fix issue https://github.com/tracim/tracim/issues/683 and issue https://github.com/tracim/tracim/issues/684

frontend/src/container/Login.jsx

             <LoginLogo customClass='loginpage__logo' logoSrc={LoginLogoImg} />
 
             <div className='row justify-content-center'>
-              <div className='col-12 col-sm-11 col-md-8 col-lg-6 col-xl-5'>
+              <div className='col-12 col-sm-11 col-md-8 col-lg-6 col-xl-4'>
 
                 <Card customClass='loginpage__connection'>
                   <CardHeader customClass='connection__header text-center'>{'Connexion'}</CardHeader>

frontend/src/css/Login.styl

       color #FFF
       font-size 25px
   .connection__form
-    margin 0 auto
-    width 70%
     &__rememberme
       &__label
         font-size 13px
         content ' '
         width 130px
   &__footer
-    text-align center
+    position fixed
+    top 95%
+    left calc(50% - 152px) // 152px => width of the text / 2
     &__text
+      width 305px
       font-size 17px
 
 @media (min-width: min-lg) and (max-width: max-lg)