:root {
    --black: #000;
    --white: #fff;
    --dark: #333;
    --gray: #505050;
    --gray2: #666;
    --light-gray: #e5e7eb;
    --light-gray2: #595959;
    --light-gray3: #f7f7f7;
    --dark-gray: #494949;
    --scroll-height: 0;
}

::selection {
    background: var(--black);
    color: var(--white);
}

* {
    -webkit-tap-highlight-color: transparent;
}

body {
    margin: 92px 0 0 0;
    background: var(--white);
    font-family: Arial, sans-serif;
    color: var(--black);
}

.wrapper {
    max-width: 850px;
    margin: 0 auto;
    padding: 0 30px;
}

.header {
    position: fixed;
    top: 0;
    width: 100%;
    background: var(--white);
    box-shadow: rgba(33, 35, 38, 0.1) 0px 10px 10px -10px;
    z-index: 2;
}

.header .wrapper {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.active-menu .header {
    box-shadow: none;
}

@keyframes fadeIn {
    from {
        opacity: 0;
    }
    to {
        opacity: 1;
    }
}

.hamb {
    display: none;
    width: 30px;
    height: 24px;
    margin-left: auto;
    cursor: pointer;
    position: relative;
}

.hamb__item {
    position: absolute;
    width: 100%;
    height: 4px;
    background: var(--black);
    transition: .3s;
}

.hamb__item:nth-child(1) {
    top: 0;
}

.hamb__item:nth-child(2) {
    top: 50%;
    transform: translate(0, -50%);
}

.hamb__item:nth-child(3) {
    bottom: 0;
}

.active-menu {
    overflow: hidden;
}

.active-menu .hamb__item:nth-child(1) {
    transform: rotate(45deg);
    top: calc(50% - 2px);
}

.active-menu .hamb__item:nth-child(2) {
    transform: rotateY(90deg);
}

.active-menu .hamb__item:nth-child(3) {
    transform: rotate(-45deg);
    bottom: calc(50% - 2px);
}

.header__logo {
    display: flex;
    height: 60px;
    padding: 16px 0;
}

.header__logo img {
    width: 100%;
}

.header__item {
    font-size: 18px;
    color: var(--light-gray2);
    text-decoration: none;
    position: relative;
}

.header__item:after {
    content: '';
    position: absolute;
    left: 0;
    bottom: -2px;
    width: 100%;
    height: 1px;
    background: transparent;
    transition: .3s;
}

.header__item:hover:after {
    background: var(--light-gray2);
}

.header__item + .header__item {
    margin-left: 16px;
}

.header__bottom {
    display: none;
}

.hero .wrapper {
    display: flex;
    flex-direction: column;
    justify-content: center;
    height: calc(100vh - 92px);
}

.hero__title {
    font-size: 94px;
    font-weight: 400;
    line-height: 1;
    text-align: center;
    color: var(--dark);
    margin: 0;
}

.hero__subtitle {
    display: block;
    font-size: 30px;
    line-height: 1;
    text-align: center;
    color: var(--light-gray2);
    margin-top: 20px;
}

.hero__text {
    font-size: 23px;
    line-height: 1.7;
    text-align: center;
    color: var(--gray);
    margin: 20px 0 0;
}

.btn {
    display: block;
    width: fit-content;
    margin: 58px auto 0;
    padding: 0;
    font-family: Arial, sans-serif;
    font-size: 16px;
    color: var(--dark);
    border: 0;
    background: transparent;
    cursor: pointer;
    text-decoration: none;
    position: relative;
}

.btn:after {
    content: '';
    position: absolute;
    left: 0;
    bottom: -9px;
    width: 100%;
    height: 2px;
    background: var(--dark);
    transition: .3s;
    pointer-events: none;
}

.btn:hover:after {
    background: transparent;
}

.research {
    padding: 96px 0 30px;
}

.home .research {
    border-top: 1px solid var(--light-gray);
}

.title {
    display: inline-block;
    font-size: 34px;
    font-weight: 400;
    line-height: 1;
    color: var(--dark);
    margin: 0;
}

.text .title {
    margin-bottom: 50px;
}

.subtitle {
    display: block;
    font-size: 16px;
    line-height: 1.3;
    color: var(--gray);
    margin-top: 24px;
}

