div class works with css but div class doesn't? : So i've tried marking up a letter, and I'm wondering why when I use span class, css is not implemented (date doesn't move to the left), but when I use div class, css is implemented. (date moves to the left). I assumed both should work but one is a block level element and the other is an inline. I changed this line: 

    <div class="receiver-column"> 20 January 2016 </div> 

to

    <span class="receiver-column">20 January 2016 </span>

Heres the html code: 

    <!DOCTYPE html>
    <html lang = "en-US">
       <head>
        <title> Project </title>
    <meta charset = "utf-8">
    <meta name = "author" content = "Eleanor Gaye">
    <link rel = "stylesheet" href = "css.css">
    </head>
        <body>
            
    <p class="receiver-column"><strong>Dr. Eleanor Gaye </strong>
    Awesome Science faculty <br>
    University of Awesome <br>
    Bobtown, CA 99999, <br>
    USA <br>
    <strong>Tel</strong>: 123-456-7890 <br>
    <strong>Email</strong>: no_reply@example.com </p>

            <div class="receiver-column"> 20 January 2016 </div> 


        </body>
</html>

here's the css code:

    body {
      max-width: 800px;
      margin: 0 auto;
    }

    .receiver-column {
      text-align: right;
    }

    h1 {
      font-size: 1.5em;
    }

    h2 {
      font-size: 1.3em;
    }

    p,ul,ol,dl,address {
      font-size: 1.1em;
    }

    p, li, dd, dt, address {
      line-height: 1.5;
    }