*{
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html, body {
    background: #f6fcff;
    color: #718393;
    font-family: "Montserrat", sans-serif;
    scroll-behavior: smooth;
}

h1 {
    font-size: calc(40px + 20 * (100vw /1280));
    font-weight: 600;
}

h2 {
    font-size: calc(25px + 10 * (100vw /1280));
    font-weight: 500;
}

h3, h4 {
    font-size: 22px;
    font-weight: 600;
}

.header {
    background-color: #a0b7cc;
}

.header.open .header__burger-btn span:nth-child(1) {
    transform: translateY(0) rotate(45deg);
}

.header.open .header__burger-btn span:nth-child(2) {
    opacity: 0;
}

.header.open .header__burger-btn span:nth-child(3) {
    transform: translateY(0) rotate(-45deg);
}

.header__content {
    display: flex;
    justify-content: end;
    align-items: center;
}

.header__burger-btn {
    display: none;
    position: relative;
    width: 40px;
    height: 40px;
    margin: 10px 0 10px 10px;
    border: none;
    background-color: transparent;
    z-index: 2;
}

.header__burger-btn span {
    position: absolute;
    width: 30px;
    height: 3px;
    background-color: aliceblue;
    left: 5px;
    transition: transform .5s, opacity .5s, background-color .5s;
}

.header__burger-btn span:nth-child(1){
    transform: translateY(-10px);
}

.header__burger-btn span:nth-child(3){
    transform: translateY(10px);
}

.header__nav {
    display: flex;
    padding: 16px;
    margin-right: 10%;
}

.header__item {
    text-decoration: none;
    color: aliceblue;
    font-size: calc(13px + 5 * (100vw /1280));
    letter-spacing: 1px;
    margin-right: 25px;
}

.header__item:hover {
    color: rgb(92, 89, 126);
}

.section-datavis {
    height: 100vh;
    color: #718393;
    text-align: center;
}

.section-datavis__container {
    position: relative;
    top: 36%;
    padding: 0 20px 0 20px;    
}

.section-datavis__title {
    padding-bottom: 30px;
}

.section-about {
    background: linear-gradient(0deg, rgb(255, 255, 255), rgb(196, 216, 230) 100%);
    padding: 10% 10%;
    line-height: 35px;
    text-align: center;
}

.section-about__title {
    white-space: nowrap;
    padding-bottom: 40px;
    
}

.section-about__description {
    font-size: calc(15px + 4 * (100vw /1280));
}

.section-advantages {
    background-color: #a0b7cc;
    padding: 3% 10%;
    line-height: 35px;
    color: aliceblue;
    text-align: center;
}

.section-advantages__title {
    padding-bottom: 20px;
    line-height: normal;
}

.section-advantages__subtitle {
    padding-bottom: 40px;
    font-weight: 400;
}

.section-advantages__item-title {
    padding-bottom: 10px;
    line-height: normal;
}

.section-advantages__item-description {
    font-size: 16px;
    line-height: normal;
}

.section-advantages__grid-container {
    display: grid;
    gap: 40px;
    grid-template-columns: repeat(3, 1fr);
    grid-template-rows: repeat(2, 1fr);
}

.section-advantages__num {
    width: 50px;
    height: 50px;
    margin: auto;
    margin-bottom: 10px;
    padding-top: 8px;
    background: aliceblue;
    font-size: 22px;
    color: #2c3c4b;
    border-radius: 50px;
}

.section-accreditation {
    background: linear-gradient(180deg, rgb(255, 255, 255), rgb(196, 216, 230) 100%);
    padding: 8% 20%;
    line-height: 35px;
}

.section-accreditation__title {
    text-align: center;
    padding-bottom: 15%;
}

.section-accreditation__container {
    position: relative;
    top: 50%;
    margin: auto;
    display: flex;
    justify-content: center;
    gap: 80px;
    width: 80%;
}

.section-accreditation__img {
    height: 301px;
    width: 219px;
}

.section-contacts {
    padding: 10% 10% 7% 10%;
    line-height: 35px;
    text-align: center;
}

.section-contacts__title {
    padding-bottom: 3%;
}

.section-contacts__subtitle {
    font-size: calc(20px + 5 * (100vw /1280));
    padding-bottom: 10%;
}

.section-contacts__container {
    display: flex;
    justify-content: center;
    gap: 80px;
}

.section-contacts__item {
    line-height: normal;
    @media screen and (min-width: 900px) {
        width: 30%;
    }
}

.section-footer {
    width: 100%;
    background-color: #a0b7cc;
    margin: 0 auto;
    text-align: center;
    padding-top: 25px;
}

.section-footer__container {
    display: flex;
    justify-content: space-around;
    padding: 25px 25px 50px 25px;
}

.section-footer__item {
    color: aliceblue;
    font-size: calc(15px + 5 * (100vw /1280));
}

.modal {
    display: none;
    position: fixed;
    z-index: 100;
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;
    overflow: auto;
    background-color: rgb(0 0 0 / 68%);
}

.modal__content {
    margin: auto;
    display: block;
    max-width: 75%;
    max-height: 95%;
    padding-top: 44px;
 }

.modal__close {
    display: none;
    position: absolute;
    top: 15px;
    right: 35px;
    color: #f1f1f1;
    transition: 0.3s;
}

.modal__close:hover, .modal__close:focus {
    color: #bbb;
    text-decoration: none;
    cursor: pointer;
}

@media (max-width: 992px) {
    .header.open .header__nav {
        transform: translateX(100%);
    }
    .header__content {
        justify-content: start;
    }
    .header__burger-btn {
        display: block;
    }
    .header__nav {
        position: absolute;
        left: -180px;
        top: 0;
        width: 180px;
        flex-direction: column;
        background-color: #bdc8cd5d;
        padding: 70px 20px 20px 20px;
        transition: transform .5s;
    }
    .header__item {
        padding: 8px 0;
        color: #445668;
    }
    .section-datavis__container {
        top: 20%;   
    }
    .section-advantages__grid-container {
      display: flex;
      flex-direction: column;
    }
    .section-advantages__grid-container:last-child {
        padding-bottom: 30px;
      }
    .section-accreditation__container {
        flex-direction: column;
        align-items: center;
    }
    .section-contacts {
        text-align: left;
    }
    .section-contacts__container {
        flex-direction: column;
        gap: 35px;
    }
  }