/* ============================================================
 * 渡渡鸟香港有限公司 DDN (HK) Limited - 官网样式
 * 深色质感 / 霓虹青蓝→浅紫渐变 / 磨砂玻璃 / 轻量化动效
 * ============================================================ */

/* ---------- 设计变量 ---------- */
:root {
  --bg: #0A0A12;            /* 全局底色 */
  --bg-card: #12121F;       /* 卡片 / 分区底色 */
  --text: #FFFFFF;          /* 主文字 */
  --text-sub: #B0B0C3;      /* 辅助文字 */
  --cyan: #22d3ee;          /* 霓虹青蓝 */
  --purple: #a78bfa;        /* 浅紫 */
  --pink: #f472b6;          /* 点缀粉 */
  --orange: #fb923c;        /* 点缀橙 */
  --grad: linear-gradient(135deg, #22d3ee 0%, #a78bfa 100%);
  --border: rgba(255, 255, 255, .08);
  --glass: rgba(255, 255, 255, .04);
  --radius: 16px;
  --shadow: 0 8px 32px rgba(0, 0, 0, .45);
  --shadow-hover: 0 16px 48px rgba(0, 0, 0, .55), 0 0 0 1px rgba(34, 211, 238, .25), 0 0 24px rgba(167, 139, 250, .18);
  --nav-h: 68px;
}

/* ---------- 基础复位 ---------- */
* { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  background: var(--bg);
  color: var(--text);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}
/* 按语言切换字体族（Inter 负责英文/数字） */
body.lang-zh-CN { font-family: 'Inter', 'Noto Sans SC', sans-serif; }
body.lang-zh-TW { font-family: 'Inter', 'Noto Sans TC', sans-serif; }
body.lang-en    { font-family: 'Inter', sans-serif; }
body.lang-ja    { font-family: 'Inter', 'Noto Sans JP', sans-serif; }

img { display: block; max-width: 100%; }
a { color: inherit; text-decoration: none; }
ul { list-style: none; }
button { font: inherit; color: inherit; background: none; border: none; cursor: pointer; }
input, select, textarea { font: inherit; color: var(--text); }

.container { width: min(1200px, 92%); margin: 0 auto; }

/* 渐变强调文字 */
.text-gradient {
  background: var(--grad);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
  color: transparent;
}

/* ---------- 通用区块 ---------- */
.section { padding: 110px 0; position: relative; }
.section-alt { background: var(--bg-card); }
.sec-tag {
  font-size: 13px; font-weight: 600; letter-spacing: .3em;
  color: var(--cyan); margin-bottom: 14px;
}
.sec-title { font-size: clamp(26px, 3.4vw, 40px); font-weight: 700; line-height: 1.3; }
.sec-sub { color: var(--text-sub); margin-top: 14px; max-width: 640px; }
.center { text-align: center; }
.sec-sub.center { margin-left: auto; margin-right: auto; }

/* ---------- 按钮 ---------- */
.btn {
  display: inline-flex; align-items: center; justify-content: center;
  padding: 13px 34px; border-radius: 999px;
  font-weight: 600; font-size: 15px; line-height: 1.4;
  transition: transform .18s ease, box-shadow .3s ease, background .3s ease, border-color .3s ease, color .3s ease;
  position: relative; overflow: hidden; white-space: nowrap;
}
.btn:active { transform: scale(.95); }   /* 点击缩放 */
.btn-primary { background: var(--grad); color: #061018; box-shadow: 0 4px 20px rgba(34, 211, 238, .3); }
.btn-primary:hover { box-shadow: 0 8px 32px rgba(167, 139, 250, .45); transform: translateY(-2px); }
.btn-ghost {
  border: 1px solid rgba(255, 255, 255, .25); color: var(--text);
  background: rgba(255, 255, 255, .04);
  backdrop-filter: blur(8px); -webkit-backdrop-filter: blur(8px);
}
.btn-ghost:hover { border-color: var(--cyan); color: var(--cyan); transform: translateY(-2px); }

/* 重点按钮流光动画 */
.btn-flow::after {
  content: ''; position: absolute; top: 0; left: -80%;
  width: 45%; height: 100%;
  background: linear-gradient(105deg, transparent, rgba(255, 255, 255, .55), transparent);
  transform: skewX(-20deg);
  animation: flow 2.8s ease-in-out infinite;
}
@keyframes flow { 0% { left: -80%; } 55%, 100% { left: 130%; } }

