Set icon widths

Author: jarrodmillman

index.rst

@@ -70,15 +70,18 @@ Scientific Python Lectures
 .. Icons from https://fonts.google.com/icons
 
 .. |pdf-icon| image:: images/icon-pdf.svg
+   :width: 1em
    :class: vcenter
    :alt: PDF icon
 
 .. |html-icon| image:: images/icon-archive.svg
+   :width: 1em
    :class: vcenter
    :alt: Archive icon
 
 
 .. |github-icon| image:: images/icon-github.svg
+   :width: 1em
    :class: vcenter
    :alt: GitHub icon