/* ============================================================
   motion.css — 全站微交互层
   ------------------------------------------------------------
   设计原则（据 2025–2026 公开实践）：
   · 按下 100–150ms、悬停 150–300ms、进场 300–500ms
   · 只动 transform / opacity（走合成层，不触发重排）
   · 弹性用 cubic-bezier(.34,1.56,.64,1)，收束用 (.16,1,.3,1)
   · 全量尊重 prefers-reduced-motion
   ============================================================ */

:root{
  --m-spring: cubic-bezier(.34,1.56,.64,1);
  --m-snappy: cubic-bezier(.16,1,.3,1);
  --m-fast: 140ms;
  --m-base: 220ms;
  --m-slow: 420ms;
}

/* ---------- 1. 按钮按下反馈 ---------- */
button,
.tool-pill,
.view-tab,
.lab-btn,
.btn,
.seg button,
.cities button,
.wide,
.fab,
.zb-btn,
.eg-ctrl button,
.eg-chips button{
  transition:
    transform var(--m-fast) ease-out,
    background-color var(--m-base) ease-out,
    color var(--m-base) ease-out,
    border-color var(--m-base) ease-out,
    box-shadow var(--m-base) ease-out;
  -webkit-tap-highlight-color: transparent;
}

button:active,
.tool-pill:active,
.view-tab:active,
.lab-btn:active,
.btn:active,
.seg button:active,
.cities button:active,
.wide:active,
.fab:active,
.zb-btn:active,
.eg-ctrl button:active,
.eg-chips button:active{
  transform: scale(.96);
}

/* 悬停抬起：只给"卡片式"大按钮，胶囊/页签不动，避免整排跳动 */
.lab-btn:hover,
.btn:hover{
  transform: translateY(-1px);
}
.lab-btn:active,
.btn:active{
  transform: translateY(0) scale(.98);
}

/* ---------- 2. 图标随悬停轻移 ---------- */
.ico,
.lab-btn svg,
.btn svg{
  transition: transform var(--m-base) var(--m-snappy);
}
.tool-pill:hover .ico,
.lab-btn:hover svg,
.btn:hover svg{
  transform: translateX(2px);
}
.zb-btn:hover .ico{ transform: rotate(90deg); }

/* ---------- 3. 键盘焦点环 ---------- */
:focus-visible{
  outline: 1.5px solid var(--gold, #c9a462);
  outline-offset: 2px;
  border-radius: inherit;
}

/* ---------- 4. 页面进场 / 离场 ---------- */
html{ scroll-behavior: smooth }

/* 进场用 CSS 动画（不依赖 JS，脚本挂了也不会白屏） */
@keyframes m-page-in{
  from{ opacity: 0 }
  to  { opacity: 1 }
}
body{ animation: m-page-in var(--m-slow) var(--m-snappy) }

html.m-leaving body{
  opacity: 0;
  animation: none;
  transition: opacity 160ms ease-in;
}

/* ---------- 5. 滚动进场（非画布页由 JS 打标） ---------- */
.m-reveal{
  opacity: 0;
  transform: translateY(14px);
  transition:
    opacity var(--m-slow) var(--m-snappy),
    transform var(--m-slow) var(--m-snappy);
  transition-delay: calc(var(--m-i, 0) * 55ms);
  will-change: transform, opacity;
}
.m-reveal.m-in{
  opacity: 1;
  transform: none;
  will-change: auto;
}

/* ---------- 6. 链接下划线扫过（正文内） ---------- */
.m-link{
  position: relative;
  text-decoration: none;
}
.m-link::after{
  content: "";
  position: absolute; left: 0; right: 0; bottom: -2px;
  height: 1px; background: currentColor;
  transform: scaleX(0); transform-origin: right;
  transition: transform var(--m-base) var(--m-snappy);
}
.m-link:hover::after{ transform: scaleX(1); transform-origin: left }

/* ---------- 7. 减少动态 ---------- */
@media (prefers-reduced-motion: reduce){
  html{ scroll-behavior: auto }
  body{ animation: none; opacity: 1 !important }
  .m-reveal{ opacity: 1; transform: none; transition: none }
  button, .tool-pill, .view-tab, .lab-btn, .btn, .seg button, .cities button,
  .wide, .fab, .zb-btn, .eg-ctrl button, .eg-chips button{
    transition: none;
  }
  button:active, .tool-pill:active, .view-tab:active, .lab-btn:active,
  .btn:active, .seg button:active, .cities button:active, .wide:active,
  .fab:active, .zb-btn:active, .eg-ctrl button:active, .eg-chips button:active{
    transform: none;
  }
  .tool-pill:hover .ico, .lab-btn:hover svg, .btn:hover svg{ transform: none }
  .m-link::after{ display: none }
}

/* ---------- 8. 跨页面转场（View Transitions，支持的浏览器自动启用） ---------- */
@view-transition{ navigation: auto }

::view-transition-old(root){
  animation: m-vt-out 160ms ease-in both;
}
::view-transition-new(root){
  animation: m-vt-in 280ms var(--m-snappy) both;
}
@keyframes m-vt-out{ to{ opacity: 0 } }
@keyframes m-vt-in{ from{ opacity: 0; transform: translateY(6px) } }

@media (prefers-reduced-motion: reduce){
  ::view-transition-old(root), ::view-transition-new(root){ animation: none }
}