.htaccess redirect all requests to a subfolder

.htaccess

# /.htaccess

RewriteEngine on
RewriteBase /

RewriteCond %{REQUEST_URI} !^/public/
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d

RewriteRule ^(.*)$ /public/$1 [L]

#----------------------------------------------------

# /public/.htaccess

# Put off automatic trailing slashes in directories
DirectorySlash Off

# Manually put back trailing slashes in directories
RewriteBase /
RewriteCond %{REQUEST_URI} ^((/?[A-Z][A-Za-z0-9]*)+[^/])$
RewriteRule ^((/?[A-Z][A-Za-z0-9]*)+[^/])$ index.php?page=$1 [L]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule ^([a-z0-9][A-Za-z0-9/]*[^/])$ $1/ [R,L]

# Redirect all requests
RewriteRule ^(.*)$ $1 [NC]

# Handle errors
ErrorDocument 404 404frompublic.html
ErrorDocument 500 500frompublic.foo