/* === 小范同学 GEO · Apple Style === */
@import url('https://fonts.googleapis.com/css2?family=Noto+Serif+SC:wght@400;600;700&display=swap');

:root {
  --bg: #f5f5f7;
  --bg-card: rgba(255,255,255,0.85);
  --bg-elevated: rgba(255,255,255,0.88);
  --surface: rgba(255,255,255,0.6);
  --border: rgba(0,0,0,0.1);
  --border-glow: rgba(0,122,255,0.15);
  --text: #1d1d1f;
  --text-secondary: #515154;
  --muted: #86868b;
  --primary: #007AFF;
  --primary-light: #3399ff;
  --primary-dim: #0056b3;
  --accent: #5856D6;
  --accent-light: #7b79e0;
  --green: #34C759;
  --red: #FF3B30;
  --orange: #FF9500;
  --gold: #FF9F0A;
  --amber: #FF9500;
  --amber-glow: rgba(255,149,0,0.08);
  --max-w: 1000px;
  --radius: 18px;
  --radius-sm: 12px;
  --max-width: 1000px;
  --font-serif: 'Noto Serif SC', 'SimSun', 'STSong', serif;
  --font-sans: -apple-system, BlinkMacSystemFont, 'SF Pro Display', 'SF Pro Text', 'PingFang SC', 'Microsoft YaHei', sans-serif;
}

* { margin: 0; padding: 0; box-sizing: border-box; }

html { scroll-behavior: smooth; -webkit-font-smoothing: antialiased; }

body {
  background: var(--bg);
  background-image:
    radial-gradient(ellipse 80% 60% at 50% -10%, rgba(0,122,255,0.06) 0%, transparent 100%),
    radial-gradient(ellipse 60% 40% at 80% 90%, rgba(88,86,214,0.03) 0%, transparent 100%),
    radial-gradient(ellipse 40% 40% at 20% 60%, rgba(52,199,89,0.02) 0%, transparent 100%);
  background-attachment: fixed;
  color: var(--text);
  font-family: var(--font-sans);
  line-height: 1.8;
  font-size: 16px;
  min-height: 100vh;
  overflow-x: hidden;
}

#particles-canvas { position: fixed; top: 0; left: 0; width: 100%; height: 100%; z-index: 1; pointer-events: none; opacity: 0.5; }
header, main, footer { position: relative; z-index: 2; }

h1, h2, h3, h4 { font-family: var(--font-serif); font-weight: 700; color: var(--text); line-height: 1.3; }
h1 { font-size: 2.8rem; letter-spacing: -0.02em; }
h2 { font-size: 1.6rem; margin: 3rem 0 1.2rem; }
h3 { font-size: 1.15rem; margin: 1.5rem 0 0.5rem; }
p { margin-bottom: 1rem; color: var(--text-secondary); line-height: 1.85; }
a { color: var(--primary); text-decoration: none; transition: all 0.25s ease; }
a:hover { color: var(--primary-dim); }

.container { max-width: var(--max-width); margin: 0 auto; padding: 0 1.5rem; }

/* Header */
header {
  background: rgba(245,245,247,0.72);
  backdrop-filter: saturate(180%) blur(20px);
  -webkit-backdrop-filter: saturate(180%) blur(20px);
  border-bottom: 1px solid var(--border);
  position: sticky; top: 0; z-index: 100;
}
nav {
  max-width: var(--max-width); margin: 0 auto; padding: 0 1.5rem;
  display: flex; align-items: center; justify-content: space-between; min-height: 56px;
}
.nav-brand { font-family: var(--font-serif); font-size: 1.2rem; font-weight: 700; color: var(--text); flex-shrink: 0; }
.nav-brand span { color: var(--primary); }
.nav-links { display: flex; align-items: center; gap: 0; list-style: none; margin: 0; padding: 0; }
.nav-links li a {
  display: inline-flex; align-items: center; padding: 0.35rem 0.7rem;
  color: var(--text-secondary); font-size: 0.88rem; border-radius: 8px; transition: all 0.25s;
}
.nav-links li a:hover, .nav-links li a.active {
  color: var(--primary); background: rgba(0,122,255,0.06);
}
.nav-links li:last-child a {
  margin-left: 0.3rem;
  background: linear-gradient(135deg, var(--primary), var(--accent));
  color: #fff; font-weight: 600; padding: 0.35rem 1rem; border-radius: 20px;
  border: none;
}
.nav-links li:last-child a:hover { opacity: 0.9; transform: translateY(-1px); box-shadow: 0 4px 12px rgba(0,122,255,0.25); }

