:root{
--ink:#101a24;--paper:#eceff3;--card:#f8fafc;--line:#d3dae2;--muted:#7d8794;
--brand:#1b4d7a;--brand-d:#164066;--accent:#b06c34;
--serif:Georgia,"Times New Roman",serif;
--sans:system-ui,"Segoe UI",Roboto,sans-serif;
--r:5px;
}
.btn{border-radius:5px}
.hero::before,.page-head::before{content:"";position:absolute;width:380px;height:170px;top:8%;right:-70px;
border:1.4px solid var(--brand);border-radius:50%;opacity:.1;transform:rotate(-24deg);animation:mrTilt 34s linear infinite;pointer-events:none}
.hero::after,.page-head::after{content:"";position:absolute;width:380px;height:170px;top:8%;right:-70px;
border:1.4px solid var(--accent);border-radius:50%;opacity:.1;transform:rotate(38deg);animation:mrTilt 46s linear infinite reverse;pointer-events:none}
@keyframes mrTilt{to{transform:rotate(336deg)}}
.hero-art{position:relative;display:flex;align-items:center;justify-content:center}
.hero-art svg{width:100%;max-width:330px;opacity:.9}
.lecture{position:relative;height:190px;border-radius:5px;overflow:hidden;border:1px solid var(--line);cursor:pointer;
background:radial-gradient(120% 120% at 25% 0,#245e8f,#12293d 72%)}
.lecture svg{position:absolute;inset:0;width:100%;height:100%;opacity:.5}
.lecture .play{position:absolute;top:50%;left:50%;transform:translate(-50%,-50%);width:52px;height:52px;border-radius:50%;
background:rgba(255,255,255,.93);display:flex;align-items:center;justify-content:center;transition:transform .2s;box-shadow:0 6px 22px rgba(0,0,0,.32)}
.lecture:hover .play{transform:translate(-50%,-50%) scale(1.08)}
.lecture .play::after{content:"";margin-left:3px;border-style:solid;border-width:9px 0 9px 15px;border-color:transparent transparent transparent var(--brand)}
.lecture .cap{position:absolute;left:14px;right:14px;bottom:11px;color:#fff;display:flex;justify-content:space-between;align-items:flex-end;gap:10px}
.lecture .cap b{font-family:var(--serif);font-weight:700;font-size:14px;line-height:1.25}
.lecture .cap span{font-family:var(--mono);font-size:10px;opacity:.85;background:rgba(0,0,0,.35);padding:2px 7px;border-radius:3px;white-space:nowrap}