/* ====== 兔老板 - 通用样式 ====== */

:root {
  --bg: #0b1020;
  --bg-2: #0f1530;
  --card: #131a36;
  --card-bg: #13131c;
  --border: #1f2a52;
  --text: #e6e9f5;
  --muted: #98a0c2;
  --primary: #7c5cff;
  --primary-2: #4d8dff;
  --accent: #22d3ee;
  --gold: #fbbf24;
  --success: #34d399;
  --radius: 14px;
  --shadow: 0 10px 30px rgba(0,0,0,.35);
}

* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; }
body {
  background: radial-gradient(1200px 600px at 20% -10%, rgba(124,92,255,.15), transparent 60%),
              radial-gradient(900px 500px at 90% 10%, rgba(34,211,238,.10), transparent 60%),
              var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}
a { color: inherit; text-decoration: none; }
img { max-width: 100%; display: block; }

.container { max-width: 1180px; margin: 0 auto; padding: 0 24px; }

/* ====== Buttons ====== */
.btn-primary, .btn-secondary {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 14px 22px;
  border-radius: 12px;
  font-weight: 600;
  font-size: 15px;
  border: 1px solid transparent;
  cursor: pointer;
  transition: all .2s ease;
}
.btn-primary {
  background: linear-gradient(135deg, var(--primary), var(--primary-2));
  color: #fff;
  box-shadow: 0 10px 24px rgba(124,92,255,.35);
}
.btn-primary:hover { transform: translateY(-2px); box-shadow: 0 14px 30px rgba(124,92,255,.45); }
.btn-secondary {
  background: transparent;
  color: var(--text);
  border-color: var(--border);
}
.btn-secondary:hover { border-color: var(--primary); }

/* ====== Navigation ====== */
.nav {
  position: sticky; top: 0; z-index: 50;
  backdrop-filter: saturate(180%) blur(10px);
  background: rgba(11,16,32,.72);
  border-bottom: 1px solid var(--border);
}
.nav-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 14px 0;
  gap: 24px;
}
.nav-left { display: flex; align-items: center; gap: 32px; flex: 1; }
.nav-right { display: flex; align-items: center; gap: 16px; }
.brand {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 700;
  font-size: 18px;
}
.brand-logo {
  width: 32px;
  height: 32px;
  border-radius: 8px;
  background: linear-gradient(135deg, var(--primary), var(--accent));
  display: grid;
  place-items: center;
  font-size: 18px;
  overflow: hidden;
  flex-shrink: 0;
}
.brand-logo img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
}
.nav-links {
  display: flex;
  gap: 26px;
  font-size: 14px;
  color: var(--muted);
}
.nav-links a:hover { color: var(--text); }
.nav-cta {
  background: linear-gradient(135deg, var(--primary), var(--primary-2));
  color: #fff;
  padding: 9px 16px;
  border-radius: 10px;
  font-size: 14px;
  font-weight: 600;
  box-shadow: 0 6px 16px rgba(124,92,255,.35);
}
.nav-cta:hover { transform: translateY(-1px); }
@media (max-width: 720px) {
  .nav-links { display: none; }
}

/* ====== Section ====== */
.section { padding: 72px 0; }
.section-title { text-align: center; margin-bottom: 48px; }
.section-title h2 { font-size: 36px; margin: 0 0 12px; font-weight: 800; letter-spacing: -.01em; }
.section-title p {
  color: var(--muted);
  margin: 0;
  font-size: 16px;
  max-width: 640px;
  margin-left: auto;
  margin-right: auto;
}

/* ====== Stats ====== */
.stats {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 20px;
}
.stat {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px;
  text-align: center;
}
.stat .num {
  font-size: 34px;
  font-weight: 800;
  background: linear-gradient(135deg, #b9a8ff, #22d3ee);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}
.stat .label { color: var(--muted); font-size: 13px; margin-top: 4px; }
@media (max-width: 720px) { .stats { grid-template-columns: repeat(2, 1fr); } }

