change the width of the search form in storefront theme

Hello, I have already read the post in this forum, with title “Change width of Search box” but adding this code

.aws-container {
    width: 400px;
}

in the additional CSS of the storefront theme and it worked only in the search results page, but in the first default page of the website the search form is still large 100% by default. any help?

The page I need help with: [log in to see the link]