/* UN R177 정보 허브 — 공유 스타일 (사이드바·히어로·번호섹션·카드/콜아웃/수식)
   톤: 공신력 있는 연구 레퍼런스. 다크 사이드바 + 블루 강조 + 티얼 포인트. */
:root{
  --bg:#f5f7fa; --surface:#ffffff; --surface2:#eef2f7; --line:#dfe6ee;
  --text:#1f2a37; --muted:#5b6b7b; --soft:#7a8896;
  --accent:#1f6feb; --accent-d:#1452c4; --teal:#0f9d8b; --warn:#b9770a; --warn-bg:#fff6e6;
  --ok:#0f9d6b; --ok-bg:#e8f7f0; --sidebar:#0f2238;
}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{margin:0;font-family:"Segoe UI","Malgun Gothic","Apple SD Gothic Neo",system-ui,sans-serif;
  background:var(--bg);color:var(--text);line-height:1.7;font-size:16px}
a{color:var(--accent);text-decoration:none}
a:hover{text-decoration:underline}
code{font-family:Consolas,"Courier New",monospace;font-size:.92em;background:var(--surface2);padding:1px 5px;border-radius:4px}

/* layout */
.layout{display:grid;grid-template-columns:280px 1fr;min-height:100vh}

/* sidebar */
aside{position:sticky;top:0;align-self:start;height:100vh;overflow-y:auto;
  background:var(--sidebar);color:#cdd9e6;padding:22px 0}
aside a.brand{display:block;padding:0 22px 16px;border-bottom:1px solid rgba(255,255,255,.1);
  margin-bottom:10px;border-left:none}
aside a.brand:hover{background:none;text-decoration:none}
aside .brand .t{color:#fff;font-weight:700;font-size:1.05rem;line-height:1.35}
aside .brand .s{color:#8fa6bd;font-size:.8rem;margin-top:4px}
aside .group{padding:16px 0 4px;margin-top:8px;border-top:1px solid rgba(255,255,255,.07)}
aside .group:first-of-type{margin-top:0;border-top:none}
aside .group .h{color:#aebfd2;font-size:.78rem;font-weight:700;letter-spacing:.07em;
  padding:0 22px 8px;display:flex;align-items:center;gap:8px}
aside .group .h::before{content:"";width:12px;height:2px;border-radius:2px;background:var(--teal);flex:none;opacity:.85}
aside a{display:block;color:#bcccdc;padding:7px 22px;font-size:.9rem;border-left:3px solid transparent}
aside a:hover{background:rgba(255,255,255,.06);color:#fff;text-decoration:none}
aside a.active{color:#fff;border-left-color:var(--accent);background:rgba(31,111,235,.16);font-weight:600}

/* main */
main{min-width:0}
.hero{background:linear-gradient(180deg,#eaf1fb,#f5f7fa);border-bottom:1px solid var(--line);padding:48px 48px 36px}
.hero .kick{color:var(--teal);font-weight:700;letter-spacing:.06em;font-size:.8rem;text-transform:uppercase}
.hero h1{font-size:2rem;margin:.25em 0 .35em;line-height:1.25;letter-spacing:-.01em}
.hero p{color:var(--muted);max-width:820px;margin:0;font-size:1.05rem}
.chips{margin-top:16px;display:flex;flex-wrap:wrap;gap:8px}
.chip{background:var(--surface);border:1px solid var(--line);border-radius:999px;padding:5px 13px;font-size:.82rem;color:var(--muted)}

/* page header (sub-pages) */
.pagehead{background:linear-gradient(180deg,#eaf1fb,#f5f7fa);border-bottom:1px solid var(--line);padding:36px 48px 26px}
.pagehead .kick{color:var(--teal);font-weight:700;letter-spacing:.06em;font-size:.8rem;text-transform:uppercase}
.pagehead h1{font-size:1.75rem;margin:.2em 0 0;letter-spacing:-.01em;color:#10233c}
.pagehead .sub{color:var(--soft);font-size:.85rem;margin-top:6px}

.content{padding:30px 48px 80px;max-width:920px}
section{padding:8px 0 24px;border-bottom:1px solid var(--line)}
section:last-child{border-bottom:none}
h2{font-size:1.5rem;margin:0 0 4px;letter-spacing:-.01em;scroll-margin-top:16px}
h2 .num{color:var(--accent);font-weight:800;margin-right:8px}
.lead{color:var(--soft);margin:0 0 20px;font-size:1.02rem}
h3{font-size:1.12rem;margin:26px 0 8px}
h4{font-size:1rem;margin:18px 0 6px;color:#2c3a4a}
p{margin:0 0 12px}
ul,ol{margin:0 0 14px;padding-left:20px}
li{margin:5px 0}

