Search field disappears when adding product to cart

When adding some product in my shopping cart the search field of the site does not appear and I can not identify why I was deleting what I could from the files .css that I have and even then I could not reach a result. / p>

I think it might be something related to clearfix, but my css knowledge does not allow me to do a better analysis.

The page can be viewed here: Insertion of Products in the cart

The search field is thus configured:

<form id="search-form" action="busca.php" method="post">
<input id="s" type="text" name="s" placeholder="Busca" style="display: none;">
<input id="search-submit" type="submit" name="search-submit" value="Search">

My cart call looks like this:

<section id="content" class="container clearfix">
<header id="page-header">
    <h1 id="page-title">MEU CARRINHO</h1>   
</header><br><br>
<p>
      <?php
            $class->setURL($url);
            $class->carrinho();
        ?>
</p>

And the css that mounts the cart is this:

.product-image {
  float: left;
  width: 20%;
}

.product-details {
  float: left;
  width: 37%;
}

.product-quantity {
  float: left;
  width: 10%;
}

/* This is used as the traditional .clearfix class */
.group:before, 
.shopping-cart:before, 
.column-labels:before, 
.product:before, 
.totals-item:before,
.group:after,
.shopping-cart:after,
.column-labels:after,
.product:after,
.totals-item:after {
  content: '';
  display: table;
}

.group:after, .shopping-cart:after, .column-labels:after, .product:after, .totals-item:after {
  clear: both;
}

.group, .shopping-cart, .column-labels, .product, .totals-item {
  zoom: 1;
}

/* Apply clearfix in a few places */
/* Apply dollar signs */
.product .product-price:before, .product .product-line-price:before, .totals-value:before {
  content: '$';
}


label {
  color: #aaa;
}

.shopping-cart {
  margin-top: -45px;
}

/* Column headers */
.column-labels label {
  padding-bottom: 15px;
  margin-bottom: 15px;
/*  border-bottom: 1px solid #eee;
*/}
.column-labels .product-image, .column-labels .product-details, .column-labels .product-removal {
  text-indent: -9999px;
}

/* Product entries */
.product {
  margin-bottom: 20px;
  padding-bottom: 10px;
}
.product .product-image {
  text-align: center;
}
.product .product-image img {
  width: 100px;
}
.product .product-details .product-title {
  margin-right: 20px;
  font-family: "HelveticaNeue-Medium", "Helvetica Neue Medium";
}
.product .product-details .product-description {
  margin: 5px 20px 5px 0;
  line-height: 1.4em;
}
.product .product-quantity input {
  width: 40px;
}
.product .remove-product {
  border: 0;
  padding: 4px 8px;
  background-color: #c66;
  color: #fff;
  font-family: "HelveticaNeue-Medium", "Helvetica Neue Medium";
  font-size: 12px;
  border-radius: 3px;
}
.product .remove-product:hover {
  background-color: #a44;
}

/* Totals section */
.totals .totals-item {
  float: right;
  clear: both;
  width: 100%;
  margin-bottom: 10px;
}
.totals .totals-item label {
  float: left;
  clear: both;
  width: 79%;
  text-align: right;
}
.totals .totals-item .totals-value {
  float: right;
  width: 21%;
  text-align: right;
}
.totals .totals-item-total {
  font-family: "HelveticaNeue-Medium", "Helvetica Neue Medium";
}

.checkout {
  float: right;
  border: 0;
  margin-top: 20px;
  padding: 6px 25px;
  background-color: #6b6;
  color: #fff;
  font-size: 25px;
  border-radius: 3px;
}

.checkout:hover {
  background-color: #494;
}

/* Make adjustments for tablet */
@media screen and (max-width: 650px) {
  .shopping-cart {
    margin: 0;
    padding-top: 20px;
    /*border-top: 1px solid #eee;*/
  }

  .column-labels {
    display: none;
  }

  .product-image {
    float: right;
    width: auto;
  }
  .product-image img {
    margin: 0 0 10px 10px;
  }

  .product-details {
    float: none;
    margin-bottom: 10px;
    width: auto;
  }

  .product-price {
    clear: both;
    width: 70px;
  }

  .product-quantity {
    width: 100px;
  }
  .product-quantity input {
    margin-left: 20px;
  }

  .product-quantity:before {
/*    content: 'x';
*/  }

  .product-removal {
    width: auto;
  }

  .product-line-price {
    float: right;
    width: 70px;
  }
}
/* Make more adjustments for phone */
@media screen and (max-width: 350px) {
  .product-removal {
    float: right;
  }

  .product-line-price {
    float: right;
    clear: left;
    width: auto;
    margin-top: 10px;
  }

  .product .product-line-price:before {
    content: 'Item Total: $';
  }

  .totals .totals-item label {
    width: 60%;
  }
  .totals .totals-item .totals-value {
    width: 40%;
  }
}