/* ===========================================================
   ARKIE AI · 官方宣传页
   深蓝 + 银灰 + 淡鎏金 | 现代科技 | 立体光影 | 高级简约
   =========================================================== */

:root{
  --navy-900:#050B18;
  --navy-800:#081226;
  --navy-700:#0C1A33;
  --navy-600:#122444;
  --navy-500:#1A3055;
  --silver-100:#E8EEF6;
  --silver-200:#C8D4E4;
  --silver-300:#9FB0C7;
  --silver-400:#7A8CA6;
  --gold:#D4AF6A;
  --gold-soft:#E8CE9A;
  --gold-deep:#B08D4A;
  --cyan:#4FC3F7;
  --line:rgba(200,212,228,.12);
  --line-strong:rgba(200,212,228,.22);
  --maxw:1180px;
  --r-sm:10px; --r-md:18px; --r-lg:28px;
}

*{margin:0;padding:0;box-sizing:border-box}
html{scroll-behavior:smooth}
body{
  font-family:'Noto Sans SC',system-ui,-apple-system,sans-serif;
  background:var(--navy-900);
  color:var(--silver-100);
  line-height:1.75;
  -webkit-font-smoothing:antialiased;
  overflow-x:hidden;
}
img{display:block;max-width:100%}
a{text-decoration:none;color:inherit}
button{font-family:inherit;cursor:pointer;border:none;background:none;color:inherit}

h1,h2,h3{font-weight:700;line-height:1.25;letter-spacing:.01em}

/* ===== 背景装饰层 ===== */
.bg-layer{position:fixed;inset:0;z-index:0;pointer-events:none;overflow:hidden}
.bg-grid{
  position:absolute;inset:0;
  background-image:
    linear-gradient(rgba(120,160,220,.045) 1px,transparent 1px),
    linear-gradient(90deg,rgba(120,160,220,.045) 1px,transparent 1px);
  background-size:64px 64px;
  mask-image:radial-gradient(ellipse 80% 60% at 50% 0%,#000 20%,transparent 75%);
}
.bg-glow{position:absolute;border-radius:50%;filter:blur(120px);opacity:.5}
.bg-glow--1{
  width:720px;height:720px;top:-260px;left:-180px;
  background:radial-gradient(circle,rgba(30,80,160,.55),transparent 70%);
}
.bg-glow--2{
  width:640px;height:640px;top:38%;right:-220px;
  background:radial-gradient(circle,rgba(212,175,106,.16),transparent 70%);
}
#particles{position:absolute;inset:0;width:100%;height:100%;opacity:.55}

/* ===== 顶部导航 ===== */
.topbar{
  position:fixed;top:0;left:0;right:0;z-index:100;
  display:flex;align-items:center;gap:24px;
  padding:14px max(20px,calc((100vw - var(--maxw))/2));
  background:rgba(5,11,24,.55);
  backdrop-filter:blur(18px) saturate(140%);
  border-bottom:1px solid transparent;
  transition:.35s;
}
.topbar.is-scrolled{
  background:rgba(5,11,24,.88);
  border-bottom-color:var(--line);
  box-shadow:0 8px 32px rgba(0,0,0,.4);
}
.brand{display:flex;align-items:center;gap:11px;flex:none}
.brand__mark{
  width:40px;height:40px;object-fit:contain;
  filter:drop-shadow(0 0 12px rgba(212,175,106,.35));
}
.brand__text{display:flex;flex-direction:column;line-height:1.15}
.brand__text b{
  font-size:15.5px;letter-spacing:.14em;color:#fff;font-weight:700;
}
.brand__text i{
  font-style:normal;font-size:10.5px;letter-spacing:.22em;
  color:var(--gold);font-weight:500;
}
.topnav{display:flex;gap:26px;margin-left:auto}
.topnav a{
  font-size:14px;color:var(--silver-300);font-weight:400;
  position:relative;padding:4px 0;transition:.25s;
}
.topnav a::after{
  content:"";position:absolute;left:0;bottom:0;width:0;height:1.5px;
  background:var(--gold);transition:.3s;
}
.topnav a:hover{color:#fff}
.topnav a:hover::after{width:100%}

