@keyframes rotation {
    from {
        transform: rotate(0deg);
    }
    to {
        transform: rotate(360deg);
    }
}


.page {
    min-width: 320px;
    max-width: 1600px;
    margin: 0 auto;
    font-family: 'Helvetica Neue', Arial, sans-serif;
}


.header {
    height: 100vh;
    min-height: 30em;
    max-height: 37.8em;
    background-color: #F2F2F2;
    position: relative;
    display: flex;
    align-items: center;
    overflow: hidden;
    font-size: 20px;
}

.logo {
    width: 15em;
    height: 7.3em;
    background: center cover;
    background-repeat: no-repeat;
}

.logo_place-header {
    position: absolute;
    top: 1.5em;
    left: 3em;
    background-image: url(image/itlogo28.svg);

}

.header__title {
    line-height: 1.04em;
    font-size: 5em;
    max-width: 5.5em;
    margin-left: .55em;
    position: relative;
    z-index: 1;
    font-weight: bold;
}

.header__subtitle {
    line-height: 1.25em;
    font-size: .9em;
    max-width: 19.4em;
    position: absolute;
    bottom: 1.5em;
    left: 3.15em;
    z-index: 1;
    margin: 0;
}

.header__link {
    text-decoration: none;
    color: #2F80ED;
    transition: opacity .2s linear;
    cursor: pointer;
}

.header__link:hover {
    opacity: .6;
}

.header__square-pic {
    height: 28.4em;
    width: 28.4em;
    background-color: #2F80ED;
    position: absolute;
    top: 3.2em;
    right: 0;
    transform: rotate(-15deg);
    animation: rotation linear 20s infinite;
}

.header__main-illustration {
    width: 38.25em;
    height: 30.4em;
    background-image: url(image/noteb3.png);
    background-size: cover;
    position: absolute;
    bottom: 0;
    right: 0;
}



.description {
    margin-top: 100px;
}

.two-columns {
    display: flex;
    justify-content: space-between;
    width: 80%;
    margin: 0 auto;
    font-size: 24px;
}

.two-columns__brief {
    max-width: 164px;
    font-size: .75em;
    color: #2F80ED;
    line-height: 1.2;
    margin: .3em 1em 0 0;
    font-weight: normal;
}

.two-columns__main-text {
    width: 80%;
    max-width: 32.5em;
}

.two-columns__paragraph {
    font-size: 1em;
    line-height: 1.45em;
    margin: 1.25em 0 0;
}

.two-columns__paragraph:first-of-type {
    margin-top: 0;
}

.two-columns__span-accent {
    font-weight: bold;
}



.technics {
    width: 80%;
    margin: 4.1em auto 0;
    font-size: 24px;
}

.section-title {
    text-align: center;
    font-size: 2.5em;
    font-weight: bold;
    margin: 0;
}

.section-title_theme-dark {
    color: white;
    position: relative;
    z-index: 1;
}

.section-subtitle {
    line-height: 1.3em;
    text-align: center;
    margin: .8em 0 0;
    padding: 0 20%;
}

.section-subtitle_theme_dark {
    color: white;
    position: relative;
    z-index: 1;
}

.cards {
    display: flex;
    flex-wrap: wrap;
    width: 80%;
    margin: 0 auto;
}

.cards__item {
    width: 10em;
    margin: 2.5em 1.3em 0;
}

.cards__image {
    width: 6.6em;
    height: 6.6em;
    border-radius: 50%;
    margin: auto;
    background: cover center;
    display: block;
}

.cards__title {
    font-size: 1em;
    text-align: center;
    font-weight: bold;
    margin: 1.7em 0 0;
}

.cards__description {
    line-height: 1em;
    font-size: .75em;
    margin: .6em 0 0;
    text-align: center;
}


.video {
    font-size: 24px;
    width: 80%;
    margin: 4.2em auto 0;
}

.video__iframes {
    display: flex;
    justify-content: center;
    position: relative;
    top: 2.08em;
}

.video__iframe {
    width: 21.4em;
    height: 13.6em;
    margin-right: .83em;
}

.video__iframe:last-of-type {
    margin-right: 0;
}


.oakley {
    background-color: #F2F2F2;
    padding: 160px 0 80px;
    position: relative;
    z-index: -1;
}


