:root {
  --bg:#f6f7fb; --surface:#ffffff; --ink:#172235; --muted:#5c6a80; --line:#dce4ee;
  --primary:#315f72; --primary2:#4d7f8f; --accent:#b6784d; --ok:#4e7f5b; --warn:#b7843b; --danger:#a24d55;
  --soft:#edf5f8; --soft2:#f7efe8; --code:#111827; --radius:18px; --shadow:0 18px 45px rgba(20,40,65,.10);
}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{margin:0;font-family:Inter,ui-sans-serif,system-ui,-apple-system,BlinkMacSystemFont,"Segoe UI",sans-serif;background:var(--bg);color:var(--ink);line-height:1.65}
a{color:var(--primary);text-decoration-thickness:.08em;text-underline-offset:.18em}
img,svg{max-width:100%;height:auto}
.layout{display:grid;grid-template-columns:320px minmax(0,1fr);min-height:100vh}
.sidebar{position:sticky;top:0;height:100vh;overflow:auto;background:linear-gradient(180deg,#fff 0%,#edf4f7 100%);border-right:1px solid var(--line);padding:22px 18px}
.brand{font-weight:900;color:var(--primary);font-size:1.03rem;letter-spacing:.01em}
.subbrand{color:var(--muted);font-size:.86rem;margin-top:4px}
.nav{display:flex;flex-direction:column;gap:5px;margin-top:20px}
.nav a{display:block;padding:9px 10px;border-radius:12px;color:var(--ink);text-decoration:none;font-size:.92rem}
.nav a:hover,.nav a.active{background:#fff;color:var(--primary);box-shadow:0 5px 18px rgba(49,95,114,.09)}
.main{max-width:1180px;width:100%;margin:0 auto;padding:34px 28px 80px}
.hero{border-radius:26px;padding:34px;background:radial-gradient(circle at top left,#e9f4f7 0%,#fff 42%,#f7efe7 100%);box-shadow:var(--shadow);border:1px solid #e3edf2}
.eyebrow{color:var(--accent);font-weight:900;text-transform:uppercase;letter-spacing:.09em;font-size:.78rem}
h1{font-size:clamp(2.0rem,4vw,4.0rem);line-height:1.03;margin:10px 0 14px;letter-spacing:-.04em}
h2{font-size:clamp(1.42rem,2.3vw,2.05rem);line-height:1.15;margin:38px 0 14px;letter-spacing:-.025em;color:#1d3542}
h3{font-size:1.16rem;margin:26px 0 10px;color:#25485a}
h4{font-size:1.02rem;margin:20px 0 8px;color:#315f72}
p{margin:0 0 14px}
.lead{font-size:1.12rem;color:#36465b;max-width:88ch}
.grid{display:grid;gap:18px}
.grid.two{grid-template-columns:repeat(2,minmax(0,1fr))}
.grid.three{grid-template-columns:repeat(3,minmax(0,1fr))}
.card{background:var(--surface);border:1px solid var(--line);border-radius:var(--radius);padding:20px;box-shadow:0 12px 34px rgba(20,40,65,.06)}
.card h3{margin-top:0}
.badge{display:inline-flex;align-items:center;gap:6px;padding:4px 10px;border-radius:999px;background:var(--soft);color:var(--primary);font-size:.78rem;font-weight:900}
.prio{background:#f7efe7;color:#855c32}
.kicker{color:var(--muted);font-size:.93rem}
.system-card{display:flex;flex-direction:column;min-height:250px}
.actions{display:flex;flex-wrap:wrap;gap:8px;margin:18px 0}
button,.btn{appearance:none;border:1px solid #cdd9e5;background:#fff;color:var(--ink);border-radius:12px;padding:9px 12px;cursor:pointer;font-weight:800;text-decoration:none;display:inline-flex;align-items:center;gap:8px}
button:hover,.btn:hover{border-color:#a9bdcc;background:#f9fbfc}
.searchbar{display:flex;gap:8px;align-items:center;margin:20px 0;position:sticky;top:0;z-index:5;padding:10px;background:rgba(247,248,251,.90);backdrop-filter:blur(10px);border-radius:16px;border:1px solid rgba(220,228,238,.7)}
.searchbar input{flex:1;border:1px solid #cbd7e2;border-radius:12px;padding:11px 12px;font:inherit}
.iconbtn{font-size:20px;line-height:1;padding:7px 12px}
mark{background:#ffe28a;padding:0 .12em;border-radius:.25em}
