RewriteEngine On
RewriteBase /
RewriteCond %{HTTP_HOST} !^www.hanspeterhassler.ch$ [NC]
RewriteRule ^(.*)$ https://www.hanspeterhassler.ch/$1 [L,R=301]

RewriteEngine On
RewriteBase /
RewriteCond %{HTTP_HOST} !^hanspeterhassler.ch$ [NC]
RewriteRule ^(.*)$ https://www.hanspeterhassler.ch/$1 [L,R=301]