CSS でテキストがフローティング画像の周囲に回り込まないようにするにはどうすればよいですか?

<div class="post-container">                
    <div class="post-thumb"><img src="thumb.jpg" /></div>
    <div class="post-content">
        <div class="post-title">Post title</div>
        <p>Post description...</p>
   </div>
</div>

.post-container {
    margin: 20px 20px 0 0;  
    border: 5px solid #333;
    display: flex; /* Create a flexible layout container */
}
.post-thumb {
    float: left;
    margin-right: 20px; /* Create some spacing between the thumbnail and text */
}
.post-thumb img {
    display: block;
}
.post-content {
    margin-left: auto; /* Push the text to the right side of the container */
}
.post-title {
    font-weight: bold;
    font-size: 200%;
}