/* 翰德学伴 · 全站主题背景层（t1 仙境星夜 / t2 水墨山水 / t3 浅色暖调）
 * 每个页面放置：<div class="theme-bg"><div class="bg bg-t1">…</div><div class="bg bg-t2">…</div><div class="bg bg-t3">…</div></div>
 * 并按 data-theme 显示对应背景。 */

/* 背景层：负 z-index，位于所有页面内容之下（修复官网非定位区块被背景盖住） */
.theme-bg{position:fixed;inset:0;z-index:-1;pointer-events:none;overflow:hidden}
.theme-bg .bg{position:absolute;inset:0;display:none}
[data-theme="t1"] .theme-bg .bg-t1{display:block}
[data-theme="t2"] .theme-bg .bg-t2{display:block}
[data-theme="t3"] .theme-bg .bg-t3{display:block}

/* ===== t1 星夜（简版，官网/培训页用；后台用自身精致版） ===== */
.bg-t1{background:radial-gradient(1100px 520px at 85% -10%,rgba(201,168,106,.12),transparent 60%),
  radial-gradient(900px 460px at -8% 108%,rgba(111,157,157,.10),transparent 60%),
  linear-gradient(172deg,#121d40 0%,#0a1226 60%,#0d1830 100%)}
.bg-t1 .moon{position:absolute;top:9%;right:14%;width:86px;height:86px;border-radius:50%;
  background:radial-gradient(circle at 36% 34%,#fffbe8,#f2e7c2 55%,#d8c58a 78%,#c3ac6e);
  box-shadow:0 0 46px rgba(242,231,194,.55),0 0 130px rgba(242,231,194,.25);
  animation:moonGlow 6s ease-in-out infinite}
@keyframes moonGlow{0%,100%{box-shadow:0 0 46px rgba(242,231,194,.5),0 0 130px rgba(242,231,194,.22)}50%{box-shadow:0 0 66px rgba(242,231,194,.7),0 0 170px rgba(242,231,194,.34)}}
.bg-t1 .star{position:absolute;width:3px;height:3px;border-radius:50%;background:#fff4dc;animation:twinkle 3.4s ease-in-out infinite}
@keyframes twinkle{0%,100%{opacity:.25}50%{opacity:1}}
.bg-t1 .mount{position:absolute;left:0;right:0;bottom:0;height:26vh;opacity:.85}
.bg-t1 .mist{position:absolute;left:0;right:0;bottom:0;height:24vh;
  background:linear-gradient(to top,rgba(120,170,180,.16),rgba(180,205,215,.06) 55%,transparent);
  animation:mistB 6s ease-in-out infinite}
@keyframes mistB{0%,100%{opacity:.5}50%{opacity:1}}

/* ===== t2 水墨山水（参考 /training/zhaosheng：墨色山影 + 云雾） ===== */
.bg-t2{background:linear-gradient(180deg,#f4efe3 0%,#ece6d4 55%,#e7e1cc 100%)}
.bg-t2 .ink-mount{position:absolute;left:0;right:0;bottom:0;width:100%;height:38vh;opacity:.9}
.bg-t2 .cloud{position:absolute;border-radius:50%;background:rgba(255,255,255,.6);
  filter:blur(2px);animation:cloudDrift 30s ease-in-out infinite}
.bg-t2 .cloud.c2{animation-duration:40s;animation-delay:-10s}
.bg-t2 .cloud.c3{animation-duration:34s;animation-delay:-20s}
@keyframes cloudDrift{0%,100%{transform:translateX(0)}50%{transform:translateX(60px)}}
.bg-t2 .stream{stroke-dasharray:12 22;animation:streamMove 7s linear infinite}
@keyframes streamMove{to{stroke-dashoffset:-150}}

/* ===== t3 浅色暖调（粉色桃花飘落） ===== */
.bg-t3{background:linear-gradient(180deg,#fdf6ec 0%,#f9e7d0 100%)}
.bg-t3::before{content:"";position:absolute;inset:0;
  background:
    radial-gradient(60% 45% at 85% 0%,rgba(248,180,200,.30),transparent 60%),
    radial-gradient(50% 40% at 8% 100%,rgba(192,57,43,.07),transparent 60%)}
/* 桃花瓣：粉色泪滴形，比旧版更大 */
.bg-t3 .petal{position:absolute;width:16px;height:16px;border-radius:50% 0 50% 50%;
  background:linear-gradient(135deg,#fbc4d4,#f28bb4);
  box-shadow:0 0 8px rgba(242,139,180,.4);
  animation:petalFall 11s linear infinite}
.bg-t3 .petal:nth-child(even){background:linear-gradient(135deg,#f7a8c2,#e8739f);animation-duration:13s}
@keyframes petalFall{0%{transform:translateY(-5vh) rotate(0)}100%{transform:translateY(108vh) rotate(360deg)}}