adjust .file.multifile to fix rows/columns when multiple images are posted

  When viewing in mobile devices with small screens, posts/ops that contained multiple images did not display
  in rows/columns of 2 or more, but rather caused the first image to consume the first row. This caused the
  next images to flex into a new row of two columns. This was previously fixed by moving the 'hide thread'
  button into it's own row with the use of block display, but by adjusting the width of multifile containers to
  compensate for the padding the images now display in groups of two without issue. This can further be
  adjusted by placing the .multifile containers into another container so that the display of image
  groups/clusters aligns properly, though may be a non-issue considering this is entirely an aesthetic choice
  with little impact to the overall presentation.