.research__items {
    margin: 50px 0 0;
}

.research__item {
    display: flex;
    gap: 32px;
    text-decoration: none;
    padding: 32px;
    border: 2px solid transparent;
    border-bottom: 2px solid var(--light-gray);
    transition: .3s;
}

.research__img {
    max-width: 320px;
    width: 100%;
    height: 100%;
    aspect-ratio: 16 / 9;
    border-radius: 16px;
}

.research__title {
    font-size: 27px;
    font-weight: 400;
    line-height: 1.3;
    hyphens: auto;
    color: var(--dark);
    margin: 0;
}

.research__text {
    display: block;
    font-size: 16px;
    line-height: 1.3;
    text-align: justify;
    hyphens: auto;
    color: var(--gray);
    margin: 10px 0 0;
}

.research__more {
    display: inline-block;
    font-size: 16px;
    color: var(--gray);
    margin: 10px 0 0;
    position: relative;
}

.research__more:after {
    content: '';
    position: absolute;
    left: 0;
    bottom: -2px;
    width: 100%;
    height: 1px;
    background: var(--gray);
    transition: .3s;
}

.research__more:hover:after {
    background: transparent;
}

.research__btn {
    display: flex;
    align-items: center;
    width: fit-content;
    font-size: 24px;
    color: var(--dark);
    text-decoration: none;
    margin: 50px auto 0;
    padding: 10px 20px;
    background: var(--light-gray);
    border: 2px solid var(--light-gray);
    transition: .3s;
}

.research__btn:hover {
    background: transparent;
    border: 2px solid var(--black);
}

.research__btn svg {
    transition: .3s;
}

.research__btn:hover svg {
    transform: translateX(10px);
}

.contacts {
    border-top: 1px solid var(--light-gray);
    padding: 96px 0;
}

.contacts__items {
    margin: 50px 0 0;
}

.contacts__item {
    display: flex;
    align-items: center;
    gap: 32px;
    font-size: 16px;
    font-weight: 400;
    line-height: 1.3;
    color: var(--black);
    position: relative;
}

.contacts__item + .contacts__item {
    margin-top: 20px;
}

.contacts__item a {
    display: flex;
    align-items: center;
    gap: 25px;
    color: var(--black);
    text-decoration: none;
    position: relative;
}

.contacts__item a:before {
    content: '';
    width: 10px;
    height: 10px;
    border-radius: 50%;
    background: var(--light-gray);
    transition: .3s;
}

.contacts__item a:hover:before {
    background: var(--black);
}

.contacts__item a span {
    position: relative;
}

.contacts__item a span:after {
    content: '';
    position: absolute;
    left: 0;
    bottom: -2px;
    width: 100%;
    height: 2px;
    background: var(--black);
    transition: .3s;
}

.footer {
    border-top: 1px solid var(--light-gray);
}

.footer .wrapper {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.footer__logo {
    display: flex;
    height: 60px;
    padding: 16px 0;
}

.footer__logo img {
    width: 100%;
}

.footer__copy {
    font-size: 14px;
    color: var(--light-gray2);
}

.social {
    display: flex;
    gap: 24px;
}

.social__item a {
    font-size: 14px;
    color: var(--dark-gray);
    text-decoration: none;
    position: relative;
}

.social__item a:after {
    content: '';
    position: absolute;
    left: 0;
    bottom: -2px;
    width: 100%;
    height: 1px;
    background: transparent;
    transition: .3s;
}

.social__item a:hover:after {
    background: var(--dark-gray);
}

.article {
    padding: 80px 0;
}

.article__content h1 {
    font-size: 42px;
    line-height: 1.2;
    color: var(--dark);
    margin: 0;
    padding-bottom: 16px;
    border-bottom: 1px solid var(--light-gray);
}

.article__content h2,
.text h2:not(.title) {
    font-size: 30px;
    line-height: 1.3;
    color: var(--dark);
    margin: 50px 0 0;
}

.article__content h3,
.text h3 {
    font-size: 22px;
    line-height: 1.3;
    color: var(--dark);
    margin: 30px 0 0;
}

.article__content p,
.text p {
    font-size: 19px;
    line-height: 1.6;
    color: var(--dark);
    margin: 16px 0 0;
    text-align: justify;
    hyphens: auto;
    overflow-wrap: break-word;
}

.text .title + p {
    margin: 0;
}

.article__content a {
    font-size: 19px;
    line-height: 1.6;
    color: var(--dark);
    text-align: justify;
    hyphens: auto;
    overflow-wrap: break-word;
}