/* BGM 开关 */
.bgm-btn{
  display:flex;align-items:center;gap:8px;
  padding:8px 14px;border-radius:100px;
  border:1px solid var(--line-strong);
  background:rgba(255,255,255,.03);
  transition:.25s;flex:none;
}
.bgm-btn:hover{border-color:var(--gold);background:rgba(212,175,106,.08)}
.bgm-btn__icon{
  width:16px;height:16px;position:relative;flex:none;
}
.bgm-btn__icon::before{
  content:"";position:absolute;left:0;top:3px;
  width:5px;height:10px;background:var(--silver-300);
  clip-path:polygon(0 30%,45% 30%,100% 0,100% 100%,45% 70%,0 70%);
}
.bgm-btn__icon::after{
  content:"";position:absolute;left:7px;top:2px;
  width:8px;height:12px;border:1.5px solid var(--silver-300);
  border-left:none;border-radius:0 8px 8px 0;
  opacity:.9;
}
.bgm-btn.is-on .bgm-btn__icon::before{background:var(--gold)}
.bgm-btn.is-on .bgm-btn__icon::after{border-color:var(--gold)}
.bgm-btn__bars{display:flex;align-items:flex-end;gap:2px;height:14px}
.bgm-btn__bars i{
  width:2.5px;background:var(--silver-400);border-radius:2px;
  height:4px;transition:.2s;
}
.bgm-btn.is-on .bgm-btn__bars i{background:var(--gold);animation:eq 1s ease-in-out infinite}
.bgm-btn.is-on .bgm-btn__bars i:nth-child(1){animation-delay:0s}
.bgm-btn.is-on .bgm-btn__bars i:nth-child(2){animation-delay:.18s}
.bgm-btn.is-on .bgm-btn__bars i:nth-child(3){animation-delay:.36s}
.bgm-btn.is-on .bgm-btn__bars i:nth-child(4){animation-delay:.54s}
@keyframes eq{
  0%,100%{height:4px}
  50%{height:13px}
}

/* ===== 首屏 ===== */
.hero{
  position:relative;z-index:1;
  padding:132px max(20px,calc((100vw - var(--maxw))/2)) 90px;
  text-align:center;
}
.hero__inner{max-width:900px;margin:0 auto}
.hero__eyebrow{
  display:inline-block;
  font-size:12px;letter-spacing:.3em;color:var(--gold);
  border:1px solid rgba(212,175,106,.3);
  padding:7px 18px;border-radius:100px;
  background:rgba(212,175,106,.06);
  margin-bottom:26px;
}
.hero__title{
  font-size:clamp(32px,5.2vw,62px);
  color:#fff;letter-spacing:.01em;
  text-shadow:0 4px 40px rgba(80,140,220,.25);
}
.hero__title .gold{
  background:linear-gradient(120deg,var(--gold-soft),var(--gold),var(--gold-deep));
  -webkit-background-clip:text;background-clip:text;
  -webkit-text-fill-color:transparent;
  filter:drop-shadow(0 0 24px rgba(212,175,106,.3));
}
.hero__sub{
  margin-top:22px;font-size:16.5px;color:var(--silver-300);
  max-width:620px;margin-left:auto;margin-right:auto;
  font-weight:300;line-height:1.9;
}

/* 视频区 */
.video-wrap{position:relative;margin-top:52px}
.video-frame{
  position:relative;
  border-radius:var(--r-lg);
  overflow:hidden;
  border:1px solid var(--line-strong);
  background:var(--navy-800);
  box-shadow:
    0 40px 100px rgba(0,0,0,.6),
    0 0 0 1px rgba(255,255,255,.04) inset,
    0 0 80px rgba(40,100,180,.18);
  aspect-ratio:16/9;
}
.video{width:100%;height:100%;object-fit:cover;display:block}
.video-fallback{
  position:absolute;inset:0;
  display:flex;align-items:center;justify-content:center;
}
.video-fallback img{
  position:absolute;inset:0;width:100%;height:100%;
  object-fit:cover;opacity:.55;
}
.video-fallback::after{
  content:"";position:absolute;inset:0;
  background:linear-gradient(180deg,rgba(5,11,24,.35),rgba(5,11,24,.75));
}
.video-play{
  position:relative;z-index:2;
  width:82px;height:82px;border-radius:50%;
  border:1.5px solid rgba(212,175,106,.6);
  background:rgba(212,175,106,.12);
  backdrop-filter:blur(8px);
  display:flex;align-items:center;justify-content:center;
  transition:.3s;
}
.video-play:hover{
  background:rgba(212,175,106,.24);
  transform:scale(1.06);
  box-shadow:0 0 40px rgba(212,175,106,.4);
}
.video-play span{
  width:0;height:0;margin-left:5px;
  border-left:20px solid var(--gold-soft);
  border-top:12px solid transparent;
  border-bottom:12px solid transparent;
}
.video-note{
  position:absolute;bottom:22px;left:0;right:0;z-index:2;
  text-align:center;font-size:12.5px;letter-spacing:.2em;
  color:var(--silver-400);
}
.video-glow{
  position:absolute;left:50%;bottom:-60px;transform:translateX(-50%);
  width:70%;height:120px;
  background:radial-gradient(ellipse,rgba(212,175,106,.22),transparent 70%);
  filter:blur(40px);z-index:-1;
}

