/* ============================================================
   SteadiVolt — steady power, certified quality
   设计系统：深蓝黑底 + 工业琥珀强调色（电源/认证行业语汇）
   所有颜色与尺寸走 CSS 变量，换配色只改 :root 一处
   ============================================================ */
:root {
  /* ── Palette：合并 GPT 方案（深海军蓝＋合规绿）与本项目差异化强调色（工业琥珀）
     ——结构规则（1200栅格、边框优先于阴影、96/64节奏、圆角12）采纳 GPT 方案 */
  --ink:            #101B2A;   /* deep base — hero/dark sections（GPT: #16202B 同族） */
  --ink-2:          #16232F;   /* elevated dark surface */
  --ink-3:          #24313F;   /* dark border/card */
  --paper:          #FFFFFF;   /* light section background */
  --paper-2:        #F7F9FC;   /* subtle light surface（GPT 指定） */
  --text:           #111827;   /* primary text on light（GPT 指定） */
  --text-soft:      #4B5563;   /* secondary text on light（GPT 指定） */
  --text-inv:       #F7F9FC;   /* primary text on dark */
  --text-inv-soft:  #AEBBCB;   /* secondary text on dark */
  --accent:         #FFB020;   /* energy / amber — 主 CTA、能量语汇（差异化） */
  --accent-strong:  #E89400;
  --accent-ink:     #1A1204;   /* text on amber */
  --verify:         #0F766E;   /* certification / trust green（GPT 指定） */
  --ok:             #17A673;   /* verified / success */
  --line:           #E2E6EC;   /* card & divider border */
  --line-strong:    #D1D5DB;   /* inputs, stronger dividers（GPT 指定） */
  --line-inv:       rgba(255,255,255,0.10);

  /* Type（尺寸采纳 GPT 方案） */
  --font: "Inter", ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "Noto Sans SC", "Microsoft YaHei", sans-serif;
  --h1: clamp(2.25rem, 4.4vw, 3.5rem);   /* 36 → 56 */
  --h2: clamp(1.75rem, 3vw, 2.5rem);     /* 28 → 40 */
  --h3: clamp(1.25rem, 1.6vw, 1.5rem);   /* 20 → 24 */
  --lead: clamp(1.02rem, 1.3vw, 1.16rem);
  --body: 1rem;
  --small: 0.8125rem;

  /* Layout（采纳 GPT 方案） */
  --wrap: 1200px;
  --pad-y: clamp(64px, 7vw, 96px);
  --gap: clamp(16px, 2vw, 28px);
  --r: 12px;
  --r-sm: 10px;
  --ease: cubic-bezier(.22,.61,.36,1);
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; -webkit-text-size-adjust: 100%; }
body {
  margin: 0; background: var(--paper); color: var(--text);
  font-family: var(--font); font-size: var(--body); line-height: 1.68;
  -webkit-font-smoothing: antialiased;
}
img, video { max-width: 100%; display: block; }
a { color: inherit; text-decoration: none; }
h1, h2, h3, h4 { margin: 0 0 .5em; line-height: 1.15; letter-spacing: -0.02em; font-weight: 760; }
h2 { font-size: var(--h2); }
h3 { font-size: var(--h3); letter-spacing: -0.01em; }
p  { margin: 0 0 1em; }
:focus-visible { outline: 3px solid var(--verify); outline-offset: 3px; border-radius: 4px; }

.wrap { width: 100%; max-width: var(--wrap); margin-inline: auto; padding-inline: clamp(18px, 4vw, 32px); }
.section { padding-block: var(--pad-y); }
.section--dark { background: var(--ink); color: var(--text-inv); }
.section--soft { background: var(--paper-2); }
.eyebrow {
  display: inline-flex; align-items: center; gap: 8px;
  font-size: .78rem; font-weight: 700; letter-spacing: .14em; text-transform: uppercase;
  color: var(--accent-strong); margin-bottom: 14px;
}
.section--dark .eyebrow { color: var(--accent); }
.lead { font-size: var(--lead); color: var(--text-soft); max-width: 62ch; }
.section--dark .lead { color: var(--text-inv-soft); }
.center { text-align: center; }
.center .lead { margin-inline: auto; }

