Theme development

Hi,
In my template (Bootstrap), in the following line:

<section<?php print $content_column_class; ?>>

I need to add a custom class AND keep the dynamic column class.
I tried <section class="myclass <?php print $content_column_class; ?>"> but it give me:

<section class=" class=" myclass"="" col-sm-12"="">

Any idea what to do?
Thanks

Hi,
I'm new to Drupal and I followed this tutorial to create a custom theme. Everything is up and running, but I have a problem with my custom js-files. This is the relevant part from my theme.libraries.yml:

I have a question.

How do I turn this default drupal login
http://s18.postimg.org/uy6ipmjgp/Capture1.png

To a customized login page
http://postimg.org/image/vbkfx8305/full/

Hi,
i want to use the classy classes/templates but not the css that comes with it
so i set classy as base theme and some library-overrides on every css library that comes with it
but when i activate my new sub theme my website crashes with the error message "A unexpected error occurred. Please try again later"
what am i missing?

Hi I am new to Drupal i am still on learning stage. I have installed Omega them with fusion after installation all pages went black I though of removing omega them but I am unable to login to drupal as I am not getting login page either the only screen I am getting is blue blank.Even I dont have access to drupal file as it is installed in pantheon server ..Can anyone help me on this?

I have a webform with a few "formula" components performing simple math calculations using the webform calculator module.
I am trying to theme the output of the webform in order to add a class to the formula component, depending on the value of the component being calculated.

In my webform-form-[formid]-tpl.php, I have something like this.