<style>
.scroll-left {
height: 50px;    
overflow: hidden;
position: relative;
background:white;
color: black;
border: 1px solid orange;
}
.scroll-left p {
position: absolute;
width: 100%;
height: 100%;
margin: 0;
line-height: 50px;
text-align: center;
/* Starting position */
transform:translateX(100%);
/* Apply animation to this element */
animation: scroll-left 15s linear infinite;
}
/* Move it (define the animation) */
@keyframes scroll-left {
0%   {
transform: translateX(100%);         
}
100% {
transform: translateX(-100%);
}
}
</style>

<div class="scroll-left">
<p>Masks are mandatory in all Greentrees Buildings </p>
</div>