CSS样式不适用于magento中的left.phtml页面

I am new to magento, and i am applying css to left navigation menu in left.phtml of magento project,here is the code

    <div id="leftnav">
    <?php
    $_menu = $this->renderCategoriesMenuHtml(0, 'level-top');
    ?>
    <?php if($_menu): ?>
    <div class="category">
        <div class="title" style="color:#fff;border:1px solid gray;padding:10px;"><?php echo $this->__('Category menu:') ?></div>

        <ul class="submenu">
            <?php echo "sidebar.phtml" ?>
        </ul>
    </div>
<?php endif ?>
</div>

but the css is not applying,so tell me how to do css modifications

probably you just using wrong Phtml for modification. but anyway - All css modification better to do in css files which can be found at SKIN/PACKAGE/THEME/CSS folder

Don't use inline styles

Just update your style.css which is located at skin/frontend/default/your-theme/css

.title {
    color:#fff;
    border:1px solid gray;
    padding:10px;
}

and then you must have to clear cache From admin panel

1. Open Magento admin panel

2. Go to System>Cache Management

3. Check all Cache types and in the Actions box select refresh