@import url('https://fonts.googleapis.com/css2?family=DM+Mono:wght@400;500&family=Fraunces:ital,opsz,wght@0,9..144,200;0,9..144,600;1,9..144,200;1,9..144,400&display=swap');

:root {
  --bg:       #F7F8FA;
  --white:    #FFFFFF;
  --surface:  #FFFFFF;
  --surface2: #F1F4F8;
  --border:   #D1D9E6;
  --text:     #0F1923;
  --dim:      #4A5568;
  --muted:    #9AA5B4;
  --accent:   #0A6E55;   /* deep teal — primary */
  --blue:     #1A4FBF;   /* strong blue */
  --orange:   #B84E05;   /* amber-brown */
  --red:      #B91C1C;
  --flow:     #0A6E55;   /* arrow colour — high contrast on white */
  --mono:     'DM Mono', monospace;
  --serif:    'Fraunces', serif;
  --nav-h:    58px;
}

*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; }

body {
  background: var(--bg);
  color: var(--text);
  font-family: var(--mono);
  font-size: 14px;
  line-height: 1.6;
  min-height: 100vh;
}

/* ── NAV ── */
.topnav {
  position: fixed; inset: 0 0 auto 0; z-index: 200;
  height: var(--nav-h);
  background: rgba(255,255,255,0.96);
  backdrop-filter: blur(12px);
  border-bottom: 2px solid var(--border);
  display: flex; align-items: center;
  padding: 0 1.5rem; gap: 0;
  box-shadow: 0 1px 8px rgba(0,0,0,0.06);
}
.nav-logo {
  font-family: var(--serif); font-size: 1rem; font-weight: 600;
  color: var(--accent); text-decoration: none; letter-spacing: -0.02em;
  margin-right: 1.5rem; white-space: nowrap;
}
.nav-links { display: flex; list-style: none; overflow-x: auto; scrollbar-width: none; flex: 1; }
.nav-links::-webkit-scrollbar { display: none; }
.nav-links a {
  display: block; padding: 0 0.85rem; height: var(--nav-h);
  line-height: var(--nav-h); color: var(--dim); text-decoration: none;
  font-size: 0.7rem; letter-spacing: 0.07em; text-transform: uppercase;
  white-space: nowrap; border-bottom: 3px solid transparent;
  transition: color 0.15s, border-color 0.15s;
}
.nav-links a:hover { color: var(--text); }
.nav-links a.active { color: var(--accent); border-bottom-color: var(--accent); font-weight: 500; }
.nav-progress { margin-left: auto; font-size: 0.65rem; color: var(--muted); letter-spacing: 0.1em; white-space: nowrap; }

/* ── PAGER ── */
.pager { position: fixed; bottom: 1.5rem; right: 1.5rem; display: flex; gap: 0.5rem; z-index: 200; }
.pager a {
  display: flex; align-items: center; justify-content: center;
  width: 42px; height: 42px; background: var(--white);
  border: 2px solid var(--border); color: var(--dim);
  text-decoration: none; font-size: 1rem; border-radius: 4px;
  transition: all 0.15s; box-shadow: 0 1px 4px rgba(0,0,0,0.08);
}
.pager a:hover { color: var(--accent); border-color: var(--accent); }
.pager a.disabled { opacity: 0.25; pointer-events: none; }

/* ── LAYOUT ── */
main { padding-top: var(--nav-h); min-height: 100vh; }
.slide {
  min-height: calc(100vh - var(--nav-h));
  padding: 3.5rem 2rem 6rem;
  max-width: 1020px; margin: 0 auto;
}

/* ── TYPE ── */
.slide-label {
  font-size: 0.65rem; letter-spacing: 0.14em; text-transform: uppercase;
  color: var(--accent); margin-bottom: 1rem;
  display: flex; align-items: center; gap: 0.75rem;
}
.slide-label::before { content:''; width:28px; height:2px; background:var(--accent); flex-shrink:0; }

h1 {
  font-family: var(--serif); font-size: clamp(2.6rem, 6vw, 4.5rem);
  font-weight: 200; line-height: 1.05; letter-spacing: -0.03em;
  color: var(--text); margin-bottom: 1.25rem;
}
h1 em { font-style: italic; color: var(--accent); }

h2 {
  font-family: var(--serif); font-size: clamp(1.8rem, 4vw, 2.8rem);
  font-weight: 200; letter-spacing: -0.025em;
  color: var(--text); margin-bottom: 0.75rem; line-height: 1.15;
}
h2 em { font-style: italic; color: var(--accent); }

h3 {
  font-size: 0.7rem; letter-spacing: 0.1em; text-transform: uppercase;
  color: var(--accent); margin: 2rem 0 0.75rem; font-weight: 500;
}

p { color: var(--dim); line-height: 1.9; margin-bottom: 1rem; max-width: 700px; }

.lead {
  font-size: 1.05rem; color: var(--text); line-height: 1.75;
  max-width: 680px; margin-bottom: 2rem;
  font-family: var(--serif); font-weight: 200;
}