/* Buttons */
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 10px;
  padding: 14px 24px; border-radius: 999px; font-weight: 700; font-size: .97rem;
  border: 1px solid transparent; cursor: pointer; transition: transform .2s var(--ease), background .2s, border-color .2s, color .2s;
  min-height: 48px;
}
.btn:hover { transform: translateY(-1px); }
.btn--primary { background: var(--accent); color: var(--accent-ink); }
.btn--primary:hover { background: var(--accent-strong); }
.btn--ghost { border-color: var(--line-inv); color: var(--text-inv); }
.btn--ghost:hover { border-color: rgba(255,255,255,.35); }
.btn--outline { border-color: var(--line); color: var(--text); background: #fff; }
.btn--outline:hover { border-color: var(--text); }
.btn--wa { background: #25D366; color: #06331B; }

/* Header */
.nav {
  position: sticky; top: 0; z-index: 60;
  background: rgba(11,18,32,.86); backdrop-filter: blur(14px);
  border-bottom: 1px solid var(--line-inv);
}
.nav__inner { display: flex; align-items: center; gap: 22px; min-height: 68px; }
.brand { display: flex; align-items: center; gap: 11px; color: var(--text-inv); font-weight: 800; letter-spacing: -0.02em; }
.brand img { width: 34px; height: 34px; border-radius: 8px; }
.brand__name { font-size: 1.1rem; }
.brand__tag { display: block; font-size: .64rem; font-weight: 600; letter-spacing: .12em; text-transform: uppercase; color: var(--text-inv-soft); }
.nav__links { display: flex; gap: 22px; margin-left: auto; }
.nav__links a { color: var(--text-inv-soft); font-size: .93rem; font-weight: 600; }
.nav__links a:hover { color: var(--text-inv); }
.nav__cta { margin-left: 6px; }
.nav__toggle { display: none; margin-left: auto; background: none; border: 1px solid var(--line-inv); color: var(--text-inv); border-radius: 8px; padding: 8px 12px; }

/* Hero */
.hero { position: relative; background: var(--ink); color: var(--text-inv); overflow: hidden; }
.hero__media { position: absolute; inset: 0; }
.hero__media video, .hero__media img { width: 100%; height: 100%; object-fit: cover; }
.hero__media::after {
  content: ""; position: absolute; inset: 0;
  background: linear-gradient(180deg, rgba(11,18,32,.82) 0%, rgba(11,18,32,.66) 45%, rgba(11,18,32,.94) 100%);
}
.hero__inner { position: relative; padding-block: clamp(84px, 12vw, 148px) clamp(56px, 8vw, 96px); }
.hero h1 { font-size: var(--h1); max-width: 20ch; }
.hero__sub { font-size: var(--lead); color: var(--text-inv-soft); max-width: 58ch; margin-bottom: 28px; }
.hero__cta { display: flex; flex-wrap: wrap; gap: 12px; margin-bottom: 34px; }
.hero__note { font-size: var(--small); color: var(--text-inv-soft); }

/* Trust bar */
.trust { border-top: 1px solid var(--line-inv); background: var(--ink-2); }
.trust__grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 1px; background: var(--line-inv); }
.trust__item { background: var(--ink-2); padding: 22px 20px; }
.trust__k { font-size: .74rem; letter-spacing: .12em; text-transform: uppercase; color: var(--accent); font-weight: 700; }
.trust__v { font-weight: 700; color: var(--text-inv); }

/* Cards */
.grid { display: grid; gap: var(--gap); }
.grid--2 { grid-template-columns: repeat(2, 1fr); }
.grid--3 { grid-template-columns: repeat(3, 1fr); }
.grid--4 { grid-template-columns: repeat(4, 1fr); }
.card {
  background: #fff; border: 1px solid var(--line); border-radius: var(--r); padding: 26px;
  transition: border-color .25s var(--ease), transform .25s var(--ease);
}
.card:hover { border-color: #C9D3E0; transform: translateY(-2px); }
.card__ico { width: 40px; height: 40px; border-radius: 10px; background: var(--paper-2); display: grid; place-items: center; font-weight: 800; color: var(--accent-strong); margin-bottom: 14px; }
.section--dark .card { background: var(--ink-2); border-color: var(--ink-3); }
.section--dark .card h3 { color: var(--text-inv); }
.section--dark .card p { color: var(--text-inv-soft); }