.feinman {
    font-size: 36px;
    height: 21.4em;
    background: #F2F2F2 url(image/с++creator.png) no-repeat bottom left;
    background-size: 23em 17em;
    position: relative;
}

.feinman__title {
    font-size: 3em;
    text-align: center;
    padding: 0 2.4em;
    margin: 0 auto;
    font-weight: bold;
}

.feinman__subtitle {
    line-height: 1.1em;
    font-size: 1em;
    text-align: center;
    margin: 1.45em 0 0;
}

.feinman__link {
    line-height: 1.4em;
    font-size: 1em;
    text-decoration: none;
    color: black;
    position: absolute;
    top: 50%;
    right: 1.3em;
    transition: opacity .2s linear;
    cursor: pointer;
}

.feinman__link:hover {
    opacity: .6;
}


.digits {
    margin-top: 4.16em;
    font-size: 24px;
}

.table {
    font-size: 24px;
    margin: auto;
    display: flex;
    flex-wrap: wrap;
    justify-content: space-between;
    align-content: space-between;
    max-width: 1100px;
    padding: 0 2em;
}

.table__cell {
    width: 10.4em;
    margin-top: 2.5em;
}

.table__heading {
    font-size: 1em;
    font-weight: bold;
    margin: 0;
}

.table__heading_theme_dark {
    font-size: 1.2em;
}

.table__text {
    font-size: 0.75em;
    margin: .83em 0 0;
    line-height: 1.2em;
}

.table__text_theme_dark {
    font-size: .9em;
}


.khan {
    font-size: 24px;
    margin-top: 4.1em;
    background-color: #F2F2F2; 
    padding-top: 4.3em;
}

.khan__container {
    width: 80%;
    margin: auto;
}

.khan__author {
    font-size: 1.25em;
    line-height: 1.75em;
    margin: 0;
}

.khan__title {
    font-size: 2.5em;
    font-weight: bold;
    margin: 0;
}

.khan__quote {
    line-height: 1.4em;
    font-size: 1em;
    margin: 2.3em 0 0;
    width: 32em;
}

.khan__quote-author {
    font-size: 1em;
    font-weight: bold;
    margin: 1.5em 0 0;
}

.khan__quote-author-subline {
    font-size: 1em;
    margin: .4em 0 0;
}

.khan__book-container {
    margin-top: 2.8em;
    display: flex;
}

.khan__book-pic {
    height: 25.3em;
    width: 25.8em;
    background-image: url(image/с++book.png);
    background-size: cover;
    background-position: 0 0;
}

.khan__buy-link {
    line-height: 1.75em;
    font-size: 1.25em;
    text-decoration: none;
    color: #2F80ED;
    margin-left: .8em;
    transition: opacity .2s linear;
    cursor: pointer;
}

.khan__buy-link:hover {
    opacity: .6;
}


.kaufman {
    background-color: #1F1F1F;
    padding: 3.75em 0;
    position: relative;
    overflow: hidden;
    font-size: 24px;
}

.table_theme_dark {
    padding: 0;
    display: grid;
    grid-template-columns: 1fr 1fr 1fr 1fr 1fr;
    grid-gap: .5em;
    font-size: 24px;
    margin: 0 auto;
    justify-content: space-between;
    align-content: space-between;
    position: relative;
    z-index: 1;
}

.table__cell_theme_dark {
    color: white;
    margin: 3.3em 0 0 0;
    width: 8em;
}

.kaufman__triangle {
    width: 36.5em;
    height: 36.5em;
    background-image: url(image/bluemachpoly.svg);
    background-size: contain;
    background-position: center;
    background-repeat: no-repeat;
    position: absolute;
    top: 0;
    right: -8.75em;
    z-index: 0;
    overflow: hidden;
    animation: rotation linear 20s infinite; 
}


.resources {
    font-size: 24px;
    margin-top: 4.1em;
}

.resources__logo-zone {
    margin: 3.3em auto 4.1em;
    display: flex;
    justify-content: center;
    min-height: 3em;
    align-content: space-between;
}