/* Hero */
.hero { padding: 5rem 0 3rem; text-align: center; }
.hero h1 { font-size: 3rem; margin-bottom: 0.6rem; }
.hero h1 em { color: var(--primary); font-style: normal; background: linear-gradient(135deg, var(--primary), var(--accent)); -webkit-background-clip: text; -webkit-text-fill-color: transparent; background-clip: text; }
.hero .subtitle { font-size: 1.05rem; color: var(--text-secondary); max-width: 560px; margin: 0 auto 2rem; }
.hero .cta-row { display: flex; gap: 1rem; justify-content: center; flex-wrap: wrap; margin-top: 1.5rem; }

/* Buttons */
.btn {
  display: inline-flex; align-items: center; gap: 0.4rem;
  padding: 0.7rem 2rem; border-radius: 24px;
  font-size: 0.92rem; font-weight: 600; cursor: pointer;
  transition: all 0.3s cubic-bezier(0.25, 0.1, 0.25, 1);
  border: none; text-decoration: none;
}
.btn-primary {
  background: linear-gradient(135deg, var(--primary), #5856D6);
  color: #fff; box-shadow: 0 4px 16px rgba(0,122,255,0.2);
}
.btn-primary:hover { transform: translateY(-2px); box-shadow: 0 8px 24px rgba(0,122,255,0.3); }
.btn-outline {
  background: var(--bg-card); color: var(--primary);
  border: 1px solid rgba(0,122,255,0.15); backdrop-filter: blur(12px);
}
.btn-outline:hover { background: rgba(0,122,255,0.06); border-color: rgba(0,122,255,0.3); }
.btn-sm { padding: 0.4rem 1rem; font-size: 0.82rem; border-radius: 16px; }

/* Trust Bar */
.trust-bar {
  display: flex; justify-content: center; gap: 3rem; flex-wrap: wrap;
  padding: 2rem 1.5rem; max-width: 700px; margin: 0 auto 2rem;
  background: var(--bg-card); border-radius: var(--radius);
  backdrop-filter: blur(16px); -webkit-backdrop-filter: blur(16px);
  border: 1px solid var(--border);
}
.trust-item { text-align: center; }
.trust-item .num { font-size: 2.2rem; font-weight: 700; color: var(--text); font-family: var(--font-serif); }
.trust-item .label { font-size: 0.82rem; color: var(--text-secondary); margin-top: 0.2rem; }

/* Tree Section */
.tree-section { padding: 2rem 0 3rem; text-align: center; }
.tree-section .section-label { font-size: 0.7rem; letter-spacing: 4px; color: var(--muted); text-transform: uppercase; margin-bottom: 0.5rem; }
.tree-section h2 { margin-top: 0; }
.stats-row { display: flex; justify-content: center; gap: 3rem; margin-bottom: 2rem; }
.stat-item { text-align: center; }
.stat-item .n { font-size: 2.6rem; font-weight: 700; font-family: var(--font-serif); background: linear-gradient(135deg, var(--primary), var(--accent)); -webkit-background-clip: text; -webkit-text-fill-color: transparent; background-clip: text; }
.stat-item .l { font-size: 0.82rem; color: var(--text-secondary); margin-top: 0.2rem; }

