css transition not working correctly in vuejs - css

Question

I am trying to animate the slide in/out of my flyout however it doesn't transition but appear and disappear in the same place.
in chrome devtools the animation works if I tick/untick right: 0;
How can I slide in/out the flyout correctly?
<template>
<portal to="modalPortal">
<div
v-if="isMoreOffersFlyoutActive"
:id="id"
class="flyOut"
#click.self="sendCloseModal(true)">
<div
:class="['flyOut__container', {'flyOut__container--active': isMoreOffersFlyoutActive}]">
<div class="flyOut__buttonContainer">
<button
id="storeInfoClose"
class="flyOut__button"
#click="sendCloseModal(false)">
<icon
:scale="closeButtonIconScale"
name="close"
color="white" />
</button>
</div>
<div class="flyOut__content">
<slot />
</div>
</div>
</div>
</portal>
</template>
.flyOut {
position: fixed;
top: 0;
left: 0;
z-index: z("overlay");
display: flex;
justify-content: flex-end;
width: 100%;
height: 100%;
overflow: auto;
background-color: $black-alpha;
&__container {
position: relative;
z-index: z("modal");
right: -50%;
width: 50%;
height: 100%;
background-color: $white;
box-shadow: -2px 0 15px 5px rgba(0,0,0,0.2);
transition: right ease 0.5s;
&--active {
right: 0;
transition: right ease 0.5s;
background: #ff00ff;
}
}

Answer 1

There isn't really an issue with Vue here. The problem stems from trying to animate a position between two different units (or in your case units and no units). Changing right: 0; to right: 10%; would probably work.
All that said, PLEASE don't animate CSS position. It's not performant and causes the browser to reflow & repaint stuff. The better solution is to use css translate(). Here's an example...
.wrapper {
/* need a positioned container for SO's editor */
position: fixed;
top:0; right:0; bottom:0; left:0;
overflow:hidden;
}
.action{
margin: 30px;
font-size: 18px;
font-weight: bold;
cursor:pointer;
font-family: sans-serif;
}
.moved{
position: absolute;
/* put the element where you want it */
top:0;
right:0;
bottom:0;
width: 150px;
background: #333;
padding: 20px;
color: #fff;
/* use transform to move to a new position (100% of element width) */
transform: translatex(100%);
transition: transform 0.5s cubic-bezier(.47,1.64,.41,.8);
}
.action:hover+.moved {
transform: translatex(0);
}
<div class="wrapper">
<div class="action">Hover Me</div>
<div class="moved">Transformed element</div>
</div>