Flask页面加载时CSS不生效，Chrome开发者工具编辑后正常

• Verify your HTML uses Flask's url_for to link the CSS file correctly, and ensure the CSS is placed in the project's static folder. Example:

  <link rel="stylesheet" href="{{ url_for('static', filename='style.css') }}">
  

• Open Chrome DevTools' Network tab to check if the CSS file loads with a 200 OK status. A 404 error means your file path is incorrect.

• Perform a hard refresh (Ctrl+Shift+R on Windows/Linux, Cmd+Shift+R on Mac) to bypass residual browser cache that a regular clear might miss.

• Inspect the .hidden-box element in DevTools to check for conflicting styles. Look for higher-specificity rules (like ID selectors or inline styles) that could be overriding your class. Even with !important, inline styles take precedence unless you add !important to them too.

• Confirm your Flask app runs in development mode with app.run(debug=True)—this disables static file caching, which can cause old CSS to persist.

• Access the CSS file directly via its URL (e.g., http://localhost:5000/static/style.css) to ensure it serves the latest code. If it shows outdated content, double-check the file path and that you saved the CSS changes.

• Test the page in another browser (like Firefox) to rule out Chrome-specific bugs or interference from extensions (e.g., ad blockers, stylus tools).

• If cache issues persist, add a unique query parameter to the CSS link to force the browser to fetch the latest version:

  <link rel="stylesheet" href="{{ url_for('static', filename='style.css') }}?v=1">
  

内容的提问来源于stack exchange，提问作者Jyoti