/* ===== RESET & VARS ===== */
*,*::before,*::after{box-sizing:border-box;margin:0;padding:0}
:root{
  --bg:#ffffff;--bg2:#f6f8fa;--bg3:#f0f2f5;
  --bg-header:#1b1f23;
  --text:#1f2328;--text2:#656d76;--text3:#8b949e;
  --border:#d1d9e0;--border2:#e8ecf0;
  --accent:#0969da;--accent-bg:#ddf4ff;--accent-light:#54aeff;
  --green:#1a7f37;--green-bg:#dafbe1;
  --amber:#9a6700;--amber-bg:#fff8c5;
  --red:#cf222e;
  --purple:#8250df;--purple-bg:#fbefff;
  --left-w:20%;--right-w:20%;--header-h:52px;
  --font:'Pretendard Variable','Pretendard',-apple-system,BlinkMacSystemFont,'Segoe UI',Roboto,sans-serif;
  --mono:'JetBrains Mono','Fira Code','SF Mono',Consolas,monospace;
}
html{font-size:15px;line-height:1.7;color:var(--text);font-family:var(--font);-webkit-font-smoothing:antialiased}
body{background:var(--bg);overflow:hidden;height:100vh;display:flex;flex-direction:column}
a{color:var(--accent);text-decoration:none}
a:hover{text-decoration:underline}

/* ===== HEADER ===== */
.app-header{
  background:var(--bg-header);color:#fff;height:var(--header-h);
  display:flex;align-items:center;padding:0 20px;gap:16px;flex-shrink:0;z-index:100;
  border-bottom:1px solid rgba(255,255,255,0.08);
}
.header-left{display:flex;align-items:center;gap:10px}
.logo{
  padding:0 8px;height:30px;background:linear-gradient(135deg,#f59e0b,#ef4444);
  border-radius:8px;display:flex;align-items:center;justify-content:center;
  font-weight:700;font-size:11px;line-height:30px;color:#fff;letter-spacing:0.02em;
}
.header-title{font-size:15px;font-weight:600;white-space:nowrap;letter-spacing:-0.01em}
.tab-bar{display:flex;gap:2px;margin-left:32px;height:100%;align-items:center}
.tab{
  background:none;border:none;color:rgba(255,255,255,0.55);
  padding:6px 16px;cursor:pointer;font-size:13.5px;font-weight:500;
  font-family:var(--font);border-bottom:none;border-radius:6px;
  transition:all 0.15s;
}
.tab:hover{color:rgba(255,255,255,0.85)}
.tab.active{color:#fff;background:rgba(255,255,255,0.1)}

/* ===== LAYOUT ===== */
.tab-content{display:none;flex:1;overflow:hidden}
.tab-content.active{display:flex}

/* Left nav */
.left-nav{
  width:var(--left-w);flex-shrink:0;background:var(--bg);
  border-right:1px solid var(--border2);overflow-y:auto;
  padding:16px 0;
}
.left-nav-header{
  padding:0 16px 12px;font-size:11px;font-weight:600;
  text-transform:uppercase;letter-spacing:0.05em;color:var(--text3);
}
.left-nav-item{
  display:flex;align-items:center;gap:10px;
  padding:9px 16px;cursor:pointer;
  font-size:13.5px;color:var(--text2);
  border-left:2px solid transparent;
  transition:all 0.12s;
}
.left-nav-item:hover{background:var(--bg2);color:var(--text)}
.left-nav-item.active{
  color:var(--accent);font-weight:600;
  background:var(--accent-bg);
  border-left-color:var(--accent);
}
.step-label{line-height:1.3}

