@import url("https://fonts.googleapis.com/css2?family=Instrument+Serif:ital@0;1&family=Space+Grotesk:wght@400;500;700&display=swap");

:root {
  --bg: #f5f2eb;
  --bg-panel: rgba(255, 255, 255, 0.45);
  --bg-panel-strong: rgba(255, 252, 246, 0.65);
  --surface-soft: rgba(255, 255, 255, 0.5);
  --input-bg: rgba(255, 255, 255, 0.8);
  --line: rgba(30, 61, 72, 0.08);
  --glass-top: rgba(255, 255, 255, 0.8);
  --glass-left: rgba(255, 255, 255, 0.5);
  --glass-inset: rgba(255, 255, 255, 0.4);
  --text: #13232b;
  --text-gradient: linear-gradient(135deg, #13232b 30%, #d9823b 100%);
  --muted: #607681;
  --accent: #d9823b;
  --accent-strong: #c75d3d;
  --mint: #1e8f7a;
  --warning: #c79b2b;
  --danger: #d65f56;
  --shadow: 0 24px 60px rgba(45, 58, 64, 0.08);
  --shadow-hover: 0 32px 72px rgba(45, 58, 64, 0.12);
  --glow-a: rgba(30, 143, 122, 0.25);
  --glow-b: rgba(217, 130, 59, 0.25);
  --bg-start: #fffaf4;
  --bg-mid: #f6f2eb;
  --bg-end: #eef5f2;
  --button-text: #fffefb;
  --secondary-bg: rgba(30, 143, 122, 0.08);
  --secondary-text: #173038;
}

/*
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #07151a;
    --bg-panel: rgba(6, 18, 23, 0.45);
    --bg-panel-strong: rgba(10, 28, 36, 0.55);
    --surface-soft: rgba(255, 255, 255, 0.03);
    --input-bg: rgba(255, 255, 255, 0.05);
    --line: rgba(144, 199, 187, 0.12);
    --glass-top: rgba(255, 255, 255, 0.06);
    --glass-left: rgba(255, 255, 255, 0.03);
    --glass-inset: rgba(255, 255, 255, 0.02);
    --text: #f5f0e7;
    --text-gradient: linear-gradient(135deg, #ffffff 20%, #f2b05e 90%);
    --muted: #9cb6af;
    --accent: #f2b05e;
    --accent-strong: #ef8658;
    --mint: #5bc0a8;
    --warning: #f3cf72;
    --danger: #f1786d;
    --shadow: 0 24px 60px rgba(0, 0, 0, 0.4);
    --shadow-hover: 0 32px 72px rgba(0, 0, 0, 0.6);
    --glow-a: rgba(91, 192, 168, 0.18);
    --glow-b: rgba(239, 134, 88, 0.22);
    --bg-start: #09181e;
    --bg-mid: #07151a;
    --bg-end: #040d10;
    --button-text: #081116;
    --secondary-bg: rgba(91, 192, 168, 0.12);
    --secondary-text: #f5f0e7;
  }
}
*/

* {
  box-sizing: border-box;
}

html, body {
  margin: 0;
  min-height: 100%;
}

body {
  background: var(--bg-mid);
  color: var(--text);
  font-family: "Space Grotesk", sans-serif;
  transition: background 160ms ease, color 160ms ease;
  line-height: 1.6;
  position: relative;
  overflow-x: hidden;
}

/* Dynamic Ambient Glow */
body::before, body::after {
  content: '';
  position: fixed;
  border-radius: 50%;
  filter: blur(120px);
  z-index: -1;
  opacity: 0.8;
  animation: floatOrb 20s infinite ease-in-out alternate;
  pointer-events: none;
}

body::before {
  width: 50vw;
  height: 50vw;
  background: var(--glow-a);
  top: -10vw;
  left: -10vw;
}

body::after {
  width: 40vw;
  height: 40vw;
  background: var(--glow-b);
  bottom: -5vw;
  right: -5vw;
  animation-delay: -10s;
  animation-duration: 25s;
}

