:root {

    --blue: #405f89;
    --blue-dark: #304b6d;
    --blue-light: #edf1f5;

    --white: #ffffff;



    --text: #333333;
    --text-muted: rgba(51, 51, 51, .58);
    --text-light: rgba(51, 51, 51, .38);

    --border: rgba(51, 51, 51, .1);

}





/* sections begin */
.section {
    padding: 2rem 0; /* 32px 0 */
}

.section > header {
    display: grid;
    grid-template-columns: 3rem 1fr; /* 48px 1fr */
    gap: 0 1rem; /* 0 16px */
    margin-bottom: 1.875rem; /* 30px */
}

.section > header h2 {
    grid-row: 1 / 2;
    grid-column: 2 / 3;
    margin-bottom: 0.5rem; /* 8px */
}

.section_description {
    grid-row: 2 / 3;
    grid-column: 2 / 3;
    color: rgba(51, 51, 51, 0.58);
}

.section_number {
    grid-row: 1 / 2;
    grid-column: 1 / 1;
    padding-top: 0.25rem; /* 4px */
    color: var(--color-primary);
    font-size: 0.75rem; /* 12px */
    font-weight: var(--fw-bold);
    letter-spacing: 0.0625rem; /* 1px */
}
/* sections end */

/* hero begin */
.subject-hero {

    min-height: 390px;

    display: grid;

    grid-template-columns: 1fr .85fr;

    gap: 70px;

    align-items: center;

    padding: 40px 0 70px;

}


.page-label {

    margin-bottom: 22px;

    color: var(--blue);

    font-size: 10px;

    font-weight: 700;

    letter-spacing: 2px;

}


.subject-hero h1 {

    margin: 0;

    font-size: clamp(58px, 7vw, 90px);

    font-weight: 500;

    letter-spacing: -5px;

    line-height: .92;

}


.subject-hero h1 span {

    display: block;

    color: var(--blue);

}


.subject-hero p {

    max-width: 540px;

    margin: 28px 0 0;

    color: var(--text-muted);

    font-size: 14px;

    line-height: 1.8;

}



.subject-hero__visual {

    min-height: 300px;

    position: relative;

    overflow: hidden;

    display: flex;

    align-items: center;

    justify-content: center;

    background: var(--blue);

    border-radius: 4px;

    box-shadow: 0 20px 50px rgba(48,75,109,.14);

}


.subject-hero__visual::before {

    content: "";

    position: absolute;

    width: 340px;

    height: 340px;

    border: 1px solid rgba(255,255,255,.12);

    border-radius: 50%;

}


.subject-hero__visual::after {

    content: "";

    position: absolute;

    width: 650px;

    height: 1px;

    background: rgba(255,255,255,.08);

    transform: rotate(-38deg);

}


.formula {

    position: absolute;

    color: rgba(255,255,255,.42);

    font-size: 13px;

    font-weight: 300;

}


.formula--1 {

    top: 14%;

    left: 8%;

}


.formula--2 {

    top: 23%;

    right: 9%;

}


.formula--3 {

    bottom: 18%;

    left: 9%;

}


.formula--4 {

    right: 14%;

    bottom: 12%;

}


.formula--main {

    position: relative;

    z-index: 2;

    color: #ffffff;

    font-size: 175px;

    font-weight: 300;

    line-height: 1;

}
/* hero end */

/* subjects begin */
.subject-navigation {

    padding: 0 0 60px;

    display: flex;

    align-items: center;

    justify-content: space-between;

    gap: 30px;

}


.back-link {

    display: inline-flex;

    align-items: center;

    gap: 10px;

    color: var(--text-muted);

    font-size: 11px;

    font-weight: 600;

}


.back-link span {

    color: var(--blue);

    font-size: 18px;

}


.back-link:hover {

    color: var(--blue);

}


.subject-switch {

    display: flex;

    gap: 8px;

