fix scroll issue and soft-navigate to /custom-properties resulting in 500 error - #400

Changed pages include:

• index.html - view
• about.html - view
• analyze-css.html - view
• ast-explorer.html - view
• baseline-overview.html - view
• blog.html - view
• css-code-quality.html - view
• css-coverage.html - view
• css-diff.html - view
• css-layers-visualizer.html - view

There are more changes not included in the list