finish register special

resources/sass/setup/_positions.scss

@@ -29,7 +29,7 @@ $base: 1rem;
 
 .flex-center {
     display: flex;
-    align-items: center;
+    justify-content: center;
 }
 
 .flex-end {
@@ -56,7 +56,7 @@ $base: 1rem;
     padding-right: auto;
 }
 
-@for $i from 1 through 5 {
+@for $i from 0 through 5 {
     .m-#{$i} {
         margin: $i * $base;
     }