:root{
  --bg:#0b1220;
  --panel:#111a2e;
  --panel2:#0f1830;
  --text:#e7eefc;
  --muted:#a9b7d0;
  --border:#24314f;
  --shadow: rgba(0,0,0,0.25);
  --max: 1100px;
}

*{box-sizing:border-box}
html,body{height:100%}
body{
  margin:0;
  font-family: system-ui, -apple-system, Segoe UI, Roboto, Helvetica, Arial;
  color:var(--text);
  background:var(--bg);
}

.layout{
  display:grid;
  grid-template-columns: 320px 1fr;
  min-height:100vh;
}

.sidebar{
  padding:18px;
  border-right:1px solid var(--border);
  background: linear-gradient(180deg, var(--panel), var(--panel2));
  position:sticky;
  top:0;
  height:100vh;
  overflow:auto;
}

.brand h1{margin:0 0 4px 0; font-size:24px}
.brand p{margin:0 0 14px 0}

.section-title{
  margin:14px 0 8px 0;
  font-size:12px;
  letter-spacing:0.08em;
  text-transform:uppercase;
  color:var(--muted);
}

.nav-item{
  display:flex;
  justify-content:space-between;
  gap:12px;
  padding:10px 12px;
  border:1px solid var(--border);
  border-radius:12px;
  color:inherit;
  text-decoration:none;
  margin:10px 0;
  box-shadow: 0 8px 22px var(--shadow);
  background: rgba(255,255,255,0.02);
}

.nav-item:hover{filter:brightness(1.08)}
.nav-item.active{outline:2px solid rgba(255,255,255,0.18)}

.pill{
  font-size:12px;
  color:var(--muted);
  white-space:nowrap;
}

.content{padding:22px}

.page-header{max-width: var(--max)}
.page-header h2{margin:0 0 6px 0}
.page-header p{margin:0 0 16px 0}

.cards{
  max-width: var(--max);
  display:grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap:14px;
}

.card{
  display:block;
  padding:14px;
  border:1px solid var(--border);
  border-radius:16px;
  text-decoration:none;
  color:inherit;
  background: rgba(255,255,255,0.02);
  box-shadow: 0 10px 30px var(--shadow);
}

.card:hover{filter:brightness(1.08)}
.card h3{margin:0 0 6px 0}
.card p{margin:0}

.note{
  max-width: var(--max);
  margin-top:18px;
  padding:14px;
  border:1px solid var(--border);
  border-radius:16px;
  background: rgba(255,255,255,0.02);
}

.muted{color:var(--muted)}
.footer{margin-top:20px; font-size:12px}

.domain-wrap{max-width: var(--max)}

.objective{
  margin:14px 0;
  padding:14px;
  border:1px solid var(--border);
  border-radius:16px;
  background: rgba(255,255,255,0.02);
  box-shadow: 0 10px 30px var(--shadow);
}

.objective h3{
  margin:0 0 10px 0;
  font-size:16px;
}

.objective .sub{
  margin:14px 0 10px 0;
  font-size:13px;
  color:var(--muted);
}

ul{margin:8px 0 0 18px}
li{margin:6px 0}
code{
  font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", monospace;
  font-size: 0.95em;
}

/* Sidebar accordion controls */
.sidebar-controls{
  display:flex;
  gap:8px;
  margin: 8px 0 12px 0;
}

.sidebtn{
  flex:1;
  cursor:pointer;
  padding:8px 10px;
  border:1px solid var(--border);
  border-radius:12px;
  background: rgba(255,255,255,0.02);
  color:var(--text);
  box-shadow: 0 8px 22px var(--shadow);
}

.sidebtn:hover{filter:brightness(1.08)}

/* Accordion tree */
.nav-group{margin:10px 0}

.nav-toggle{
  width:100%;
  display:flex;
  justify-content:space-between;
  align-items:center;
  gap:10px;
  text-align:left;
  padding:10px 12px;
  border:1px solid var(--border);
  border-radius:12px;
  background: rgba(255,255,255,0.02);
  color:inherit;
  cursor:pointer;
  box-shadow: 0 8px 22px var(--shadow);
}

.nav-toggle:hover{filter:brightness(1.08)}
.nav-toggle.active{outline:2px solid rgba(255,255,255,0.18)}

.nav-toggle .left{display:flex; flex-direction:column; gap:2px}
.nav-toggle .title{font-size:14px}
.nav-toggle .meta{font-size:12px; color:var(--muted)}
.nav-toggle .chev{opacity:0.8}

.subnav{
  margin-top:8px;
  padding-left:10px;
  display:flex;
  flex-direction:column;
  gap:8px;
}

.subnav a{
  display:flex;
  align-items:baseline;
  gap:10px;
  padding:8px 10px;
  border:1px solid var(--border);
  border-radius:12px;
  text-decoration:none;
  color:inherit;
  background: rgba(255,255,255,0.02);
}

.subnav a:hover{filter:brightness(1.08)}
.subnav a.active{outline:2px solid rgba(255,255,255,0.18)}

