@media only screen and (min-width: 1400px) and (max-width: 4000px) {

}

@media only screen and (min-width: 767px) and (max-width: 991px)  {

}       

@media only screen and (min-width: 0px) and (max-width: 767px)  {

    .nav-btn {
        z-index: 10000;
        width: 36px;
        height: 42px;
        cursor: pointer;
        position: relative;
        margin: 25px 5px 0 0;
        display: block;
        padding-right: 35px;
    }

    .nav-btn span {
        display: block;
        border-radius: 20%;
        height: 4px;
        background-color: #3c5a5d;
        position: absolute;
        right: 0;
        top: 0;

        -webkit-transform: rotate(0deg);
        -moz-transform: rotate(0deg);
        -o-transform: rotate(0deg);
        transform: rotate(0deg);

        -webkit-transition: .1s ease-in-out;
        -moz-transition: .1s ease-in-out;
        -o-transition: .1s ease-in-out;
        transition: .1s ease-in-out;

        -webkit-transform-origin: left center;
        -moz-transform-origin: left center;
        -o-transform-origin: left center;
        transform-origin: left center;
    }

    .nav-btn span:nth-child(1) {width:100%;}
    .nav-btn span:nth-child(2) {width:100%; top: 7px;}
    .nav-btn span:nth-child(3) {width:100%; top: 14px;}

    .nav-btn:hover span:nth-child(2) {width: 100%;}
    .nav-btn:hover span:nth-child(3) {width: 100%;}

    .nav-btn.open {transition-duration: .3s;}
    .nav-btn.open span {box-shadow: none; background-color: #3c5a5d; right: -5px;}

    .nav-btn.open span:nth-child(1) {width:100%; transform: rotate(45deg); top: -3px;}
    .nav-btn.open span:nth-child(2) {opacity: 0;}
    .nav-btn.open span:nth-child(3) {width:100%; transform: rotate(-45deg); top: 22px;}

    nav {
        height: 0;
        overflow: hidden;
    }

    nav.open {
        height: 100%;
    }

    .space {
        padding: 35px 0;
    }

    .heading {
        margin: 0 0 25px 0;
        font-size: 26px;
        line-height: 30px;
    }

    header .button-sm {
        display: none;
    }

    .calculator .calculator-form {
        padding: 0;
    }

    .calculator .calculator-form .form-group {
        margin-bottom: 20px;
    }

    .calculator .calculator-result {
        margin: 10px 0 30px 0;
        padding: 20px 20px;
    }

    footer {
        padding: 35px 0 35px 0;
    }

    footer h3 {
        font-size: 18px;
        line-height: 24px;
        margin: 0 0 15px 0;
    }

    footer .footer-socials {
        margin: 0 0 5px 0;
    }

    footer .footer-socials ul li a {
        font-size: 26px;
    }

    footer .copyright {
        margin: 0 0 5px 0;
    }

    footer .certificate li {
        background-size: 120px 35px;
        width: 120px;
    }

}