.hero__actions{
  display:flex;gap:14px;justify-content:center;
  margin-top:44px;flex-wrap:wrap;
}

/* ===== 按钮 ===== */
.btn{
  display:inline-flex;align-items:center;justify-content:center;
  padding:14px 34px;border-radius:100px;
  font-size:15px;font-weight:500;letter-spacing:.04em;
  transition:.3s;white-space:nowrap;
}
.btn--gold{
  background:linear-gradient(135deg,var(--gold-soft),var(--gold));
  color:#1A1206;font-weight:700;
  box-shadow:0 10px 30px rgba(212,175,106,.28);
}
.btn--gold:hover{
  transform:translateY(-2px);
  box-shadow:0 16px 40px rgba(212,175,106,.42);
}
.btn--ghost{
  border:1px solid var(--line-strong);
  color:var(--silver-200);
  background:rgba(255,255,255,.02);
}
.btn--ghost:hover{
  border-color:var(--gold);
  color:var(--gold-soft);
  background:rgba(212,175,106,.06);
}
.btn--lg{padding:17px 46px;font-size:16px}

/* ===== 通用区块 ===== */
.sec-eyebrow{
  font-size:12px;letter-spacing:.28em;color:var(--gold);
  margin-bottom:16px;font-weight:500;
}
.sec-eyebrow--center{text-align:center}
.sec-title{
  font-size:clamp(26px,3.4vw,42px);
  color:#fff;line-height:1.3;
}
.sec-title--center{text-align:center}

/* ===== 理念 ===== */
.story{
  position:relative;z-index:1;
  padding:100px max(20px,calc((100vw - var(--maxw))/2));
}
.story__inner{
  display:grid;grid-template-columns:.92fr 1.08fr;
  gap:64px;align-items:center;
}
.story__media{position:relative}
.story__img{
  width:100%;border-radius:var(--r-lg);
  border:1px solid var(--line-strong);
  box-shadow:0 30px 80px rgba(0,0,0,.55);
}
.story__media-glow{
  position:absolute;inset:-30px;z-index:-1;
  background:radial-gradient(circle at 50% 50%,rgba(40,100,180,.28),transparent 70%);
  filter:blur(50px);
}
.lines{display:flex;flex-direction:column;gap:20px;margin-top:34px}
.line{
  font-size:16.5px;color:var(--silver-300);font-weight:300;
  line-height:1.9;padding-left:20px;
  border-left:2px solid rgba(212,175,106,.25);
  opacity:0;transform:translateY(18px);
  transition:opacity .8s ease,transform .8s cubic-bezier(.2,.7,.3,1);
}
.line.is-in{opacity:1;transform:none}
.line em{
  font-style:normal;color:var(--gold-soft);font-weight:500;
  text-shadow:0 0 20px rgba(212,175,106,.3);
}

/* ===== 价值 ===== */
.value{
  position:relative;z-index:1;
  padding:100px max(20px,calc((100vw - var(--maxw))/2));
  background:linear-gradient(180deg,transparent,rgba(12,26,51,.5),transparent);
}
.value__inner{max-width:var(--maxw);margin:0 auto}
.value__grid{
  display:grid;grid-template-columns:repeat(3,1fr);
  gap:24px;margin-top:52px;
}
.vcard{
  position:relative;
  padding:38px 30px;
  border-radius:var(--r-md);
  border:1px solid var(--line);
  background:linear-gradient(160deg,rgba(18,36,68,.7),rgba(8,18,38,.5));
  backdrop-filter:blur(10px);
  transition:.35s;
  overflow:hidden;
}
.vcard::before{
  content:"";position:absolute;top:0;left:0;right:0;height:1px;
  background:linear-gradient(90deg,transparent,rgba(212,175,106,.5),transparent);
  opacity:0;transition:.35s;
}
.vcard:hover{
  transform:translateY(-6px);
  border-color:rgba(212,175,106,.3);
  box-shadow:0 24px 60px rgba(0,0,0,.45),0 0 40px rgba(212,175,106,.08);
}
.vcard:hover::before{opacity:1}
.vcard__no{
  font-family:'Noto Serif SC',serif;
  font-size:13px;letter-spacing:.2em;color:var(--gold);
  display:block;margin-bottom:18px;
}
.vcard h3{
  font-size:19px;color:#fff;margin-bottom:14px;line-height:1.45;
}
.vcard p{font-size:14.5px;color:var(--silver-400);font-weight:300;line-height:1.85}

