Alignement menu header (symmetry)

[Emiperruques]

Hi, 

I have a problem with the header of my website : emiperruques.com (password : 123456). 

I have the symmetry theme. When I select underneath in menu alignment, I have a small space on the left of my page (cf. screenshot). 

Could you please help me to remove it ? Do you know what i can do ? 

Thank you.

Best regards. 

P