:root{color-scheme:dark;--gate-bg:#020615;--gate-panel:rgba(10,18,39,.82);--gate-line:rgba(102,232,225,.22);--gate-cyan:#66e8e1;--gate-lime:#c8ff74;--gate-text:#f4f7ff;--gate-muted:#8997b6}
*{box-sizing:border-box}
body.lesson-gate-page{margin:0;min-height:100vh;overflow:hidden;background:var(--gate-bg);color:var(--gate-text);font-family:Inter,"Noto Sans TC","PingFang TC",system-ui,sans-serif}
.lesson-gate{position:relative;isolation:isolate;min-height:100vh;display:grid;place-items:center;padding:32px}
.lesson-gate::before{content:"";position:absolute;inset:0;z-index:-2;background:linear-gradient(rgba(65,111,172,.07) 1px,transparent 1px),linear-gradient(90deg,rgba(65,111,172,.07) 1px,transparent 1px);background-size:72px 72px;mask-image:linear-gradient(to bottom,black,transparent 90%)}
.lesson-gate::after{content:"";position:absolute;z-index:-1;width:min(760px,88vw);aspect-ratio:1;top:50%;left:50%;translate:-50% -50%;background:radial-gradient(circle,rgba(34,124,189,.2),rgba(83,28,170,.1) 38%,transparent 68%);filter:blur(16px)}
.lesson-gate-card{width:min(500px,100%);padding:42px 42px 38px;text-align:center;border:1px solid var(--gate-line);border-radius:24px;background:linear-gradient(145deg,rgba(14,24,50,.94),var(--gate-panel));box-shadow:0 32px 90px rgba(0,0,0,.38),inset 0 1px rgba(255,255,255,.05);backdrop-filter:blur(18px)}
.lesson-gate-logo{display:block;width:188px;height:auto;margin:0 auto 38px}
.lesson-gate-orbit{position:relative;width:76px;height:76px;margin:0 auto 26px;border:1px solid rgba(102,232,225,.16);border-radius:50%}
.lesson-gate-orbit::before{content:"";position:absolute;inset:8px;border:2px solid rgba(102,232,225,.14);border-top-color:var(--gate-cyan);border-right-color:var(--gate-lime);border-radius:50%;animation:gate-spin 1.15s linear infinite}
.lesson-gate-orbit::after{content:"";position:absolute;width:8px;height:8px;inset:50% auto auto 50%;translate:-50% -50%;border-radius:50%;background:var(--gate-cyan);box-shadow:0 0 20px var(--gate-cyan)}
.lesson-gate-card[data-state="error"] .lesson-gate-orbit::before{animation:none;border-color:rgba(255,133,148,.35)}
.lesson-gate-card[data-state="error"] .lesson-gate-orbit::after{width:22px;height:2px;border-radius:2px;background:#ff8594;box-shadow:0 0 18px rgba(255,133,148,.7);transform:rotate(45deg)}
.lesson-gate-eyebrow{margin:0 0 12px;color:var(--gate-cyan);font:700 11px/1.4 ui-monospace,SFMono-Regular,Menlo,monospace;letter-spacing:.18em;text-transform:uppercase}
.lesson-gate-title{margin:0;font-size:clamp(24px,5vw,32px);line-height:1.25;letter-spacing:-.02em}
.lesson-gate-detail{min-height:44px;margin:14px auto 0;color:var(--gate-muted);font-size:14px;line-height:1.7}
.lesson-gate-progress{width:100%;height:2px;margin-top:28px;overflow:hidden;background:rgba(137,151,182,.12)}
.lesson-gate-progress span{display:block;width:42%;height:100%;background:linear-gradient(90deg,transparent,var(--gate-cyan),var(--gate-lime),transparent);animation:gate-scan 1.5s ease-in-out infinite}
.lesson-gate-card[data-state="error"] .lesson-gate-progress{display:none}
.lesson-gate-action{display:none;margin:26px auto 0;min-height:44px;padding:0 22px;border:1px solid var(--gate-cyan);border-radius:10px;background:rgba(102,232,225,.1);color:var(--gate-cyan);font:700 14px inherit;cursor:pointer}
.lesson-gate-action:hover{background:var(--gate-cyan);color:#04101c}
.lesson-gate-action:focus-visible{outline:3px solid rgba(102,232,225,.32);outline-offset:3px}
.lesson-gate-card[data-state="error"] .lesson-gate-action{display:inline-flex;align-items:center;justify-content:center}
@keyframes gate-spin{to{transform:rotate(360deg)}}
@keyframes gate-scan{from{transform:translateX(-130%)}to{transform:translateX(240%)}}
@media (max-width:560px){.lesson-gate{padding:20px}.lesson-gate-card{padding:34px 24px 30px;border-radius:20px}.lesson-gate-logo{width:164px;margin-bottom:32px}}
@media (prefers-reduced-motion:reduce){.lesson-gate-orbit::before,.lesson-gate-progress span{animation:none}.lesson-gate-progress span{width:100%;background:var(--gate-cyan)}}