mark.current{background:#ffb36b}
details{border:1px solid var(--line);border-radius:16px;background:#fff;margin:12px 0;overflow:hidden}
summary{cursor:pointer;padding:14px 16px;font-weight:900;color:#244555;background:#f7fafb}
details .details-body{padding:16px}
ul.clean{margin:0;padding-left:1.2rem}
ol.steps{margin:0;padding-left:1.35rem}
.flow{margin:18px 0;display:grid;gap:16px;grid-template-columns:1fr 1fr}
.diagram{background:#fff;border:1px solid var(--line);border-radius:20px;padding:14px;box-shadow:0 10px 30px rgba(20,40,65,.06)}
.caption{color:var(--muted);font-size:.88rem;margin-top:8px}
.code-card{background:#111827;color:#e5e7eb;border-radius:18px;overflow:hidden;box-shadow:0 18px 45px rgba(17,24,39,.18);margin:18px 0}
.code-title{display:flex;justify-content:space-between;align-items:center;padding:10px 14px;background:#0b1220;color:#dbe7f0;font-weight:900;font-size:.9rem}
.copy-btn{padding:5px 8px;border-radius:10px;background:#162235;color:#dbe7f0;border:1px solid #334155;font-size:0}
.copy-btn::before{content:'⧉';font-size:14px}
.highlight{margin:0!important;padding:16px!important;overflow:auto;background:#111827!important;color:#e5e7eb!important;font-size:.91rem;line-height:1.55}
.highlight pre{margin:0}
pre { line-height: 125%; }
td.linenos .normal { color: inherit; background-color: transparent; padding-left: 5px; padding-right: 5px; }
span.linenos { color: inherit; background-color: transparent; padding-left: 5px; padding-right: 5px; }
td.linenos .special { color: #000000; background-color: #ffffc0; padding-left: 5px; padding-right: 5px; }
span.linenos.special { color: #000000; background-color: #ffffc0; padding-left: 5px; padding-right: 5px; }
.highlight .hll { background-color: #ffffcc }
.highlight { background: #f8f8f8; }
.highlight .c { color: #3D7B7B; font-style: italic } /* Comment */
.highlight .err { border: 1px solid #F00 } /* Error */
.highlight .k { color: #008000; font-weight: bold } /* Keyword */
.highlight .o { color: #666 } /* Operator */
.highlight .ch { color: #3D7B7B; font-style: italic } /* Comment.Hashbang */
.highlight .cm { color: #3D7B7B; font-style: italic } /* Comment.Multiline */
.highlight .cp { color: #9C6500 } /* Comment.Preproc */
.highlight .cpf { color: #3D7B7B; font-style: italic } /* Comment.PreprocFile */
.highlight .c1 { color: #3D7B7B; font-style: italic } /* Comment.Single */
.highlight .cs { color: #3D7B7B; font-style: italic } /* Comment.Special */
.highlight .gd { color: #A00000 } /* Generic.Deleted */
.highlight .ge { font-style: italic } /* Generic.Emph */
.highlight .ges { font-weight: bold; font-style: italic } /* Generic.EmphStrong */
.highlight .gr { color: #E40000 } /* Generic.Error */
.highlight .gh { color: #000080; font-weight: bold } /* Generic.Heading */
.highlight .gi { color: #008400 } /* Generic.Inserted */
.highlight .go { color: #717171 } /* Generic.Output */
.highlight .gp { color: #000080; font-weight: bold } /* Generic.Prompt */
.highlight .gs { font-weight: bold } /* Generic.Strong */
.highlight .gu { color: #800080; font-weight: bold } /* Generic.Subheading */
.highlight .gt { color: #04D } /* Generic.Traceback */
.highlight .kc { color: #008000; font-weight: bold } /* Keyword.Constant */
.highlight .kd { color: #008000; font-weight: bold } /* Keyword.Declaration */
.highlight .kn { color: #008000; font-weight: bold } /* Keyword.Namespace */
.highlight .kp { color: #008000 } /* Keyword.Pseudo */
