/* 四要素板块（R14）：四层一次性展开 —— 不依赖滚动、不监听 scroll、不做 sticky 固定 */
.nv-section.nv-four{background:#EFF5F5;padding:72px 0}
.nv-four .nv-wrap{max-width:760px;margin:0 auto}
.nv-four .nv-sec-title{margin-bottom:10px}
.nv-four-guide{text-align:center;font-size:.88rem;color:var(--nv-ink-soft,#6B6B6B);margin:0 auto 24px;max-width:540px;line-height:1.7}
.nv-four .nv-bubble-demo{max-width:640px}

/* 旧版是「绝对定位 + 只显示一条」，这里改成四条全部可见的列表 */
.nv-four .nv-four-list{position:static;min-height:0;margin:0 0 18px;padding:0;list-style:none;display:grid;gap:10px;text-align:left;counter-reset:nvs}
.nv-four .nv-bt-item{position:static;left:auto;right:auto;opacity:1;transform:none;pointer-events:auto;
  display:flex;gap:12px;align-items:flex-start;background:#fff;border-radius:14px;padding:14px 16px;
  box-shadow:0 2px 10px rgba(0,0,0,.045);counter-increment:nvs}
.nv-four .nv-bt-label{margin-top:2px;flex:none;background:var(--nv-apricot-deep,#E5A94F);color:#fff;font-size:.74rem;
  font-weight:700;border-radius:99px;padding:3px 10px;white-space:nowrap;letter-spacing:.02em}
.nv-four .nv-bt-label::before{content:counter(nvs) " · ";font-weight:700;opacity:.85}
.nv-four .nv-bt-item p{margin:0;font-size:1rem;line-height:1.65;color:var(--nv-ink,#3D3D3D);font-family:var(--nv-serif,inherit)}
.nv-four .nv-bt-item[data-step="1"] .nv-bt-label{background:#5B9EA6}
.nv-four .nv-bt-item[data-step="2"] .nv-bt-label{background:#EF8B7D}
.nv-four .nv-bt-item[data-step="3"] .nv-bt-label{background:#E0A34A}
.nv-four .nv-bt-item[data-step="4"] .nv-bt-label{background:#7FA99B}
.nv-four .nv-bubble-original{margin-bottom:0}
.nv-four .nv-bubble-arrow{margin:10px 0;animation:none}
.nv-four .nv-bubble-note{margin:14px 0 0}

/* 入场：只播一次；没有 JS 时四条直接可见（JS 才加 .nv-anim） */
.nv-four-demo.nv-anim .nv-bubble-original,
.nv-four-demo.nv-anim .nv-bubble-arrow,
.nv-four-demo.nv-anim .nv-bt-item,
.nv-four-demo.nv-anim .nv-bubble-note{opacity:0;transform:translateY(10px);
  transition:opacity .45s ease,transform .45s ease}
.nv-four-demo.nv-anim.nv-in .nv-bubble-original,
.nv-four-demo.nv-anim.nv-in .nv-bubble-arrow,
.nv-four-demo.nv-anim.nv-in .nv-bt-item,
.nv-four-demo.nv-anim.nv-in .nv-bubble-note{opacity:1;transform:none}
.nv-four-demo.nv-anim.nv-in .nv-bt-item:nth-child(1){transition-delay:.05s}
.nv-four-demo.nv-anim.nv-in .nv-bt-item:nth-child(2){transition-delay:.13s}
.nv-four-demo.nv-anim.nv-in .nv-bt-item:nth-child(3){transition-delay:.21s}
.nv-four-demo.nv-anim.nv-in .nv-bt-item:nth-child(4){transition-delay:.29s}
.nv-four-demo.nv-anim.nv-in .nv-bubble-note{transition-delay:.37s}

@media (prefers-reduced-motion:reduce){
  .nv-four-demo.nv-anim .nv-bubble-original,
  .nv-four-demo.nv-anim .nv-bubble-arrow,
  .nv-four-demo.nv-anim .nv-bt-item,
  .nv-four-demo.nv-anim .nv-bubble-note{transition:none!important;opacity:1;transform:none}
}
@media (max-width:640px){
  .nv-section.nv-four{padding:56px 0}
  .nv-four .nv-bt-item{flex-direction:column;gap:6px;padding:13px 14px}
  .nv-four .nv-bt-item p{font-size:.96rem}
  .nv-four .nv-bt-label{margin-top:0}
}