}


.subject-switch__item {

    min-height: 50px;

    padding: 7px 15px;

    display: flex;

    align-items: center;

    gap: 10px;

    background: #ffffff;

    border: 1px solid var(--border);

    color: var(--text-muted);

    font-size: 11px;

    font-weight: 600;

    transition: .2s ease;

}


.subject-switch__item:hover {

    color: var(--blue);

    border-color: rgba(64,95,137,.3);

}


.subject-switch__item--active {

    background: var(--blue);

    border-color: var(--blue);

    color: #ffffff;

}


.subject-switch__symbol {

    width: 29px;

    height: 29px;

    display: flex;

    align-items: center;

    justify-content: center;

    background: var(--blue-light);

    color: var(--blue);

    font-size: 13px;

}


.subject-switch__item--active
.subject-switch__symbol {

    background: rgba(255,255,255,.12);

    color: #ffffff;

}
/* subjects end */

/* topics begin */
.topics-heading {

    display: grid;

    grid-template-columns: 48px 1fr auto;

    gap: 16px;

    align-items: start;

    margin-bottom: 35px;

}


.topics-heading__number {

    padding-top: 5px;

    color: var(--blue);

    font-size: 10px;

    font-weight: 700;

    letter-spacing: 1.5px;

}


.section-label {

    margin-bottom: 7px;

    color: var(--blue);

    font-size: 9px;

    font-weight: 700;

    letter-spacing: 1.5px;

}


.topics-heading h2 {

    margin: 0;

    font-size: 40px;

    font-weight: 600;

    letter-spacing: -1.5px;

}


.topics-heading p {

    max-width: 540px;

    margin: 11px 0 0;

    color: var(--text-muted);

    font-size: 12px;

    line-height: 1.7;

}


.topics-count {

    min-width: 80px;

    padding-top: 5px;

    display: flex;

    align-items: baseline;

    gap: 5px;

    color: var(--text-muted);

}


.topics-count strong {

    color: var(--blue);

    font-size: 26px;

    font-weight: 500;

}


.topics-count span {

    font-size: 10px;

}




.topics-list {

    display: flex;

    flex-direction: column;

    gap: 8px;

}




.topic-card {

    min-height: 120px;

    padding: 18px 22px;

    display: grid;

    grid-template-columns: 45px 1fr auto;

    gap: 20px;

    align-items: center;

    background: #ffffff;

    border: 1px solid var(--border);

    transition:
        transform .2s ease,
        border-color .2s ease,
        box-shadow .2s ease;

}


.topic-card:hover {

    transform: translateX(4px);

    border-color: rgba(64,95,137,.28);

    box-shadow: 0 10px 30px rgba(48,75,109,.07);

}





.topic-card__number {

    color: rgba(64,95,137,.42);

    font-size: 11px;

    font-weight: 700;

    letter-spacing: 1px;

}





.topic-card__main {

    display: flex;

    align-items: center;

    gap: 18px;

}


.topic-card__symbol {

    flex: 0 0 auto;

    width: 52px;

    height: 52px;

    display: flex;

    align-items: center;

    justify-content: center;

    background: var(--blue-light);

    color: var(--blue);

    font-size: 15px;

    font-weight: 400;

}


.topic-card__text h3 {

    margin: 0 0 6px;

    font-size: 15px;

    font-weight: 700;

}


.topic-card__text p {

    max-width: 650px;

    margin: 0;

    color: var(--text-muted);

    font-size: 11px;

    line-height: 1.6;

}





.topic-card__meta {

    display: flex;

    align-items: center;

    gap: 18px;

}


.topic-card__meta span {

    color: var(--text-light);

    font-size: 9px;

    font-weight: 600;

    white-space: nowrap;

}


.topic-card__meta span:last-child {

    color: var(--blue);

    font-size: 20px;

    font-weight: 400;

    transition: transform .2s ease;

}


.topic-card:hover
.topic-card__meta span:last-child {

    transform: translateX(4px);

