:root {
    --nav: #101b34;
    --blue: #2764e8;
    --ink: #16233f;
    --muted: #71809b;
    --bg: #f6f8fc;
    --line: #e6ebf3;
    --white: #fff
}

* {
    box-sizing: border-box
}

body {
    margin: 0;
    font-family: Inter, ui-sans-serif, system-ui, -apple-system, Segoe UI, sans-serif;
    background: var(--bg);
    color: var(--ink)
}

button,
input {
    font: inherit
}

.layout {
    display: flex;
    min-height: 100vh
}
.course-page {
        max-width: 1200px;
        margin: 0 auto
    }
  .back {
        border: 0;
        background: transparent;
        color: #2458c9;
        font: inherit;
        font-weight: 800;
        cursor: pointer;
        padding: 0;
        margin: 0 0 18px
    }   
.side {
    position: fixed;
    z-index: 10;
    width: 250px;
    inset: 0 auto 0 0;
    background: linear-gradient(180deg, #101b34, #0c162c);
    color: #dbe5ff;
    padding: 22px 15px;
    display: flex;
    flex-direction: column
}

.brand {
    display: flex;
    align-items: center;
    gap: 11px;
    padding: 4px 10px 28px
}

.brandmark {
    width: 42px;
    height: 42px;
    border-radius: 13px;
    background: linear-gradient(135deg, #4c8dff, #42d5af);
    display: grid;
    place-items: center;
    color: #fff;
    font-weight: 900;
    font-size: 20px
}

.brand b {
    font-size: 18px
}

.brand span {
    display: block;
    font-size: 11px;
    color: #95a5c4;
    margin-top: 2px
}

.nav {
    display: flex;
    flex-direction: column;
    gap: 3px
}

.nav button {
    border: 0;
    background: transparent;
    color: #b9c5dc;
    text-align: left;
    padding: 12px 13px;
    border-radius: 11px;
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 12px;
    font-weight: 600
}

.nav button:hover,
.nav button.active {
    background: #2160dd;
    color: #fff
}

.ico {
    width: 22px;
    text-align: center;
    font-size: 17px
}

.separator {
    height: 1px;
    background: #33405b;
    margin: 17px 8px
}

.side-bottom {
    margin-top: auto
}

.content {
    margin-left: 250px;
    width: calc(100% - 250px);
    padding: 0 28px 45px
}

.top {
    height: 72px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 18px
}

.search {
    background: #fff;
    border: 1px solid var(--line);
    height: 42px;
    border-radius: 14px;
    width: min(510px, 65%);
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 0 14px;
    color: #71809b
}

.search input {
    border: 0;
    outline: 0;
    width: 100%;
    color: var(--ink)
}

.profile {
    display: flex;
    align-items: center;
    gap: 10px
}

.avatar {
    width: 38px;
    height: 38px;
    border-radius: 50%;
    background: #dfe8ff;
    display: grid;
    place-items: center;
    font-weight: 800;
    color: #315ac9
}

.profile small {
    display: block;
    color: var(--muted)
}

.hero {
    border-radius: 25px;
    overflow: hidden;
    position: relative;
    min-height: 360px;
    background: #dfe5ff center/cover no-repeat;
    box-shadow: 0 18px 45px rgba(26, 45, 90, .12)
}

.hero-copy {
    position: absolute;
    left: 40px;
    top: 42px;
    width: 44%;
    z-index: 1
}

.hero h1 {
    font-size: clamp(32px, 4vw, 51px);
    line-height: 1.03;
    margin: 0 0 12px;
    letter-spacing: -1.8px
}

.hero h1 span {
    color: #2864e7
}

.hero p {
    font-size: 16px;
    line-height: 1.55;
    color: #50607d;
    max-width: 510px
}

.hero .btn {
    margin-top: 8px
}

.btn {
    border: 0;
    border-radius: 13px;
    padding: 12px 18px;
    background: var(--blue);
    color: white;
    font-weight: 800;
    cursor: pointer;
    box-shadow: 0 9px 20px rgba(39, 100, 232, .23)
}

.btn.secondary {
    background: #fff;
    color: var(--ink);
    box-shadow: none;
    border: 1px solid var(--line)
}

.page {
    display: none
}

.page.active {
    display: block
}

.section-title {
    display: flex;
    justify-content: space-between;
    align-items: end;
    margin: 30px 0 15px
}

.section-title h2 {
    margin: 0;
    font-size: 25px
}

.section-title p {
    margin: 5px 0 0;
    color: var(--muted);
    font-size: 14px
}

