Hey there! Let's work through this step by step to figure out whether your problem comes from an incorrect CSS import or Safari-specific behavior on your MacBook. We'll start with the most common culprits first.

Step 1: Verify Your CSS Import is Set Up Correctly #

First, rule out basic import mistakes—these are way more common than browser-specific bugs:

• Double-check the file path: Make sure your link tag uses the right relative path. Examples:
  • If stylesheet.css is in the same folder as new.html:

    <link rel="stylesheet" href="stylesheet.css">
    

  • If it's in a subfolder named css:

    <link rel="stylesheet" href="css/stylesheet.css">
    

  • If it's one level above new.html:

    <link rel="stylesheet" href="../stylesheet.css">
    

  Pro tip: MacOS file systems are case-insensitive by default, but Safari can occasionally be picky—make sure the filename in your code matches the actual file's name exactly (e.g., don't mix Stylesheet.css and stylesheet.css).
• Validate the link tag attributes: Ensure you've included the required rel="stylesheet" attribute. The type="text/css" attribute is optional now, but if you add it, double-check it's spelled correctly.
• Check for 404 errors in Safari's Dev Tools:
  1. Enable Safari's Developer Menu: Go to Safari > Settings > Advanced and check "Show Develop menu in menu bar".
  2. Open new.html, then go to Develop > Show Web Inspector.
  3. Switch to the Console tab—if you see a "404 Not Found" error for stylesheet.css, your path is definitely wrong.
• Test direct access to the CSS file: Paste the full file path into Safari's address bar (e.g., file:///Users/YourName/Projects/your-site/stylesheet.css). If the file doesn't load, it's either missing, in the wrong location, or has permissions issues.

Step 2: Rule Out Safari-Specific Issues #

If your import checks out, let's tackle Safari-specific quirks:

• Clear Safari's cache: Browsers often cache old (or broken) CSS. Try a hard refresh with Cmd + Shift + R, or enable "Disable Caches" in the Network tab of Web Inspector before reloading the page.
• Test with simplified CSS: Replace all code in stylesheet.css with a basic rule like:

  body {
    background-color: #ff0000;
  }
  

  If this loads and turns your page red, the issue is with your original CSS (not the import)—check for Safari-incompatible properties (e.g., missing -webkit- prefixes for newer features like backdrop-filter).
• Test via a local server: Safari sometimes handles file:// protocol files differently than server-hosted content. Spin up a simple local server:
  1. Open Terminal, navigate to your project folder with cd /path/to/your/project.
  2. Run python3 -m http.server (or python -m http.server for older Python versions).
  3. Open http://localhost:8000/new.html in Safari. If the CSS loads here, the problem was Safari's handling of local file paths.
• Update Safari: Outdated versions can have known bugs. Go to System Settings > General > Software Update to install the latest Safari updates.

Final Tip #

If you still can't narrow it down, share a snippet of your link tag and your project folder structure—this will help pinpoint the issue faster!

内容的提问来源于stack exchange，提问作者Chris Murphy