Change Style of 'Submit" Button On Mailchimp Form & Remove 3D Shadow

Hello, I created a MailChimp newsletter sign up from using the MailChimp for WP plugin. I went to the additional CSS tab on the customize page and put in this code to change the style of the form:

/*———-Mailchimp SignUp———-*/

.mc4wp-form input[type=text] {
-webkit-border-radius: 7px;
-moz-border-radius: 7px;
border-radius: 0px;
box-shadow: inset 0 1px 15px rgba(0, 0, 0, 0);
box-shadow: inset 0 1px 15px rgba(0, 0, 0, 0);
box-shadow: inset 0 1px 15px rgba(0, 0, 0, 0);
float: left;
padding: 15px;
background: #1e1e1e;
border: px;
margin-right: 12px;
font-size: 15px;
width: 30%!important;
}

.mc4wp-form input[type=email] {
-webkit-border-radius: 0px;
-moz-border-radius: 0px;
border-radius: 0px;
box-shadow: inset 0 1px 15px rgba(0, 0, 0, 0);
box-shadow: inset 0 1px 15px rgba(0, 0, 0, 0);
box-shadow: inset 0 1px 15px rgba(0, 0, 0, 0);
float: left;
padding: 15px;
background: #1e1e1e;
border: px;
margin-right: 12px;
font-size: 15px;
width: 32%!important;
}

.mc4wp-form input[type=submit] {
-webkit-border-radius: 50px;
-moz-border-radius: 0px;
border-radius: 0px;
float: left;
color: #ffffff!important;
background-color: #1e1e1e!important;
border: 0px;
border-bottom: 100px;
border-bottom-color: 000000;
font-size: 15px;
text-transform: uppercase;
font-weight: bold;
padding: 0px;
border: px;
width: 30%!important;
}

.mc4wp-form input[type=submit]:hover {
background-color: #1e1e1e!important;
color: white!important;
cursor: pointer;
}

/*———-Sidebar Mailchimp SignUp———-*/

#sidebar .mc4wp-form input[type=text] {
background: #f1f1f1;
width: 100%!important;
margin-bottom: 10px;
}

#sidebar .mc4wp-form input[type=email] {
background: #f1f1f1;
width: 100%!important;
margin-bottom: 10px;
}

#sidebar .mc4wp-form input[type=submit] {
width: 100%!important;
}

/*———-Mailchimp SignUp Tablet Settings———-*/

@media only screen and (max-width: 980px) {

.mc4wp-form input[type=text] {
width: 49%!important;
margin-right: 5px;
}

.mc4wp-form input[type=email] {
width: 50%!important;
margin-right: 0px;
}

.mc4wp-form input[type=submit] {
width: 100%!important;
margin-top: 10px;
}
}

/*———-Mailchimp SignUp Mobile Settings———-*/

@media only screen and (max-width: 623px) {

.mc4wp-form input[type=text] {
width: 100%!important;
margin-right: 0px;
margin-bottom: 10px;
}

.mc4wp-form input[type=email] {
width: 100%!important;
margin-right: 0px;
}

.mc4wp-form input[type=submit] {
width: 100%!important;
margin-right: 0px;
margin-top: 10px;
}
}

It changed the Email and Name boxes to look exactly how I want them (just plain white rectangles) but for some reason, the Submit button is a weird grey color and has a shadow behind it… How can I make the submit button look exactly like the other two boxes?

The form I’m referring to is at the very bottom of this page: https://shaedelea.com/

I am still designing the site around the mobile size so it looks a lot more complete if you look at it on that size (Don’t mind how scattered everything is, there is A LOT that still needs to be done but I can’t move forward until this form looks perfect). Thank you in advance!:)