.article__content figure {
    margin: 0;
}

.article__content img {
    display: block;
    width: 100%;
    max-width: 500px;
    aspect-ratio: 16 / 9;
    border-radius: 32px;
    margin: 32px auto 0;
}

.article__content ul,
.article__content ol,
.text ul {
    margin: 16px 0 0;
    padding: 0;
    list-style: none;
}

.article__content ul li ul {
    padding-left: 16px;
}

.article__content li,
.text li {
    font-size: 19px;
    line-height: 1.6;
    color: var(--dark);
    text-align: justify;
    hyphens: auto;
    overflow-wrap: break-word;
    position: relative;
}

.article__content ul li:before,
.text ul li:before {
    content: '';
    display: inline-block;
    width: 10px;
    height: 10px;
    border-radius: 50%;
    margin-right: 10px;
    background: var(--light-gray);
}

.article__content li + li,
.text li + li {
    margin-top: 16px;
}

.article__content blockquote {
    margin: 16px 0 0;
    padding: 16px;
    background: var(--light-gray3);
    border-left: 2px solid var(--light-gray);
}

.article__content blockquote p {
    margin: 0;
}

.article__top {
    display: flex;
    gap: 32px;
    margin-top: 16px;
}

.article__item {
    display: flex;
    gap: 3px;
    line-height: 1;
    color: var(--light-gray2);
}

.article__item svg {
    width: 16px;
    height: 16px;
    margin-top: -1px;
}

.navigation {
    position: fixed;
    top: 172px;
    left: 0;
    width: 400px;
    padding: 0 20px;
    box-sizing: border-box;
    border-right: 1px solid var(--light-gray);
}

.navigation:after {
    content: '';
    position: absolute;
    top: 0;
    right: -1px;
    width: 1px;
    height: var(--scroll-height);
    background: var(--black);
    transition: .3s;
}

.navigation__title {
    font-size: 18px;
    font-weight: bold;
    color: var(--dark);
    position: relative;
}

.navigation__title:before {
    content: '';
    position: absolute;
    bottom: -3px;
    width: 100%;
    height: 1px;
    background: var(--light-gray);
}

.navigation__list {
    margin: 32px 0 0;
    padding: 0;
    list-style: none;
    overflow-y: auto;
    max-height: calc(100vh - 330px);
}

.navigation__item + .navigation__item {
    margin-top: 12px;
}

.navigation__link {
    display: block;
    font-size: 16px;
    line-height: 1.4;
    color: var(--gray2);
    text-decoration: none;
    transition: .3s;
}

.navigation__link:hover,
.navigation__item.active .navigation__link {
    color: var(--black);
    -webkit-text-stroke: 0.5px;
}

.last-research {
    position: absolute;
    top: 172px;
    right: 0;
    width: 400px;
    padding: 0 20px;
    box-sizing: border-box;
    border-left: 1px solid var(--light-gray);
}

.last-research__title {
    font-size: 18px;
    font-weight: bold;
    color: var(--dark);
    position: relative;
}

.last-research__title:before {
    content: '';
    position: absolute;
    bottom: -3px;
    width: 100%;
    height: 1px;
    background: var(--light-gray);
}

.last-research__list {
    display: flex;
    flex-direction: column;
    margin-top: 32px;
}

.last-research__item {
    text-decoration: none;
}

.last-research__item + .last-research__item {
    border-top: 1px solid var(--light-gray);
    margin-top: 16px;
    padding-top: 16px;
}

.last-research__img {
    display: block;
    width: 224px;
    margin: 0 auto;
    aspect-ratio: 16 / 9;
    border-radius: 16px;
}

.last-research__name {
    font-size: 16px;
    line-height: 1.4;
    color: var(--gray2);
    margin-top: 12px;
    transition: .3s;
}

.last-research__item:hover .last-research__name {
    color: var(--black);
    -webkit-text-stroke: 0.5px;
}

.updown {
    position: fixed;
    bottom: 30px;
    right: 30px;
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.updown__button {
    display: flex;
    padding: 2px;
    border: 2px solid var(--gray2);
    background: none;
    color: var(--gray2);
    backdrop-filter: blur(10px);
    cursor: pointer;
    transition: .3s;
}

