Try changing:
RewriteRule ^guide-(.*)\.html$ guide.php?guida=$1 [L]
to
RewriteRule ^/guide-(.*)\.html$ guide.php?guida=$1 [L]

Although you have the rewrite base directive, that applies to the rewrite only, not the pattern at the beginning. I think that is causing the pattern that starts with guide- to never evaluate as true. But you will also still need the directives to be in reverse order.

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