/* ==========================================================================
   BCFF / 潮汐货场 TIDAL FREIGHT · 01 core
   带货直播分拨机构 · 深海墨 + 浪青 + 信号橙 · 纯 CSS 零图片
   ========================================================================== */

:root {
  /* 港口色板 */
  --bc-deep: #071e26;
  --bc-deep-2: #0c303c;
  --bc-deep-3: #12414f;
  --bc-ink: #0b1c22;
  --bc-mid: #3f5a61;
  --bc-soft: #7a9298;
  --bc-paper: #f2f5f3;
  --bc-paper-2: #e4ece8;
  --bc-card: #fbfdfc;
  --bc-line: #ccd9d5;
  --bc-line-2: #b5c7c2;
  --bc-teal: #12a08d;
  --bc-teal-2: #0b7f71;
  --bc-mint: #c9e9e1;
  --bc-mint-2: #e4f4ef;
  --bc-orange: #ff6a2a;
  --bc-orange-2: #e0531a;
  --bc-orange-soft: #ffe6da;

  /* 结构 */
  --bc-wrap: 1240px;
  --bc-wrap-slim: 840px;
  --bc-pad: clamp(16px, 4vw, 48px);
  --bc-gap: clamp(16px, 2.4vw, 28px);
  --bc-sec: clamp(54px, 7.2vw, 104px);
  --bc-bd: 2px;

  /* 字体 */
  --bc-sans: "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Source Han Sans SC", sans-serif;
  --bc-mono: "Cascadia Mono", "JetBrains Mono", "SFMono-Regular", Consolas, "Courier New", monospace;

  /* 动态 */
  --bc-ease: cubic-bezier(.2, .75, .25, 1);
  --bc-fast: .18s;
  --bc-mid: .36s;

  /* 底纹 */
  --bc-grid-lines:
    linear-gradient(to right, rgba(11, 28, 34, .045) 1px, transparent 1px),
    linear-gradient(to bottom, rgba(11, 28, 34, .045) 1px, transparent 1px);
  --bc-rib: repeating-linear-gradient(90deg, currentColor 0 2px, transparent 2px 7px);
}

*,
*::before,
*::after { box-sizing: border-box; }

html {
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
  scroll-padding-top: 108px;
}

body,
h1, h2, h3, h4, h5, p, figure, blockquote, dl, dd, ul, ol, form { margin: 0; }
ul, ol { padding: 0; list-style: none; }
img, svg { display: block; max-width: 100%; }
a { color: inherit; text-decoration: none; }
button { font: inherit; color: inherit; background: none; border: 0; cursor: pointer; }
input, textarea, select { font: inherit; color: inherit; }
table { border-collapse: collapse; width: 100%; }

:focus-visible {
  outline: 3px solid var(--bc-teal);
  outline-offset: 3px;
}

::selection {
  background: var(--bc-orange);
  color: #fff;
}

body {
  min-height: 100vh;
  font-family: var(--bc-sans);
  font-size: 16px;
  line-height: 1.78;
  color: var(--bc-ink);
  background-color: var(--bc-paper);
  background-image: var(--bc-grid-lines);
  background-size: 72px 72px;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}

/* 页面外壳：长页面滚动时锁定合成层，避免网格底纹抖动 */
body.bc-page {
  position: relative;
  text-rendering: optimizeLegibility;
}

/* 筛选等交互依赖 hidden 属性，必须压过组件自身的 display */
[hidden] { display: none !important; }

h1, h2, h3, h4 {
  font-weight: 900;
  line-height: 1.14;
  letter-spacing: -.035em;
  text-wrap: balance;
}

h1 { font-size: clamp(2.35rem, 6vw, 5rem); }
h2 { font-size: clamp(1.65rem, 3.4vw, 2.7rem); }
h3 { font-size: clamp(1.1rem, 1.8vw, 1.36rem); letter-spacing: -.02em; }
h4 { font-size: 1.02rem; letter-spacing: -.01em; }

p { color: var(--bc-mid); }
strong { font-weight: 800; color: var(--bc-ink); }
a strong { color: inherit; }

/* ---------- 通用容器 ---------- */

.bc-wrap {
  width: 100%;
  max-width: var(--bc-wrap);
  margin-inline: auto;
  padding-inline: var(--bc-pad);
}

.bc-wrap--slim { max-width: var(--bc-wrap-slim); }

.bc-mono {
  font-family: var(--bc-mono);
  font-size: .72rem;
  line-height: 1.6;
  letter-spacing: .18em;
  text-transform: uppercase;
}

