<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.html [L]
</IfModule>
So, we need to modify this code rewrite conditions and change the rule. To do this we comment out the lines, so there's no need to delete them. Now, your code should look like this:
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
#RewriteCond %{REQUEST_FILENAME} !-f
#RewriteCond %{REQUEST_FILENAME} !-d
#RewriteRule . /index.php [L]
</IfModule>
Now, add this line underneath to send all page requests to your custom index.html page.
RewriteRule !^index\.html$ /index.html [L,R=302]
Once you have completed changes to your websites files, just remove the rewrite rule above and undo the hashed lines.
Any questions feel free to ask!