@keyframes floatOrb {
  0% { transform: translate(0, 0) scale(1); }
  50% { transform: translate(5vw, 5vh) scale(1.1); }
  100% { transform: translate(-3vw, 8vh) scale(0.9); }
}

/* Typography Enhancements */
.hero-brand {
  font-family: "Instrument Serif", serif;
  font-weight: 400;
  letter-spacing: -0.04em;
  background: var(--text-gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  padding-bottom: 0.1em;
  display: block;
  width: fit-content;
  margin: 0 auto;
  font-size: clamp(4rem, 8vw, 7rem);
  line-height: 0.95;
}

.section-title {
  font-family: "Instrument Serif", serif;
  font-weight: 400;
  letter-spacing: -0.01em;
  background: var(--text-gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  padding-bottom: 0.1em;
  display: block;
  width: fit-content;
  margin: 0 auto 2rem auto;
  text-align: center;
  transform: scaleX(1.15); /* Stretch individual letters to be wider */
  transform-origin: center;
  font-size: clamp(2rem, 5vw, 3rem);
}

/* Disable stretching for Chinese characters */
[lang="zh-CN"] .section-title,
[lang="zh-CN"] .hero-brand {
  transform: none !important;
}

.eyebrow {
  color: var(--mint);
  font-size: 0.9rem;
  letter-spacing: 0.25em;
  text-transform: uppercase;
  font-weight: 700;
  display: inline-block;
  padding: 0.4rem 1rem;
  background: var(--secondary-bg);
  border-radius: 999px;
  border: 1px solid var(--line);
}

.hero-copy h2 {
  font-size: clamp(1.1rem, 2vw, 1.45rem);
  font-weight: 400;
  letter-spacing: -0.01em;
  line-height: 1.5;
  margin: 0;
  color: var(--muted);
}

/* Animations */
@keyframes slideUpFade {
  from { opacity: 0; transform: translateY(30px); }
  to { opacity: 1; transform: translateY(0); }
}

.hero-copy {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 1.25rem;
  max-width: min(900px, 100%);
  animation: slideUpFade 1s cubic-bezier(0.16, 1, 0.3, 1) forwards;
}

/* Floating Image */
@keyframes floatImg {
  0% { transform: translateY(0); }
  50% { transform: translateY(-15px); }
  100% { transform: translateY(0); }
}

.demo-img {
  width: 100%;
  max-width: 1400px;
  border-radius: 20px;
  box-shadow: var(--shadow);
  margin-top: 3rem;
  border: 1px solid var(--glass-top);
  border-left: 1px solid var(--glass-left);
  aspect-ratio: auto;
  animation: slideUpFade 1s cubic-bezier(0.16, 1, 0.3, 1) forwards, floatImg 8s ease-in-out infinite;
  animation-delay: 0s, 1s;
}

/* Glass Panels */
.page-shell {
  display: grid;
  gap: 1.5rem; /* 稍微减少卡片/组件间的间距 */
  padding: 0.7rem 1.5rem 2rem; /* 桌面端顶部同步微调为 0.7rem */
  max-width: 1600px;
  margin: 0 auto;
}

.app-shell {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1.5rem; /* 稍微减少卡片间的垂直间距 */
}

.lang-container {
  display: flex;
  justify-content: flex-end;
  width: 100%;
}

.hero-center {
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  padding: 3rem 1rem 1rem;
}

.hero-copy {
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
}

.hero-copy img {
  width: 80px;
  height: 80px;
  margin-bottom: -0.5rem;
  margin-top: 1.5rem;
}

.hero-copy h2 {
  max-width: 850px;
  text-align: center;
  margin: 1.5rem auto 0 auto;
  font-size: clamp(1.1rem, 2vw, 1.45rem);
  line-height: 1.5;
  color: var(--muted);
}

