Fix learning objectives line wrapping (restore lost fix from merge)

The merge from podcast branch lost commit 0662141 which fixed learning
objectives line wrapping. The podcast branch had diverged before that
commit was made.

Restored changes:
- .objectives: Change max-width from 90% to 100%
- .objectives: Remove flexbox properties (display, flex-direction, justify-content)
- .objectives h3: Add margin-left: 0 and margin-right: 0
- .objectives ul: Change selector to :global(.reveal) .objectives ul
- .objectives ul: Add display: block, max-width: 100%, margin-left/right: 0

This prevents learning objectives text from wrapping incorrectly in
presentation slides.

Author: ofriw

website/src/components/PresentationMode/RevealSlideshow.module.css

@@ -54,22 +54,25 @@
 .objectives {
   margin-top: 1.5em;
   text-align: left;
-  max-width: 90%;
+  max-width: 100%;
   margin-left: auto;
   margin-right: auto;
-  display: flex;
-  flex-direction: column;
-  justify-content: center;
 }
 
 .objectives h3 {
   font-size: clamp(1rem, 2vw, 1.2em);
   margin-bottom: 0.5em;
+  margin-left: 0;
+  margin-right: 0;
 }
 
-.objectives ul {
+:global(.reveal) .objectives ul {
   list-style: none;
   padding: 0;
+  display: block;
+  max-width: 100%;
+  margin-left: 0;
+  margin-right: 0;
 }
 
 .objectives li {