.chapter-hero {
    padding: 68px 0 60px;
    color: #ffffff;
    background: linear-gradient(135deg, var(--theme-dark), var(--theme-mid), var(--theme-primary));
}

.chapter-hero h1 {
    margin-top: 22px;
    font-size: clamp(3rem, 6vw, 6rem);
    line-height: 0.98;
    letter-spacing: -0.055em;
}

.chapter-badge {
    display: inline-flex;
    padding: 9px 17px;
    border-radius: 999px;
    background: rgba(255, 255, 255, 0.12);
    font-weight: 900;
}

.chapter-hero p {
    max-width: 1000px;
    margin-top: 18px;
    color: rgba(255, 255, 255, 0.88);
}

.slide-shell {
    padding: 28px;
}

.slide-heading-row {
    display: flex;
    align-items: flex-end;
    justify-content: space-between;
    gap: 20px;
}

.slide-heading-row p,
.slide-heading-row > span {
    color: var(--muted);
}

.slide-tabs {
    display: flex;
    gap: 9px;
    overflow-x: auto;
    margin: 18px 0;
}

.slide-tab {
    flex: 0 0 auto;
    padding: 11px 16px;
    border: 1px solid var(--theme-soft);
    border-radius: 11px;
    background: #ffffff;
    color: var(--theme-primary);
    font-weight: 800;
    cursor: pointer;
}

.slide-tab.active {
    background: linear-gradient(135deg, var(--theme-mid), var(--theme-primary));
    color: #ffffff;
}

.slide-current {
    margin-bottom: 10px;
    color: var(--theme-dark);
    font-weight: 850;
}

.slide-frame {
    aspect-ratio: 16 / 9;
    overflow: hidden;
    border-radius: 18px;
    background: var(--theme-dark);
}

.slide-frame iframe {
    width: 100%;
    height: 100%;
    border: 0;
}

.slide-placeholder {
    height: 100%;
    display: grid;
    place-items: center;
    padding: 30px;
    text-align: center;
    color: #ffffff;
    background:
        radial-gradient(circle at 20% 20%, rgba(255, 255, 255, 0.14), transparent 28%),
        linear-gradient(135deg, var(--theme-dark), var(--theme-mid));
}

.resource-divider {
    margin: 42px 0 28px;
    padding: 26px;
    border-radius: 24px;
    background: linear-gradient(135deg, var(--theme-dark), var(--theme-primary));
    box-shadow: 0 14px 32px rgba(17, 40, 63, 0.14);
    text-align: center;
}

.resource-divider span {
    display: inline-flex;
    padding: 8px 20px;
    border-radius: 999px;
    background: rgba(255, 255, 255, 0.9);
    color: var(--theme-mid);
    font-size: clamp(1.15rem, 2vw, 1.55rem);
    font-weight: 950;
    letter-spacing: 0.035em;
}

.resource-grid {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 24px;
}

.resource-card {
    --resource-colour: var(--theme-primary);
    --resource-soft: var(--theme-soft);
    min-height: 430px;
    display: flex;
    flex-direction: column;
    padding: 28px;
}

.resource-card-exercise {
    --resource-colour: #15935a;
    --resource-soft: #e9f8f0;
}

.resource-card-lab {
    --resource-colour: #2563d9;
    --resource-soft: #edf3ff;
}

.resource-card-case {
    --resource-colour: #df7b11;
    --resource-soft: #fff3e6;
}

.resource-card-quiz {
    --resource-colour: #7b43b7;
    --resource-soft: #f4ebfb;
}

.resource-head {
    display: grid;
    grid-template-columns: 58px 1fr auto;
    align-items: start;
    gap: 16px;
    margin-bottom: 18px;
}

.resource-icon {
    width: 58px;
    height: 58px;
    display: grid;
    place-items: center;
    border-radius: 17px;
    background: var(--resource-soft);
    color: var(--resource-colour);
    font-size: 1.4rem;
    font-weight: 900;
}

.resource-copy h2 {
    font-size: 1.5rem;
}

.resource-copy p {
    margin-top: 4px;
    color: var(--muted);
}

.resource-badge {
    padding: 6px 12px;
    border-radius: 9px;
    background: var(--resource-colour);
    color: #ffffff;
    font-size: 0.76rem;
    font-weight: 900;
}

.resource-items {
    overflow: hidden;
    border: 1px solid var(--line);
    border-radius: 16px;
}

.resource-row {
    display: grid;
    grid-template-columns: minmax(0, 1fr) auto;
    align-items: center;
    gap: 18px;
    padding: 18px 20px;
    border-bottom: 1px solid var(--line);
}

.resource-row:last-child {
    border-bottom: 0;
}

.resource-row p {
    margin-top: 4px;
    color: var(--muted);
    font-size: 0.9rem;
}

.resource-action {
    min-width: 104px;
    padding: 10px 15px;
    border: 2px solid var(--resource-colour);
    border-radius: 10px;
    color: var(--resource-colour);
    font-weight: 850;
    text-align: center;
}

.resource-action:hover {
    background: var(--resource-colour);
    color: #ffffff;
}

.resource-tip {
    margin-top: auto;
    padding-top: 20px;
    color: var(--muted);
    font-size: 0.88rem;
}

.chapter-nav {
    display: flex;
    justify-content: space-between;
    margin-top: 28px;
}

.chapter-nav a {
    padding: 12px 16px;
    border: 1px solid var(--theme-primary);
    border-radius: 11px;
    color: var(--theme-primary);
    font-weight: 800;
}

@media (max-width: 900px) {
    .slide-heading-row {
        align-items: flex-start;
        flex-direction: column;
    }

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

    .resource-row {
        grid-template-columns: 1fr;
    }

    .resource-action {
        width: 100%;
    }
}

@media (max-width: 620px) {
    .resource-head {
        grid-template-columns: 52px 1fr;
    }

    .resource-badge {
        grid-column: 2;
        justify-self: start;
    }
}