:root{
    --bg:#f4f8ff;
    --bg-soft:#eef6ff;
    --card:#ffffff;
    --text:#1d2a3a;
    --muted:#66758a;
    --line:#dfe8f5;
    --primary:#4b8df8;
    --primary-dark:#2f6fe0;
    --accent:#7ed6c3;
    --radius:24px;
    --shadow:0 14px 36px rgba(43, 88, 160, .10);
}

*{box-sizing:border-box}
html,body{margin:0;padding:0}
body{
    background:
        radial-gradient(circle at top right, #ffffff 0%, #f4f8ff 42%, #eef5ff 100%);
    color:var(--text);
    font-family:Tahoma, Arial, sans-serif;
    line-height:1.8;
}

a{color:inherit;text-decoration:none}
img{max-width:100%;display:block}

.container{
    width:min(1180px, calc(100% - 28px));
    margin-inline:auto;
}

.site-header{
    position:sticky;
    top:0;
    z-index:20;
    background:rgba(255,255,255,.88);
    backdrop-filter:blur(10px);
    border-bottom:1px solid rgba(223,232,245,.8);
}

.site-header__inner{
    display:flex;
    align-items:center;
    justify-content:space-between;
    gap:16px;
    padding:16px 0;
}

.logo{
    font-weight:900;
    font-size:24px;
    color:var(--primary);
    letter-spacing:.3px;
}

.nav{
    display:flex;
    flex-wrap:wrap;
    gap:14px;
}

.nav a{
    color:var(--muted);
    font-weight:700;
    padding:8px 12px;
    border-radius:12px;
}

.nav a:hover{
    background:#fff;
    color:var(--primary);
}

.page-content{
    padding:28px 0 44px;
}

.hero{
    position:relative;
    overflow:hidden;
    background:linear-gradient(135deg, #ffffff 0%, #eef6ff 100%);
    border:1px solid var(--line);
    border-radius:32px;
    box-shadow:var(--shadow);
    padding:42px 30px;
    margin-bottom:26px;
}

.hero::before{
    content:"";
    position:absolute;
    width:240px;
    height:240px;
    border-radius:50%;
    background:rgba(126,214,195,.18);
    left:-60px;
    bottom:-60px;
}

.hero::after{
    content:"";
    position:absolute;
    width:220px;
    height:220px;
    border-radius:50%;
    background:rgba(75,141,248,.10);
    right:-60px;
    top:-60px;
}

.hero__content{
    position:relative;
    z-index:1;
}

.eyebrow{
    display:inline-flex;
    align-items:center;
    gap:8px;
    background:#e8f1ff;
    color:var(--primary-dark);
    padding:8px 14px;
    border-radius:999px;
    font-size:13px;
    font-weight:900;
    margin-bottom:14px;
}

.hero h1{
    margin:0 0 10px;
    font-size:clamp(30px,4.5vw,48px);
    line-height:1.25;
}

.hero p{
    margin:0;
    color:var(--muted);
    max-width:760px;
    font-size:18px;
}

.hero__actions{
    display:flex;
    flex-wrap:wrap;
    gap:12px;
    margin-top:24px;
}

.btn{
    display:inline-flex;
    align-items:center;
    justify-content:center;
    min-height:46px;
    padding:0 18px;
    border-radius:14px;
    border:1px solid var(--line);
    background:#fff;
    font-weight:800;
    box-shadow:0 6px 16px rgba(0,0,0,.03);
}

.btn--primary{
    background:var(--primary);
    color:#fff;
    border-color:var(--primary);
}

.btn--primary:hover{
    background:var(--primary-dark);
}

.section{
    margin-bottom:28px;
}

.section__head{
    display:flex;
    align-items:center;
    justify-content:space-between;
    gap:12px;
    margin-bottom:14px;
}

.section__head h1,
.section__head h2{
    margin:0;
    font-size:28px;
}

.featured{
    display:grid;
    grid-template-columns:minmax(280px, 460px) 1fr;
    overflow:hidden;
    background:var(--card);
    border:1px solid var(--line);
    border-radius:28px;
    box-shadow:var(--shadow);
}