.resources__logo {
    width: 10em;
    height: 1.5em;
    background: center no-repeat;
    background-size: contain;
}

.resources__logo_arzamas {
    background-image: url(image/gitlogo4.svg);
}
.resources__logo_n1 {
    background-image: url(image/habr4.svg);
}

.resources__logo_strelka {
    background-image: url(image/cyberfor.svg);
}

.resources__logo_polka {
    background-image: url(image/codeac.svg);
}


.footer {
    font-size: 24px;
    background-color: #1F1F1F;
    min-height: 14.5em;
    box-sizing: border-box;
    padding: 2.5em 0 1.3em;
}

.logo_footer {
    
    position: absolute;
    top: -0.5em;
    width: 15em;
    height: 7.3em;
    background: center cover;
    background-repeat: no-repeat;
    background-image: url(image/logoitwite4.svg);
}

.footer__columns {
    display: flex;
    justify-content: space-between;
    width: 90%;
    margin: auto;
}

.footer__column {
    min-height: 10.5em;
}

.footer__column_content_copyright {
    flex-basis: 29em;
    position: relative;
}

.footer__logo {
    width: 7.7em;
    height: 1.5em;
    background-image: url(image/itlogo2.svg);
    background-size: cover;
    background-position: center;
}

.footer__author {
    position: absolute;
    left: 0;
    bottom: 0;
    line-height: 1em;
    font-size: .75em;
    color: #4F4F4F;
}

.footer__column-heading {
    line-height: 1.25em;
    font-size: .75em;
    color: #FFFFFF;
    margin: 0 0 .8em 0;
}

.footer__column-links {
    padding: 0;
    cursor: pointer;
}

.footer__list-item {
    display: block;
}

.footer__link {
    text-decoration: none;
    line-height: 1.3em;
    font-size: .75em;
    color: #4F4F4F;
    transition: opacity .2s linear;
    cursor: pointer;
}

.footer__link:hover {
    opacity: .6;
}

.footer__social-icon {
    margin-right: .4em;
}

.footer__column_content_info {
    margin-right: 1em;
}

.footer__columns_info {
    display: flex;
}


 @media screen and (max-width : 1280px) {

    .cards__item {
        width: 9em;
        margin: 2.5em 1em 0;
    }

}

@media screen and (max-width : 1240px) {
    .header {
        font-size: 18px;
    }

    .logo {
        width: 15em;
        height: 7.3em;
        background: center cover;
    }

    .cards {
        width: 85%;
    }

    .cards__item {
        width: 8.5em;
        margin: 2.3em 1em 0;
    }
    .feinman {
        font-size: 32px;
        background-size: 20em 15em;
    }

    .feinman__title {
        font-size: 3em;
    }
    
    .feinman__subtitle {
        font-size: 1em;
        margin: 1em 0 0;
    }

    .feinman__link {
        font-size: .9em;
    }

    .khan {
        font-size: 22px;
    }
}

@media screen and (max-width : 1130px) {
    .header {
        font-size: 16px;
    }
    .logo {
        top: 2em;  
        z-index: 1;
        width: 15em;
        height: 7.3em;
        background: center cover;
    }

    .header__main-illustration {
        width: 35em;
        height: 28em;
    }

    .header__square-pic {
        height: 24em;
        width: 24em;
    }

    .header__title {
        font-size: 5em;
    }

    .description {
        margin-top: 80px;
    }

    .two-columns {
        font-size: 21px;
    }
    
    .technics {
        font-size: 22px;
    }

    .video {
        font-size: 22px;
    }

    .digits {
        font-size: 22px;
    }

    .table {
        font-size: 22px;
        padding: 0 1em;
    }

    .kaufman {
        font-size: 22px; 
    }

    .cards__item {
        width: 8em;
    }

    .oakley {
        padding: 120px 0 60px;
    }

    .khan {
        font-size: 20px;
    }

    .table_theme_dark {
        display: grid;
        grid-template-columns: 1fr 1fr 1fr 1fr;
        grid-gap: .5em;
        padding: 0 2em;
    }