.inline-actions {
  display: flex;
  margin-top: 2.5rem;
  justify-content: center;
  gap: 1rem;
}

#bot-title {
  font-size: clamp(2.2rem, 6vw, 3.5rem);
  margin-bottom: 1rem;
}

.privacy-box {
  background: var(--surface-soft);
  padding: 2rem;
  border-radius: 20px;
  border: 1px solid var(--line);
  text-align: left;
  width: 100%;
  max-width: 800px;
}

.panel, .brand-card, .hero {
  backdrop-filter: blur(36px); /* Very strong blur */
  -webkit-backdrop-filter: blur(36px);
  background: var(--bg-panel);
  border: 1px solid var(--line);
  border-top-color: var(--glass-top);
  border-left-color: var(--glass-left);
  border-radius: 32px;
  box-shadow: var(--shadow), inset 0 1px 0 var(--glass-inset);
  padding: 3rem;
  transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.hero {
  background: var(--bg-panel-strong);
}

.stage-card {
  align-items: flex-start;
  background: var(--surface-soft);
  border: 1px solid var(--line);
  border-top-color: var(--glass-top);
  border-left-color: var(--glass-left);
  border-radius: 24px;
  color: var(--text);
  display: grid;
  gap: 1rem;
  padding: 2rem 1.8rem;
  text-align: left;
  transition: all 0.4s cubic-bezier(0.16, 1, 0.3, 1);
  box-shadow: 0 10px 30px rgba(0,0,0,0.03), inset 0 1px 0 var(--glass-inset);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
}

.stage-card:hover {
  transform: translateY(-8px) scale(1.01);
  box-shadow: var(--shadow-hover), inset 0 1px 0 var(--glass-inset);
  background: var(--bg-panel-strong);
  border-color: var(--accent);
}

.stage-index {
  color: var(--accent);
  font-size: 2.2rem;
  font-weight: 700;
  line-height: 1;
  opacity: 0.8;
}

.stage-card h3 {
  margin: 0;
  font-size: 1.35rem;
  font-weight: 600;
  letter-spacing: -0.02em;
}

.stage-card p {
  color: var(--muted);
  margin: 0;
  font-size: 1rem;
  line-height: 1.6;
}

.grid.two-up {
  display: grid;
  gap: 1.5rem;
  grid-template-columns: repeat(2, minmax(0, 1fr));
}

/* Buttons */
button {
  font: inherit;
  border: 0;
  border-radius: 999px;
  background: linear-gradient(135deg, var(--accent), var(--accent-strong));
  color: var(--button-text);
  cursor: pointer;
  font-weight: 600;
  padding: 0.9rem 1.6rem;
  font-size: 1.05rem;
  transition: all 0.3s cubic-bezier(0.16, 1, 0.3, 1);
  box-shadow: 0 8px 24px rgba(217, 130, 59, 0.3), inset 0 1px 0 rgba(255,255,255,0.3);
}

button:hover {
  transform: translateY(-2px);
  box-shadow: 0 12px 32px rgba(217, 130, 59, 0.4), inset 0 1px 0 rgba(255,255,255,0.4);
  filter: brightness(1.1);
}

button:active {
  transform: translateY(1px);
  box-shadow: 0 4px 12px rgba(217, 130, 59, 0.3);
}

button.secondary {
  background: var(--surface-soft);
  color: var(--text);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border: 1px solid var(--line);
  box-shadow: 0 8px 24px rgba(0,0,0,0.05);
}

button.secondary:hover {
  background: var(--input-bg);
  box-shadow: 0 12px 32px rgba(0,0,0,0.08);
  border-color: var(--glass-top);
  color: var(--accent);
}

a {
  color: var(--accent);
  text-decoration: none;
  font-weight: 500;
  transition: color 0.2s;
}