.featured__thumb{
    position:relative;
    background:#e8eef9;
}

.featured__thumb img{
    width:100%;
    aspect-ratio:16/9;
    object-fit:cover;
}

.featured__body{
    padding:22px;
}

.featured__body h3{
    margin:0 0 8px;
    font-size:28px;
    line-height:1.4;
}

.meta{
    color:var(--muted);
    font-size:14px;
}

.video-grid{
    display:grid;
    grid-template-columns:repeat(auto-fit,minmax(260px,1fr));
    gap:18px;
}

.video-card{
    overflow:hidden;
    background:var(--card);
    border:1px solid var(--line);
    border-radius:24px;
    box-shadow:var(--shadow);
    transition:transform .18s ease, box-shadow .18s ease;
}

.video-card:hover{
    transform:translateY(-4px);
    box-shadow:0 18px 42px rgba(43,88,160,.14);
}

.video-card__thumb{
    position:relative;
    display:block;
    background:#eef3fb;
}

.video-card__thumb img{
    width:100%;
    aspect-ratio:16/9;
    object-fit:cover;
}

.video-card__body{
    padding:16px;
}

.video-card__body h3{
    margin:0 0 8px;
    font-size:19px;
    line-height:1.5;
}

.play-badge{
    position:absolute;
    inset:auto auto 14px 14px;
    background:rgba(29,42,58,.78);
    color:#fff;
    padding:8px 14px;
    border-radius:999px;
    font-size:13px;
    font-weight:900;
}

.play-badge--large{
    font-size:16px;
    padding:10px 16px;
}

.topic-grid,
.faq-grid{
    display:grid;
    grid-template-columns:repeat(auto-fit,minmax(220px,1fr));
    gap:16px;
}

.topic-card,
.faq-card,
.social-card{
    background:var(--card);
    border:1px solid var(--line);
    border-radius:22px;
    box-shadow:var(--shadow);
    padding:18px;
}

.topic-card{
    transition:transform .16s ease;
}

.topic-card:hover{
    transform:translateY(-3px);
}

.topic-card strong,
.faq-card h3{
    display:block;
    margin-bottom:8px;
    font-size:18px;
}

.topic-card span,
.faq-card p,
.social-card p,
.topic-intro{
    color:var(--muted);
}

.filters{
    display:flex;
    flex-wrap:wrap;
    gap:12px;
    margin-bottom:18px;
}

.filters input,
.filters select{
    min-height:48px;
    padding:0 14px;
    border-radius:14px;
    border:1px solid var(--line);
    background:#fff;
    min-width:220px;
}

.empty-state{
    background:#fff;
    border:1px dashed var(--line);
    border-radius:18px;
    padding:24px;
    color:var(--muted);
}

.video-embed{
    margin-bottom:20px;
    background:#fff;
    border:1px solid var(--line);
    border-radius:28px;
    overflow:hidden;
    box-shadow:var(--shadow);
}

.video-embed__poster{
    display:block;
    width:100%;
    padding:0;
    border:0;
    background:none;
    cursor:pointer;
    position:relative;
}

.video-embed__poster img{
    width:100%;
    aspect-ratio:16/9;
    object-fit:cover;
}

.subsection{
    margin:18px 0 0;
    background:#fff;
    border:1px solid var(--line);
    border-radius:22px;
    box-shadow:var(--shadow);
    padding:20px;
}

.subsection h2{
    margin-top:0;
}

.transcript-box{
    max-height:460px;
    overflow:auto;
    padding:16px;
    background:#f8fbff;
    border:1px solid var(--line);
    border-radius:16px;
    line-height:2;
    font-size:16px;
}

.prose{
    background:#fff;
    border:1px solid var(--line);
    border-radius:22px;
    box-shadow:var(--shadow);
    padding:20px;
}

.site-footer{
    border-top:1px solid var(--line);
    background:rgba(255,255,255,.9);
    color:var(--muted);
}

.site-footer .container{
    padding:18px 0;
}

@media (max-width: 780px){
    .featured{
        grid-template-columns:1fr;
    }

    .site-header__inner{
        flex-direction:column;
        align-items:flex-start;
    }

    .nav{
        gap:8px;
    }

    .hero{
        padding:28px 20px;
    }

    .hero p{
        font-size:16px;
    }
}