/* ---------- 滚动渐入 ---------- */
.reveal {
  opacity: 0; transform: translateY(36px);
  transition: opacity .7s ease var(--d, 0s), transform .7s cubic-bezier(.2, .7, .3, 1) var(--d, 0s);
  will-change: opacity, transform;
}
.reveal.visible { opacity: 1; transform: none; }

/* ============================================================
 * 1. 顶部导航
 * ============================================================ */
.nav {
  position: fixed; top: 0; left: 0; right: 0; z-index: 100;
  height: var(--nav-h);
  transition: background .35s ease, box-shadow .35s ease, border-color .35s ease;
  border-bottom: 1px solid transparent;
}
/* 滚动吸顶后：半透明磨砂 */
.nav.scrolled {
  background: rgba(10, 10, 18, .72);
  backdrop-filter: blur(14px); -webkit-backdrop-filter: blur(14px);
  border-bottom-color: var(--border);
  box-shadow: 0 6px 24px rgba(0, 0, 0, .35);
}
.nav-inner { display: flex; align-items: center; justify-content: space-between; height: var(--nav-h); gap: 20px; }

.nav-logo { display: inline-flex; align-items: center; gap: 10px; flex-shrink: 0; }
.logo-badge {
  width: 38px; height: 38px; border-radius: 50%;
  background: var(--grad);
  display: inline-flex; align-items: center; justify-content: center;
  box-shadow: 0 0 16px rgba(34, 211, 238, .4);
}
.logo-text { font-weight: 700; font-size: 17px; letter-spacing: .02em; }

.nav-menu { display: flex; gap: 6px; }
.nav-link {
  padding: 8px 16px; border-radius: 999px;
  color: var(--text-sub); font-size: 15px;
  transition: color .25s, background .25s;
}
.nav-link:hover, .nav-link.active { color: var(--text); background: rgba(255, 255, 255, .07); }

.nav-right { display: flex; align-items: center; gap: 12px; }

/* 语言下拉 */
.lang-dropdown { position: relative; }
.lang-btn {
  display: inline-flex; align-items: center; gap: 7px;
  padding: 8px 14px; border-radius: 999px;
  border: 1px solid var(--border);
  background: var(--glass); color: var(--text-sub);
  font-size: 13.5px; transition: border-color .25s, color .25s;
}
.lang-btn:hover { border-color: var(--cyan); color: var(--text); }
.lang-caret { transition: transform .25s; }
.lang-dropdown.open .lang-caret { transform: rotate(180deg); }
.lang-list {
  position: absolute; top: calc(100% + 8px); right: 0; min-width: 148px;
  background: rgba(18, 18, 31, .92);
  backdrop-filter: blur(16px); -webkit-backdrop-filter: blur(16px);
  border: 1px solid var(--border); border-radius: 12px;
  padding: 6px; box-shadow: var(--shadow);
  opacity: 0; visibility: hidden; transform: translateY(-6px);
  transition: opacity .22s, transform .22s, visibility .22s;
}
.lang-dropdown.open .lang-list { opacity: 1; visibility: visible; transform: none; }
.lang-list li {
  padding: 9px 14px; border-radius: 8px; font-size: 14px;
  color: var(--text-sub); cursor: pointer; transition: background .2s, color .2s;
}
.lang-list li:hover { background: rgba(255, 255, 255, .07); color: var(--text); }
.lang-list li.active { color: var(--cyan); background: rgba(34, 211, 238, .1); }

/* 移动端汉堡按钮（默认隐藏） */
.nav-toggle { display: none; flex-direction: column; gap: 5px; padding: 8px; }
.nav-toggle span { width: 22px; height: 2px; background: var(--text); border-radius: 2px; transition: transform .3s, opacity .3s; }
.nav-toggle.open span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.nav-toggle.open span:nth-child(2) { opacity: 0; }
.nav-toggle.open span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

