How to display inline with rails?

I would like to know how I can display my Post "inline" I'm begining on css, and I don't know where do I have to put the code display:inline on my css sheet. I'd try post, main_content, body, but it's not working. Can you explain me how to doo it, I follow a lot of tuto and the result it's never the same for me, so I don't understand how to do it .

my actual post display :

My code : Index post view :

<div class="transitions-enabled" id="post">

<%- @posts.each do |post|%>

  <div class="row">

      <div class="post">


        <div class="panel-body">
          <div class="form-group text-center">
            <h3> <%=post.title%></h3>
          </div>
        </div> 

        <div class="box panel panel-default">
          <div class="image_wrapper">
             <%= link_to (image_tag post.image.url(:medium), class: 'img-responsive'), post_path(post)%>
          </div>
        </div>

        <div class="panel-body">
          <div class="form-group text-center">
            <p><%= post.prix %></p>
          </div> 
        </div> 


    </div>
  </div> 

<%end%>
</div>

& my application css :

@import "bootstrap-sprockets";
@import "bootstrap";

@mixin box-shadow {
  -webkit-box-shadow: rgba(0, 0, 0, 0.09) 0 2px 0;
  -moz-box-shadow: rgba(0, 0, 0, 0.09) 0 2px 0;
  box-shadow: rgba(0, 0, 0, 0.09) 0 2px 0;
}

$red: #DB6161;

body {
  background: rgb(235, 238, 243);
}

.main_content {
  padding: 0 0 50px 0;

}

.alert {
  padding: 15px;
  margin-bottom: 20px;
  border: 1px solid transparent;
  border-radius: 5px;
  @include box-shadow;
  background: white;
  font-weight: bold;
}


.navbar {
  margin-bottom: 50px;
  @include box-shadow;
  border: none;
  .navbar-brand {
    text-transform: uppercase;
    letter-spacing: -1px;
    font-weight: bold;
    font-size: 25px;
    a {
      color: $red;
    }
  }
}

.post {
  background: white;
  border-radius: 5px;
  margin-bottom: 40px;
  @include box-shadow;
  float: left;


  .image_wrapper {
    width: 400px;
    height: 300px;
    border-radius: 5px 5px 5px 5px;
    overflow: hidden;
  }
  img {
    width: 100%;
    -webkit-transition: all .3s ease-out;
    -moz-transition: all .3s ease-out;
    -o-transition: all .3s ease-out;
    transition: all .3s ease-out;
    &:hover {
      transform: scale(1.075);
    }
  .panel-body {
    padding: 35px;
    h1 {
      margin: 0 0 10px 0;
    }
    .description {
      color: #868686;
      line-height: 1.75;
      margin: 0;
    }
  }
  }
  h2 {
    padding: 15px 5%;
    margin: 0;
    font-size: 20px;
    font-weight: normal;
    line-height: 1.5;
    a {
      color: $red;
    }
  }
}

#post_top {
  margin-bottom: 50px;
}

#post_info, #ingredients, #directions {
  background: white;
  @include box-shadow;
  min-height: 360px;
  border-radius: 5px;
  padding: 2em 8%;
}

.post_image {
  max-width: 100%;
  border-radius: 5px;
  @include box-shadow;
}

#post_info {
  h1 {
    font-size: 36px;
    font-weight: normal;
    color: $red;
  }
  .description {
    color: #8A8A8A;
    font-size: 20px;
  }
}

#ingredients, #directions {
  margin-bottom: 50px;
  ul, ol {
    padding-left: 18px;
    li {
      padding: 1em 0;
      border-bottom: 1px solid #EAEAEA;
    }
  }
}

.form-inline {
  margin-top: 15px;
}
.form-input {
  width: 65% !important;
  float: left;
}
.form-button {
  float: left;
  width: 30% !important;
  margin-left: 5%;
}
.add-button {
  margin-top: 25px;
}