create register page

src/theme/mixins.scss

@@ -16,7 +16,7 @@
     @include flex-center;
 }
 
-@mixin page-content-wrapper {
+@mixin page-content-wrapper($desktopWidth: 400px) {
     margin: 10px;
     padding: 10px;
     background-color: $color-white;
@@ -25,6 +25,6 @@
 
     @include desktop {
         padding: 20px;
-        width: 400px;
+        width: $desktopWidth;
     }
 }

src/theme/reset.scss

@@ -2,6 +2,12 @@ body,
 h1,
 div,
 input,
-button {
+textarea,
+button,
+dl,
+dt,
+dd {
     box-sizing: border-box;
+    margin: 0;
+    padding: 0;
 }