.highlight .kr { color: #008000; font-weight: bold } /* Keyword.Reserved */
.highlight .kt { color: #B00040 } /* Keyword.Type */
.highlight .m { color: #666 } /* Literal.Number */
.highlight .s { color: #BA2121 } /* Literal.String */
.highlight .na { color: #687822 } /* Name.Attribute */
.highlight .nb { color: #008000 } /* Name.Builtin */
.highlight .nc { color: #00F; font-weight: bold } /* Name.Class */
.highlight .no { color: #800 } /* Name.Constant */
.highlight .nd { color: #A2F } /* Name.Decorator */
.highlight .ni { color: #717171; font-weight: bold } /* Name.Entity */
.highlight .ne { color: #CB3F38; font-weight: bold } /* Name.Exception */
.highlight .nf { color: #00F } /* Name.Function */
.highlight .nl { color: #767600 } /* Name.Label */
.highlight .nn { color: #00F; font-weight: bold } /* Name.Namespace */
.highlight .nt { color: #008000; font-weight: bold } /* Name.Tag */
.highlight .nv { color: #19177C } /* Name.Variable */
.highlight .ow { color: #A2F; font-weight: bold } /* Operator.Word */
.highlight .w { color: #BBB } /* Text.Whitespace */
.highlight .mb { color: #666 } /* Literal.Number.Bin */
.highlight .mf { color: #666 } /* Literal.Number.Float */
.highlight .mh { color: #666 } /* Literal.Number.Hex */
.highlight .mi { color: #666 } /* Literal.Number.Integer */
.highlight .mo { color: #666 } /* Literal.Number.Oct */
.highlight .sa { color: #BA2121 } /* Literal.String.Affix */
.highlight .sb { color: #BA2121 } /* Literal.String.Backtick */
.highlight .sc { color: #BA2121 } /* Literal.String.Char */
.highlight .dl { color: #BA2121 } /* Literal.String.Delimiter */
.highlight .sd { color: #BA2121; font-style: italic } /* Literal.String.Doc */
.highlight .s2 { color: #BA2121 } /* Literal.String.Double */
.highlight .se { color: #AA5D1F; font-weight: bold } /* Literal.String.Escape */
.highlight .sh { color: #BA2121 } /* Literal.String.Heredoc */
.highlight .si { color: #A45A77; font-weight: bold } /* Literal.String.Interpol */
.highlight .sx { color: #008000 } /* Literal.String.Other */
.highlight .sr { color: #A45A77 } /* Literal.String.Regex */
.highlight .s1 { color: #BA2121 } /* Literal.String.Single */
.highlight .ss { color: #19177C } /* Literal.String.Symbol */
.highlight .bp { color: #008000 } /* Name.Builtin.Pseudo */
.highlight .fm { color: #00F } /* Name.Function.Magic */
.highlight .vc { color: #19177C } /* Name.Variable.Class */
.highlight .vg { color: #19177C } /* Name.Variable.Global */
.highlight .vi { color: #19177C } /* Name.Variable.Instance */
.highlight .vm { color: #19177C } /* Name.Variable.Magic */
.highlight .il { color: #666 } /* Literal.Number.Integer.Long */
.highlight .c,.highlight .c1,.highlight .cm{color:#8da3b8!important;font-style:italic}
.highlight .k,.highlight .kd,.highlight .kn,.highlight .kr{color:#93c5fd!important;font-weight:700}
.highlight .kt,.highlight .nc,.highlight .nf{color:#67e8f9!important;font-weight:700}
.highlight .s,.highlight .s1,.highlight .s2,.highlight .sd{color:#a7f3d0!important}
.highlight .m,.highlight .mi,.highlight .mf{color:#fcd34d!important}
.highlight .na,.highlight .nt{color:#f0abfc!important}
.table-wrap{overflow:auto;border:1px solid var(--line);border-radius:16px;background:#fff;margin:16px 0}
table{width:100%;border-collapse:collapse;font-size:.94rem}
th,td{padding:10px 12px;border-bottom:1px solid var(--line);vertical-align:top;text-align:left}
th{background:#f1f6f8;color:#274757;font-weight:900}
