/* 页面配色与基础布局。 */
:root{
  --accent:#4c7dff; --accent2:#8fb5ff;
  --ink:#273854; --ink2:#576e91; --dim:#7b8eaa;
  --glass:#fff;
  --glass-border:#e1e9f5;
  --line:rgba(226,230,240,.85);
  --safe-t:env(safe-area-inset-top,0px);
  --safe-b:env(safe-area-inset-bottom,0px);
}

*{box-sizing:border-box;-webkit-tap-highlight-color:transparent}
html,body{height:100%}
body{
  margin:0;
  font:16px/1.7 var(--product-font);
  color:var(--ink);
  background:#f5f7ff;
  overflow:hidden;
}

.page{
  height:100dvh;
  display:flex;flex-direction:column;
  max-width:760px;margin:0 auto;
}

/* ── 顶栏 ── */
.topbar{
  flex:0 0 auto;display:flex;align-items:center;gap:10px;
  padding:calc(10px + var(--safe-t)) 16px 10px;
}
.brand{display:flex;align-items:center;gap:9px;min-width:0}
.brand-logo{width:28px;height:28px;border-radius:9px;object-fit:cover;
  box-shadow:0 4px 12px rgba(76,125,255,.24)}
.brand-text{font-weight:700;font-size:15.5px;letter-spacing:.4px;white-space:nowrap;
  overflow:hidden;text-overflow:ellipsis}
.ghost-btn{
  margin-left:auto;flex:0 0 auto;
  background:var(--glass);border:1px solid var(--glass-border);color:var(--accent);
  border-radius:12px;padding:6px 14px;cursor:pointer;
  font-size:13px;font-weight:600;line-height:normal;font-family:inherit;
  box-shadow:none;transition:.15s;
}
.ghost-btn:active{transform:scale(.95)}
.ghost-btn[disabled]{opacity:.45;pointer-events:none}

/* ── 滚动区 ── */
.scroll{
  flex:1 1 auto;min-height:0;
  overflow-y:auto;-webkit-overflow-scrolling:touch;
  padding:4px 16px 8px;
}

/* ── 开场区 ── */
.hero{
  background:var(--glass);
  border:1px solid var(--glass-border);

  border-radius:12px;
  padding:18px 18px 16px;
  box-shadow:none;
  margin-bottom:14px;
}
.hero-row{display:flex;gap:13px;align-items:flex-start}
.hero-avatar{
  width:56px;height:56px;border-radius:12px;object-fit:cover;flex:0 0 auto;
  box-shadow:none;
}
.hero-txt{min-width:0}
.hero-txt h1{font-size:19px;margin:2px 0 5px;font-weight:700;letter-spacing:.3px}
.hero-txt p{margin:0;color:var(--ink2);font-size:14px;line-height:1.65}
.chips{display:flex;flex-wrap:wrap;gap:9px;margin-top:15px}
.chip{
  background:rgba(255,255,255,.86);
  border:1px solid rgba(226,230,240,.95);
  color:var(--ink2);
  border-radius:12px;padding:8px 15px;cursor:pointer;
  font-size:13.5px;font-weight:500;line-height:1.3;font-family:inherit;
  transition:.15s;text-align:left;
}
.chip:hover{border-color:var(--accent2);color:var(--accent)}
.chip:active{transform:scale(.97)}
.chips:empty{display:none}

/* ── 消息 ── */
.msgs{display:flex;flex-direction:column;gap:12px}
.msg{display:flex;gap:9px;align-items:flex-start;max-width:100%}
.msg .bubble{
  padding:11px 15px;border-radius:12px;font-size:15.2px;line-height:1.72;
  word-break:break-word;white-space:pre-wrap;max-width:100%;
}
/* 助手：左对齐、玻璃白、虚线描边（和截图一致，显得"是它自己的话"） */
.msg.bot .bubble{
  background:rgba(255,255,255,.78);
  border:1px solid var(--line);
  border-top-left-radius:6px;
  box-shadow:none;
}
/* 用户：右对齐、蓝渐变实心 */
.msg.me{flex-direction:row-reverse}
.msg.me .bubble{
  background:#4c7dff;
  color:#fff;border-top-right-radius:6px;
  box-shadow:none;
}
.msg .who{
  width:30px;height:30px;border-radius:10px;flex:0 0 auto;object-fit:cover;
  margin-top:3px;box-shadow:none;
}
.msg.me .who{display:none}
.msg .bubble b,.msg .bubble strong{font-weight:700}

