/* SakaMo作品 · StudyHub 启动器 —— 暗色科技风 + 动画 */
*{margin:0;padding:0;box-sizing:border-box}
:root{
  --bg:#06090f;--bg2:#0b1120;--card:#0f1626;--line:rgba(255,255,255,.08);
  --txt:#eaf2ff;--muted:#8aa0c0;--accent:#00e5ff;--accent2:#7de3e0;
  --cyan-glow:rgba(0,229,255,.35);
}
html{scroll-behavior:smooth}
body{font-family:"PingFang SC","Microsoft YaHei",system-ui,-apple-system,"Segoe UI",Roboto,sans-serif;background:var(--bg);color:var(--txt);line-height:1.6;overflow-x:hidden}
a{color:inherit;text-decoration:none}
img{max-width:100%;display:block}
button{font-family:inherit;color:inherit;background:none;border:none;cursor:pointer}

/* 预加载 */
.preloader{position:fixed;inset:0;z-index:9999;background:var(--bg);display:flex;flex-direction:column;align-items:center;justify-content:center;gap:22px;transition:opacity .5s,visibility .5s}
.preloader.done{opacity:0;visibility:hidden}
.pl-logo{font-size:26px;font-weight:800;display:flex;align-items:center;gap:12px}
.pl-dot{width:14px;height:14px;border-radius:50%;background:var(--accent);box-shadow:0 0 20px var(--cyan-glow);animation:pulse 1.2s infinite}
.pl-bar{width:220px;height:3px;border-radius:99px;background:rgba(255,255,255,.1);overflow:hidden}
.pl-bar span{display:block;height:100%;width:40%;background:linear-gradient(90deg,var(--accent),var(--accent2));border-radius:99px;animation:load 1s infinite}
@keyframes pulse{0%,100%{transform:scale(1);opacity:1}50%{transform:scale(1.3);opacity:.6}}
@keyframes load{0%{transform:translateX(-120%)}100%{transform:translateX(300%)}}

/* 导航 */
.nav{position:fixed;top:0;left:0;right:0;z-index:100;backdrop-filter:blur(14px);background:rgba(6,9,15,.55);border-bottom:1px solid transparent;transition:.3s}
.nav.scrolled{background:rgba(6,9,15,.85);border-bottom-color:var(--line);box-shadow:0 8px 30px rgba(0,0,0,.4)}
.nav-inner{max-width:1200px;margin:0 auto;padding:0 24px;height:64px;display:flex;align-items:center;justify-content:space-between}
.brand{display:flex;align-items:center;gap:10px;font-weight:700;font-size:20px;letter-spacing:.5px}
.logo-dot{width:12px;height:12px;border-radius:50%;background:var(--accent);box-shadow:0 0 14px var(--cyan-glow),0 0 28px var(--cyan-glow)}
.nav-links{display:flex;gap:26px;list-style:none}
.nav-links a{color:var(--muted);font-size:15px;position:relative;padding:4px 0;transition:.2s}
.nav-links a::after{content:"";position:absolute;left:0;bottom:-2px;width:0;height:2px;background:var(--accent);transition:.25s}
.nav-links a:hover{color:var(--accent)}
.nav-links a.active{color:var(--accent)}
.nav-links a.active::after{width:100%}
.nav-toggle{display:none;font-size:24px;color:var(--txt)}

/* Hero */
.hero{position:relative;height:100vh;min-height:640px;display:flex;align-items:center;justify-content:center;text-align:center;overflow:hidden}
.hero-particles{position:absolute;inset:0;z-index:0}
.hero-video{position:absolute;inset:0;width:100%;height:100%;object-fit:cover;filter:brightness(.7) saturate(1.05)}
.hero-overlay{position:absolute;inset:0;background:radial-gradient(ellipse at center,transparent 0%,rgba(6,9,15,.35) 55%,var(--bg) 100%),linear-gradient(180deg,rgba(6,9,15,.15),rgba(6,9,15,.4))}
.hero-content{position:relative;z-index:2;max-width:900px;padding:0 24px}
.hero-kicker{font-size:13px;letter-spacing:6px;color:var(--accent2);margin-bottom:18px;opacity:.9}
.hero-title{font-size:clamp(44px,9vw,96px);font-weight:900;letter-spacing:1px;background:linear-gradient(120deg,#fff 0%,#cfeafe 45%,var(--accent) 100%);-webkit-background-clip:text;background-clip:text;-webkit-text-fill-color:transparent;position:relative}
.hero-title .glow{position:absolute;inset:0;background:linear-gradient(90deg,transparent,var(--accent),transparent);background-size:200% 100%;-webkit-background-clip:text;background-clip:text;-webkit-text-fill-color:transparent;animation:sheen 2.5s linear infinite;mix-blend-mode:screen}
@keyframes sheen{0%{background-position:200% 0}100%{background-position:-200% 0}}
.hero-sub{font-size:clamp(16px,2.4vw,24px);color:var(--muted);margin:18px 0 34px;opacity:.95}
.btn-download{display:inline-flex;align-items:center;gap:10px;font-size:18px;font-weight:700;color:#04252d;padding:16px 44px;border-radius:999px;background:linear-gradient(120deg,var(--accent),var(--accent2));box-shadow:0 10px 40px var(--cyan-glow);transition:.3s;position:relative;overflow:hidden}
.btn-download::before{content:"";position:absolute;top:0;left:-80%;width:50%;height:100%;background:linear-gradient(100deg,transparent,rgba(255,255,255,.7),transparent);transform:skewX(-20deg);transition:.5s}
.btn-download:hover::before{left:130%}
.btn-download:hover{transform:translateY(-2px);box-shadow:0 16px 50px var(--cyan-glow)}
.btn-icon{font-size:20px}
.hero-note{margin-top:16px;font-size:13px;color:var(--muted)}
.scroll-hint{position:absolute;bottom:26px;left:50%;transform:translateX(-50%);z-index:2;color:var(--accent2);font-size:24px;animation:bounce 1.8s infinite}
@keyframes bounce{0%,100%{transform:translate(-50%,0)}50%{transform:translate(-50%,8px)}}