tr:last-child td{border-bottom:0}
.callout{border-left:5px solid var(--primary);background:#eef6f8;border-radius:14px;padding:16px;margin:16px 0}
.warn{border-left-color:var(--warn);background:#fff7eb}
.ok{border-left-color:var(--ok);background:#eff8f1}
.footer,footer{margin-top:42px;padding-top:20px;border-top:1px solid var(--line);color:var(--muted);font-size:.9rem}
.toc-list{columns:2;column-gap:26px}
.toc-list a{display:block;break-inside:avoid;padding:5px 0}
@media(max-width:900px){.layout{display:block}.sidebar{position:relative;height:auto}.main{padding:22px 16px 60px}.grid.two,.grid.three,.flow{grid-template-columns:1fr}.searchbar{position:relative;top:auto}.toc-list{columns:1}}
@media(prefers-color-scheme:dark){
  :root{--bg:#0e1623;--surface:#172235;--ink:#e6edf6;--muted:#aab7c8;--line:#2c3b4f;--soft:#1f3444;--soft2:#332a22}
  body{background:var(--bg);color:var(--ink)}
  .sidebar{background:linear-gradient(180deg,#111b2a 0%,#182536 100%)}
  .hero,.card,details,.diagram,.table-wrap{background:#172235;border-color:#2c3b4f}
  summary,th{background:#1d2b3d;color:#d9edf7}
  .nav a{color:#e6edf6}.nav a:hover,.nav a.active{background:#1d2b3d}
  button,.btn,.searchbar input{background:#111b2a;color:#e6edf6;border-color:#33465e}
  .searchbar{background:rgba(14,22,35,.92)}
  h2,h3,h4{color:#d9edf7}
}


/* V3 Refactoring additions */
.refactoring-hero { background: radial-gradient(circle at top left,#e7f2f4 0%,#fff 48%,#f6eee4 100%); }
.diff-grid{display:grid;grid-template-columns:1fr 1fr;gap:16px;margin:16px 0}
.stage-map{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:12px;margin:18px 0}
.stage{border:1px solid var(--line);border-radius:16px;padding:14px;background:var(--surface)}
.stage b{display:block;color:var(--primary);margin-bottom:5px}
.before-box,.after-box{border-radius:18px;padding:16px;border:1px solid var(--line)}
.before-box{background:#fff7eb;border-left:5px solid var(--warn)}
.after-box{background:#eff8f1;border-left:5px solid var(--ok)}
.refactor-note{border-radius:16px;border:1px dashed #b8c7d4;background:#f7fafb;padding:14px;margin:14px 0}
.pattern-row{display:flex;flex-wrap:wrap;gap:8px;margin:12px 0}
.pattern-pill{display:inline-flex;align-items:center;border-radius:999px;padding:5px 10px;background:var(--soft);color:var(--primary);font-weight:900;font-size:.82rem}
.metric-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:14px;margin:16px 0}
.metric{border-radius:16px;border:1px solid var(--line);padding:14px;background:#fff}.metric strong{font-size:1.35rem;color:var(--primary);display:block}
@media(max-width:900px){.diff-grid,.stage-map,.metric-grid{grid-template-columns:1fr}}
@media(prefers-color-scheme:dark){.before-box{background:#332a22}.after-box{background:#1b3326}.refactor-note,.metric,.stage{background:#172235;border-color:#2c3b4f}}


/* V4 Migration additions */
.migration-hero{background:radial-gradient(circle at top left,#e5f1f4 0%,#fff 45%,#f8efe7 100%)}
.migration-step{border-left:5px solid var(--primary);background:#eef6f8;border-radius:16px;padding:14px;margin:12px 0}
.cutover-band{display:grid;grid-template-columns:repeat(5,minmax(0,1fr));gap:10px;margin:16px 0}
.cutover-band span{background:var(--soft);color:var(--primary);font-weight:900;border-radius:999px;padding:8px 10px;text-align:center}
@media(max-width:900px){.cutover-band{grid-template-columns:1fr}}
@media(prefers-color-scheme:dark){.migration-step{background:#1f3444}.cutover-band span{background:#1f3444}}