}
/* topics end */

/* additional begin */
.subject-tools {

    margin-top: 100px;

    padding-top: 50px;

    border-top: 1px solid var(--border);

    display: grid;

    grid-template-columns: .8fr 1.2fr;

    gap: 60px;

}


.subject-tools__intro h2 {

    margin: 0 0 12px;

    font-size: 28px;

    font-weight: 600;

    letter-spacing: -1px;

}


.subject-tools__intro p {

    max-width: 390px;

    margin: 0;

    color: var(--text-muted);

    font-size: 11px;

    line-height: 1.8;

}


.subject-tools__grid {

    display: grid;

    grid-template-columns: repeat(2, 1fr);

    gap: 8px;

}


.subject-tool {

    min-height: 150px;

    padding: 20px;

    position: relative;

    display: flex;

    flex-direction: column;

    background: #ffffff;

    border: 1px solid var(--border);

    transition: .2s ease;

}


.subject-tool:hover {

    transform: translateY(-3px);

    border-color: rgba(64,95,137,.28);

}


.subject-tool__symbol {

    width: 38px;

    height: 38px;

    display: flex;

    align-items: center;

    justify-content: center;

    background: var(--blue);

    color: #ffffff;

    font-size: 14px;

}


.subject-tool > div:nth-child(2) {

    margin-top: auto;

}


.subject-tool span {

    display: block;

    margin-bottom: 5px;

    color: var(--blue);

    font-size: 8px;

    font-weight: 700;

    letter-spacing: 1.4px;

}


.subject-tool h3 {

    margin: 0;

    font-size: 14px;

}


.subject-tool b {

    position: absolute;

    top: 20px;

    right: 20px;

    color: var(--blue);

    font-size: 18px;

    font-weight: 400;

}
/* additional end */

/* seo begin */
.subject-seo {

    max-width: 760px;

    margin: 75px auto 0;

    text-align: center;

}


.subject-seo h2 {

    margin-bottom: 14px;

    font-size: 22px;

    font-weight: 600;

}


.subject-seo p {

    margin: 0;

    color: var(--text-muted);

    font-size: 11px;

    line-height: 1.8;

}
/* seo end */

/* media queries begin */
@media (width < 1280px) {}

@media (width < 992px) {}

@media (width < 768px) {}

@media (width < 600px) {}

@media (width < 480px) {}



@media (max-width: 950px) {

    .subject-hero {

        grid-template-columns: 1fr;

        gap: 40px;

    }


    .subject-hero__visual {

        min-height: 260px;

    }


    .subject-tools {

        grid-template-columns: 1fr;

        gap: 35px;

    }

}

@media (max-width: 750px) {

    .site-nav {

        display: none;

    }


    .site-login {

        margin-left: auto;

    }


    .subject-navigation {

        align-items: flex-start;

        flex-direction: column;

    }


    .subject-switch {

        width: 100%;

    }


    .subject-switch__item {

        flex: 1;

        justify-content: center;

    }


    .topics-heading {

        grid-template-columns: 40px 1fr;

    }


    .topics-count {

        display: none;

    }


    .topic-card {

        grid-template-columns: 35px 1fr;

        gap: 12px;

    }


    .topic-card__meta {

        grid-column: 2;

        padding-top: 4px;

    }


    .subject-tools__grid {

        grid-template-columns: 1fr;

    }

}

@media (max-width: 500px) {

    .subject-hero h1 {

        font-size: 54px;

        letter-spacing: -3px;

    }


    .subject-hero__visual {

        min-height: 220px;

    }


    .formula--main {

        font-size: 125px;

    }


    .topic-card {

        padding: 15px;

    }


    .topic-card__main {

        align-items: flex-start;

    }


    .topic-card__symbol {

        width: 44px;

        height: 44px;

    }


    .topic-card__text h3 {

        font-size: 13px;

    }


    .topic-card__text p {

        font-size: 10px;

    }


    .topic-card__meta {

        gap: 12px;

    }

}
/* media queries end */