/* Center content */
.center-content{
  flex:1;overflow-y:auto;padding:32px 48px 80px;
  min-width:0;
}
.center-content .section-content{
  max-width:720px;margin:0 auto;
}
.center-content h1{font-size:1.75rem;font-weight:700;margin:0 0 20px;letter-spacing:-0.02em;color:var(--text);line-height:1.3}
.center-content h2{font-size:1.35rem;font-weight:650;margin:36px 0 14px;padding-top:20px;border-top:1px solid var(--border2);color:var(--text);letter-spacing:-0.01em}
.center-content h3{font-size:1.1rem;font-weight:600;margin:28px 0 10px;color:var(--text)}
.center-content h4{font-size:0.95rem;font-weight:600;margin:22px 0 8px;color:var(--text2)}
.center-content p{margin:0 0 12px;color:var(--text)}
.center-content ul,.center-content ol{margin:0 0 14px;padding-left:24px}
.center-content li{margin:3px 0;color:var(--text)}
.center-content li+li{margin-top:4px}
.center-content hr{border:none;border-top:1px solid var(--border2);margin:28px 0}
.center-content code{
  font-family:var(--mono);font-size:0.85em;
  background:var(--bg2);padding:2px 6px;border-radius:4px;
  color:var(--red);
}
.center-content pre{
  margin:14px 0;border-radius:8px;border:1px solid var(--border2);
  overflow-x:auto;background:#f6f8fa;
  padding:14px 16px;
  font-family:var(--mono);font-size:13px;line-height:1.55;
}
.center-content pre code{background:none;padding:0;color:inherit;font-size:inherit}
.center-content img{max-width:100%;border-radius:8px;margin:8px 0}

/* Blockquote */
.center-content blockquote{
  margin:14px 0;padding:12px 16px;
  background:var(--accent-bg);border-left:3px solid var(--accent);
  border-radius:0 8px 8px 0;
  font-size:0.92em;color:var(--text);
}
.center-content blockquote p{margin:0 0 6px}
.center-content blockquote p:last-child{margin:0}

/* Table */
.center-content table{
  width:100%;border-collapse:collapse;font-size:0.88em;
  margin:14px 0;border-radius:8px;border:1px solid var(--border2);
  overflow:hidden;
}
.center-content th{
  background:var(--bg2);padding:10px 14px;text-align:left;
  font-weight:600;border-bottom:1px solid var(--border);
}
.center-content td{
  padding:9px 14px;border-bottom:1px solid var(--border2);
  vertical-align:top;
}
.center-content tr:last-child td{border-bottom:none}
.center-content tbody tr:hover{background:var(--bg2)}

/* Heading anchor */
.center-content h2,
.center-content h3,
.center-content h4{position:relative}
.heading-anchor{
  position:absolute;left:-1.3em;
  font-size:0.85em;color:var(--text3);text-decoration:none;
  opacity:0;transition:opacity 0.15s;font-weight:400;
}
.center-content h2:hover .heading-anchor,
.center-content h3:hover .heading-anchor,
.center-content h4:hover .heading-anchor{opacity:1}
.heading-anchor:hover{color:var(--accent);text-decoration:none}

/* Right TOC */
.right-toc{
  width:var(--right-w);flex-shrink:0;background:var(--bg);
  border-left:1px solid var(--border2);overflow-y:auto;
  padding:20px 0;
}
.right-toc-header{
  padding:0 16px 10px;font-size:11px;font-weight:600;
  text-transform:uppercase;letter-spacing:0.05em;color:var(--text3);
}
.right-toc-item{
  display:block;padding:5px 16px;
  font-size:12.5px;color:var(--text3);
  cursor:pointer;border-left:2px solid transparent;
  transition:all 0.12s;line-height:1.4;
  text-overflow:ellipsis;overflow:hidden;white-space:nowrap;
}
.right-toc-item:hover{color:var(--text)}
.right-toc-item.active{color:var(--accent);border-left-color:var(--accent)}
.right-toc-item.level-3{padding-left:28px;font-size:12px}
.right-toc-item.level-4{padding-left:40px;font-size:11.5px}

/* Scrollbar */
::-webkit-scrollbar{width:6px;height:6px}
::-webkit-scrollbar-track{background:transparent}
::-webkit-scrollbar-thumb{background:var(--border);border-radius:3px}
::-webkit-scrollbar-thumb:hover{background:var(--text3)}

