* {
    box-sizing: border-box;
}

body {
    margin: 0;
    color: #252525;
    font-family: Arial, Helvetica, sans-serif;
    background: #f7f7f3;
}

a {
    color: inherit;
}

.site-header {
    position: sticky;
    top: 0;
    z-index: 20;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 24px;
    padding: 18px clamp(16px, 4vw, 56px);
    background: #ffffff;
    border-bottom: 1px solid #dddddd;
}


.brand {
    display: flex;
    align-items: center;
    gap: 12px;
    color: #252525;
    text-decoration: none;
}

.site-footer {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    align-items: center;
    gap: 10px 18px;
    width: 100%;
    margin: 0 auto;
    padding: 20px clamp(16px, 4vw, 40px) 28px;
    text-align: center;
    color: #4c585b;
    font-size: 14px;
    border-top: 1px solid #d8d8d0;
}

.site-footer a {
    color: #005ea8;
    font-weight: 700;
    text-underline-offset: 2px;
}

.brand img {
    width: 172px;
    height: auto;
}

.site-header nav {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
}

.site-header nav a,
.form-nav a {
    padding: 8px 12px;
    border-radius: 4px;
    text-decoration: none;
    background: #ece9df;
}

.site-header nav a.active,
.form-nav a.active {
    color: #ffffff;
    background: #2f6f73;
}

main {
    max-width: 1360px;
    margin: 0 auto;
    padding: 24px clamp(16px, 4vw, 40px) 48px;
}

.materials-layout {
    display: grid;
    grid-template-columns: 180px minmax(0, 1fr);
    grid-template-areas:
        "nav books"
        "nav detail";
    column-gap: 28px;
    row-gap: 14px;
    align-items: start;
    padding: 18px 0 10px;
}

.form-nav {
    grid-area: nav;
    display: grid;
    gap: 8px;
    align-content: start;
}

.form-nav h1 {
    margin: 0 0 12px;
    font-size: 32px;
}

.subject-nav {
    display: grid;
    gap: 5px;
    margin: -3px 0 4px 14px;
}

.subject-nav a {
    padding: 6px 9px;
    font-size: 14px;
    background: #ffffff;
    border: 1px solid #d8d8d0;
}

.subject-nav a.active {
    color: #ffffff;
    background: #4d7f55;
    border-color: #4d7f55;
}

.books-panel {
    grid-area: books;
    min-width: 0;
}

.books-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(145px, 180px));
    gap: 16px;
    align-items: start;
}

.book-tile {
    display: grid;
    grid-template-rows: 170px auto auto;
    gap: 8px;
    min-width: 0;
    padding: 10px;
    color: #ffffff;
    text-decoration: none;
    background: #35676d;
    border: 3px solid transparent;
    border-radius: 6px;
}

.book-tile.selected {
    border-color: #f1c84c;
}

.book-tile img {
    width: 100%;
    height: 170px;
    object-fit: contain;
    background: #ffffff;
}

.book-tile span,
.book-tile small {
    overflow-wrap: anywhere;
}

.material-detail {
    display: grid;
    grid-template-columns: minmax(0, 1fr) minmax(190px, 250px);
    gap: 28px;
    align-items: start;
    grid-area: detail;
    padding-top: 14px;
    border-top: 1px solid #d8d8d0;
}

.study-sets {
    display: grid;
    gap: 18px;
}

.eyebrow {
    display: block;
    margin-bottom: 4px;
    color: #687277;
    font-size: 13px;
    text-transform: uppercase;
}

.study-sets h2,
.sample-pages h2,
.supplements h2 {
    margin: 0 0 12px;
    font-size: 20px;
}

.set-book {
    display: block;
    padding: 7px 0;
    border-top: 1px solid #d8d8d0;
    text-decoration: none;
}

.selected-book {
    display: grid;
    grid-template-columns: minmax(170px, 240px) minmax(0, 1fr);
    gap: 28px;
    align-items: start;
}

.book-audio,
.additional-materials {
    grid-column: 2;
    min-width: 0;
    margin-top: -6px;
    padding-top: 20px;
    border-top: 1px solid #d8d8d0;
}

.book-audio h2,
.additional-materials h2 {
    margin: 0 0 12px;
    font-size: 22px;
}