a:hover {
  color: var(--accent-strong);
}

/* Theme Toggle */
.theme-toggle {
  align-items: center;
  background: var(--surface-soft);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border: 1px solid var(--line);
  border-radius: 999px;
  display: inline-grid;
  gap: 0.2rem;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  min-width: 130px;
  padding: 0.3rem;
  box-shadow: 0 4px 12px rgba(0,0,0,0.05);
}
.theme-option {
  background: transparent;
  border-radius: 999px;
  color: var(--muted);
  min-width: 0;
  padding: 0.5rem 1rem;
  font-weight: 600;
  cursor: pointer;
  border: 0;
  transition: all 0.3s ease;
  box-shadow: none;
  font-size: 0.95rem;
}
.theme-option.active {
  background: linear-gradient(135deg, var(--accent), var(--accent-strong));
  color: var(--button-text);
  box-shadow: 0 4px 16px rgba(217, 130, 59, 0.4);
}

.workflow-grid {
  display: grid;
  gap: 1.5rem;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
}
.check-list li {
  margin-bottom: 0.8rem;
  position: relative;
}

/* 仅精准控制切换按钮与其下方内容的距离 */
.lang-container {
  margin-bottom: -0.8rem; /* 配合 1.5rem gap，使下方实际间距为 0.7rem */
}

@media (max-width: 900px) {
  .grid.two-up {
    grid-template-columns: 1fr;
    gap: 0.8rem; /* 同步缩减 Pipeline 部分的卡片间距 */
  }
  .page-shell {
    padding: 0.3rem 1.5rem 2rem; /* 移动端顶部微调为 0.3rem */
    gap: 1.5rem; /* 恢复原始间距并微调 */
  }
  .app-shell {
    gap: 1.5rem; /* 恢复原始间距并微调 */
  }
  .lang-container {
    margin-bottom: -1.2rem; /* 配合 1.5rem gap，使下方实际间距为 0.3rem */
  }
  .panel, .brand-card, .hero {
    padding: 2rem 1.5rem; /* 恢复原始移动端内边距 */
  }
  .hero {
    padding-top: 3rem; /* 恢复原始高度 */
  }
  .section-title {
    font-size: 1.7rem !important;
    font-weight: 700;
    letter-spacing: -0.02em;
  }
  .stage-card h3 {
    font-size: 1.2rem;
    font-weight: 700;
  }
  .hero-brand {
    font-size: 3.5rem !important;
    font-weight: 700;
    letter-spacing: -0.02em;
  }
  .workflow-grid {
    gap: 0.8rem; /* 仅移动端收紧子卡片间距 */
  }
}

/* Back to Top Button */
#back-to-top {
  position: fixed;
  bottom: 2.5rem;
  left: 50%;
  width: 56px;
  height: 56px;
  border-radius: 50%;
  background: var(--bg-panel-strong);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border: 1px solid var(--line);
  border-top-color: var(--glass-top);
  border-left-color: var(--glass-left);
  color: var(--accent);
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  z-index: 1000;
  opacity: 0;
  visibility: hidden;
  transition: all 0.4s cubic-bezier(0.16, 1, 0.3, 1);
  box-shadow: var(--shadow), inset 0 1px 0 var(--glass-inset);
  transform: translateX(-50%) translateY(20px);
}

#back-to-top.visible {
  opacity: 1;
  visibility: visible;
  transform: translateX(-50%) translateY(0);
}

#back-to-top:hover {
  background: var(--accent);
  color: var(--button-text);
  transform: translateX(-50%) translateY(-5px);
  box-shadow: 0 12px 32px rgba(217, 130, 59, 0.4);
  border-color: var(--accent-strong);
}

#back-to-top svg {
  width: 24px;
  height: 24px;
  fill: none;
  stroke: currentColor;
  stroke-width: 2.5;
  stroke-linecap: round;
  stroke-linejoin: round;
  transition: transform 0.3s ease;
}

#back-to-top:hover svg {
  transform: translateY(-2px);
}