new.html.erb

<div class="container">
  <%= form_for @album, url: albums_path, html: {class: "nifty-form"} do |f| %>
    <%= f.label :name %>  
    <%= f.text_field :name %>
    <%= f.submit "Create" %>
  <% end %>
</div>

new.scss

.container {
    max-width: 600px;
    margin: 0 auto;
}

.nifty-form label {
    font-size: 15px;
    font-family: sans-serif;
}

.nifty-form input[type=text] {
    width: 100%;
    padding: 12px 20px;
    margin: 8px 0;
    display: inline-block;
    border: 1px solid #ccc;
    border-radius: 4px;
    box-sizing: border-box;
    font-size: 16px;
}

.nifty-form input:focus {
    border: 1px solid grey;
}

.nifty-form input[type=submit] {
    width: 100%;
    background-color: blueviolet;
    color: white;
    padding: 14px 20px;
    margin: 8px 0;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    font-size: 16px;
}