    .resources__logo-zone {
        padding: 0 2em;
    }

    .footer {
        font-size: 22px;
    }

}

@media screen and (max-width : 975px) {
     
    .cards__item {
        width: 8em;
        margin: 2.3em .6em 0;
    }

    .feinman {
        font-size: 30px;
        background-size: 18em 14em;
    }

    .feinman__title {
        padding: 0 1.3em;
    }

    .table {
        font-size: 20px;
    }

    .kaufman {
        font-size: 20px; 
    }

    .footer {
        font-size: 20px;
    }


}

@media screen and (max-width : 892px) {

    .logo_footer { 
  
    top: -1em;
    width: 13em;
    height: 6.3em;  
}


    .technics {
        font-size: 20px;
    }

    .video {
        font-size: 20px;
    }

    .digits {
        font-size: 20px;
    }

    .cards__item {
        margin: 2.3em .7em 0;
    }

    .table {
        font-size: 22px;
        display: grid;
        grid-template-columns: 1fr 1fr 1fr;
        grid-gap: 1em;
    }

    .resources {
        font-size: 20px;
    }

    .footer {
        font-size: 18px;
        min-height: 11em;
    }

    .footer__column {
        min-height: 8em;
    }

    .footer__column_content_copyright {
        flex-basis: 25em;
    }
}

@media screen and (max-width : 870px) {

      .logo {
        top: 1.5em;  
        z-index: 1;
        width: 12em;
        height: 6.3em;
        background: center cover;
    }


    .header {
        max-height: 30em;
        font-size: 14px;
    }

    .header__title {
        font-size: 4em;
        margin-left: .65em;
    }

    .header__main-illustration {
        width: 30em;
        height: 23em;
    }

    .header__square-pic {
        height: 20em;
        width: 20em;
        top: 7em;
    }

    .description {
        margin-top: 60px;
    }

    .two-columns {
        flex-direction: column;
        font-size: 20px;
    }

    .two-columns__brief {
        max-width: 300px;
        margin-bottom: 1em;
    }

    .two-columns__main-text {
        width: 100%;
    }

    .cards__item {
        width: 7em;
        margin: 2.3em 1em 0;
    }

    .video__iframes {
        flex-direction: column;
    }
    
    .video__iframe {
        width: 100%;
        height: 19em;
    }

    .video__iframe:first-of-type {
        margin-bottom: 1.5em;
    }

    .oakley {
        padding: 100px 0 50px;
    }



}

@media screen and (max-width : 806px) {
    .technics {
        font-size: 18px;
    }

    .cards__item {
        width: 8em;
        margin: 2.2em .8em 0;
    }

    .video {
        font-size: 18px;
    }

    .kaufman {
        font-size: 18px; 
    }


    .khan {
        font-size: 18px;
    }

    .resources {
        font-size: 18px;
    }
}

@media screen and (max-width : 765px) {

    .cards__item {
        width: 10em;
        margin: 2.5em 1.5em 0;
    }

    .cards__title {
        font-size: 1.2em;
        text-align: center;
        font-weight: bold;
        margin: 1.7em 0 0;
    }
    
    .cards__description {
        line-height: 1.2em;
        font-size: 1em;
        margin: .7em 0 0;
        text-align: center;
    }

    .table {
        font-size: 20px;
    }

    .cell {
       max-width: 9em;
    }

    .footer__column_content_copyright {
        flex-basis: 21em;
    }
}

@media screen and (max-width : 690px) {

    .khan__container {
        width: 90%;
    }

    .cards__item {
        width: 9em;
        margin: 2.5em .9em 0;
    }

}

@media screen and (max-width : 680px) {

    .header__main-illustration {
        display: none;
    }

    .description {
        margin-top: 50px;
    }


    .two-columns {
        font-size: 16px;
    }

    .video__iframe {
        height: 16em;
    }

    .oakley {
        padding: 80px 0 40px;
    }

    .feinman {
        font-size: 20px;
        background-size: 18em 14em;
    }

    .feinman__title {
        padding: 0 1.5em;
    }

    .table {
        font-size: 18px;
    }

    .kaufman {
        font-size: 13.5px; 
    }


    .khan {
        font-size: 16px;
    }

    .khan__quote {
        font-size: .9em;
    }

    .resources__logo-zone {
        padding: 0 5em;
        display: grid;
        grid-template-columns: 1fr 1fr;
        grid-row-gap: 2em;
        grid-column-gap: 5em;
    }