/* ============================================================
 * 2. 首屏 Banner
 * ============================================================ */
.hero {
  min-height: 100vh;
  display: flex; align-items: center;
  position: relative; overflow: hidden;
  background: var(--bg) url('../assets/hero-bg.jpg') center / cover no-repeat;
  padding: calc(var(--nav-h) + 40px) 0 80px;
}
.hero-particles { position: absolute; inset: 0; width: 100%; height: 100%; }
.hero-overlay {
  position: absolute; inset: 0;
  background: radial-gradient(ellipse 70% 60% at 30% 45%, transparent 30%, rgba(10, 10, 18, .82) 100%),
              linear-gradient(180deg, rgba(10, 10, 18, .35) 0%, rgba(10, 10, 18, .15) 50%, var(--bg) 100%);
}
.hero-content { position: relative; z-index: 2; }
.hero-tag {
  display: inline-block;
  padding: 7px 18px; border-radius: 999px;
  border: 1px solid rgba(34, 211, 238, .35);
  background: rgba(34, 211, 238, .08);
  color: var(--cyan); font-size: 13.5px; letter-spacing: .12em;
  margin-bottom: 26px;
}
.hero-title { font-size: clamp(38px, 6.5vw, 72px); font-weight: 800; line-height: 1.18; letter-spacing: .01em; }
.hero-sub { color: var(--text-sub); font-size: clamp(15px, 1.6vw, 18px); max-width: 560px; margin-top: 22px; }
.hero-btns { display: flex; gap: 16px; margin-top: 40px; flex-wrap: wrap; }

.hero-stats { display: flex; gap: clamp(28px, 5vw, 72px); margin-top: 64px; flex-wrap: wrap; }
.hero-stat { display: flex; flex-direction: column; gap: 4px; }
.stat-v {
  font-size: clamp(26px, 3vw, 38px); font-weight: 800;
  background: var(--grad); -webkit-background-clip: text; background-clip: text;
  -webkit-text-fill-color: transparent; color: transparent;
}
.stat-l { color: var(--text-sub); font-size: 13.5px; }

/* ============================================================
 * 3. 公司简介
 * ============================================================ */
.about-grid { display: grid; grid-template-columns: 1.15fr .85fr; gap: clamp(36px, 5vw, 72px); align-items: center; }
.about-p { color: var(--text-sub); margin-top: 20px; font-size: 15.5px; }

.adv-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; margin-top: 36px; }
.adv-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px 22px;
  transition: transform .3s ease, border-color .3s ease, box-shadow .3s ease;
}
.adv-card:hover { transform: translateY(-4px); border-color: rgba(34, 211, 238, .4); box-shadow: 0 10px 30px rgba(0, 0, 0, .4), 0 0 18px rgba(34, 211, 238, .12); }
.adv-card h3 { font-size: 16px; margin-bottom: 6px; }
.adv-card p { color: var(--text-sub); font-size: 13.5px; }

/* 配图：渐变边框 + 发光阴影 */
.img-frame {
  position: relative; border-radius: 20px; padding: 3px;
  background: var(--grad);
  box-shadow: 0 0 40px rgba(34, 211, 238, .18), 0 24px 60px rgba(0, 0, 0, .5);
}
.img-frame img { border-radius: 17px; width: 100%; height: auto; }

/* ============================================================
 * 4. 四大核心业务
 * ============================================================ */
.biz-grid {
  display: grid; grid-template-columns: repeat(4, 1fr);
  gap: 22px; margin-top: 56px;
}
.biz-card {
  --accent: var(--cyan);
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 30px 26px;
  display: flex; flex-direction: column;   /* 内容自适应高度，不截断长文 */
  transition: transform .35s ease, border-color .35s ease, box-shadow .35s ease;
  position: relative;
}
.biz-card:hover {
  transform: translateY(-8px) scale(1.02);
  border-color: color-mix(in srgb, var(--accent) 55%, transparent);
  box-shadow: 0 18px 48px rgba(0, 0, 0, .5), 0 0 24px color-mix(in srgb, var(--accent) 22%, transparent);
}
.accent-cyan   { --accent: var(--cyan); }
.accent-purple { --accent: var(--purple); }
.accent-pink   { --accent: var(--pink); }
.accent-orange { --accent: var(--orange); }

.biz-icon {
  width: 52px; height: 52px; border-radius: 14px;
  display: inline-flex; align-items: center; justify-content: center;
  color: var(--accent);
  background: color-mix(in srgb, var(--accent) 12%, transparent);
  border: 1px solid color-mix(in srgb, var(--accent) 30%, transparent);
  margin-bottom: 20px;
}
.biz-card h3 { font-size: 18px; margin-bottom: 10px; }
.biz-desc { color: var(--text-sub); font-size: 13.5px; margin-bottom: 16px; }
.biz-points { display: flex; flex-direction: column; gap: 9px; margin-top: auto; }
.biz-points li {
  position: relative; padding-left: 16px;
  color: var(--text-sub); font-size: 13.5px;
}
.biz-points li::before {
  content: ''; position: absolute; left: 0; top: .62em;
  width: 6px; height: 6px; border-radius: 50%;
  background: var(--accent);
  box-shadow: 0 0 8px var(--accent);
}

