fix iframe for buttons

Author: tachyons

docs/chapter4/2input.md

@@ -29,7 +29,7 @@ The **Button** circuit element  is a simple push button mechanism for controllin
 
 You can verify the behavior of the **Button** circuit element in the live circuit embedded below:
 
-<div><iframe>[https://circuitverse.org/users/3671/projects/11912]</iframe></div>
+<div><iframe src="https://circuitverse.org/simulator/embed/untitled-184db5e7-689f-4ce3-9221-467d1830bf16?theme=default&display_title=false&clock_time=true&fullscreen=true&zoom_in_out=true" style="border-width:; border-style: solid; border-color:;" name="myiframe" id="projectPreview" scrolling="no" frameborder="1" marginheight="0px" marginwidth="0px" height="500" width="500" allowFullScreen></iframe></div>
 
 
 ## Power
@@ -92,4 +92,4 @@ The value is also displayed in decimal notation on the counter element.
 
 You can verify the behavior of the Counter circuit element in the live circuit embedded below:
 
-<iframe width="500px" height="400px" src="https://circuitverse.org/simulator/embed/12036" id="projectPreview" scrolling="no" webkitAllowFullScreen mozAllowFullScreen allowFullScreen> </iframe>
+<iframe width="500px" height="400px" src="https://circuitverse.org/simulator/embed/12036" id="projectPreview" scrolling="no" webkitAllowFullScreen mozAllowFullScreen allowFullScreen> </iframe>