表格动作GET + Mod Rewrite

I'm sorry if I'm repeating a question, but I can't seem to solve this looking at other answers :(

I have a FORM with GET action:

<form action="tag" role="form" method="get">

Which contains a search input named "q"

What I want is that when I submit the form, the URL displayed in the navigation bar is:

http://localhost/web/tag/dress

Instead, of

http://localhost/web/tag?q=dress

In my .htaccess I have

RewriteRule ^tag/([0-9a-z]+)/?$ index.php?tag=$1 [L]

Which works fine when I access directly to:

http://localhost/web/tag/dress

All I want is the form to take me to this clean URL instead of using the ?q= parameter in the navigation bar.

Any suggestions?

A simplified version of my .htaccess is:

ErrorDocument 404 http://localhost/web/#404
RewriteEngine on

RewriteRule ^index.html index.php [L]

###TAG
RewriteRule ^tag/([0-9a-z]+)/?$ index.php?seccion=home&tag=$1[L]

###USER PROFILE
RewriteRule ^([0-9a-z]+)/?$ index.php?seccion=profile&user=$1 [L]

Add this additional rule before your existing rule:

# external redirect from actual URL to pretty one
RewriteCond %{THE_REQUEST} \s/+web/tag\?q=([^\s&]+) [NC]
RewriteRule ^ /web/tag/%1? [R=302,L]

UPDATE: Your complete .htaccess: NOTE: "/" was missing. Now it should work.

ErrorDocument 404 web/#404

RewriteEngine on
RewriteBase /web/

# external redirect from actual URL to pretty one
RewriteCond %{THE_REQUEST} /tag/\?q=([^\s&]+) [NC]
RewriteRule ^ tag/%1? [R=302,L]

RewriteRule ^index\.html$ index.php [L,NC]

###TAG
RewriteRule ^tag/([0-9a-z]+)/?$ index.php?seccion=home&tag=$1 [L,NC,QSA]

###USER PROFILE
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^([0-9a-z]+)/?$ index.php?seccion=profile&user=$1 [L,NC,QSA]

I wonder if I am forced to do this with javascript?

Something like:

$('.search-form').submit(function (event) { 
    var tag = $('#q').val();
    window.location='tag/'+tag;
    return false;
});