.bc-kicker {
  display: inline-flex;
  align-items: center;
  gap: 9px;
  font-family: var(--bc-mono);
  font-size: .7rem;
  letter-spacing: .2em;
  text-transform: uppercase;
  color: var(--bc-teal-2);
}

.bc-kicker::before {
  content: "";
  width: 9px;
  height: 9px;
  background: var(--bc-orange);
  flex: none;
}

.bc-kicker--light { color: var(--bc-mint); }

.bc-sr {
  position: absolute;
  width: 1px; height: 1px;
  padding: 0; margin: -1px;
  overflow: hidden;
  clip: rect(0 0 0 0);
  white-space: nowrap;
  border: 0;
}

.bc-skip {
  position: absolute;
  left: 16px;
  top: -90px;
  z-index: 900;
  padding: 11px 20px;
  background: var(--bc-ink);
  color: var(--bc-paper);
  font-family: var(--bc-mono);
  font-size: .74rem;
  letter-spacing: .16em;
  transition: top var(--bc-fast) var(--bc-ease);
}

.bc-skip:focus { top: 14px; }

/* ---------- 按钮 ---------- */

.bc-btn {
  --bc-btn-bg: transparent;
  --bc-btn-fg: var(--bc-ink);
  --bc-btn-bd: var(--bc-ink);
  display: inline-flex;
  align-items: center;
  gap: 10px;
  min-height: 46px;
  padding: 0 22px;
  border: var(--bc-bd) solid var(--bc-btn-bd);
  background: var(--bc-btn-bg);
  color: var(--bc-btn-fg);
  font-family: var(--bc-mono);
  font-size: .76rem;
  font-weight: 700;
  letter-spacing: .12em;
  text-transform: uppercase;
  transition: transform var(--bc-fast) var(--bc-ease), box-shadow var(--bc-fast) var(--bc-ease), background-color var(--bc-fast) var(--bc-ease), color var(--bc-fast) var(--bc-ease);
}

.bc-btn::after {
  content: "→";
  font-size: .95rem;
  line-height: 1;
}

.bc-btn:hover {
  transform: translate(-2px, -2px);
  box-shadow: 5px 5px 0 var(--bc-teal);
}

.bc-btn--fill {
  --bc-btn-bg: var(--bc-deep);
  --bc-btn-fg: var(--bc-paper);
  --bc-btn-bd: var(--bc-deep);
}

.bc-btn--fill:hover { box-shadow: 5px 5px 0 var(--bc-orange); }

.bc-btn--orange {
  --bc-btn-bg: var(--bc-orange);
  --bc-btn-fg: #fff;
  --bc-btn-bd: var(--bc-orange-2);
}

.bc-btn--orange:hover { box-shadow: 5px 5px 0 var(--bc-ink); }

.bc-btn--ghost {
  --bc-btn-fg: var(--bc-mint);
  --bc-btn-bd: rgba(201, 233, 225, .4);
}

.bc-btn--ghost:hover {
  --bc-btn-bg: rgba(201, 233, 225, .1);
  box-shadow: 5px 5px 0 rgba(255, 106, 42, .55);
}

.bc-btn--sm { min-height: 38px; padding: 0 15px; font-size: .68rem; }

.bc-link {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  border-bottom: 2px solid var(--bc-teal);
  padding-bottom: 2px;
  font-weight: 700;
  transition: gap var(--bc-fast) var(--bc-ease), color var(--bc-fast) var(--bc-ease);
}

.bc-link::after { content: "↗"; font-size: .85em; }

.bc-link:hover { gap: 14px; color: var(--bc-teal-2); }

/* ---------- 章节头 ---------- */

.bc-sec {
  padding-block: var(--bc-sec);
  position: relative;
}

.bc-sec--tight { padding-block: clamp(32px, 4vw, 56px); }

.bc-sec--mist { background: var(--bc-paper-2); }
.bc-sec--deep { background: var(--bc-deep); color: var(--bc-paper); }
.bc-sec--deep p { color: rgba(242, 245, 243, .72); }
.bc-sec--deep h2 { color: var(--bc-paper); }

.bc-sechead {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, .9fr);
  gap: clamp(16px, 4vw, 56px);
  align-items: end;
  padding-bottom: 22px;
  border-bottom: var(--bc-bd) solid var(--bc-ink);
  margin-bottom: clamp(26px, 3.4vw, 44px);
}

.bc-sec--deep .bc-sechead { border-bottom-color: rgba(242, 245, 243, .25); }

.bc-sechead__tag {
  display: flex;
  align-items: baseline;
  gap: 14px;
  margin-bottom: 12px;
  font-family: var(--bc-mono);
  font-size: .7rem;
  letter-spacing: .2em;
  text-transform: uppercase;
  color: var(--bc-teal-2);
}

