How do I adjust the size of the Quick Search box?

Hi Paul,

WHat files do I need to edit to do this? 
Also, can I just use the custom CSS feature to resize this search box?

Please go to the file: app\design\frontend\Ubertheme\bookshop\Magento_Theme\web\css\source\_module.less (at around line 2522), change min-width: 290px; -> min-width: 250px;
Once done, please follow steps below to compile LESS -> CSS:

You should back up your site first. Then, you access your server via SSH and navigate to your Magento 2 folder, then run the following commands one by one:
Step 1: php bin/magento maintenance:enable
Step 2: rm -rf var/di/* var/generation/* var/cache/* var/log/* var/page_cache/* var/session/* var/view_preprocessed/* pub/static/frontend/Ubertheme/bookshop/*
Step 3: php bin/magento setup:static-content:deploy -t Ubertheme/bookshop -f (Make sure you are using developer (or default) mode)
Step 4: php bin/magento cache:flush
step 5: php bin/magento maintenance:disable
Step 6: clear your browser cache

Please let me know how it goes then.
Best Regards,
Ziven.