Используйте display:flex
до warp
div:
.warp{
display:flex;
}
<div class="warp">
<div class="textbox-feild">
<input type="text" class="textfield" name="Email" placeholder="Email *" title="Email * is mandatory and it should be a valid email address">
</div>
<div class="button-field">
<input type="button" class="buttonfield" value="Sign up now">
</div>
</div>
Вы можете сделать это с помощью display: inline-block;
.textbox-feild,.button-field{
display: inline-block;
}
<div class="textbox-feild">
<input type="text" class="textfield" name="Email" placeholder="Email *" title="Email * is mandatory and it should be a valid email address">
</div>
<div class="button-field">
<input type="button" class="buttonfield" value="Sign up now">
</div>