.tree-canvas {
  display: flex; flex-wrap: wrap; justify-content: center; gap: 1.2rem;
  max-width: 800px; margin: 0 auto; padding: 2rem 1rem;
  min-height: 120px;
}
.tree-leaf {
  position: relative; width: 48px; height: 48px;
  display: flex; align-items: center; justify-content: center;
  border-radius: 50%; transition: all 0.6s cubic-bezier(0.25, 0.1, 0.25, 1);
  animation: leafAppear 0.8s ease-out both;
}
.tree-leaf::after {
  content: ''; position: absolute; inset: -4px; border-radius: 50%;
  opacity: 0; transition: opacity 2s ease;
}
.tree-leaf.seed { background: rgba(174,174,178,0.2); }
.tree-leaf.seed::after { box-shadow: 0 0 8px rgba(174,174,178,0.3); opacity: 0.4; }
.tree-leaf.seedling { background: rgba(88,86,214,0.15); }
.tree-leaf.seedling::after { box-shadow: 0 0 16px rgba(88,86,214,0.3), 0 0 32px rgba(88,86,214,0.1); opacity: 0.6; }
.tree-leaf.sapling { background: rgba(0,122,255,0.15); }
.tree-leaf.sapling::after { box-shadow: 0 0 20px rgba(0,122,255,0.35), 0 0 40px rgba(0,122,255,0.12); opacity: 0.7; animation: leafGlow 2s ease-in-out infinite; }
.tree-leaf.tree { background: rgba(52,199,89,0.2); }
.tree-leaf.tree::after { box-shadow: 0 0 24px rgba(52,199,89,0.4), 0 0 48px rgba(52,199,89,0.15); opacity: 0.8; animation: leafGlow 1.5s ease-in-out infinite; }
.tree-leaf .leaf-icon { font-size: 1.2rem; position: relative; z-index: 1; }

@keyframes leafAppear {
  from { opacity: 0; transform: scale(0) rotate(-20deg); }
  to { opacity: 1; transform: scale(1) rotate(0); }
}
@keyframes leafGlow {
  0%, 100% { opacity: 0.6; }
  50% { opacity: 0.9; }
}

.tree-legend { display: flex; justify-content: center; gap: 1.5rem; margin-top: 1rem; font-size: 0.82rem; color: var(--text-secondary); }
.tree-legend .dot { display: inline-block; width: 10px; height: 10px; border-radius: 50%; margin-right: 0.3rem; }
.dot.seed { background: rgba(174,174,178,0.4); }
.dot.seedling { background: rgba(88,86,214,0.5); }
.dot.sapling { background: rgba(0,122,255,0.6); }
.dot.tree { background: rgba(52,199,89,0.7); }

/* Section */
.section { padding: 3rem 0; }
.section-header { text-align: center; margin-bottom: 2rem; }
.section-label { font-size: 0.68rem; letter-spacing: 4px; color: var(--muted); text-transform: uppercase; margin-bottom: 0.3rem; }
.section-header h2 { margin-top: 0; margin-bottom: 0; }

/* Cards */
.card {
  background: var(--bg-card); border-radius: var(--radius);
  padding: 1.5rem; border: 1px solid var(--border);
  backdrop-filter: blur(12px); -webkit-backdrop-filter: blur(12px);
  transition: all 0.3s ease;
}
.card:hover { transform: translateY(-2px); box-shadow: 0 8px 24px rgba(0,0,0,0.1); border-color: rgba(0,122,255,0.12); }
.card h3 { margin-top: 0; }
.card-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(280px, 1fr)); gap: 1rem; }
.grid-2 { display: grid; grid-template-columns: repeat(auto-fill, minmax(220px, 1fr)); gap: 0.8rem; }

/* Articles list */
#articles-list { max-width: 700px; margin: 0 auto; }
.article-item { padding: 1.2rem 0; border-bottom: 1px solid var(--border); }
.article-item:last-child { border-bottom: none; }
.article-item h3 { margin: 0 0 0.2rem; font-size: 1.05rem; }
.article-item .date { font-size: 0.8rem; color: var(--muted); }
.article-item .excerpt { font-size: 0.9rem; color: var(--text-secondary); margin: 0.3rem 0 0; }