.subid{
  font-size:12px;
  color:var(--muted);
  white-space:nowrap;
}

/* Home button */
.home-btn{
  display:block;
  margin: 0 0 10px 0;
  padding:10px 12px;
  border:1px solid var(--border);
  border-radius:12px;
  text-decoration:none;
  color:inherit;
  background: rgba(255,255,255,0.02);
  box-shadow: 0 8px 22px var(--shadow);
}
.home-btn:hover{filter:brightness(1.08)}

/* Socials */
.social-title{
  margin:16px 0 8px 0;
  font-size:12px;
  letter-spacing:0.08em;
  text-transform:uppercase;
  color:var(--muted);
}

.social-icons{
  display:flex;
  gap:10px;
  flex-wrap:wrap;
}

.social-icons a{
  width:38px;
  height:38px;
  display:inline-flex;
  align-items:center;
  justify-content:center;
  border:1px solid var(--border);
  border-radius:12px;
  background: rgba(255,255,255,0.02);
  box-shadow: 0 8px 22px var(--shadow);
  color: var(--text);
  text-decoration:none;
}

.social-icons a:hover{filter:brightness(1.08)}
.social-icons svg{width:18px; height:18px; fill: currentColor; opacity:0.95}

/* Pager (Prev/Home/Next) */
.pager{
  max-width: var(--max);
  margin-top: 18px;
  display:flex;
  gap:12px;
  flex-wrap:wrap;
}

.pager-btn{
  display:inline-block;
  padding:10px 12px;
  border:1px solid var(--border);
  border-radius:12px;
  text-decoration:none;
  color:inherit;
  background: rgba(255,255,255,0.02);
  box-shadow: 0 10px 30px var(--shadow);
}
.pager-btn:hover{filter:brightness(1.08)}

/* YouTube embed */
.yt{
  position:relative;
  width:100%;
  padding-top:56.25%;
  border:1px solid var(--border);
  border-radius:16px;
  overflow:hidden;
  background: rgba(255,255,255,0.02);
  box-shadow: 0 10px 30px var(--shadow);
  margin-top: 6px;
}

.yt iframe{
  position:absolute;
  inset:0;
  width:100%;
  height:100%;
  border:0;
}

/* Markdown styling */
.md{
  margin-top: 14px;
  line-height: 1.65;
}

.md h1,.md h2,.md h3{
  margin: 16px 0 10px 0;
}

.md p{
  margin: 10px 0;
}

.md pre{
  padding: 12px;
  border: 1px solid var(--border);
  border-radius: 12px;
  background: rgba(255,255,255,0.02);
  overflow:auto;
}

.md blockquote{
  margin: 10px 0;
  padding: 10px 12px;
  border-left: 3px solid var(--border);
  background: rgba(255,255,255,0.02);
  border-radius: 10px;
}

.md table{
  width:100%;
  border-collapse: collapse;
  margin-top: 12px;
}

.md th,.md td{
  border:1px solid var(--border);
  padding: 8px;
  vertical-align: top;
}

.md a{
  color: var(--text);
  text-decoration: underline;
}

/* Force the native [hidden] attribute to actually hide elements */
[hidden] {
  display: none !important;
}

/* Markdown images (per-objective assets) */
.md-img{
  max-width: 100%;
  height: auto;
  display: block;
  border-radius: 12px;
  border: 1px solid var(--border);
  background: rgba(255,255,255,0.02);
  box-shadow: 0 10px 30px var(--shadow);
}

/* -----------------------------
   Mobile Hamburger Drawer Sidebar
   ----------------------------- */

/* Floating hamburger button (mobile only) */
.hamburger-fab{
  position: fixed;
  top: 14px;
  left: 14px;
  z-index: 1101;
  width: 44px;
  height: 44px;
  border-radius: 14px;
  border: 1px solid var(--border);
  background: rgba(255,255,255,0.04);
  color: var(--text);
  box-shadow: 0 10px 30px var(--shadow);
  cursor: pointer;
  display: none; /* enabled on mobile via media query */
  font-size: 20px;
  line-height: 1;
}
.hamburger-fab:hover{filter:brightness(1.08)}

/* Backdrop behind drawer */
.sidebar-backdrop{
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.55);
  z-index: 1100;
  display: none;
}

/* Drawer behavior only on mobile */
@media (max-width: 900px){
  /* show hamburger */
  .hamburger-fab{ display: inline-flex; align-items:center; justify-content:center; }

  /* make layout single column */
  .layout{
    grid-template-columns: 1fr;
  }

  /* sidebar becomes a drawer */
  .sidebar{
    position: fixed;
    top: 0;
    left: 0;
    height: 100vh;
    width: min(86vw, 360px);
    z-index: 1102;
    transform: translateX(-110%);
    transition: transform 180ms ease;
    border-right: 1px solid var(--border);
    overflow: auto;
  }

  /* open state */
  body.sidebar-open .sidebar{
    transform: translateX(0);
  }

  body.sidebar-open .sidebar-backdrop{
    display: block;
  }

  /* content spacing so hamburger doesn't cover header text */
  .content{
    padding-top: 64px;
  }
}

@media (max-width: 900px){
  .cards{ grid-template-columns: 1fr !important; }
  .layout{ grid-template-columns: 1fr !important; }
  .page-header, .cards, .note, .domain-wrap{ max-width: 100% !important; }
}