/* 通用 section */
section{position:relative}
.eyebrow{font-size:12px;letter-spacing:4px;color:var(--accent2);margin-bottom:12px;opacity:.85}
.section-title{font-size:clamp(26px,4.4vw,40px);font-weight:800;letter-spacing:.5px}
.section-desc{color:var(--muted);margin-top:10px}
.section-head{max-width:1200px;margin:0 auto;padding:0 24px;display:flex;align-items:flex-end;justify-content:space-between;flex-wrap:wrap;gap:16px;margin-bottom:44px}

/* 数据条 */
.stats{background:var(--bg2);border-top:1px solid var(--line);border-bottom:1px solid var(--line)}
.stats-inner{max-width:1200px;margin:0 auto;display:grid;grid-template-columns:repeat(4,1fr);gap:20px;padding:40px 24px;text-align:center}
.stat-num{font-size:clamp(32px,5vw,52px);font-weight:900;color:var(--accent);text-shadow:0 0 30px var(--cyan-glow)}
.stat-lbl{color:var(--muted);margin-top:6px;font-size:15px}

/* 游戏轮播 */
.games{padding:90px 0;background:var(--bg)}
.game-track{max-width:1200px;margin:0 auto;padding:0 24px;display:flex;gap:20px;overflow-x:auto;scroll-snap-type:x mandatory;padding-bottom:10px}
.game-track::-webkit-scrollbar{height:0}
.game-card{flex:0 0 280px;height:340px;border-radius:18px;position:relative;overflow:hidden;display:flex;align-items:flex-end;padding:22px;border:1px solid var(--line);scroll-snap-align:start;transition:.3s;cursor:pointer}
.game-card:hover{transform:translateY(-6px);border-color:rgba(0,229,255,.5);box-shadow:0 20px 60px rgba(0,0,0,.5)}
.game-card::before{content:"";position:absolute;inset:0;background:linear-gradient(180deg,transparent,rgba(0,0,0,.55))}
.game-card::after{content:"";position:absolute;top:-120%;left:-80%;width:60%;height:200%;background:linear-gradient(100deg,transparent,rgba(255,255,255,.18),transparent);transform:skewX(-20deg);transition:.6s}
.game-card:hover::after{top:-60%;left:130%}
.gc-badge{position:absolute;top:16px;right:16px;z-index:2;background:linear-gradient(120deg,var(--accent),var(--accent2));color:#04252d;font-size:12px;font-weight:800;padding:5px 12px;border-radius:99px}
.gc-name{position:relative;z-index:2;font-size:22px;font-weight:800}
.gq{background:radial-gradient(circle at 30% 30%,#ff6b8a,#3a0d1f 75%)}
.gy{background:radial-gradient(circle at 30% 30%,#54c8ff,#0d2a3a 75%)}
.gx{background:radial-gradient(circle at 30% 30%,#b07dff,#241445 75%)}
.gz{background:radial-gradient(circle at 30% 30%,#ffd166,#4a3300 75%)}
.carousel-nav{display:flex;gap:10px}
.cnav{width:40px;height:40px;border-radius:50%;border:1px solid var(--line);color:var(--txt);font-size:20px;display:flex;align-items:center;justify-content:center;transition:.2s}
.cnav:hover{background:var(--accent);color:#04252d;border-color:var(--accent)}