.grid{display:grid;gap:16px}
.g2{grid-template-columns:1fr 1fr}
.g3{grid-template-columns:repeat(3,1fr)}
.card{background:var(--surface);border:1px solid var(--line);border-radius:12px;padding:16px 18px}
.card h4{margin:0 0 6px;color:var(--text)}
.card p{margin:0;color:var(--muted);font-size:.94rem}

table{width:100%;border-collapse:collapse;font-size:.9rem;margin:6px 0 8px}
th,td{border:1px solid var(--line);padding:9px 11px;text-align:left;vertical-align:top}
th{background:var(--surface2);font-weight:700;color:#2c3a4a}
tr:nth-child(even) td{background:#fafcfe}

.formula{background:#0f2238;color:#dbe7f5;border-radius:9px;padding:11px 14px;font-family:Consolas,"Courier New",monospace;font-size:.9rem;overflow-x:auto;margin:8px 0;white-space:pre-wrap}
.content img{max-width:100%;height:auto;display:block;margin:16px auto;border:1px solid var(--line);border-radius:8px;background:#fff;padding:6px}
.callout{border-radius:10px;padding:13px 16px;margin:14px 0;font-size:.94rem;border:1px solid}
.info{background:#eef5ff;border-color:#cfe0fb;color:#1d3a63}
.warn{background:var(--warn-bg);border-color:#f0d9a8;color:#7a5206}
.ok{background:var(--ok-bg);border-color:#bce8d4;color:#0a5c3e}

.badge{font-size:.7rem;padding:2px 8px;border-radius:6px;font-weight:700;vertical-align:middle}
.b-ok{background:var(--ok-bg);color:var(--ok);border:1px solid #bce8d4}
.b-warn{background:var(--warn-bg);color:var(--warn);border:1px solid #f0d9a8}
.b-info{background:#eef5ff;color:var(--accent);border:1px solid #cfe0fb}

/* timeline */
.timeline{position:relative;margin:10px 0 0;padding-left:24px}
.timeline::before{content:"";position:absolute;left:7px;top:6px;bottom:6px;width:2px;background:var(--line)}
.tl{position:relative;padding:6px 0 14px 10px}
.tl::before{content:"";position:absolute;left:-21px;top:11px;width:11px;height:11px;border-radius:50%;background:var(--accent);box-shadow:0 0 0 4px #dbe8fc}
.tl .d{color:var(--accent-d);font-weight:700;font-size:.9rem}
.tl .e{color:var(--text)}

.src{font-size:.82rem;color:var(--soft);margin-top:8px}
.src b{color:var(--muted)}
.reflinks{margin:26px 0 4px;border-top:1px solid var(--line);padding-top:14px}
.reflinks h4{margin:0 0 9px;font-size:.78rem;color:var(--soft);font-weight:700;letter-spacing:.04em;text-transform:uppercase}
.reflinks ul{margin:0;padding:0;list-style:none;display:grid;gap:6px}
.reflinks li{font-size:.85rem;line-height:1.5;padding-left:15px;position:relative;color:var(--muted)}
.reflinks li::before{content:"↗";position:absolute;left:0;top:0;color:var(--accent);font-size:.78rem}
.reflinks a{color:var(--accent)}
.reflinks .m{color:var(--soft);font-size:.8rem}

.pagenav{display:flex;justify-content:space-between;gap:12px;margin-top:28px;padding-top:18px;border-top:1px solid var(--line);font-size:.9rem}
.pagenav a{color:var(--accent)}
footer{padding:26px 48px 60px;color:var(--soft);font-size:.85rem;background:var(--surface2)}

.toggle{display:none}
@media(max-width:900px){
  .layout{grid-template-columns:1fr}
  aside{position:sticky;top:0;height:auto;max-height:none;z-index:20;padding:10px 0}
  aside .groups{display:none}
  aside.open .groups{display:block}
  .toggle{display:block;margin:8px 16px 4px;padding:8px 12px;background:rgba(255,255,255,.1);color:#fff;border:none;border-radius:8px;font-size:.9rem}
  .hero,.pagehead,.content,footer{padding-left:20px;padding-right:20px}
  .g2,.g3{grid-template-columns:1fr}
  .hero h1{font-size:1.6rem}
}