/* ============================================================
   Footer v3.1 — 移动端全面优化
   新增：手风琴折叠、更好的间距、触摸友好
   ============================================================ */
.footer {
  background: var(--color-black);
  color: var(--text-inverse-secondary);
}

.footer__main { padding: 88px 0 56px; }

.footer__grid {
  display: grid;
  grid-template-columns: 1.8fr 1fr 1fr 1fr 1.2fr;
  gap: 56px;
}

.footer__logo {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 24px;
  font-size: 1.2rem;
  font-weight: 500;
  color: var(--color-white);
  letter-spacing: 1.5px;
}

.footer__logo-img {
  height: 40px;
  width: auto;
  object-fit: contain;
  opacity: 0.9;
  transition: opacity 0.3s ease;
}

.footer__logo:hover .footer__logo-img {
  opacity: 1;
}

.footer__desc {
  font-size: 0.84rem;
  line-height: 1.95;
  margin-bottom: 28px;
  color: rgba(255, 255, 255, 0.32);
  font-weight: 300;
  max-width: 320px;
}

.footer__contact-info {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.footer__contact-item {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 0.82rem;
  color: rgba(255, 255, 255, 0.32);
  font-weight: 300;
  -webkit-tap-highlight-color: transparent;
}

.footer__contact-item svg { color: rgba(255, 255, 255, 0.18); flex-shrink: 0; }

.footer__col-title {
  font-size: 0.84rem;
  font-weight: 500;
  color: rgba(255, 255, 255, 0.75);
  margin-bottom: 24px;
  letter-spacing: 0.6px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

/* 移动端手风琴箭头 */
.footer__col-arrow {
  display: none;
  font-size: 12px;
  transition: transform 0.3s ease;
  color: rgba(255,255,255,0.3);
}

.footer__links {
  display: flex;
  flex-direction: column;
  gap: 13px;
}

.footer__links a {
  font-size: 0.82rem;
  color: rgba(255, 255, 255, 0.32);
  transition: all 0.35s var(--ease-out-quart);
  font-weight: 300;
  display: inline-block;
  text-decoration: none;
  -webkit-tap-highlight-color: transparent;
}

.footer__links a:hover {
  color: rgba(255, 255, 255, 0.65);
  transform: translateX(4px);
}

.footer__links a:active {
  color: rgba(255, 255, 255, 0.85);
  transform: translateX(8px) scale(1.02);
}

.footer__qrcode-placeholder {
  width: 108px; height: 108px;
  background: rgba(255, 255, 255, 0.025);
  border: 1px solid rgba(255, 255, 255, 0.05);
  border-radius: var(--radius-md);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 4px;
  font-size: 0.7rem;
  color: rgba(255, 255, 255, 0.18);
  transition: all 0.3s ease;
  -webkit-tap-highlight-color: transparent;
  margin: 0 auto;
}

.footer__qrcode-placeholder:hover {
  border-color: rgba(255, 255, 255, 0.12);
  transform: scale(1.05);
}

.footer__wechat-tip {
  font-size: 0.72rem;
  color: rgba(255, 255, 255, 0.22);
  font-weight: 300;
  text-align: center;
  margin-top: 12px;
}

.footer__bottom {
  border-top: 1px solid rgba(255, 255, 255, 0.05);
  padding: 28px 0;
}

.footer__bottom-content {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 14px;
  font-size: 0.78rem;
  color: rgba(255, 255, 255, 0.22);
  font-weight: 300;
}

.footer__beian {
  display: flex;
  align-items: center;
  gap: 12px;
  flex-wrap: wrap;
}

.footer__beian a {
  color: rgba(255, 255, 255, 0.22);
  text-decoration: none;
  transition: color 0.2s;
}

.footer__beian a:hover {
  color: rgba(255, 255, 255, 0.45);
}

.footer__divider { color: rgba(255, 255, 255, 0.06); }

/* ========== 平板端 ========== */
@media (max-width: 968px) {
  .footer__main { padding: 60px 0 40px; }
  .footer__grid {
    grid-template-columns: 1fr 1fr;
    gap: 40px 32px;
  }
  .footer__desc { max-width: 100%; }
}

/* ========== 手机端（核心优化） ========== */
@media (max-width: 640px) {
  .footer__main { padding: 48px 0 32px; }
  .footer__grid {
    grid-template-columns: 1fr;
    gap: 0;
  }

  /* 品牌区域 - 手机端居中 */
  .footer__brand {
    text-align: center;
    padding-bottom: 28px;
    border-bottom: 1px solid rgba(255,255,255,0.04);
    margin-bottom: 8px;
  }

  .footer__logo {
    justify-content: center;
    font-size: 1.15rem;
    margin-bottom: 16px;
  }

  .footer__desc {
    max-width: 100%;
    font-size: 0.8rem;
    line-height: 1.8;
    margin-bottom: 20px;
    padding: 0 8px;
  }

  .footer__contact-info {
    align-items: center;
    gap: 10px;
  }

  .footer__contact-item {
    font-size: 0.8rem;
  }

  /* 手风琴折叠 - 每个列块 */
  .footer__grid > div:not(.footer__brand) {
    border-bottom: 1px solid rgba(255,255,255,0.04);
    padding: 18px 0;
  }

  .footer__grid > div:last-child {
    border-bottom: none;
    padding-top: 28px;
    text-align: center;
  }

  /* 列标题 - 可点击展开 */
  .footer__col-title {
    font-size: 0.82rem;
    margin-bottom: 0;
    padding: 6px 0;
    cursor: pointer;
    -webkit-tap-highlight-color: transparent;
    user-select: none;
    color: rgba(255,255,255,0.65);
  }

  .footer__col-title:active {
    color: rgba(255,255,255,0.85);
  }

  /* 手机端显示箭头 */
  .footer__col-arrow {
    display: inline-block;
  }

  .footer__col-title.open .footer__col-arrow {
    transform: rotate(180deg);
  }

  /* 链接列表 - 默认折叠 */
  .footer__links {
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.35s var(--ease-out-quart), padding 0.35s var(--ease-out-quart), opacity 0.25s ease;
    opacity: 0;
    padding-top: 0;
    gap: 0;
  }

  .footer__links.open {
    max-height: 300px;
    opacity: 1;
    padding-top: 16px;
    gap: 14px;
  }

  .footer__links a {
    font-size: 0.8rem;
    padding: 8px 0;
    display: block;
    width: 100%;
    border-radius: 6px;
    padding-left: 4px;
  }

  .footer__links a:active {
    background: rgba(255,255,255,0.03);
    padding-left: 12px;
  }

  /* 微信公众号区域 */
  .footer__qrcode-placeholder {
    width: 96px; height: 96px;
    margin: 0 auto;
  }

  .footer__wechat-tip {
    font-size: 0.7rem;
    margin-top: 10px;
  }

  /* 底部版权 */
  .footer__bottom {
    padding: 22px 0;
  }

  .footer__bottom-content {
    flex-direction: column;
    text-align: center;
    gap: 10px;
    font-size: 0.72rem;
  }

  .footer__beian {
    justify-content: center;
    font-size: 0.7rem;
    gap: 8px;
  }

  .footer__divider {
    display: none;
  }
}

/* ========== 超小屏 ========== */
@media (max-width: 380px) {
  .footer__main { padding: 40px 0 24px; }
  .footer__logo { font-size: 1.05rem; }
  .footer__desc { font-size: 0.76rem; }
  .footer__col-title { font-size: 0.78rem; }
  .footer__links a { font-size: 0.76rem; }
}