

  • direction: Specifies the starting point and direction of the gradient. This can be keywords like to top, to right, to bottom, to left.
  • angle: Defines the angle of the gradient line, specified in degrees (e.g., 45deg, 90deg). 0deg is to top.
  • color-stop: These are the colors that the gradient transitions between. You need at least two. You can optionally specify a position for each color stop (e.g., red 0%, blue 100%).

Practical Examples of Applying Linear Gradients

Let's explore various ways to apply linear gradients as a background to an element.

1. Basic Two-Color Gradient

This creates a gradient that goes from top to bottom by default.

<div class="gradient-basic"></div>
.gradient-basic {
    height: 150px;
    width: 300px;
    background-image: linear-gradient(red, blue); /* Default: top to bottom */
}

2. Gradient with Direction

You can explicitly set the direction using keywords.

<div class="gradient-right"></div>
<div class="gradient-left"></div>
.gradient-right {
    height: 150px;
    width: 300px;
    background-image: linear-gradient(to right, #ff00cc, #333399); /* Left to right */
    margin-bottom: 10px;
}
.gradient-left {
    height: 150px;
    width: 300px;
    background-image: linear-gradient(to left, #00ffff, #9933ff); /* Right to left */
}

3. Gradient with Angle

For more precise control, use angles. 0deg is equivalent to to top.

<div class="gradient-angle"></div>
.gradient-angle {
    height: 150px;
    width: 300px;
    background-image: linear-gradient(45deg, #fceabb, #fbefb7); /* 45-degree angle */
}

4. Gradient with Multiple Color Stops

Add more colors to create complex transitions.

<div class="gradient-multi"></div>
.gradient-multi {
    height: 150px;
    width: 300px;
    background-image: linear-gradient(to right, red, orange, yellow, green, blue, indigo, violet);
}

5. Gradient with Color Stop Positions

Control exactly where a color begins and ends its transition.

<div class="gradient-positions"></div>
.gradient-positions {
    height: 150px;
    width: 300px;
    background-image: linear-gradient(to right, red 0%, yellow 50%, blue 100%);
}

Applying a Linear Gradient Over an Existing Image

Often, you might want to apply a gradient effect on top of an actual image (e.g., an <img> tag or a background image). This is achieved by layering backgrounds or using pseudo-elements.

Method 1: Using Multiple background-image Values

You can specify multiple background images, stacking them with the linear-gradient() on top of your url() image.

<div class="image-overlay-bg"></div>
.image-overlay-bg {
    height: 250px;
    width: 400px;
    background-image: linear-gradient(rgba(0,0,0,0.5), rgba(0,0,0,0.5)), /* Black overlay */
                      url('https://via.placeholder.com/400x250/777'); /* Your image URL */
    background-size: cover; /* Ensures image covers the area */
    background-position: center;
    color: white;
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: 1.5em;
    text-shadow: 2px 2px 4px rgba(0,0,0,0.7);
}

In this example, the linear-gradient() with rgba colors creates a semi-transparent dark overlay. The first background image declared (the gradient) is on top of the second one (the actual image).

Method 2: Using Pseudo-elements (::before or ::after)

For more complex overlays, or when working with <img> tags, pseudo-elements offer flexibility.

<div class="image-overlay-pseudo">
    <img src="https://via.placeholder.com/400x250/999" alt="Nature Scene">
    <h3>Beautiful Overlay</h3>
</div>
.image-overlay-pseudo {
    position: relative; /* Needed for pseudo-element positioning */
    width: 400px;
    height: 250px;
    display: inline-block; /* Or block, depending on layout */
    overflow: hidden; /* Ensures pseudo-element doesn't spill */
}

.image-overlay-pseudo img {
    width: 100%;
    height: 100%;
    object-fit: cover; /* Ensures image fills container */
    display: block;
}

.image-overlay-pseudo::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-image: linear-gradient(to top, rgba(0,123,255,0.7), rgba(255,193,7,0.7)); /* Blue to yellow gradient */
    opacity: 1; /* Adjust for transparency */
    transition: opacity 0.3s ease; /* Optional: for hover effects */
}

/* Optional: Fade gradient on hover */
.image-overlay-pseudo:hover::before {
    opacity: 0.8;
}

/* Styling for content over overlay */
.image-overlay-pseudo h3 {
    position: absolute;
    bottom: 15px;
    left: 15px;
    color: white;
    z-index: 1; /* Ensures text is above gradient */
    font-size: 1.8em;
    margin: 0;
}

This method provides excellent control, allowing you to animate the gradient or add other content on top of it.

Method 3: Using background-blend-mode

For blending modes similar to Photoshop, background-blend-mode can be used, though its effect depends on the chosen mode.

<div class="image-blend-mode"></div>
.image-blend-mode {
    height: 250px;
    width: 400px;
    background-image: linear-gradient(to right, red, blue),
                      url('https://via.placeholder.com/400x250/eee'); /* Your image URL */
    background-blend-mode: multiply; /* Blends the gradient with the image */
    background-size: cover;
    background-position: center;
}

This method applies the gradient as a layer and then blends it with the underlying image based on the specified blend mode (e.g., multiply, screen, overlay).

Key Considerations for Linear Gradients

  • Browser Compatibility: linear-gradient() is widely supported across modern browsers. Older browsers might require vendor prefixes (e.g., -webkit-linear-gradient()), but these are largely unnecessary today.
  • Performance: Gradients are rendered by the browser and are generally efficient, especially compared to large image files.
  • Accessibility: Ensure sufficient contrast between text and the gradient background for readability.

By understanding the linear-gradient() function and its application as a background or an overlay, you can effectively enhance the visual appeal of your web content with dynamic color transitions.

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