.bc-sec--deep .bc-sechead__tag { color: var(--bc-mint); }

.bc-sechead__tag b {
  font-size: 1.35rem;
  letter-spacing: 0;
  color: var(--bc-orange);
}

.bc-sechead h2 { margin-bottom: 0; }
.bc-sechead__note {
  font-size: .95rem;
  line-height: 1.85;
  padding-bottom: 4px;
}

.bc-sechead__note strong { color: inherit; }

/* ---------- 波浪分隔 ---------- */

.bc-wave {
  display: block;
  line-height: 0;
  margin-bottom: -1px;
  color: var(--bc-paper);
}

.bc-wave svg { width: 100%; height: clamp(28px, 4vw, 56px); }
.bc-wave--mist { color: var(--bc-paper-2); }
.bc-wave--deep { color: var(--bc-deep); }
.bc-wave--card { color: var(--bc-card); }

/* ---------- 顶栏 ---------- */

.bc-head {
  position: sticky;
  top: 0;
  z-index: 120;
  background: rgba(242, 245, 243, .94);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--bc-line);
}

.bc-head__strip {
  background: var(--bc-deep);
  color: rgba(242, 245, 243, .76);
}

.bc-head__strip-in {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 18px;
  min-height: 34px;
  padding-block: 6px;
}

.bc-head__tag {
  display: flex;
  align-items: center;
  gap: 10px;
  font-family: var(--bc-mono);
  font-size: .64rem;
  letter-spacing: .14em;
  text-transform: uppercase;
  color: var(--bc-mint);
  white-space: nowrap;
}

.bc-dot {
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: var(--bc-orange);
  box-shadow: 0 0 0 3px rgba(255, 106, 42, .22);
  flex: none;
}

.bc-head__meta {
  display: flex;
  align-items: center;
  gap: clamp(12px, 2.4vw, 28px);
  font-family: var(--bc-mono);
  font-size: .64rem;
  letter-spacing: .1em;
}

.bc-head__meta a:hover { color: var(--bc-orange); }
.bc-head__meta li:first-child { color: var(--bc-mint); }

.bc-head__main {
  display: flex;
  align-items: center;
  gap: 24px;
  min-height: 74px;
}

.bc-logo {
  display: flex;
  align-items: center;
  gap: 12px;
  flex: none;
}

.bc-logo__mark {
  display: grid;
  place-items: center;
  width: 42px;
  height: 42px;
  background: var(--bc-deep);
  color: var(--bc-mint);
}

.bc-logo__mark svg { width: 26px; height: 26px; }

.bc-logo__txt {
  display: flex;
  flex-direction: column;
  line-height: 1.2;
}

.bc-logo__txt strong {
  font-size: 1.1rem;
  font-weight: 900;
  letter-spacing: -.02em;
}

.bc-logo__txt em {
  font-family: var(--bc-mono);
  font-style: normal;
  font-size: .56rem;
  letter-spacing: .22em;
  text-transform: uppercase;
  color: var(--bc-soft);
}

.bc-burger {
  display: none;
  margin-left: auto;
  padding: 9px 13px;
  border: 2px solid var(--bc-ink);
  font-family: var(--bc-mono);
  font-size: .68rem;
  letter-spacing: .14em;
}

.bc-nav {
  display: flex;
  align-items: center;
  gap: clamp(10px, 1.8vw, 26px);
  margin-left: auto;
}

.bc-nav__list {
  display: flex;
  align-items: center;
  gap: clamp(8px, 1.4vw, 20px);
}

.bc-nav__list a {
  display: block;
  position: relative;
  padding-block: 6px;
  font-size: .92rem;
  font-weight: 600;
  white-space: nowrap;
  transition: color var(--bc-fast) var(--bc-ease);
}

.bc-nav__list i {
  display: none;
  font-family: var(--bc-mono);
  font-style: normal;
  font-size: .56rem;
  color: var(--bc-teal);
  margin-right: 5px;
  vertical-align: super;
}

.bc-nav__list a::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  height: 3px;
  background: var(--bc-orange);
  transform: scaleX(0);
  transform-origin: left;
  transition: transform var(--bc-mid) var(--bc-ease);
}

.bc-nav__list a:hover { color: var(--bc-teal-2); }
.bc-nav__list a:hover::after { transform: scaleX(1); }

.bc-nav__list a[aria-current="page"]::after { transform: scaleX(1); }
.bc-nav__list a[aria-current="page"] { color: var(--bc-teal-2); }

