add fontSize option

README.md

@@ -19,3 +19,4 @@ useful-markdown-card
 Options:
 
 - `padding` -  Adjust padding of markdown card (default `'16px'`)
+- `fontSize` -  Adjust font-size of markdown card 

useful-markdown-card.js

@@ -54,6 +54,7 @@ class UsefulMarkdownCard extends Polymer.Element {
     this.title = config.title;
     this.content = config.content;
     this.padding = config.padding || null;
+    this.fontSize = config.fontSize|| null;
     if(!this.padding){
       if(this.title){
         this.padding = '0 16px 16px';
@@ -89,6 +90,9 @@ class UsefulMarkdownCard extends Polymer.Element {
       if(!this.$.md.style.padding){
         this.$.md.style.padding = this.padding;
       }
+      if(!this.$.md.style.fontSize){
+        this.$.md.style.fontSize= this.fontSize;
+      }
     }
     this.renderedContent = this.process(this.content);
   }