add hr component styles.

src/components.css

@@ -80,6 +80,29 @@
     }
   }
 
+  hr {
+    margin: 0;
+    padding: 0;
+    border-width: 0;
+    border-top-width: 1px;
+    border-color: var(--color-outline-variant);
+    border-style: solid;
+    width: 100%;
+    align-self: stretch;
+    &.dashed {
+      border-style: dashed;
+    }
+    &.dotted {
+      border-style: dotted;
+    }
+    &.vertical {
+      border-top-width: 0;
+      border-left-width: 1px;
+      width: auto;
+      height: 100%;
+    }
+  }
+
   :where(button, .button) {
     border: none;
     border-radius: calc(var(--border-radius) * 2);