/* 沟通数据天文台 · 公共样式（index / insights / zotero 页共用） */
:root {
  --paper: #FAF8F2;
  --paper-2: #FFFEFB;
  --paper-3: #F2EEE5;
  --ink: #1C1917;
  --ink-warm: #2A2018;
  --ink-2: #57534E;
  --ink-dim: #78716C;
  --rule: #E8E3D9;
  --rule-soft: #F1EDE3;
  --accent: #D97706;
  --accent-deep: #B45309;
  --accent-glow: rgba(217, 119, 6, 0.14);
  --good: #4D7C5F;
  --warn: #B45309;
  --bad: #DC2626;
  --serif: "Noto Serif SC", "Songti SC", "STSong", serif;
  --sans: "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", system-ui, sans-serif;
  --mono: "SF Mono", "JetBrains Mono", Menlo, Consolas, monospace;
}
* { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; }
body { background: var(--paper); color: var(--ink); font-family: var(--sans); line-height: 1.75; font-size: 16px; }
::selection { background: var(--accent-glow); }

.wrap { max-width: 1120px; margin: 0 auto; padding: 0 28px; }
.kicker { font-family: var(--mono); font-size: 12px; letter-spacing: .18em; text-transform: uppercase; color: var(--accent-deep); margin-bottom: 14px; }
h2.sec-title { font-family: var(--serif); font-size: clamp(30px, 4vw, 46px); font-weight: 700; line-height: 1.25; margin-bottom: 14px; letter-spacing: -0.01em; }
.sec-sub { color: var(--ink-2); max-width: 740px; margin-bottom: 40px; }
section { padding: 96px 0; }
section + section { border-top: 1px solid var(--rule); }
section > .wrap > h2.sec-title:first-child, section > .wrap > .kicker + h2.sec-title { position: relative; }

nav { position: sticky; top: 0; z-index: 50; background: rgba(250,248,242,.92); backdrop-filter: blur(8px); border-bottom: 1px solid var(--rule); }
.nav-inner { max-width: 1120px; margin: 0 auto; padding: 0 28px; display: flex; align-items: center; justify-content: space-between; height: 60px; }
.logo { font-family: var(--serif); font-weight: 700; font-size: 18px; display: flex; align-items: center; gap: 9px; }
.logo a { color: inherit; text-decoration: none; display: flex; align-items: center; gap: 9px; }
.logo .dot { width: 10px; height: 10px; border-radius: 50%; background: var(--accent); box-shadow: 0 0 0 4px var(--accent-glow); }
.logo .en { font-family: var(--mono); font-size: 12px; color: var(--ink-dim); font-weight: 400; }
.nav-links { display: flex; gap: 24px; align-items: center; }
.nav-links a { color: var(--ink-2); text-decoration: none; font-size: 14px; }
.nav-links a:hover { color: var(--accent-deep); }
.nav-links a.on { color: var(--accent-deep); font-weight: 600; }
.nav-cta { background: var(--ink); color: var(--paper) !important; padding: 7px 16px; border-radius: 999px; font-size: 13px !important; }
.nav-cta:hover { background: var(--accent-deep); }

.btn { display: inline-block; text-decoration: none; padding: 12px 26px; border-radius: 999px; font-size: 15px; transition: transform .15s ease; }
.btn:hover { transform: translateY(-1px); }
.btn:active { transform: translateY(0) scale(0.98); }
.btn-primary { background: var(--ink); color: var(--paper); }
.btn-primary:hover { background: var(--accent-deep); }
.btn-ghost { border: 1.5px solid var(--rule); color: var(--ink); background: var(--paper-2); }
.btn-ghost:hover { border-color: var(--accent); color: var(--accent-deep); }

.card { background: var(--paper-2); border: 1px solid var(--rule); border-radius: 16px; padding: 26px; }
.card h3 { font-family: var(--serif); font-size: 19px; margin-bottom: 10px; }
.card p { font-size: 14px; color: var(--ink-2); }
.grid-3 { display: grid; grid-template-columns: repeat(3, 1fr); gap: 22px; }
.grid-2 { display: grid; grid-template-columns: repeat(2, 1fr); gap: 22px; }

.pill { display: inline-block; font-size: 11px; font-family: var(--mono); padding: 1px 8px; border-radius: 999px; background: var(--paper-3); color: var(--ink-2); border: 1px solid var(--rule); }

footer { border-top: 1px solid var(--rule); padding: 44px 0 60px; }
footer p { font-size: 13px; color: var(--ink-dim); max-width: 620px; }
footer .brand { font-family: var(--serif); font-weight: 700; font-size: 16px; color: var(--ink); margin-bottom: 8px; }

@media (max-width: 900px) {
  .grid-3, .grid-2 { grid-template-columns: 1fr; }
  .nav-links { gap: 14px; }
  .nav-links a:not(.nav-cta) { font-size: 13px; }
}

/* 氛围层：纸面颗粒 + 暖光晕（fixed + pointer-events-none，不进滚动容器） */
body::before {
  content: ""; position: fixed; inset: 0; z-index: 90; pointer-events: none;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='160' height='160'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.9' numOctaves='2'/%3E%3C/filter%3E%3Crect width='160' height='160' filter='url(%23n)' opacity='0.5'/%3E%3C/svg%3E");
  opacity: 0.028; mix-blend-mode: multiply;
}
body::after {
  content: ""; position: fixed; z-index: -1; pointer-events: none;
  top: -240px; right: -180px; width: 720px; height: 720px;
  background: radial-gradient(circle, rgba(217,119,6,.10), transparent 62%);
}
@media (prefers-reduced-motion: reduce) { .rv { opacity: 1 !important; transform: none !important; } }

/* 键盘可达性 + 标题断行优化 */
a:focus-visible, button:focus-visible { outline: 2.5px solid var(--accent); outline-offset: 3px; border-radius: 4px; }
h1, h2 { text-wrap: balance; }

/* 投影演示模式：整体放大 + 次要文字加深（教室投影仪对比度低） */
body.present { zoom: 1.12; }
body.present, body.present * { --ink-2: #44403C; --ink-dim: #57534E; --rule: #DDD7CB; }
.present-toggle {
  font-family: var(--mono); font-size: 11px; cursor: pointer;
  border: 1px solid var(--rule); border-radius: 999px; padding: 4px 12px;
  background: var(--paper-2); color: var(--ink-2); white-space: nowrap;
}
.present-toggle.on { background: var(--accent); color: #fff; border-color: var(--accent); }

/* 需求导向开头：问题 → 所以 */
.problem-lead { max-width: 780px; margin: 24px 0 8px; padding: 2px 0 2px 18px; border-left: 3px solid var(--accent); }
.problem-lead .q { font-size: 15.5px; color: var(--ink-2); line-height: 1.9; }
.problem-lead .a { font-size: 15.5px; font-weight: 700; color: var(--ink); margin-top: 8px; line-height: 1.85; }