.bc-nav__cta {
  display: flex;
  align-items: center;
  gap: 8px;
  padding-left: clamp(10px, 1.6vw, 22px);
  border-left: 1px solid var(--bc-line);
}

.bc-progress {
  position: absolute;
  left: 0;
  right: 0;
  bottom: -1px;
  height: 2px;
  background: transparent;
  overflow: hidden;
}

.bc-progress span {
  display: block;
  width: 0;
  height: 100%;
  background: var(--bc-orange);
}

.bc-head.is-stuck { box-shadow: 0 10px 30px rgba(7, 30, 38, .1); }

/* ---------- 页脚 ---------- */

.bc-foot {
  position: relative;
  background: var(--bc-deep);
  color: rgba(242, 245, 243, .72);
  overflow: hidden;
  padding-top: clamp(40px, 6vw, 76px);
}

.bc-foot::before {
  content: "BCFF";
  position: absolute;
  right: -2vw;
  bottom: 34px;
  font-family: var(--bc-mono);
  font-size: clamp(6rem, 17vw, 15rem);
  font-weight: 700;
  letter-spacing: -.02em;
  line-height: .8;
  color: rgba(201, 233, 225, .045);
  pointer-events: none;
}

.bc-foot__top {
  position: relative;
  display: grid;
  grid-template-columns: 1.5fr 1fr 1fr 1fr;
  gap: clamp(24px, 4vw, 60px);
  padding-bottom: clamp(32px, 4vw, 52px);
}

.bc-foot h3 {
  font-family: var(--bc-mono);
  font-size: .68rem;
  font-weight: 700;
  letter-spacing: .2em;
  text-transform: uppercase;
  color: var(--bc-orange);
  margin-bottom: 16px;
}

.bc-foot__brand .bc-logo__txt strong { color: var(--bc-paper); }
.bc-foot__brand .bc-logo__mark { background: rgba(242, 245, 243, .1); }
.bc-foot__brand p {
  margin-top: 16px;
  font-size: .9rem;
  line-height: 1.85;
  color: rgba(242, 245, 243, .62);
  max-width: 34em;
}

.bc-foot__addr {
  font-family: var(--bc-mono);
  font-size: .7rem !important;
  letter-spacing: .04em;
  line-height: 1.9 !important;
  color: rgba(201, 233, 225, .7) !important;
  margin-top: 14px !important;
}

.bc-foot__col li + li { margin-top: 9px; }
.bc-foot__col a {
  font-size: .9rem;
  color: rgba(242, 245, 243, .72);
  transition: color var(--bc-fast) var(--bc-ease);
}
.bc-foot__col a:hover { color: var(--bc-orange); }

.bc-foot__legal {
  position: relative;
  display: grid;
  grid-template-columns: 1.2fr 1fr;
  gap: clamp(20px, 4vw, 56px);
  padding-block: clamp(24px, 3vw, 36px);
  border-top: 1px solid rgba(242, 245, 243, .14);
}

.bc-foot__legal h4 {
  font-size: .86rem;
  color: var(--bc-mint);
  margin-bottom: 8px;
}

.bc-foot__legal p {
  font-size: .78rem;
  line-height: 1.9;
  color: rgba(242, 245, 243, .6);
}

.bc-foot__legal ul {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 6px 20px;
}

.bc-foot__legal li {
  position: relative;
  padding-left: 14px;
  font-family: var(--bc-mono);
  font-size: .64rem;
  letter-spacing: .04em;
  line-height: 1.8;
  color: rgba(201, 233, 225, .74);
}

.bc-foot__legal li::before {
  content: "";
  position: absolute;
  left: 0;
  top: .78em;
  width: 5px;
  height: 5px;
  background: var(--bc-teal);
}

.bc-foot__base {
  position: relative;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
  padding-block: 18px 22px;
  border-top: 1px solid rgba(242, 245, 243, .12);
  font-family: var(--bc-mono);
  font-size: .64rem;
  letter-spacing: .08em;
  color: rgba(242, 245, 243, .45);
}

.bc-totop {
  position: fixed;
  right: 20px;
  bottom: 22px;
  z-index: 150;
  width: 46px;
  height: 46px;
  display: grid;
  place-items: center;
  background: var(--bc-deep);
  color: var(--bc-mint);
  border: 1px solid rgba(201, 233, 225, .35);
  font-family: var(--bc-mono);
  font-size: .58rem;
  letter-spacing: .08em;
  opacity: 0;
  visibility: hidden;
  transform: translateY(10px);
  transition: opacity var(--bc-mid) var(--bc-ease), transform var(--bc-mid) var(--bc-ease), visibility var(--bc-mid);
}

