frontend_rc3.css: remove initial animation

If we have an animation, this is unusable for OBS studio mode, because
then there's only two options:
- switch to live without being able to verify information
- skip the animation entirely

I don't think Option 1 is a good option, thus users will most likely
always wait for the information to appear. Having to wait for the
information is not suitable then.

pretalx_broadcast_tools/static/pretalx_broadcast_tools/frontend_rc3.css

@@ -23,13 +23,11 @@ p {
   position: absolute;
   bottom: 80px;
   left: 50%;
-  margin-left: -2010px;
+  margin-left: -510px;
   color: white;
   background-color: transparent !important;
   border:1px solid #ccc !important;
   border-bottom: none !important;
-  animation: slide 0.7s forwards;
-  animation-delay: 2s;
 }
 
 #l3title {
@@ -63,9 +61,3 @@ p {
   padding: 0 20px;
   text-align: right;
 }
-
-@keyframes slide {
-  100% {
-    margin-left: -510px;
-  }
-}