/* Media blocks */
.media { border-radius: var(--r); overflow: hidden; background: var(--ink-2); position: relative; }
.media img { width: 100%; height: 100%; object-fit: cover; aspect-ratio: 4 / 3; }
.media--wide img { aspect-ratio: 16 / 9; }
.media__cap { position: absolute; left: 0; right: 0; bottom: 0; padding: 14px 16px; font-size: .88rem; font-weight: 600;
  background: linear-gradient(transparent, rgba(8,13,22,.88)); color: #fff; }
.media-grid { display: grid; grid-template-columns: 1.35fr 1fr; gap: var(--gap); }
.media-grid__side { display: grid; gap: var(--gap); }

/* Products */
.products { display: grid; grid-template-columns: repeat(3, 1fr); gap: var(--gap); }
.product { border: 1px solid var(--line); border-radius: var(--r); overflow: hidden; background: #fff; display: flex; flex-direction: column; }
.product img { aspect-ratio: 4 / 3; object-fit: cover; width: 100%; }
.product__body { padding: 20px 22px 24px; }
.product__body h3 { margin-bottom: 6px; }
.product__body p { color: var(--text-soft); font-size: .95rem; margin: 0; }
.product__tag { display: inline-block; font-size: .72rem; font-weight: 700; letter-spacing: .08em; text-transform: uppercase; color: var(--verify); margin-bottom: 8px; }

/* Certifications */
.certs { display: flex; flex-wrap: wrap; gap: 10px; margin: 22px 0 16px; }
.cert {
  border: 1px solid var(--line); background: #fff; border-radius: 999px;
  padding: 10px 18px; font-weight: 700; font-size: .9rem; color: var(--text);
}
.cert--pending { border-style: dashed; color: var(--text-soft); font-weight: 600; }
.note { font-size: var(--small); color: var(--text-soft); border-left: 3px solid var(--accent); padding-left: 14px; margin-top: 10px; }

/* Process */
.steps { display: grid; grid-template-columns: repeat(4, 1fr); gap: var(--gap); counter-reset: step; }
.step { position: relative; padding-top: 46px; }
.step::before {
  counter-increment: step; content: "0" counter(step);
  position: absolute; top: 0; left: 0; font-size: 1.5rem; font-weight: 800; color: var(--accent);
  letter-spacing: -0.03em;
}
.step h3 { font-size: 1.06rem; }
.step p { color: var(--text-soft); font-size: .95rem; margin: 0; }

/* FAQ */
.faq { max-width: 860px; margin-inline: auto; }
.faq details { border-bottom: 1px solid var(--line); padding: 18px 0; }
.faq summary { cursor: pointer; font-weight: 700; font-size: 1.04rem; list-style: none; display: flex; justify-content: space-between; gap: 16px; }
.faq summary::-webkit-details-marker { display: none; }
.faq summary::after { content: "+"; color: var(--accent-strong); font-weight: 800; }
.faq details[open] summary::after { content: "–"; }
.faq p { margin: 12px 0 0; color: var(--text-soft); }

/* Contact */
.contact__grid { display: grid; grid-template-columns: 1.1fr .9fr; gap: clamp(24px, 4vw, 56px); align-items: start; }
.contact__box { background: var(--ink-2); border: 1px solid var(--ink-3); border-radius: var(--r); padding: 28px; }
.checklist { list-style: none; padding: 0; margin: 0 0 22px; }
.checklist li { position: relative; padding-left: 28px; margin-bottom: 10px; color: var(--text-inv-soft); }
.checklist li::before { content: "✓"; position: absolute; left: 0; color: var(--ok); font-weight: 800; }
.kv { display: grid; grid-template-columns: auto 1fr; gap: 8px 16px; font-size: .94rem; }
.kv dt { color: var(--text-inv-soft); }
.kv dd { margin: 0; color: var(--text-inv); font-weight: 600; word-break: break-word; }

