<style>
    .block-noborder {
        border: 0;
        box-shadow: 0 0 0;
        border-radius: 0 0 0 0;
    }
</style>
<div class="article-search row" style="margin: 0">
    <form action="<?php echo $this->escape($block['url']); ?>" method="post" style="margin: 0; width: 100%; padding: 0"
          class="form-inline navbar-left">
        <div class="form-group" style="width: 81%">
            <input name="keyword" class="form-control" type="text" placeholder="<?php echo _b('Keyword'); ?>">
        </div>
        <button class="btn" style="width: 60px" type="submit"><?php echo _b('Search'); ?></button>
    </form>
</div>

<script>
    $('.article-search').parent().addClass('block-nopadding');
</script>
