Why is my CSS not showing changes in my HTML page

Question

Here is my stylesheet.css code. It is not working when I am running my page. I have checked for the link as well .<link rel="stylesheet" href="stylesheet.css">

It is not working when I write the type as well.

/* Style the header with a grey background and some padding */

    .header {
        overflow: hidden;
        background-color: #f1f1f1;
        padding: 20px 10px;
      }
      
      /* Style the header links */
      .header a {
        float: left;
        color: black;
        text-align: center;
        padding: 12px;
        text-decoration: none;
        font-size: 18px;
        line-height: 25px;
        border-radius: 4px;
      }
    
      .styled-table {
        border-collapse: collapse;
        margin: 25px 0;
        font-size: 0.9em;
        font-family: sans-serif;
        min-width: 400px;
        box-shadow: 0 0 20px rgba(0, 0, 0, 0.15);
    }
    .styled-table thead tr {
      background-color: #009879;
      color: #ffffff;
      text-align: left;
    }
    .styled-table th,
    .styled-table td {
        padding: 12px 15px;
    }
    .styled-table tbody tr {
      border-bottom: 1px solid #dddddd;
    }
    
    .styled-table tbody tr:nth-of-type(even) {
      background-color: #f3f3f3;
    }
    
    .styled-table tbody tr:last-of-type {
      border-bottom: 2px solid #009879;
    }
    .styled-table tbody tr.active-row {
      font-weight: bold;
      color: #009879;
    }

Answer 1

1. Check if your path is correct.

2. Clean your cache (search shortcut for your browser), on google that's CTRL + F5.