/* 精选软件 */
.software{padding:90px 0;background:var(--bg)}
.cards{max-width:1200px;margin:0 auto;padding:0 24px;display:grid;grid-template-columns:repeat(3,1fr);gap:24px}
.card{border-radius:18px;overflow:hidden;background:var(--card);border:1px solid var(--line);transition:.35s;position:relative;padding:0;text-align:left}
.card:hover{transform:translateY(-8px);border-color:rgba(0,229,255,.45);box-shadow:0 20px 60px rgba(0,0,0,.5)}
.card::after{content:"";position:absolute;top:-120%;left:-80%;width:60%;height:200%;background:linear-gradient(100deg,transparent,rgba(255,255,255,.12),transparent);transform:skewX(-20deg);transition:.6s}
.card:hover::after{top:-60%;left:130%}
.card-cover{position:relative;height:200px;display:flex;align-items:center;justify-content:center;overflow:hidden}
.card-cover::after{content:"";position:absolute;inset:0;background:linear-gradient(180deg,transparent,rgba(15,22,38,.9))}
.card-icon{width:88px;height:88px;object-fit:contain;filter:drop-shadow(0 10px 30px rgba(0,229,255,.35));position:relative;z-index:1;border-radius:20%;transition:.35s}
.card:hover .card-icon{transform:scale(1.12)}
.cover-cstudy{background:radial-gradient(circle at 20% 20%,#1d4ed8,#0b1120 70%)}
.cover-aistudy{background:radial-gradient(circle at 30% 30%,#7c3aed,#0b1120 70%)}
.cover-fileorg{background:radial-gradient(circle at 25% 25%,#0e7490,#0b1120 70%)}
.card-body{padding:22px;display:block;position:relative;z-index:2}
.card-cat{display:block;font-size:11px;letter-spacing:2px;color:var(--accent2);opacity:.8;margin-bottom:8px}
.card-name{display:block;font-size:22px;font-weight:800;margin-bottom:4px}
.card-sub{display:block;color:var(--muted);font-size:14px;margin-bottom:16px}
.card-btn{display:inline-block;padding:9px 26px;border-radius:999px;font-size:14px;font-weight:600;border:1px solid var(--line);color:var(--txt);background:rgba(255,255,255,.04);transition:.25s}
.card:hover .card-btn{background:var(--accent);color:#04252d;border-color:var(--accent)}

/* 公告资讯 */
.news{padding:90px 0;background:var(--bg2)}
.news-container{max-width:1200px;margin:0 auto;padding:0 24px}
.news-ticker{display:flex;align-items:center;gap:16px;border:1px solid var(--line);border-radius:99px;padding:12px 22px;margin-bottom:34px;overflow:hidden;background:var(--card)}
.news-ticker b{font-size:20px}
.ticker-track{display:flex;gap:60px;white-space:nowrap;animation:marquee 24s linear infinite}
.ticker-track span{color:var(--muted);font-size:14px}
@keyframes marquee{0%{transform:translateX(0)}100%{transform:translateX(-50%)}}
.news-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:20px}
.news-card{background:var(--card);border:1px solid var(--line);border-radius:16px;padding:26px;transition:.3s}
.news-card:hover{transform:translateY(-5px);border-color:rgba(0,229,255,.4)}
.nc-tag{display:inline-block;font-size:12px;color:var(--accent);border:1px solid rgba(0,229,255,.4);border-radius:99px;padding:3px 12px;margin-bottom:16px}
.news-card h3{font-size:18px;margin-bottom:10px}
.news-card p{color:var(--muted);font-size:14px}
.news-card time{display:block;margin-top:16px;font-size:12px;color:#5a6b85}

/* 下载中心 */
.download{padding:90px 0;background:var(--bg)}
.dl-grid{max-width:1200px;margin:0 auto;padding:0 24px;display:grid;grid-template-columns:repeat(2,1fr);gap:20px}
.dl-item{display:flex;align-items:center;gap:16px;background:var(--card);border:1px solid var(--line);border-radius:16px;padding:22px;transition:.3s}
.dl-item:hover{border-color:rgba(0,229,255,.4);transform:translateY(-3px)}
.dl-ico{width:52px;height:52px;border-radius:14%;object-fit:contain;filter:drop-shadow(0 6px 16px rgba(0,229,255,.3))}
.dl-info{flex:1}
.dl-name{font-size:17px;font-weight:700}
.dl-meta{color:var(--muted);font-size:13px;margin-top:4px}
.dl-btn{background:linear-gradient(120deg,var(--accent),var(--accent2));color:#04252d;font-weight:700;padding:10px 22px;border-radius:999px;font-size:14px;transition:.25s}
.dl-btn:hover{box-shadow:0 8px 26px var(--cyan-glow);transform:translateY(-2px)}

