在铁轨上的bootsrap网格

Question

我确信我错过了一些简单的事情，但无法弄明白...... 这让我疯狂...... 我的网格无法正常工作...... 当窗口变小时，我需要让其他人“进步”......

.container
 .section
  .row
   .col-xs-12
    h1 
      |Work In Progress  [
      = @progresses.count 
      | ]
    hr

 .row.progress_container
  - @progresses.each do |progress|
    .col-xs-12.col-sm-6.col-md-4.progress_content
      =image_tag("guitars/guitar-12.jpg", class: "mini_index")  
      h3.text-gold = progress.title.upcase
      h5 = progress.date 
      small = progress.created_at 
      br
      br
      p = truncate(progress.content, length: 100)
      = link_to "Open", progress_path(progress),
        class:"btn btn-primary btn-thumb"

ps：我会解决css中的列高，但这不是问题

感谢您的帮助