I need to give my body tag a page-specific id to better target css

Question

Editorial Team

Asked: June 5, 20262026-06-05T03:44:05+00:00 2026-06-05T03:44:05+00:00

I need to give my body tag a page-specific id to better target css selectors.

To this end I have set up the following in my application.erb layout:

<body id="<%= content_for :page_id %>">

Inside a page’s view I can then do this:

<% content_for :page_id do %>
  <%='some-page-id'%>
<% end %>

The problem is that I am getting extra whitespace returned around the returned value resulting in the rendered body tag looking like this:

<body id="    some-page-id " >

This prevents the id from working. I have a workaround in place where I do this:

<% body_id = content_for :page_id %>
<body id="<%= body_id.strip %>">

But is there a way to fix this so that content_for returns its value without extra whitespace? What is causing this extra whitespace to be returned?

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Editorial Team · Answer 1 · 2026-06-05T03:44:06+00:00

Editorial Team

What is causing this extra whitespace to be returned?

The space

<% content_for :page_id do %>
  <%='some-page-id'%>
<% end %>

You could try this:

<%- content_for :page_id do -%>
  <%='some-page-id'%>
<%- end -%>

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