Revert "Try fix form getting squashed on Mobile Safari"

This reverts commit ad4125a964.

src/components/compose.css

@@ -141,7 +141,6 @@
   display: flex;
   flex-direction: column;
   gap: var(--form-spacing-block);
-  flex-shrink: 0;
 
   @media (min-width: 40em) {
     --form-spacing-inline: 8px;