_form.html.haml

= simple_form_for @product, html: { multipart: true } do |f|
	- if @product.errors.any?
		#errors
			%h2
				= pluralize(@product.errors.count, "error")
				prevented this product from saving
			%ul
				- @product.errors.full_messages.each do |msg|
					%li= msg

	...
	...
	
	.form-group
		= f.collection_select :category_id, Category.all, :id, :name, data_html: { class: 'dropdown-header' }

	= f.button :submit, class: "btn btn-primary"

application.css.scss

/*
 * This is a manifest file that'll be compiled into application.css, which will include all the files
 * listed below.
 *
 * Any CSS and SCSS file within this directory, lib/assets/stylesheets, vendor/assets/stylesheets,
 * or any plugin's vendor/assets/stylesheets directory can be referenced here using a relative path.
 *
 * You're free to add application-wide styles to this file and they'll appear at the bottom of the
 * compiled file so the styles you add here take precedence over styles defined in any styles
 * defined in the other CSS/SCSS files in this directory. It is generally better to create a new
 * file per style scope.
 *
 *= require_tree .
 *= require_self
 */
 
@import "bootstrap-sprockets";
@import "bootstrap";

body {
	background: #E9E9E9;
}

h1, h2, h3, h4, h5, h6 {
	font-weight: 100;
}

nav {
	box-shadow: 0 1px 2px 0 rgba(0, 0, 0, 0.22);
	.navbar-brand {
		a {
			color: #BD1E23;
			font-weight: bold;
			&:hover {
				text-decoration: none;
			}
		}
	}
}

#products {
  margin: 0 auto;
  width: 100%;
  .box {
	  margin: 10px;
	  width: 350px;
	  box-shadow: 0 1px 2px 0 rgba(0, 0, 0, 0.22);
	  border-radius: 7px;
	  text-align: center;
	  img {
	  	max-width: 100%;
	  	height: auto;
	  }
	  h2 {
	  	font-size: 22px;
	  	margin: 0;
	  	padding: 25px 10px;
	  	a {
				color: #474747;
	  	}
	  }
	  .user {
	  	font-size: 12px;
	  	border-top: 1px solid #EAEAEA;
			padding: 15px;
			margin: 0;
	  }
	}
}

#edit_page {
	.current_image {
		img {
			display: block;
			margin: 20px 0;
		}
	}
}

#product_show {
	.panel-heading {
		padding: 0;
	}
	.product_image {
		img {
			max-width: 100%;
			width: 100%;
			display: block;
			margin: 0 auto;
		}
	}
	.panel-body {
		padding: 35px;
		h1 {
			margin: 0 0 10px 0;
		}
		.description {
			color: #868686;
			line-height: 1.75;
			margin: 0;
		}
	}
	.panel-footer {
		padding: 20px 35px;
		p {
			margin: 0;
		}
		.user {
			padding-top: 8px;
		}
	}
}

textarea {
	min-height: 250px;
}

.dropdown-header {
  display: block;
  padding: 3px 20px;
  font-size: 12px;
  line-height: 1.42857143;
  color: #777;
  white-space: nowrap;
}

application.js

// This is a manifest file that'll be compiled into application.js, which will include all the files
// listed below.
//
// Any JavaScript/Coffee file within this directory, lib/assets/javascripts, vendor/assets/javascripts,
// or any plugin's vendor/assets/javascripts directory can be referenced here using a relative path.
//
// It's not advisable to add code directly here, but if you do, it'll appear at the bottom of the
// compiled file.
//
// Read Sprockets README (https://github.com/rails/sprockets#sprockets-directives) for details
// about supported directives.
//
//= require jquery
//= require jquery_ujs
//= require bootstrap
//= require masonry/jquery.masonry
//= require bootstrap-sprockets
//= require turbolinks
//= require_tree .