/* ===== imath 数学设计系统 ===== */

/* 数学色彩变量 */
:root{
  --math-navy:#0a1628;
  --math-blue:#1d4ed8;
  --math-blue-light:#3b82f6;
  --math-gold:#c7940a;
  --math-gold-light:#eab308;
  --math-ink:#1e293b;
  --math-chalk:#f8fafc;
  --math-grid:#e2e8f0;
  --math-shadow:0 4px 24px rgba(15,23,42,.08);
  --math-radius:4px;
  --math-font:'Inter',-apple-system,'PingFang SC','Noto Sans SC',sans-serif;
  --math-mono:'JetBrains Mono','Fira Code','Consolas',monospace;
}

/* 坐标纸底纹 */
body.math-bg{
  background-color:var(--math-chalk);
  background-image:
    linear-gradient(rgba(148,163,184,.06) 1px,transparent 1px),
    linear-gradient(90deg,rgba(148,163,184,.06) 1px,transparent 1px);
  background-size:20px 20px;
  font-family:var(--math-font);
}
body.math-bg::before{
  content:'';
  position:fixed;inset:0;
  background-image:
    linear-gradient(rgba(148,163,184,.12) 1px,transparent 1px),
    linear-gradient(90deg,rgba(148,163,184,.12) 1px,transparent 1px);
  background-size:100px 100px;
  pointer-events:none;z-index:0;opacity:.4;
}

/* 数学图标替换 */
.math-icon{font-family:var(--math-mono);font-weight:400}

/* 黄金分割比例容器 */
.math-phi{aspect-ratio:1.618}

/* 几何阴影 */
.math-shadow-geo{box-shadow:6px 6px 0 rgba(29,78,216,.06),4px 4px 0 rgba(199,148,10,.04)}

/* 数学引用块 */
.math-quote{
  border-left:4px solid var(--math-gold);
  padding:16px 24px;
  margin:24px 0;
  background:linear-gradient(135deg,rgba(29,78,216,.03),transparent);
  font-style:italic;
  color:var(--math-ink);
  font-size:15px;
}
.math-quote::before{content:'\201C';font-size:40px;color:var(--math-gold);line-height:0;vertical-align:-16px;margin-right:4px}
.math-quote .author{display:block;margin-top:8px;font-size:12px;color:var(--math-gold);font-style:normal;font-weight:600}

/* 数学按钮 */
.math-btn{
  display:inline-flex;align-items:center;gap:6px;
  padding:10px 24px;
  background:var(--math-blue);
  color:#fff;
  border:none;border-radius:var(--math-radius);
  font-weight:600;font-size:14px;
  cursor:pointer;
  text-decoration:none;
  transition:all .2s;
  font-family:var(--math-font);
  letter-spacing:.3px;
}
.math-btn:hover{background:var(--math-navy);transform:translateY(-1px);box-shadow:0 4px 12px rgba(29,78,216,.3)}
.math-btn.gold{background:var(--math-gold)}
.math-btn.gold:hover{background:var(--math-navy)}
.math-btn.outline{
  background:transparent;color:var(--math-blue);
  border:2px solid var(--math-blue);
}
.math-btn.outline:hover{background:var(--math-blue);color:#fff}

/* 数学标签 */
.math-tag{
  display:inline-flex;align-items:center;gap:4px;
  padding:3px 10px;
  border-radius:var(--math-radius);
  font-size:11px;font-weight:600;
  font-family:var(--math-mono);
  letter-spacing:.5px;
}

/* 数学分隔线 */
.math-divider{
  height:1px;border:none;
  background:repeating-linear-gradient(90deg,var(--math-grid) 0,var(--math-grid) 8px,transparent 8px,transparent 16px);
  margin:40px 0;
}

/* 数学空状态 */
.math-empty{
  text-align:center;padding:80px 20px;color:var(--math-grid);
}
.math-empty .math-empty-symbol{font-family:var(--math-mono);font-size:64px;font-weight:300;margin-bottom:16px;opacity:.3}
.math-empty p{font-size:14px;color:#94a3b8}

/* 伽利略引用动画 */
.math-hero-quote{
  font-size:20px;
  font-style:italic;
  opacity:.85;
  font-weight:300;
  letter-spacing:1px;
}

/* 滚动出现动画 */
@keyframes mathFadeUp{
  from{opacity:0;transform:translateY(24px)}
  to{opacity:1;transform:translateY(0)}
}
.math-animate{animation:mathFadeUp .6s ease-out both}
.math-animate:nth-child(1){animation-delay:0s}
.math-animate:nth-child(2){animation-delay:.1s}
.math-animate:nth-child(3){animation-delay:.2s}
.math-animate:nth-child(4){animation-delay:.3s}

/* ===== iPhet 兼容（保留） ===== */
:root{
  --iphet-navy:var(--math-navy);
  --iphet-blue:var(--math-blue-light);
  --iphet-muted:#94a3b8;
  --iphet-border:#1e293b;
}