CSS Animation Not Playing Fix

In this tutorial, you'll learn about CSS Animation Not Playing Fix. We cover key concepts, practical examples, and best practices.

The Problem

You define a @keyframes animation and apply it with animation-name, but nothing happens. The element stays static. Common causes include missing keyframe syntax, incorrect animation property values, or the element starting in a display: none state.

Quick Fix

Step 1: Verify @keyframes syntax

/* Wrong — missing @keyframes keyword or incorrect syntax */
from { opacity: 0; }
to { opacity: 1; }

/* Right */
@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}

Expected output: The animation is defined and can be applied.

Step 2: Apply both animation-name and animation-duration

The animation shorthand requires at least name and duration:

.element {
    /* Wrong — missing duration */
    animation-name: fadeIn;
    /* Right */
    animation: fadeIn 0.5s ease;
}

Expected output: The element fades in over half a second.

Step 3: Ensure the element is visible

Animations do not play on display: none elements:

/* Wrong — hidden element */
.element {
    display: none;
    animation: fadeIn 0.5s;
}
/* Right — use opacity and visibility */
.element {
    visibility: visible;
    opacity: 0;
    animation: fadeIn 0.5s forwards;
}

Expected output: The animation plays when the element becomes visible.

Step 4: Check fill mode for retained end state

Without animation-fill-mode: forwards, the element snaps back to its pre-animation state:

.element {
    /* Wrong — snaps back after animation ends */
    animation: slideIn 0.5s;
    /* Right — retains final state */
    animation: slideIn 0.5s forwards;
}

Expected output: The element stays at the final keyframe position.

Step 5: Add vendor prefixes for older browsers

.element {
    -webkit-animation: fadeIn 0.5s;
    animation: fadeIn 0.5s;
}
@-webkit-keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}
@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}

Expected output: The animation works in Safari and older browsers.

Prevention

• Always include both animation-name and animation-duration
• Use the animation shorthand to avoid missing properties
• Test with animation: name 1s before adding easing or delays
• Avoid display: none on elements that need entrance animations

Common Mistakes with animation not working

1. Forgetting that lazy evaluation defers computation until the value is forced, causing space leaks with unevaluated thunks
2. Using return to exit a function early instead of wrapping a pure value in the monad
3. Mixing let bindings with <- bindings in do notation, producing type errors

These mistakes appear frequently in real-world CSS code. DodaTech's contributors have identified these patterns through analysis of open-source projects and production systems.

Practice Exercise

Write a pure function that safely divides two integers using Maybe, then test it with edge cases like division by zero and negative numbers.

This exercise reinforces the concepts covered in this guide. Try implementing it before checking online solutions.

FAQ