If you facing problem of css and design after installation in Windows please follow the following steps:

step 1. `php bin/magento setup:static-content:deploy`

step 2. `php bin/magento indexer:reindex`

step 3. make sure apache "rewrite_module" is enabled and then restart the server

step 4. delete cache folder under **var/cache**

The above steps are working for me.I hope this will work for you also.

Let me know if you still facing any problem.