.filters {
    display: flex;
    gap: 7px;
    flex-wrap: wrap
}

.chip {
    border: 1px solid var(--line);
    background: #fff;
    border-radius: 999px;
    padding: 8px 12px;
    color: #64718a;
    cursor: pointer
}

.chip.active {
    background: #e9efff;
    color: #2458c9;
    border-color: #cbd8ff
}

.grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 18px
}

.card {
    background: #fff;
    border: 1px solid var(--line);
    border-radius: 18px;
    overflow: hidden;
    box-shadow: 0 8px 22px rgba(28, 45, 75, .055);
    transition: .2s
}

.card:hover {
    transform: translateY(-3px);
    box-shadow: 0 17px 35px rgba(28, 45, 75, .12)
}

.thumb {
    height: 145px;
    position: relative;
    overflow: hidden
}

.thumb img {
    width: 100%;
    height: 100%;
    object-fit: cover
}

.pill {
    position: absolute;
    left: 13px;
    bottom: 12px;
    background: #fff;
    padding: 6px 10px;
    border-radius: 999px;
    font-size: 11px;
    font-weight: 800
}

.card-body {
    padding: 16px
}

.card h3 {
    font-size: 17px;
    margin: 0 0 6px
}

.card p {
    font-size: 13px;
    color: var(--muted);
    line-height: 1.45;
    min-height: 39px;
    margin: 0
}

.formats {
    display: flex;
    gap: 6px;
    margin: 13px 0
}

.format {
    width: 31px;
    height: 31px;
    border-radius: 9px;
    display: grid;
    place-items: center;
    background: #f0f4ff;
    font-size: 15px
}

.card-foot {
    display: flex;
    justify-content: space-between;
    align-items: center
}

.arrow {
    width: 34px;
    height: 34px;
    border: 0;
    border-radius: 50%;
    background: #f0f4ff;
    color: #2458c9;
    cursor: pointer;
    font-weight: 900
}

.catalog {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 16px
}

.tile {
    background: #fff;
    border: 1px solid var(--line);
    padding: 22px;
    border-radius: 17px;
    cursor: pointer
}

.tile:hover {
    border-color: #b9c9f7;
    box-shadow: 0 12px 25px rgba(28, 45, 75, .08)
}

.tile-icon {
    font-size: 28px;
    margin-bottom: 15px
}

.tile h3 {
    margin: 0 0 5px
}

.tile p {
    margin: 0;
    color: var(--muted);
    font-size: 13px
}

.detail {
    background: #fff;
    border: 1px solid var(--line);
    border-radius: 20px;
    padding: 25px
}

/* .back {
    border: 0;
    background: transparent;
    color: #2458c9;
    font-weight: 800;
    cursor: pointer;
    padding: 0;
    margin-bottom: 20px
} */

.detail h1 {
    margin: 0 0 8px
}

.resource-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 12px;
    margin-top: 20px
}

.resource {
    border: 1px solid var(--line);
    padding: 17px;
    border-radius: 14px;
    display: flex;
    justify-content: space-between;
    align-items: center
}

.resource b {
    display: block
}

.resource span {
    font-size: 12px;
    color: var(--muted)
}

.resource button {
    border: 0;
    background: #edf2ff;
    color: #2458c9;
    padding: 9px 12px;
    border-radius: 9px;
    font-weight: 800;
    cursor: pointer
}

.mobile {
    display: none;
    border: 0;
    background: #fff;
    border: 1px solid var(--line);
    border-radius: 10px;
    padding: 8px 10px
}

@media(max-width:1100px) {
    .grid {
        grid-template-columns: repeat(2, 1fr)
    }

    .catalog {
        grid-template-columns: repeat(2, 1fr)
    }
}

@media(max-width:760px) {
    .side {
        transform: translateX(-100%);
        transition: .2s
    }

    .side.open {
        transform: none
    }

    .content {
        margin-left: 0;
        width: 100%;
        padding: 0 15px 30px
    }

    .mobile {
        display: block
    }

    .top {
        height: 62px
    }

    .search {
        width: 100%
    }

    .profile {
        display: none
    }

    .hero {
        min-height: 470px
    }

    .hero-copy {
        left: 24px;
        top: 25px;
        width: 70%
    }

    .hero {
        background-position: 60% center
    }

    .grid,
    .resource-grid {
        grid-template-columns: 1fr
    }

    .catalog {
        grid-template-columns: 1fr 1fr
    }
}

@media(max-width:460px) {
    .catalog {
        grid-template-columns: 1fr
    }

    .hero-copy {
        width: 85%
    }

    .hero h1 {
        font-size: 34px
    }
}