.bc-totop.is-on { opacity: 1; visibility: visible; transform: none; }
.bc-totop:hover { background: var(--bc-orange); color: #fff; }

/* ---------- 入场动效（脚本缺失时内容始终可见） ---------- */

.bc-js [data-bc-reveal] {
  opacity: 0;
  transform: translateY(20px);
  transition: opacity .6s var(--bc-ease), transform .6s var(--bc-ease);
}

.bc-js [data-bc-reveal].is-in {
  opacity: 1;
  transform: none;
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .bc-js [data-bc-reveal] { opacity: 1; transform: none; transition: none; }
  .bc-btn, .bc-totop { transition: none; }
}

/* ---------- 断点 ---------- */

@media (max-width: 1180px) {
  .bc-nav__list i { display: inline; }
  .bc-nav { gap: 10px; }
  .bc-logo__txt em { display: none; }
}

@media (max-width: 1024px) {
  .bc-head__main { min-height: 66px; }
  .bc-burger { display: block; }
  .bc-nav {
    position: fixed;
    inset: 0 0 0 auto;
    z-index: 130;
    flex-direction: column;
    align-items: stretch;
    justify-content: flex-start;
    gap: 0;
    width: min(86vw, 360px);
    padding: 88px 26px 32px;
    background: var(--bc-deep);
    color: var(--bc-paper);
    transform: translateX(100%);
    transition: transform var(--bc-mid) var(--bc-ease);
    overflow-y: auto;
  }
  .bc-nav.is-open { transform: none; box-shadow: -20px 0 60px rgba(7, 30, 38, .35); }
  .bc-nav__list { flex-direction: column; align-items: stretch; gap: 0; }
  .bc-nav__list li { border-bottom: 1px solid rgba(242, 245, 243, .12); }
  .bc-nav__list a { padding-block: 14px; font-size: 1.02rem; }
  .bc-nav__list a::after { display: none; }
  .bc-nav__list a[aria-current="page"] { color: var(--bc-orange); }
  .bc-nav__list i { color: var(--bc-teal); font-size: .62rem; }
  .bc-nav__cta {
    flex-direction: column;
    align-items: stretch;
    gap: 10px;
    margin-top: 24px;
    padding: 0;
    border: 0;
  }
  .bc-nav__cta .bc-btn { justify-content: space-between; min-height: 46px; }
  .bc-nav__cta .bc-btn--fill { --bc-btn-bg: var(--bc-orange); --bc-btn-bd: var(--bc-orange); --bc-btn-fg: #fff; }
  .bc-head.is-nav-open .bc-burger { position: relative; z-index: 140; color: var(--bc-paper); border-color: rgba(242, 245, 243, .4); }
  .bc-head.is-nav-open .bc-logo { position: relative; z-index: 140; }
  .bc-head.is-nav-open .bc-logo__txt strong { color: var(--bc-paper); }
  .bc-head.is-nav-open .bc-logo__txt em { color: rgba(201, 233, 225, .6); }
  .bc-head.is-nav-open .bc-logo__mark { background: rgba(242, 245, 243, .12); }
  .bc-foot__top { grid-template-columns: 1fr 1fr; }
  .bc-foot__brand { grid-column: 1 / -1; }
}

@media (max-width: 860px) {
  .bc-head__strip-in { justify-content: center; }
  .bc-head__tag { display: none; }
  .bc-head__meta { font-size: .6rem; gap: 14px; }
  .bc-head__meta li:first-child { display: none; }
  .bc-head { position: relative; }
  .bc-head__main { min-height: 62px; }
  .bc-sec { padding-block: clamp(44px, 8vw, 64px); }
  .bc-sechead { grid-template-columns: 1fr; align-items: start; gap: 14px; }
  .bc-sechead__note { padding-bottom: 0; }
  .bc-foot__legal { grid-template-columns: 1fr; }
  .bc-foot__legal ul { grid-template-columns: 1fr; }
}

@media (max-width: 620px) {
  body { font-size: 15.5px; }
  .bc-logo__txt strong { font-size: 1rem; }
  .bc-logo__mark { width: 38px; height: 38px; }
  .bc-btn { min-height: 44px; padding: 0 16px; font-size: .7rem; }
  .bc-foot__top { grid-template-columns: 1fr; gap: 26px; }
  .bc-foot__base { flex-direction: column; align-items: flex-start; }
  .bc-totop { width: 42px; height: 42px; right: 12px; bottom: 14px; }
}