You can try adding <pre><span><style>
before @keyframe, maybe.
Sorry, it takes a lot of effort to understand English. @L.M
<div style =" position: fixed;
animation: slidedissolve 3s;
animation-fill-mode: forwards;
top: 35px;
width: 99%;
height: 93%;
left: 3%;
max-width: 680px;
opacity: 30;
margin-left: -10px;
background-color: rgba(143, 96, 114, 0.3);
backdrop-filter: blur(10px);
border-radius: 16px;
padding-top: 1%;
padding-left: 7%;
padding-right: 7%;
box-shadow: 0 4px 30px pink;
rgba(0, 0, 0, 0.1);
text-align: center;
z-index:-1 !important;"
border: 1px solid rgba(143, 96, 114, 1);
}
<pre><span><style>
@keyframes slidedissolve {
from {left: 0px; opacity:1;}
to {left: -400px; opacity:0.1; }
}
>