/* ============================================================
 * 5. 作品案例
 * ============================================================ */
.case-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 24px; margin-top: 56px;
}
.case-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden; cursor: pointer;
  display: flex; flex-direction: column;
  transition: transform .35s ease, border-color .35s ease, box-shadow .35s ease;
}
.case-card:hover, .case-card:focus-visible {
  transform: translateY(-8px) scale(1.02);
  border-color: rgba(34, 211, 238, .45);
  box-shadow: var(--shadow-hover);
  outline: none;
}
.case-cover { overflow: hidden; aspect-ratio: 1024 / 1460; }
.case-cover img { width: 100%; height: 100%; object-fit: cover; transition: transform .6s ease; }
.case-card:hover .case-cover img { transform: scale(1.06); }
.case-info { padding: 20px 22px 24px; display: flex; flex-direction: column; gap: 6px; flex: 1; }
.case-tag {
  align-self: flex-start;
  font-size: 12px; padding: 3px 12px; border-radius: 999px;
  color: var(--purple);
  background: rgba(167, 139, 250, .12);
  border: 1px solid rgba(167, 139, 250, .35);
}
.case-info h3 { font-size: 19px; margin-top: 4px; }
.case-genre { color: var(--text-sub); font-size: 13.5px; }
.case-stat { margin-top: auto; padding-top: 10px; display: flex; align-items: baseline; gap: 8px; }
.case-stat span {
  font-size: 20px; font-weight: 800;
  background: var(--grad); -webkit-background-clip: text; background-clip: text;
  -webkit-text-fill-color: transparent; color: transparent;
}
.case-stat em { font-style: normal; color: var(--text-sub); font-size: 12.5px; }

/* ---------- 弹窗通用 ---------- */
.modal {
  position: fixed; inset: 0; z-index: 200;
  display: flex; align-items: center; justify-content: center;
  padding: 24px;
  opacity: 0; visibility: hidden;
  transition: opacity .3s ease, visibility .3s ease;
}
.modal.open { opacity: 1; visibility: visible; }
.modal-mask {
  position: absolute; inset: 0;
  background: rgba(5, 5, 10, .72);
  backdrop-filter: blur(8px); -webkit-backdrop-filter: blur(8px);
}
.modal-box {
  position: relative; z-index: 1;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 20px;
  box-shadow: 0 32px 80px rgba(0, 0, 0, .6), 0 0 32px rgba(167, 139, 250, .12);
  transform: translateY(24px) scale(.97);
  transition: transform .35s cubic-bezier(.2, .7, .3, 1.2);
  max-height: calc(100vh - 48px);
  overflow: auto;
}
.modal.open .modal-box { transform: none; }
.modal-close {
  position: absolute; top: 14px; right: 14px; z-index: 2;
  width: 38px; height: 38px; border-radius: 50%;
  background: rgba(255, 255, 255, .08);
  border: 1px solid var(--border);
  color: var(--text-sub); font-size: 22px; line-height: 1;
  display: flex; align-items: center; justify-content: center;
  transition: color .25s, border-color .25s, transform .25s;
}
.modal-close:hover { color: var(--text); border-color: var(--cyan); transform: rotate(90deg); }

/* 案例详情弹窗 */
.case-modal-box {
  width: min(860px, 100%);
  display: grid; grid-template-columns: 320px 1fr;
}
.case-modal-cover { min-height: 100%; }
.case-modal-cover img { width: 100%; height: 100%; object-fit: cover; }
.case-modal-body { padding: 34px 32px; }
.case-modal-body h3 { font-size: 26px; margin: 10px 0 18px; }
.cm-rows { display: flex; flex-direction: column; gap: 10px; margin-bottom: 18px; }
.cm-row { display: flex; gap: 14px; font-size: 14px; align-items: baseline; }
.cm-row em { font-style: normal; color: var(--text-sub); flex-shrink: 0; min-width: 74px; font-size: 13px; }
.cm-stat b {
  font-size: 20px; font-weight: 800; margin-right: 8px;
  background: var(--grad); -webkit-background-clip: text; background-clip: text;
  -webkit-text-fill-color: transparent; color: transparent;
}
.cm-stat i { font-style: normal; color: var(--text-sub); font-size: 12.5px; }
.cm-intro { color: var(--text-sub); font-size: 14.5px; border-top: 1px solid var(--border); padding-top: 18px; }