/* ====== Mentor ====== */
.mentor {
  display: grid;
  grid-template-columns: 220px 1fr;
  gap: 36px;
  background: linear-gradient(160deg, rgba(19,26,54,0.9), rgba(15,21,48,0.95));
  border: 1px solid rgba(124,92,255,0.18);
  border-radius: var(--radius);
  padding: 36px;
  align-items: center;
  position: relative;
  overflow: hidden;
}
.mentor::before {
  content: "";
  position: absolute;
  inset: 0;
  border-radius: var(--radius);
  padding: 1px;
  background: linear-gradient(135deg, rgba(124,92,255,.3), rgba(34,211,238,.2) 60%, transparent);
  -webkit-mask: linear-gradient(#fff 0 0) content-box, linear-gradient(#fff 0 0);
  -webkit-mask-composite: xor;
  mask-composite: exclude;
  pointer-events: none;
}
.avatar {
  width: 220px;
  height: 220px;
  border-radius: var(--radius);
  background: linear-gradient(135deg, #7c5cff, #22d3ee);
  display: grid;
  place-items: center;
  font-size: 88px;
  box-shadow: 0 12px 40px rgba(124,92,255,.35);
  position: relative;
  z-index: 1;
}
.mentor > div { position: relative; z-index: 1; }
.mentor h3 { margin: 0 0 6px; font-size: 26px; }
.mentor .title { color: var(--primary-2); font-size: 15px; margin-bottom: 16px; font-weight: 600; }
.mentor p { color: var(--muted); margin: 0 0 12px; }
.mentor .creds { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 18px; }
.mentor .cred {
  background: rgba(124,92,255,.1);
  border: 1px solid rgba(124,92,255,.3);
  padding: 5px 12px;
  border-radius: 6px;
  font-size: 12px;
  color: #b9a8ff;
  transition: all .2s ease;
}
.mentor .cred:hover { background: rgba(124,92,255,.18); }
@media (max-width: 720px) {
  .mentor { grid-template-columns: 1fr; text-align: center; }
  .avatar { margin: 0 auto; }
}

/* ====== FAQ Accordion (课程页仍使用) ====== */
.faq { max-width: 760px; margin: 0 auto; }
.faq-item {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  margin-bottom: 12px;
  overflow: hidden;
}
.faq-q {
  width: 100%;
  text-align: left;
  background: transparent;
  color: var(--text);
  border: 0;
  padding: 18px 22px;
  font-size: 16px;
  font-weight: 600;
  display: flex;
  justify-content: space-between;
  align-items: center;
  cursor: pointer;
}
.faq-q .plus { color: var(--primary); font-size: 20px; transition: transform .2s; }
.faq-a { max-height: 0; overflow: hidden; transition: max-height .3s ease; }
.faq-a-inner { padding: 0 22px 18px; color: var(--muted); font-size: 14px; }
.faq-item.open .faq-a { max-height: 300px; }
.faq-item.open .plus { transform: rotate(45deg); }

/* ====== CTA Final ====== */
.cta-final {
  background: linear-gradient(135deg, rgba(124,92,255,.2), rgba(34,211,238,.15));
  border: 1px solid var(--border);
  border-radius: 20px;
  padding: 56px 40px;
  text-align: center;
}
.cta-final h2 { font-size: 32px; margin: 0 0 14px; }
.cta-final p {
  color: var(--muted);
  margin: 0 0 28px;
  font-size: 16px;
  max-width: 560px;
  margin-left: auto;
  margin-right: auto;
}

/* ====== Footer ====== */
.footer {
  border-top: 1px solid var(--border);
  padding: 36px 0;
  color: var(--muted);
  font-size: 14px;
  text-align: center;
}
.footer .links {
  display: flex;
  gap: 20px;
  justify-content: center;
  margin-bottom: 12px;
  flex-wrap: wrap;
}
.footer .links a:hover { color: var(--text); }

/* ====== Language Switch ====== */
.lang-switch {
  display: inline-flex;
  align-items: center;
  gap: 2px;
  background: rgba(124,92,255,.08);
  border: 1px solid var(--border);
  border-radius: 999px;
  padding: 3px;
}
.lang-switch button {
  border: none;
  background: transparent;
  color: var(--muted);
  font-size: 13px;
  font-weight: 600;
  padding: 5px 11px;
  border-radius: 999px;
  cursor: pointer;
  transition: all .18s ease;
  line-height: 1;
}
.lang-switch button:hover { color: var(--text); }
.lang-switch button.active {
  background: linear-gradient(135deg, var(--primary), var(--primary-2));
  color: #fff;
  box-shadow: 0 4px 12px rgba(124,92,255,.3);
}
.nav-right .lang-switch { margin-right: 4px; }
.bottom-lang {
  border: none;
  background: rgba(124,92,255,.12);
  color: var(--accent);
  font-size: 12px;
  font-weight: 700;
  padding: 4px 10px;
  border-radius: 999px;
  cursor: pointer;
}
.bottom-lang.active { background: linear-gradient(135deg, var(--primary), var(--primary-2)); color: #fff; }

/* ===== 回到顶部 ===== */
html { scroll-behavior: smooth; }
#backToTop {
  position: fixed; right: 20px; bottom: 180px;
  width: 44px; height: 44px; border-radius: 50%;
  border: 1px solid #1f2a52; background: rgba(19, 26, 54, 0.85);
  color: #e6e9f5; font-size: 20px; line-height: 1; cursor: pointer;
  display: none; align-items: center; justify-content: center;
  z-index: 9998; backdrop-filter: blur(8px);
  box-shadow: 0 4px 16px rgba(0, 0, 0, 0.3);
  transition: border-color .2s, color .2s;
}
#backToTop:hover { border-color: #7c5cff; color: #fff; }
@media (max-width: 768px) {
  #backToTop { right: 14px; bottom: 170px; width: 40px; height: 40px; }
}