/* Copy Button */
.copy-btn {
  background: rgba(0,122,255,0.08); border: 1px solid rgba(0,122,255,0.15);
  color: var(--primary); font-size: 0.8rem; padding: 0.3rem 0.8rem;
  border-radius: 12px; cursor: pointer; transition: all 0.25s;
  white-space: nowrap; flex-shrink: 0;
}
.copy-btn:hover { background: rgba(0,122,255,0.14); }
.copy-btn.copied { background: var(--green); color: #fff; border-color: var(--green); }

.copy-tooltip {
  position: fixed; bottom: 2rem; left: 50%; transform: translateX(-50%) translateY(20px);
  background: var(--text); color: #fff; padding: 0.5rem 1.5rem;
  border-radius: 20px; font-size: 0.85rem; opacity: 0; transition: all 0.3s ease;
  pointer-events: none; z-index: 1000;
}
.copy-tooltip.show { opacity: 1; transform: translateX(-50%) translateY(0); }

/* Highlight box */
.highlight-box {
  background: linear-gradient(135deg, rgba(0,122,255,0.06), rgba(88,86,214,0.04));
  border-left: 3px solid var(--primary);
  border-radius: 0 12px 12px 0;
}

/* Footer */
footer { text-align: center; padding: 3rem 1.5rem; color: var(--muted); font-size: 0.85rem; border-top: 1px solid var(--border); margin-top: 3rem; }
footer a { color: var(--primary); }

/* Loading */
.loading { text-align: center; color: var(--muted); padding: 2rem; }

/* Responsive */
@media (max-width: 768px) {
  h1 { font-size: 2rem; }
  .hero { padding: 3rem 0 2rem; }
  .hero h1 { font-size: 2.2rem; }
  .trust-bar { gap: 1.5rem; }
  .trust-item .num { font-size: 1.6rem; }
  .stats-row { gap: 1.5rem; }
  .stat-item .n { font-size: 2rem; }
  .nav-links li a { padding: 0.3rem 0.5rem; font-size: 0.8rem; }
}