/* 提交成功弹窗 */
.success-box { width: min(420px, 100%); padding: 44px 36px; text-align: center; }
.success-icon {
  width: 64px; height: 64px; border-radius: 50%;
  margin: 0 auto 20px;
  background: var(--grad); color: #061018;
  display: flex; align-items: center; justify-content: center;
  box-shadow: 0 0 28px rgba(34, 211, 238, .4);
}
.success-box h3 { font-size: 22px; margin-bottom: 10px; }
.success-box p { color: var(--text-sub); font-size: 14.5px; margin-bottom: 26px; }

/* ============================================================
 * 6. 商务合作
 * ============================================================ */
.contact-grid {
  display: grid; grid-template-columns: 1fr 1.1fr;
  gap: clamp(28px, 4vw, 48px); margin-top: 56px; align-items: start;
}
.contact-h { font-size: 17px; margin-bottom: 16px; }
.contact-h:not(:first-child) { margin-top: 32px; }

.scope-list { display: flex; flex-direction: column; gap: 10px; }
.scope-list li {
  position: relative; padding: 12px 16px 12px 40px;
  background: var(--bg); border: 1px solid var(--border);
  border-radius: 12px; font-size: 14.5px;
  transition: border-color .3s, transform .3s;
}
.scope-list li:hover { border-color: rgba(34, 211, 238, .35); transform: translateX(4px); }
.scope-list li::before {
  content: ''; position: absolute; left: 16px; top: 50%;
  width: 8px; height: 8px; border-radius: 50%;
  background: var(--grad); transform: translateY(-50%);
  box-shadow: 0 0 10px rgba(34, 211, 238, .6);
}

.info-list { display: flex; flex-direction: column; gap: 14px; }
.info-item { display: flex; flex-direction: column; gap: 2px; }
.info-label { color: var(--text-sub); font-size: 12.5px; letter-spacing: .06em; }
.info-value { font-size: 15px; font-weight: 500; }

/* CSS 绘制的二维码占位框 */
.qr-box {
  margin-top: 32px; display: flex; align-items: center; gap: 16px;
  color: var(--text-sub); font-size: 13.5px;
}
.qr-fake {
  width: 96px; height: 96px; flex-shrink: 0;
  border-radius: 12px; padding: 10px;
  background:
    conic-gradient(from 90deg at 12px 12px, var(--cyan) 25%, transparent 0) 0 0 / 24px 24px,
    repeating-linear-gradient(45deg, rgba(167, 139, 250, .55) 0 6px, transparent 6px 12px),
    var(--bg);
  border: 1px solid rgba(34, 211, 238, .35);
  display: grid; place-items: center;
  position: relative; opacity: .9;
}
.qr-fake i {
  position: absolute; width: 20px; height: 20px;
  border: 3px solid var(--cyan); border-radius: 4px; background: var(--bg);
}
.qr-fake i:nth-child(1) { top: 8px; left: 8px; }
.qr-fake i:nth-child(2) { top: 8px; right: 8px; border-color: var(--purple); }
.qr-fake i:nth-child(3) { bottom: 8px; left: 8px; border-color: var(--purple); }
.qr-fake i:nth-child(4) {
  bottom: 12px; right: 12px; width: 14px; height: 14px;
  border: none; background: var(--cyan); border-radius: 3px;
  box-shadow: 0 0 10px rgba(34, 211, 238, .7);
}