/* 等待/出错的提示 */
.msg.bot.error .bubble{border-style:solid;border-color:rgba(247,212,212,.95);
  background:rgba(253,234,234,.9);color:#c0392b}
.dots{display:inline-flex;gap:4px;align-items:center;height:22px}
.dots i{width:6px;height:6px;border-radius:50%;background:var(--accent2);animation:blink 1.2s infinite}
.dots i:nth-child(2){animation-delay:.2s}
.dots i:nth-child(3){animation-delay:.4s}
@keyframes blink{0%,60%,100%{opacity:.28;transform:translateY(0)}30%{opacity:1;transform:translateY(-3px)}}

.tail{height:6px}

/* ── 拍照讲题入口 ── */
.cta-wrap{flex:0 0 auto;padding:0 16px 10px}
.cta{
  display:flex;align-items:center;gap:12px;text-decoration:none;color:inherit;
  background:#fff;
  border:1px solid rgba(160,190,255,.7);
  border-radius:12px;padding:12px 15px;
  box-shadow:none;
  transition:.15s;
}
.cta:active{transform:scale(.985)}
.cta-ico{font-size:21px;flex:0 0 auto}
.cta-txt{min-width:0;display:flex;flex-direction:column;line-height:1.4}
.cta-txt b{font-size:14.5px;font-weight:700;color:#2c3f70}
.cta-txt small{font-size:12px;color:var(--ink2)}
.cta-arrow{margin-left:auto;color:var(--accent);font-size:22px;line-height:1;flex:0 0 auto}
.contact-entry{display:flex;align-items:center;justify-content:center;gap:7px;flex-wrap:wrap;
  padding:7px 4px 0;color:var(--dim);font-size:12px;line-height:1.5;text-align:center}
.contact-entry a{color:var(--accent);font-weight:600;text-decoration:underline;text-underline-offset:2px}
.data-link{display:block;padding-top:3px;text-align:center;color:var(--dim);font-size:12px;text-underline-offset:2px}

/* ── 输入区 ── */
.composer{
  flex:0 0 auto;display:flex;gap:9px;align-items:center;
  padding:0 16px calc(8px + var(--safe-b));
}
.input{
  flex:1 1 auto;min-width:0;
  padding:13px 17px;border:1.5px solid var(--line);border-radius:12px;
  font-size:16px;font-weight:normal;line-height:normal;font-family:inherit;color:var(--ink);
  background:rgba(255,255,255,.9);outline:none;transition:.15s;
  box-shadow:none;
}
.input:focus{border-color:var(--accent);background:#fff;box-shadow:0 0 0 4px rgba(76,125,255,.12)}
.input[disabled]{background:rgba(240,242,250,.85);color:var(--dim)}
.send{
  flex:0 0 auto;width:46px;height:46px;border:none;border-radius:50%;cursor:pointer;
  display:flex;align-items:center;justify-content:center;color:#fff;
  background:#4c7dff;
  box-shadow:none;
  transition:.15s;
}
.send:active{transform:scale(.94)}
.send[disabled]{background:#b8d1f2;
  box-shadow:none;cursor:default}
.composer-tip{
  flex:0 0 auto;text-align:center;font-size:11.5px;color:var(--dim);
  padding:0 16px calc(8px + var(--safe-b));min-height:0;
}
.composer-tip:empty{display:none}

/* 桌面端稍微收一点，别把气泡拉得太宽 */
@media (min-width:760px){
  .scroll{padding:4px 20px 8px}
  .cta-wrap,.composer{padding-left:20px;padding-right:20px}
}

