fix(MdApp): remove height 100 to make md-app-content span content height (#1957)

* remove height 100 to make md-app-content span content height

* use min-height of 100 instead of height

Co-authored-by: xxRockOnxx <xxRockOnxx@users.noreply.github.com>

Author: xxRockOnxx

src/components/MdApp/MdAppContent.vue

@@ -22,7 +22,7 @@
 
 <style lang="scss">
   .md-app-content {
-    height: 100%;
+    min-height: 100%;
 
     .md-card {
       margin-right: 16px;