/* 表单：磨砂玻璃卡片 */
.contact-form {
  background: var(--glass);
  backdrop-filter: blur(16px); -webkit-backdrop-filter: blur(16px);
  border: 1px solid var(--border);
  border-radius: 20px;
  padding: 34px 32px;
  box-shadow: var(--shadow);
}
.contact-form .contact-h { margin-bottom: 22px; font-size: 19px; }
.form-row { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; }
.form-field { margin-bottom: 16px; display: flex; flex-direction: column; }
.form-field label { font-size: 13.5px; color: var(--text-sub); margin-bottom: 7px; }
.form-field input, .form-field select, .form-field textarea {
  background: rgba(10, 10, 18, .6);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 12px 14px; font-size: 14.5px;
  transition: border-color .25s, box-shadow .25s;
  width: 100%;
}
.form-field textarea { resize: vertical; min-height: 100px; }
.form-field select {
  appearance: none; -webkit-appearance: none;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 24 24' fill='none' stroke='%23B0B0C3' stroke-width='2.5'%3E%3Cpath d='M6 9l6 6 6-6'/%3E%3C/svg%3E");
  background-repeat: no-repeat; background-position: right 14px center;
  cursor: pointer;
}
.form-field select option { background: var(--bg-card); color: var(--text); }
.form-field input:focus, .form-field select:focus, .form-field textarea:focus {
  outline: none; border-color: var(--cyan);
  box-shadow: 0 0 0 3px rgba(34, 211, 238, .15);
}
.form-field input::placeholder, .form-field textarea::placeholder { color: rgba(176, 176, 195, .45); }
.form-field.invalid input, .form-field.invalid select, .form-field.invalid textarea { border-color: #f87171; }
.form-err { color: #f87171; font-size: 12.5px; margin-top: 6px; min-height: 0; display: none; }
.form-field.invalid .form-err { display: block; }
.form-submit { width: 100%; margin-top: 6px; }

/* ============================================================
 * 7. Footer
 * ============================================================ */
.footer { border-top: 1px solid var(--border); padding: 64px 0 32px; background: #08080f; }
.footer-grid { display: grid; grid-template-columns: 1.4fr 1fr 1.2fr 1.2fr; gap: 40px; }
.footer-brand p { color: var(--text-sub); font-size: 14px; margin-top: 16px; max-width: 300px; }
.footer-col h4 { font-size: 15px; margin-bottom: 16px; }
.footer-col a { display: block; color: var(--text-sub); font-size: 14px; padding: 4px 0; transition: color .25s; }
.footer-col a:hover { color: var(--cyan); }
.footer-col p { color: var(--text-sub); font-size: 14px; }
.footer-bottom { margin-top: 48px; padding-top: 24px; border-top: 1px solid var(--border); }
.footer-privacy { color: rgba(176, 176, 195, .6); font-size: 12.5px; margin-bottom: 8px; }
.footer-rights { color: var(--text-sub); font-size: 13px; }

/* ============================================================
 * 响应式
 * ============================================================ */
@media (max-width: 1024px) {
  .biz-grid { grid-template-columns: repeat(2, 1fr); }        /* 平板两列 */
  .footer-grid { grid-template-columns: 1fr 1fr; }
  .about-grid { grid-template-columns: 1fr; }
  .about-img { max-width: 560px; }
  .case-modal-box { grid-template-columns: 1fr; width: min(480px, 100%); }
  .case-modal-cover img { max-height: 300px; }
}

@media (max-width: 768px) {
  .section { padding: 76px 0; }

  /* 移动端导航：菜单折叠为抽屉 */
  .nav-menu {
    position: fixed; top: var(--nav-h); left: 0; right: 0;
    flex-direction: column; gap: 4px;
    background: rgba(10, 10, 18, .96);
    backdrop-filter: blur(18px); -webkit-backdrop-filter: blur(18px);
    border-bottom: 1px solid var(--border);
    padding: 16px 4%;
    transform: translateY(-12px); opacity: 0; visibility: hidden;
    transition: opacity .3s, transform .3s, visibility .3s;
  }
  .nav-menu.open { transform: none; opacity: 1; visibility: visible; }
  .nav-link { padding: 12px 16px; font-size: 16px; }
  .nav-toggle { display: flex; }

  .contact-grid { grid-template-columns: 1fr; }                /* 手机单列 */
  .form-row { grid-template-columns: 1fr; }
  .hero-stats { gap: 24px; }
  .lang-btn { padding: 7px 10px; }
  .lang-btn svg:first-child { display: none; }
}

@media (max-width: 560px) {
  .biz-grid { grid-template-columns: 1fr; }                    /* 手机单列 */
  .adv-grid { grid-template-columns: 1fr; }
  .case-grid { grid-template-columns: 1fr; }
  .footer-grid { grid-template-columns: 1fr; }
  .hero-btns .btn { flex: 1; }
  .contact-form { padding: 26px 20px; }
}

/* 锚点滚动预留吸顶导航高度 */
section[id] { scroll-margin-top: var(--nav-h); }

/* 减少动态偏好兼容 */
@media (prefers-reduced-motion: reduce) {
  .reveal { transition: none; opacity: 1; transform: none; }
  .btn-flow::after { animation: none; }
  html { scroll-behavior: auto; }
}