Reports

the code works when running it as a StackOverflow snippet:

body {
  background-color: rgb(148, 68, 223);
  margin: 50px;
}
#main {
  background-color: rgb(198, 173, 221);
  border-radius: 20px;
  border: 3px solid rgb(165, 116, 211);
  margin: 30px;
}

<html>
  
  <head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Pierogi Lover's Personal Site</title>
    <link href="/style.css" rel="stylesheet" type="text/css" media="all">
  </head>

  <body>
    <div id="flex-container">
      <div id="main">
        <h1>Welcome!</h1>
      </div>
    </div>
  </body>

</html>

thus, it may be an issue with file structure / import.

if both files are in the same folder, then a way to import CSS can be:

<link href="./style.css" rel="stylesheet" type="text/css" media="all">

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