.updown__button.down {
    transform: rotate(180deg);
}

.text {
    border-top: 1px solid var(--light-gray);
    padding: 96px 0 30px;
}

.error404 main {
    display: flex;
    justify-content: center;
    align-items: center;
    height: calc(100vh - 92px - 93px);
    font-size: 94px;
    color: var(--dark);
}

@media (min-width: 1440px) {
    .last-research .wrapper {
        max-width: none;
        margin: 0;
        padding: 0;
    }
}

@media (min-width: 1024px) {
    .research__item:hover {
        border: 2px solid var(--black);
    }
}

@media (min-width: 768px) {
    .updown__button.up:hover {
        transform: rotate(360deg);
    }

    .updown__button.down:hover {
        transform: rotate(540deg);
    }
}

@media (max-width: 1919px) {
    .navigation,
    .last-research {
        width: 265px;
    }

    .navigation__title,
    .last-research__title {
        font-size: 16px;
    }

    .navigation__link,
    .last-research__name {
        font-size: 14px;
    }
}

@media (max-width: 1439px) {
    .navigation {
        display: none;
    }

    .last-research {
        position: static;
        width: auto;
        padding: 0 0 80px;
    }

    .last-research__title {
        font-size: 30px;
        line-height: 1.3;
        color: var(--dark);
        margin: 50px 0 0;
    }

    .last-research__list {
        flex-direction: row;
        gap: 16px;
    }

    .last-research__item + .last-research__item {
        border-top: none;
        margin-top: 0;
        padding-top: 0;
    }

    .article {
        padding: 80px 0 0;
    }
}

@media (max-width: 1023px) {
    .research__item {
        flex-direction: column;
        align-items: center;
        gap: 16px;
        padding: 16px 0;
    }
}

@media (max-width: 767px) {
    body {
        margin: 62px 0 0 0;
    }

    .hamb {
        display: block;
    }

    .wrapper {
        padding: 0 16px;
    }

    .hero .wrapper {
        height: calc(100vh - 62px);
    }

    .header__logo {
        height: 30px;
    }

    .hero__title {
        font-size: 50px;
    }

    .hero__subtitle {
        font-size: 20px;
    }

    .hero__text {
        font-size: 18px;
    }

    .title {
        font-size: 32px;
    }

    .subtitle {
        margin-top: 16px;
    }

    .research__title {
        font-size: 26px;
    }

    .research__btn {
        font-size: 20px;
    }

    .header__menu {
        position: fixed;
        top: 62px;
        right: 0;
        bottom: calc(0px + 100px);
        left: 0;
        display: flex;
        flex-direction: column;
        justify-content: center;
        align-items: center;
        gap: 18px;
        background: var(--white);
        margin: 0;
        opacity: 1;
        z-index: 1;
        transition: .3s;
        transform: translate(100%, 0);
    }

    .header__bottom {
        display: block;
        position: fixed;
        right: 0;
        bottom: -100px;
        left: 0;
        height: 100px;
        background: var(--black);
        opacity: .5;
    }

    .active-menu .header__menu {
        transform: translate(0, 0);
    }

    .header__item {
        font-size: 20px;
    }

    .header__item + .header__item {
        margin-left: 0;
    }

    .header__item + .header__item:before {
        display: none;
    }

    .contacts__item a {
        gap: 16px;
    }

    .footer .wrapper {
        flex-direction: column;
        gap: 16px;
        padding: 16px;
    }

    .footer__logo {
        padding: 0;
        order: 1;
    }

    .social {
        order: 2;
    }

    .footer__copy {
        order: 3;
    }

    .article {
        padding: 40px 0 0;
    }

    .article__content h1 {
        font-size: 30px;
        line-height: 1.3;
    }

    .article__content h2 {
        font-size: 26px;
    }

    .article__content h3,
    .text h3 {
        font-size: 22px;
    }

    .article__content img {
        border-radius: 18px;
        margin: 16px auto 0;
    }

    .article__top {
        justify-content: space-between;
        gap: 0;
    }

    .article__item {
        font-size: 10px;
    }

    .article__item svg {
        width: 10px;
        height: 10px;
        margin-top: 0;
    }

    .last-research__title {
        font-size: 26px;
    }

    .last-research__list {
        flex-direction: column;
        gap: 32px;
    }

    .error404 main {
        height: calc(100vh - 62px - 159px);
        font-size: 50px;
    }
}