/* Section animation */
.section-content{animation:fadeIn 0.15s ease}
@keyframes fadeIn{from{opacity:0;transform:translateY(4px)}to{opacity:1;transform:translateY(0)}}

/* Empty state */
.empty-state{
  display:flex;flex-direction:column;align-items:center;justify-content:center;
  height:300px;color:var(--text3);gap:12px;font-size:14px;
}

/* ===== MOBILE: 햄버거 메뉴 버튼 ===== */
.mobile-menu-btn{
  display:none;background:none;border:none;color:#fff;
  font-size:22px;cursor:pointer;padding:4px 8px;line-height:1;
  margin-left:auto;
}
.mobile-nav-overlay{
  display:none;position:fixed;inset:0;z-index:200;
  background:rgba(0,0,0,0.4);
}
.mobile-nav-overlay.open{display:block}
.mobile-nav-panel{
  position:fixed;top:0;left:0;bottom:0;width:280px;
  background:var(--bg);z-index:201;
  transform:translateX(-100%);transition:transform 0.25s ease;
  overflow-y:auto;padding:16px 0;
  box-shadow:2px 0 12px rgba(0,0,0,0.15);
}
.mobile-nav-panel.open{transform:translateX(0)}
.mobile-nav-close{
  display:flex;justify-content:flex-end;padding:4px 12px 12px;
}
.mobile-nav-close button{
  background:none;border:none;font-size:24px;color:var(--text2);
  cursor:pointer;padding:4px 8px;
}
.mobile-nav-tab{
  padding:10px 16px;font-size:14px;font-weight:600;
  color:var(--text);cursor:pointer;
  border-left:3px solid transparent;
}
.mobile-nav-tab:hover{background:var(--bg2)}
.mobile-nav-tab.active{color:var(--accent);border-left-color:var(--accent);background:var(--accent-bg)}
.mobile-nav-section{
  padding:8px 16px 8px 28px;font-size:13px;color:var(--text2);
  cursor:pointer;border-left:3px solid transparent;
}
.mobile-nav-section:hover{background:var(--bg2);color:var(--text)}
.mobile-nav-section.active{color:var(--accent);font-weight:600}
.mobile-nav-divider{height:1px;background:var(--border2);margin:8px 16px}

/* ===== RESPONSIVE ===== */
@media(max-width:1024px){
  :root{--right-w:0px}
  .right-toc{display:none}
  .center-content{padding:24px 32px 60px}
}
@media(max-width:768px){
  :root{--left-w:0px;--right-w:0px}
  .left-nav{display:none}
  .right-toc{display:none}
  .center-content{padding:16px 14px 80px}
  .center-content .section-content{max-width:100%}
  .tab-bar{display:none}
  .mobile-menu-btn{display:block}
  .header-title{font-size:13px}
  .app-header{padding:0 12px;gap:10px}
  body{overflow-x:hidden}
  .center-content h1{font-size:1.3rem;margin-bottom:14px}
  .center-content h2{font-size:1.1rem;margin:24px 0 10px;padding-top:14px}
  .center-content h3{font-size:0.95rem;margin:18px 0 8px}
  .center-content{font-size:14px;line-height:1.8}
  .center-content p{word-break:keep-all}
  .center-content li{word-break:keep-all;line-height:1.7}
  .center-content blockquote{padding:10px 12px;font-size:0.88em}
  .center-content blockquote p{word-break:keep-all}
  .center-content pre{font-size:12px;padding:10px 12px}
  /* 모바일 테이블 */
  .center-content table{font-size:0.82em;width:100%;display:table;overflow-x:auto}
  .center-content th{padding:8px 10px}
  .center-content td{padding:7px 10px;white-space:normal;word-break:keep-all}
  .center-content ol{padding-left:20px}
  .center-content ul{padding-left:18px}
  .center-content hr{margin:20px 0}
}