/* === Public Redesign 2026-07-02b === */
:root{--xf-ink:#0b1020;--xf-soft:#f5f7fb;--xf-line:rgba(15,23,42,.10);--xf-blue:#2563eb;--xf-cyan:#06b6d4;--xf-gold:#f59e0b;--xf-radius:24px;--xf-shadow:0 22px 70px rgba(15,23,42,.10)}
body{background:radial-gradient(circle at 18% 0%,rgba(37,99,235,.13),transparent 28%),radial-gradient(circle at 82% 12%,rgba(6,182,212,.12),transparent 30%),linear-gradient(180deg,#f8fbff 0%,#ffffff 42%,#f6f8fc 100%);color:var(--xf-ink)}
header{position:sticky;top:0;z-index:20;background:rgba(255,255,255,.78);backdrop-filter:blur(18px);border-bottom:1px solid var(--xf-line)}
nav{max-width:1180px;margin:0 auto;padding:.82rem 1.2rem}.nav-brand{font-weight:900;letter-spacing:-.03em}.nav-brand span{color:var(--xf-blue)}.nav-links a{border-radius:999px;padding:.42rem .75rem}.nav-links a.active,.nav-links a:hover{background:#eef4ff;color:var(--xf-blue);text-decoration:none}
.xf-shell{max-width:1180px;margin:0 auto;padding-left:1.1rem;padding-right:1.1rem}.xf-hero{padding:5.2rem 1.1rem 3.2rem;text-align:center}.xf-hero.small{padding-top:3.8rem}.xf-kicker{display:inline-flex;align-items:center;gap:.4rem;color:var(--xf-blue);font-weight:800;font-size:.88rem;letter-spacing:.08em;text-transform:uppercase}.xf-hero h1{max-width:930px;margin:.8rem auto 1rem;font-size:clamp(2.25rem,6vw,5.2rem);line-height:1.02;letter-spacing:-.07em}.xf-hero h1 em{font-style:normal;background:linear-gradient(135deg,var(--xf-blue),var(--xf-cyan));-webkit-background-clip:text;background-clip:text;color:transparent}.xf-sub{max-width:760px;margin:0 auto;color:#526071;font-size:1.08rem;line-height:1.9}.xf-actions{display:flex;gap:.8rem;justify-content:center;flex-wrap:wrap;margin:1.8rem 0}.xf-btn{display:inline-flex;align-items:center;justify-content:center;min-height:42px;padding:.72rem 1.08rem;border-radius:999px;border:1px solid var(--xf-line);background:#fff;color:#162033;text-decoration:none;font-weight:750;box-shadow:0 8px 28px rgba(15,23,42,.06)}.xf-btn.primary{background:linear-gradient(135deg,var(--xf-blue),var(--xf-cyan));color:#fff;border-color:transparent}.xf-btn:hover{transform:translateY(-1px);text-decoration:none}.xf-metrics{display:grid;grid-template-columns:repeat(4,minmax(120px,1fr));gap:.9rem;max-width:880px;margin:2rem auto 0}.xf-metric{background:rgba(255,255,255,.76);border:1px solid var(--xf-line);border-radius:20px;padding:1rem;box-shadow:0 14px 44px rgba(15,23,42,.06)}.xf-metric .num{font-size:2rem;font-weight:900;color:var(--xf-blue)}.xf-metric .label{font-size:.88rem;color:#64748b}.xf-section{padding:2.8rem 1.1rem}.xf-section-head{display:flex;align-items:end;justify-content:space-between;gap:2rem;margin-bottom:1.3rem}.xf-section-head h2{font-size:clamp(1.55rem,3vw,2.55rem);letter-spacing:-.04em;margin:.25rem 0}.xf-section-head p{max-width:520px;color:#64748b;line-height:1.75}.xf-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:1rem}.cases-grid{grid-template-columns:repeat(3,minmax(0,1fr))}.xf-card{position:relative;display:block;min-height:190px;padding:1.35rem;border-radius:var(--xf-radius);border:1px solid var(--xf-line);background:rgba(255,255,255,.82);box-shadow:0 12px 38px rgba(15,23,42,.06);color:inherit;text-decoration:none;overflow:hidden;transition:.22s ease}.xf-card:before{content:"";position:absolute;inset:0;background:linear-gradient(135deg,rgba(37,99,235,.08),rgba(6,182,212,.02));opacity:0;transition:.22s}.xf-card:hover{transform:translateY(-3px);box-shadow:var(--xf-shadow);border-color:rgba(37,99,235,.24);text-decoration:none}.xf-card:hover:before{opacity:1}.xf-card>*{position:relative}.xf-card h3{font-size:1.12rem;line-height:1.45;margin:.45rem 0 .55rem;letter-spacing:-.02em}.xf-card p{color:#5d6b7c;line-height:1.75;margin:0}.eyebrow{font-size:.78rem;color:var(--xf-blue);font-weight:850;letter-spacing:.08em}.xf-tag-row{display:flex;flex-wrap:wrap;gap:.45rem;margin-top:1rem}.xf-tag{background:#eef4ff;color:#2457d6;border:1px solid rgba(37,99,235,.12);border-radius:999px;padding:.22rem .55rem;font-size:.78rem;font-weight:700}.case-score{position:absolute;right:1rem;top:1rem;display:flex;gap:.35rem;align-items:baseline}.case-score span{font-size:1.45rem;font-weight:900;color:var(--xf-blue)}.case-score em{font-style:normal;color:var(--xf-gold);font-weight:900}.xf-detail{max-width:900px;margin:0 auto;padding:2.2rem 1.1rem 4rem}.xf-detail-head{text-align:center;padding:2.6rem 0 1.4rem}.xf-detail-head h1{font-size:clamp(1.9rem,4vw,3.3rem);line-height:1.18;letter-spacing:-.05em;margin:.7rem 0}.xf-article-body{background:rgba(255,255,255,.9);border:1px solid var(--xf-line);border-radius:var(--xf-radius);padding:clamp(1.2rem,3vw,2.2rem);box-shadow:0 12px 42px rgba(15,23,42,.06);line-height:1.9}.xf-article-body h2,.xf-article-body h3{letter-spacing:-.02em}.xf-note{margin-top:1rem;padding:1rem;border-radius:16px;background:#f8fafc;border:1px dashed rgba(37,99,235,.25);color:#64748b}.xf-footer{margin-top:2rem;padding:2.2rem 0;background:#0b1020;color:#dbeafe}.footer-grid{display:flex;justify-content:space-between;gap:1rem;align-items:center}.footer-grid p{color:#93a4bd;margin:.45rem 0 0}.footer-links{display:flex;gap:.8rem;flex-wrap:wrap}.footer-links a{color:#dbeafe;text-decoration:none}.course-hero,.lesson-header{background:linear-gradient(180deg,rgba(255,255,255,.5),rgba(255,255,255,0));border-radius:24px}.lesson-card,.lesson-player-section,.transcript{box-shadow:0 12px 38px rgba(15,23,42,.055)}
@media(max-width:820px){.xf-grid,.cases-grid{grid-template-columns:1fr}.xf-metrics{grid-template-columns:repeat(2,1fr)}.xf-section-head{display:block}.footer-grid{display:block}.xf-hero{padding-top:3.5rem}.nav-links{gap:.15rem}.nav-links a{padding:.35rem .5rem;font-size:.88rem}}
@media(max-width:520px){.xf-metrics{grid-template-columns:1fr}.xf-actions{display:grid}.xf-card{min-height:auto}.xf-hero h1{font-size:2.4rem}}