/* ===== 数据 ===== */
.stats{
  position:relative;z-index:1;
  padding:70px max(20px,calc((100vw - var(--maxw))/2));
}
.stats__inner{
  display:grid;grid-template-columns:repeat(4,1fr);
  border-top:1px solid var(--line);
  border-bottom:1px solid var(--line);
}
.stat{
  padding:38px 20px;text-align:center;
  border-right:1px solid var(--line);
}
.stat:last-child{border-right:none}
.stat b{
  display:block;
  font-family:'Noto Serif SC',serif;
  font-size:clamp(30px,4vw,46px);
  background:linear-gradient(135deg,var(--gold-soft),var(--gold-deep));
  -webkit-background-clip:text;background-clip:text;
  -webkit-text-fill-color:transparent;
  line-height:1.1;
}
.stat span{
  display:block;margin-top:8px;
  font-size:13px;color:var(--silver-400);letter-spacing:.08em;
}

/* ===== 加入 ===== */
.join{
  position:relative;z-index:1;
  padding:120px max(20px,calc((100vw - var(--maxw))/2));
  text-align:center;
  background:
    radial-gradient(ellipse 60% 50% at 50% 40%,rgba(212,175,106,.10),transparent 70%);
}
.join__inner{max-width:680px;margin:0 auto}
.join__title{
  font-size:clamp(28px,4vw,50px);color:#fff;line-height:1.3;
}
.join__sub{
  margin:22px 0 38px;font-size:16px;color:var(--silver-300);font-weight:300;
}
.join__note{
  margin-top:34px;font-size:12px;letter-spacing:.24em;color:var(--silver-400);
}

/* ===== 页脚 ===== */
.foot{
  position:relative;z-index:1;
  padding:40px max(20px,calc((100vw - var(--maxw))/2));
  border-top:1px solid var(--line);
}
.foot__inner{
  display:flex;align-items:center;justify-content:space-between;
  gap:20px;flex-wrap:wrap;
}
.foot__brand{display:flex;align-items:center;gap:10px;font-size:13.5px;color:var(--silver-300)}
.foot__mark{width:28px;height:28px;object-fit:contain;opacity:.85}
.foot__copy{font-size:12.5px;color:var(--silver-400)}

/* ===== 滚动渐显 ===== */
.reveal{opacity:0;transform:translateY(30px);transition:opacity .9s ease,transform .9s cubic-bezier(.2,.7,.3,1)}
.reveal.is-in{opacity:1;transform:none}

/* ===== 响应式 ===== */
@media(max-width:1024px){
  .story__inner{grid-template-columns:1fr;gap:44px}
  .value__grid{grid-template-columns:1fr;gap:18px}
  .stats__inner{grid-template-columns:repeat(2,1fr)}
  .stat:nth-child(2){border-right:none}
  .stat:nth-child(1),.stat:nth-child(2){border-bottom:1px solid var(--line)}
}
@media(max-width:720px){
  .topnav{display:none}
  .hero{padding:112px 20px 64px}
  .story,.value,.join{padding:64px 20px}
  .stats{padding:48px 20px}
  .video-frame{aspect-ratio:4/3}
  .video-play{width:64px;height:64px}
  .video-play span{border-left-width:16px;border-top-width:10px;border-bottom-width:10px}
  .brand__text i{display:none}
  .hero__actions{gap:10px}
  .btn{padding:13px 26px;font-size:14px}
  .foot__inner{flex-direction:column;align-items:flex-start;gap:12px}
}
@media(max-width:460px){
  .stats__inner{grid-template-columns:1fr}
  .stat{border-right:none;border-bottom:1px solid var(--line)}
  .stat:last-child{border-bottom:none}
}
@media(prefers-reduced-motion:reduce){
  *{animation:none!important;transition:none!important}
  .reveal,.line{opacity:1;transform:none}
}