/* Footer */
.footer { background: var(--ink); color: var(--text-inv-soft); border-top: 1px solid var(--line-inv); padding-block: 46px 30px; font-size: .92rem; }
.footer__grid { display: grid; grid-template-columns: 1.4fr 1fr 1fr; gap: 28px; margin-bottom: 26px; }
.footer h4 { color: var(--text-inv); font-size: .82rem; letter-spacing: .12em; text-transform: uppercase; margin-bottom: 12px; }
.footer a:hover { color: var(--accent); }
.footer ul { list-style: none; padding: 0; margin: 0; }
.footer li { margin-bottom: 8px; }
.footer__bottom { border-top: 1px solid var(--line-inv); padding-top: 18px; display: flex; justify-content: space-between; gap: 14px; flex-wrap: wrap; font-size: .85rem; }

/* Reveal on scroll（动效时长采纳 GPT 规范：240–320ms，克制不花哨） */
.reveal { opacity: 0; transform: translateY(12px); transition: opacity .32s var(--ease), transform .32s var(--ease); }
.reveal.is-in { opacity: 1; transform: none; }
@media (prefers-reduced-motion: reduce) { .reveal { opacity: 1; transform: none; transition: none; } html { scroll-behavior: auto; } }

/* Responsive */
@media (max-width: 1000px) {
  .grid--4 { grid-template-columns: repeat(2, 1fr); }
  .products { grid-template-columns: repeat(2, 1fr); }
  .steps { grid-template-columns: repeat(2, 1fr); }
  .media-grid { grid-template-columns: 1fr; }
  .contact__grid { grid-template-columns: 1fr; }
  .footer__grid { grid-template-columns: 1fr 1fr; }
}
@media (max-width: 760px) {
  .nav__links { display: none; }
  .nav__links.is-open {
    display: flex; flex-direction: column; position: absolute; top: 68px; left: 0; right: 0;
    background: var(--ink-2); padding: 18px 22px 24px; gap: 14px; border-bottom: 1px solid var(--line-inv);
  }
  .nav__toggle { display: block; }
  .nav__cta { display: none; }
  .trust__grid { grid-template-columns: 1fr 1fr; }
  .grid--3, .grid--2, .grid--4, .products, .steps { grid-template-columns: 1fr; }
  .footer__grid { grid-template-columns: 1fr; }
}

/* ── 组件补充：跳过链接 / 证书槽 / 图片容错 / 其他可选项 ── */
.skip {
  position: absolute; left: -9999px; top: 0; z-index: 100;
  background: var(--accent); color: var(--accent-ink); padding: 10px 16px; border-radius: 0 0 8px 0; font-weight: 700;
}
.skip:focus { left: 0; }

section[id], main [id] { scroll-margin-top: 84px; }

.also { margin-top: 34px; }
.also h3 { font-size: 1.06rem; margin-bottom: 12px; }

.cert-slots { display: grid; grid-template-columns: repeat(3, 1fr); gap: var(--gap); }
.cert-slot {
  border: 1px dashed var(--line-strong); border-radius: var(--r-sm); background: var(--paper-2);
  min-height: 132px; display: grid; place-items: center; text-align: center; padding: 18px;
  color: var(--text-soft); font-size: .9rem; font-weight: 600;
}
.img-fallback {
  aspect-ratio: 16 / 10; display: grid; place-items: center; text-align: center;
  background: repeating-linear-gradient(45deg, var(--paper-2), var(--paper-2) 10px, #EEF2F7 10px, #EEF2F7 20px);
  color: var(--text-soft); font-weight: 700; font-size: .92rem;
}
.img-fallback small { font-weight: 500; color: var(--text-soft); }
.product img { aspect-ratio: 16 / 10; }
.kv a { color: var(--text-inv); text-decoration: underline; text-underline-offset: 3px; }
.kv a:hover { color: var(--accent); }
code { background: var(--paper-2); border: 1px solid var(--line); border-radius: 6px; padding: 1px 6px; font-size: .88em; }
@media (max-width: 1000px) { .cert-slots { grid-template-columns: 1fr 1fr; } }
@media (max-width: 760px) { .cert-slots { grid-template-columns: 1fr; } }