/* === Round2 Public Polish 2026-07-02c === */
.xf-swarm-hero{position:relative;overflow:hidden;min-height:680px;display:flex;align-items:center;justify-content:center}.xf-hero-inner{position:relative;z-index:2;width:100%}#xf-swarm-canvas{position:absolute;inset:0;width:100%;height:100%;z-index:0;opacity:.82}.xf-swarm-hero:after{content:"";position:absolute;inset:0;z-index:1;background:radial-gradient(circle at 50% 38%,rgba(255,255,255,.18),rgba(255,255,255,.82) 58%,rgba(248,251,255,.94) 100%);pointer-events:none}.xf-steps{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:1rem}.xf-step{background:rgba(255,255,255,.86);border:1px solid var(--xf-line);border-radius:24px;padding:1.25rem;box-shadow:0 12px 38px rgba(15,23,42,.06)}.xf-step b{display:inline-flex;width:34px;height:34px;border-radius:999px;align-items:center;justify-content:center;background:linear-gradient(135deg,var(--xf-blue),var(--xf-cyan));color:#fff}.xf-step h3{margin:.8rem 0 .45rem}.plugin-card.must{border-color:rgba(37,99,235,.34)}.plugin-card.good{border-color:rgba(6,182,212,.28)}.plugin-card.optional{opacity:.92}.xf-story{max-width:820px;margin:0 auto;background:rgba(255,255,255,.9);border:1px solid var(--xf-line);border-radius:28px;padding:clamp(1.4rem,3vw,2.4rem);box-shadow:0 18px 58px rgba(15,23,42,.08)}.xf-story p{font-size:1.05rem;line-height:2;color:#475569;margin:.2rem 0 1rem}.about-metrics{max-width:980px}@media(max-width:900px){.xf-steps{grid-template-columns:1fr 1fr}.xf-swarm-hero{min-height:620px}}@media(max-width:560px){.xf-steps{grid-template-columns:1fr}.xf-swarm-hero{min-height:620px}.xf-swarm-hero:after{background:rgba(248,251,255,.84)}}