/* 版本日志 / 关于 / FAQ */
.changelog,.about,.faq{padding:90px 0;background:var(--bg2)}
.about{background:var(--bg)}
.changelog .section-head,.about .section-head,.faq .section-head{margin-bottom:36px}
.cl-list,.faq-list{max-width:880px;margin:0 auto;padding:0 24px}
.cl-item{display:flex;gap:20px;padding:20px 0;border-bottom:1px solid var(--line)}
.cl-ver{flex:0 0 auto;background:rgba(0,229,255,.12);color:var(--accent);border:1px solid rgba(0,229,255,.35);padding:4px 14px;border-radius:99px;font-weight:700;height:fit-content}
.cl-item h4{font-size:16px;margin-bottom:6px}
.cl-item p{color:var(--muted);font-size:14px}
.about-box{max-width:880px;margin:0 auto;padding:0 24px;text-align:center}
.about-box p{color:var(--muted);font-size:17px;max-width:640px;margin:0 auto 26px}
.socials{display:flex;justify-content:center;gap:16px}
.socials a{border:1px solid var(--line);padding:10px 22px;border-radius:99px;font-size:14px;color:var(--muted);transition:.25s}
.socials a:hover{border-color:var(--accent);color:var(--accent)}

/* FAQ 折叠 */
.faq-item{border:1px solid var(--line);border-radius:14px;margin-bottom:12px;background:var(--card);overflow:hidden}
.faq-q{width:100%;text-align:left;padding:18px 22px;font-size:16px;font-weight:700;display:flex;justify-content:space-between;align-items:center}
.faq-q::after{content:"+";font-size:22px;color:var(--accent);transition:.3s}
.faq-item.open .faq-q::after{transform:rotate(45deg)}
.faq-a{max-height:0;overflow:hidden;transition:max-height .35s}
.faq-a p{padding:0 22px 18px;color:var(--muted);font-size:14px}

/* 页脚 */
.footer{background:#04070c;border-top:1px solid var(--line);padding:60px 24px 40px;text-align:center}
.f-brand{font-size:22px;font-weight:800;margin-bottom:18px;letter-spacing:1px}
.f-links{display:flex;flex-wrap:wrap;justify-content:center;gap:20px;margin-bottom:20px}
.f-links a{color:var(--muted);font-size:14px}
.f-links a:hover{color:var(--accent)}
.f-copy{color:#5a6b85;font-size:13px}

/* 回到顶部 */
.back-top{position:fixed;right:26px;bottom:26px;width:48px;height:48px;border-radius:50%;background:rgba(0,229,255,.12);border:1px solid rgba(0,229,255,.4);color:var(--accent);font-size:20px;z-index:90;opacity:0;visibility:hidden;transition:.3s;backdrop-filter:blur(6px)}
.back-top.show{opacity:1;visibility:visible}
.back-top:hover{background:var(--accent);color:#04252d}

/* 弹窗 */
.modal{position:fixed;inset:0;z-index:200;background:rgba(0,0,0,.6);backdrop-filter:blur(6px);display:none;align-items:center;justify-content:center;padding:24px}
.modal.open{display:flex}
.modal-box{position:relative;width:100%;max-width:560px;background:var(--card);border:1px solid var(--line);border-radius:18px;padding:34px;animation:pop .3s}
@keyframes pop{0%{transform:scale(.9);opacity:0}100%{transform:scale(1);opacity:1}}
.modal-x{position:absolute;top:14px;right:18px;font-size:26px;color:var(--muted)}
.modal-x:hover{color:var(--accent)}
.modal-ico{width:64px;height:64px;border-radius:20%;object-fit:contain;margin-bottom:16px;filter:drop-shadow(0 8px 24px rgba(0,229,255,.3))}
.modal h3{font-size:22px;margin-bottom:8px}
.modal .m-sub{color:var(--muted);font-size:14px;margin-bottom:18px}
.modal .m-desc{color:var(--muted);font-size:15px;margin-bottom:24px}
.modal .dl-btn{display:inline-block}

/* 关于/常见问题/更新日志/公告/下载：标题区居中 */
.about .section-head,.faq .section-head,.changelog .section-head,.news .section-head,.download .section-head{justify-content:center;flex-direction:column;align-items:center;text-align:center}
.about .eyebrow,.faq .eyebrow,.changelog .eyebrow,.news .eyebrow,.download .eyebrow{margin-bottom:14px}
.about-box,.faq-list,.cl-list,.news-container,.dl-grid{margin-left:auto;margin-right:auto}

/* 滚动淡入 */
.card,.game-card,.news-card,.dl-item,.stat,.cl-item{opacity:0;transform:translateY(24px);transition:opacity .6s ease,transform .6s ease}
.revealed{opacity:1!important;transform:none!important}

/* 响应式 */
@media(max-width:860px){
  .nav-links{display:none}
  .nav-toggle{display:block}
  .cards,.news-grid,.dl-grid,.stats-inner{grid-template-columns:1fr}
  .game-card{flex:0 0 240px;height:300px}
  .dl-grid{grid-template-columns:1fr}
}