/* Course consultation: expressive opening, calm reading surface. */
body{background:radial-gradient(ellipse at 90% 0,rgba(142,189,255,.25),transparent 48%),radial-gradient(ellipse at 0 60%,rgba(159,223,234,.2),transparent 45%),radial-gradient(ellipse at 92% 94%,rgba(232,200,236,.15),transparent 40%),var(--page)}
.topbar{border-bottom:1px solid var(--line);margin-bottom:16px;padding-bottom:14px}
.brand-logo,.hero-avatar,.msg .who{box-shadow:none;object-fit:contain}
.hero{position:relative;overflow:hidden;background:linear-gradient(125deg,#fff 25%,#edf5ff);padding:30px 24px;border-radius:20px;border-color:#d7e5fc;margin-bottom:20px;animation:productEnter .35s var(--ease) both}
.hero::after{content:'';position:absolute;right:-28px;top:-35px;width:145px;height:145px;border:1px solid #d9def8;border-radius:40px;transform:rotate(30deg);pointer-events:none}
.hero-avatar{width:44px;height:44px;border-radius:12px}.hero-txt{position:relative;z-index:1}
.hero-txt h1{font-size:26px;line-height:1.35;font-weight:750;letter-spacing:-.6px}.hero-txt p{margin-top:10px;max-width:480px}
.chips{position:relative;z-index:1;margin-top:24px;gap:8px}.chip,.ghost-btn{border-radius:9px;background:#fff;box-shadow:none;border-color:#d7e5fc}
.msg{animation:productEnter .28s var(--ease) both}.msg .bubble{border-radius:16px}.msg.bot .bubble{background:#fff;box-shadow:0 3px 14px rgba(39,56,84,.035)}.msg.me .bubble{background:linear-gradient(120deg,#4c7dff,#6f95ff);box-shadow:none}
.cta{background:linear-gradient(110deg,#edf5ff,#f8f9ff);border-color:#d7e5fc;border-radius:14px;box-shadow:none}.cta-ico{display:flex;align-items:center;color:var(--accent)}.cta-txt b{color:var(--ink)}
.input{border-radius:12px;box-shadow:none;background:#fff}.send{border-radius:12px;box-shadow:none}.contact-entry{padding-top:10px}
@media(min-width:900px){.page{max-width:880px}.hero{margin-top:20px;padding:40px}.hero-txt h1{font-size:32px}.msgs{max-width:760px;margin:auto}}
@media(max-width:440px){.hero{padding:24px 18px}.hero-txt h1{font-size:23px}.hero-avatar{width:38px;height:38px}.hero-row{gap:12px}.hero::after{width:110px;height:110px}}

/* Frosted conversation surfaces. */
.topbar{background:rgba(255,255,255,.56);border:1px solid var(--glass-edge);border-radius:14px;margin:8px 12px 16px;padding:calc(12px + var(--safe-t)) 12px 12px;backdrop-filter:blur(16px) saturate(1.25);-webkit-backdrop-filter:blur(16px) saturate(1.25);box-shadow:inset 0 1px 0 #fff}
.hero,.cta,.msg.bot .bubble,.composer .input{background:var(--glass-bg);border-color:var(--glass-edge);backdrop-filter:var(--glass-filter);-webkit-backdrop-filter:var(--glass-filter);box-shadow:var(--glass-shadow)}
.hero{background:linear-gradient(125deg,rgba(255,255,255,.77),rgba(234,246,255,.6))}
.hero::after{border-color:rgba(159,197,242,.4)}
.cta{background:linear-gradient(110deg,rgba(228,242,255,.68),rgba(255,255,255,.73))}
.msg.bot .bubble{background:rgba(255,255,255,.76)}
@supports not ((backdrop-filter:blur(1px)) or (-webkit-backdrop-filter:blur(1px))){.topbar,.hero,.cta,.msg.bot .bubble,.composer .input{background:#fff}}