    .resources__logo {
        width: 100%;
        height: 2em;
    }

    .footer {
        font-size: 16px;
    }

    .footer__column_content_copyright {
        flex-basis: 20em;
    }
}

@media screen and (max-width : 612px) {

.table {
        font-size: 16.8px;
    }

}

@media screen and (max-width : 572px) {

    .cards{
        flex-direction: column;
        align-items: center;
    }

    .cards__item {
        width: 12em;
        margin: 2.5em 2em 0;

    }

    .cards__image {
        width: 10em;
        height: 10em;
        border-radius: 50%;
        margin: auto;
        background: cover center;
        display: block;
    }

    .cards__title {
        font-size: 1.2em;
        text-align: center;
        font-weight: bold;
        margin: 1em 0 0;
    }
    
    .cards__description {
        line-height: 1.2em;
        font-size: .8em;
        margin: .7em 0 0;
        text-align: center;
    }

    .table {
        font-size: 22px;
        grid-template-columns: 1fr 1fr;
        grid-gap: 1em;
    }

    .table__cell {
        width: 100%;
    }

    .footer {
        font-size: 14px;
    }

    .footer__logo {
        width: 7.5em;

    }

    .footer__column_content_copyright {
        flex-basis: 16em;
    }
}

@media screen and (max-width : 510px) {

    .technics {
        font-size: 14px;
    }

    .cards {
        font-size: 18px;
    }

    .video {
        font-size: 14px;
    }

    .feinman {
        font-size: 18px;
        background-size: 16em 12em;
    }

    .technics {
        font-size: 14px;
    }

    .video {
        font-size: 14px;
    }

    .resources {
        font-size: 14px;
    }

    .feinman__title {
        font-size: 2em;
        padding: 0 3em;
    }

    .digits {
        font-size: 14px;
    }

    .khan {
        font-size: 14px;
    }

    .khan__quote {
        font-size: .8em;
    }

    .khan__buy-link {
        line-height: 1.3em;
        font-size: 1.25em;
    }

    .table_theme_dark {
        padding: 0 1.5em;
    }
}

@media screen and (max-width : 425px) {

    .footer__author{

        width: 14em;
        top: 3em;
       
    }

    .logo_footer { 
    top: -2em;
    width: 4em;
    height: 5.3em;
}

    .two-columns {
        font-size: 12px;
    }

    .feinman__title {
        padding: 0 2em;
    }

    .khan {
        font-size: 12px;
    }

    .khan__quote {
        font-size: .85em;
    }

    .table {
        font-size: 18px;
    }

    .resources__logo-zone {
        padding: 0 2em;
        display: grid;
        grid-row-gap: 2em;
        grid-column-gap: 2em;
    }

    .footer {
        padding: 2em 0 1.6em;
        font-size: 18px;
    }

    .footer__column {
        min-height: 6em;
        max-height: 8em;
    }

    .footer__column-heading {
        margin: 0 0 .2em 0;
    }

    .footer__column_content_copyright {
        flex-basis: 13em;
        min-height: 3em;
        max-height: 4em;
    }

    .footer__columns {
        padding: -1em 1em;
        display: flex;
        flex-direction: column-reverse;
        width: 90%;
        align-items: flex-start;
    }

    .section-title_theme-dark {
        font-size: 2em;
    }
}


@media screen and (max-width : 396px) {

    .logo {
       
       z-index: 1;
       top: 1.5em;
       width: 12em;
       height: 6em;
       background: center cover;
    }

    .header {
        font-size: 12px;
    }

    .technics {
        font-size: 11px;
    }

    .cards {
        font-size: 14px;
    }

    .cards__image {
        width: 10em;
        height: 10em;
    }

    .video {
        font-size: 11px;
    }

    .table {      
        font-size: 18px;
    }

    .resources {
        font-size: 11px;
    }

    .table {
        grid-gap: .4em;
    }

    .khan__title {
        font-size: 2em;
    }

    .khan__quote {
        font-size: .75em;
    }
}

@media screen and (max-width : 340px) {

    .table {
        font-size: 16px;
    }
}