render_box with 'bloc'

use bootstrap responsive breakpoints for columns,
mixed with flex-bloc cascade for growing and vertical align blocs.

src/Bundle/ChillPersonBundle/Resources/public/chill/scss/render_box.scss

@@ -1,3 +1,6 @@
+@import '~ChillMainAssets/module/bootstrap/bootstrap';
+@import '~ChillMainAssets/chill/scss/mixins';
+
 section.chill-entity {
     // have no effect for render label, row, bloc
     display: inline;
@@ -22,4 +25,11 @@ section.chill-entity {
         div.entity-row {}
         div.entity-bloc {}
     }
+
+    // don't break flex cascade with section tag
+    div.flex-bloc & {
+        display: flex;
+        flex-grow: 1; flex-shrink: 1; flex-basis: auto;
+    }
 }
+