.additional-materials h3 {
    margin: 18px 0 12px;
    font-size: 18px;
}

.additional-context {
    margin: -4px 0 14px;
    color: #687277;
}

.additional-copy {
    font-size: 15px;
    line-height: 1.55;
}

.additional-copy p {
    margin: 0 0 12px;
}

.additional-copy ul {
    margin: 0 0 12px 20px;
    padding: 0;
}

.additional-copy li {
    margin: 6px 0;
}

.additional-copy a {
    color: #005ea8;
    font-weight: 700;
    text-decoration-thickness: 2px;
    text-underline-offset: 2px;
}

.additional-copy a:hover,
.additional-copy a:focus-visible {
    color: #003f73;
}

.book-media {
    display: grid;
    gap: 14px;
    min-width: 0;
}

.cover {
    width: 100%;
    max-height: 420px;
    object-fit: contain;
}

.book-copy h2 {
    margin: 0 0 8px;
    font-size: 30px;
}

.title-part,
.authors,
.format,
.year {
    margin: 6px 0;
}

.annotation {
    margin-top: 18px;
    line-height: 1.55;
}

.sample-pages {
    min-width: 0;
    margin-top: 8px;
}

.sample-pages h2 {
    margin-bottom: 10px;
}

.samples {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(72px, 1fr));
    gap: 8px;
    overflow: visible;
}

.samples a {
    position: relative;
    display: block;
    min-width: 0;
    border: 1px solid #d8d8d0;
    background: #ffffff;
    transition: transform 160ms ease, box-shadow 160ms ease;
    transform-origin: left bottom;
}

.samples img {
    width: 100%;
    aspect-ratio: 908 / 604;
    object-fit: cover;
    display: block;
}

.samples a:hover,
.samples a:focus-visible {
    z-index: 5;
    transform: scale(8.00);
    box-shadow: 0 10px 28px rgba(0, 0, 0, 0.28);
}

.supplements {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 28px;
    margin-top: 36px;
    padding-top: 28px;
    border-top: 1px solid #d8d8d0;
}

.audio-list {
    display: grid;
    gap: 10px;
}

.audio-item {
    display: grid;
    grid-template-columns: minmax(0, 1fr) minmax(220px, 300px);
    column-gap: 18px;
    row-gap: 6px;
    align-items: center;
    padding: 8px 0;
    border-bottom: 1px solid #e1e1d9;
}

.audio-heading {
    margin-top: 8px;
    color: #2f6f73;
    font-weight: 700;
}

.audio-heading:not(.audio-playable) {
    grid-template-columns: 1fr;
}

.audio-heading:not(.audio-playable) .audio-title-row {
    grid-column: 1 / -1;
}

.audio-subheading {
    margin-left: 28px;
}

.audio-subheading .audio-title-row {
    padding-left: 0;
    text-indent: 0;
}

.audio-track {
    margin-left: 28px;
}

.audio-title-row {
    display: block;
    line-height: 1.35;
}

.audio-heading .audio-title-row {
    padding-left: 28px;
    text-indent: -28px;
}

.audio-title {
    overflow-wrap: anywhere;
}

.audio-item audio {
    justify-self: end;
    width: 100%;
    max-width: 360px;
    height: 34px;
}

.apps-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(110px, 1fr));
    gap: 12px;
}

.app-card {
    display: grid;
    gap: 8px;
    align-content: start;
    padding: 10px;
    min-width: 0;
    text-decoration: none;
    background: #ffffff;
    border: 1px solid #d8d8d0;
    border-radius: 6px;
}

.app-card img {
    width: 54px;
    height: 54px;
    object-fit: contain;
}

.app-card span {
    overflow-wrap: anywhere;
    font-size: 14px;
}

@media (max-width: 820px) {
    .site-header,
    .materials-layout,
    .material-detail,
    .selected-book,
    .supplements {
        grid-template-columns: 1fr;
    }

    .materials-layout {
        grid-template-areas: none;
    }

    .site-header {
        align-items: flex-start;
    }

    .material-detail {
        grid-area: auto;
    }

    .book-audio,
    .additional-materials {
        grid-column: auto;
    }

    .audio-item {
        grid-template-columns: 1fr;
    }

    .audio-track {
        margin-left: 18px;
    }

    .audio-item audio {
        justify-self: stretch;
        max-width: none;
    }

    .samples {
        grid-template-columns: repeat(auto-fill, minmax(72px, 1fr));
    }
}