As you are trying to emulate bootstrap input, @James Lawruk's suggestion for use. form-control is the fastest way to do this.
But if you want to learn how to emulate the style that you see elsewhere (what you need), you need to check the css used in .form-control (if in Chrome, right-click and "check element"), copy the corresponding style and create your own class.
In this case:
.form-control{ display: block; width: 100%; height: 34px; padding: 6px 12px; font-size: 14px; line-height: 1.42857143; color: #555; background-color: #fff; background-image: none; border: 1px solid #ccc; border-radius: 4px; }
becomes
.custom{ width: 100%; color: #555; border: 1px solid #ccc; border-radius: 4px; }
NOTE. I ignore several pseudo-classes also associated with .form-control, for example: focus, but pseudo-elements are another reason why you would not want to use a class that was designed for another purpose.
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