/* ── CARDS ── */
.cards {
  display: grid; grid-template-columns: repeat(auto-fill, minmax(240px,1fr));
  gap: 1px; background: var(--border); border: 1px solid var(--border);
  margin: 1.5rem 0; box-shadow: 0 2px 8px rgba(0,0,0,0.06);
}
.card {
  background: var(--white); padding: 1.5rem; transition: background 0.15s;
  position: relative;
}
.card:hover { background: var(--surface2); }
.card-num { font-size: 0.65rem; letter-spacing: 0.1em; color: var(--accent); margin-bottom: 0.4rem; }
.card-title { font-size: 0.9rem; color: var(--text); margin-bottom: 0.4rem; font-weight: 500; }
.card-desc { font-size: 0.8rem; color: var(--dim); line-height: 1.75; margin: 0; max-width: none; }
.card-bar { position: absolute; left:0; top:0; bottom:0; width:4px; }

/* ── G2 ── */
.g2 {
  display: grid; grid-template-columns: 1fr 1fr;
  gap: 1px; background: var(--border); border: 1px solid var(--border);
  margin: 1.5rem 0; box-shadow: 0 2px 8px rgba(0,0,0,0.06);
}
.g2-item { background: var(--white); padding: 1.5rem; }
.g2-item.problem { border-top: 3px solid var(--orange); }
.g2-item.solution { border-top: 3px solid var(--accent); }

/* ── TABLE ── */
.tbl { width:100%; border-collapse:collapse; margin:1.25rem 0; font-size:0.8rem; }
.tbl th {
  text-align:left; padding:0.6rem 1rem;
  font-size:0.65rem; letter-spacing:0.1em; text-transform:uppercase;
  color: var(--muted); border-bottom: 2px solid var(--border); font-weight:500;
  background: var(--surface2);
}
.tbl td { padding:0.65rem 1rem; color:var(--dim); border-bottom:1px solid var(--border); vertical-align:top; }
.tbl tr:hover td { background:var(--surface2); }
.tbl td strong { color: var(--text); }

/* ── TAGS ── */
.tag { display:inline-block; padding:0.15rem 0.5rem; font-size:0.65rem; letter-spacing:0.06em; text-transform:uppercase; border:1px solid; border-radius:2px; font-weight:500; }
.tag-green  { background:rgba(10,110,85,0.08);  color:var(--accent); border-color:rgba(10,110,85,0.25); }
.tag-blue   { background:rgba(26,79,191,0.08);  color:var(--blue);   border-color:rgba(26,79,191,0.25); }
.tag-orange { background:rgba(184,78,5,0.08);   color:var(--orange); border-color:rgba(184,78,5,0.25); }
.tag-red    { background:rgba(185,28,28,0.08);  color:var(--red);    border-color:rgba(185,28,28,0.25); }

/* ── CALLOUT ── */
.callout { border-left: 3px solid var(--accent); padding: 1rem 1.25rem; background: rgba(10,110,85,0.05); margin: 1.25rem 0; border-radius: 0 4px 4px 0; }
.callout.warn   { border-left-color: var(--orange); background: rgba(184,78,5,0.05); }
.callout.danger { border-left-color: var(--red);    background: rgba(185,28,28,0.05); }
.callout.info   { border-left-color: var(--blue);   background: rgba(26,79,191,0.05); }
.callout p { margin:0; font-size:0.85rem; max-width:none; }

/* ── DIAGRAM ── */
.diagram {
  background: var(--white); border: 2px solid var(--border);
  padding: 1.75rem; margin: 1.5rem 0; overflow-x: auto;
  box-shadow: 0 2px 8px rgba(0,0,0,0.06);
}
.diagram pre {
  font-family: var(--mono); font-size: 0.82rem;
  line-height: 1.9; color: var(--dim); white-space: pre;
}
.diagram pre .a { color: var(--accent); font-weight: 500; }
.diagram pre .b { color: var(--blue); font-weight: 500; }
.diagram pre .c { color: var(--orange); font-weight: 500; }
.diagram pre .m { color: var(--muted); }

/* ── CODE ── */
.code-block { background: var(--surface2); border: 1px solid var(--border); margin: 1.25rem 0; overflow: hidden; }
.code-block-header {
  display: flex; align-items: center; justify-content: space-between;
  padding: 0.5rem 1rem; border-bottom: 1px solid var(--border);
  background: var(--white);
}
.code-block-label { font-size: 0.65rem; letter-spacing: 0.1em; text-transform: uppercase; color: var(--muted); }
.code-block pre { padding: 1.25rem; overflow-x: auto; font-family: var(--mono); font-size: 0.8rem; line-height: 1.9; color: var(--accent); white-space: pre; }

/* ── STEPS ── */
.steps { display: flex; align-items: stretch; gap: 0; margin: 1.5rem 0; flex-wrap: wrap; }
.step { background: var(--white); border: 2px solid var(--border); padding: 1rem 1.25rem; min-width: 120px; flex: 1; border-top: 3px solid var(--accent); }
.step-n { font-size: 0.65rem; color: var(--accent); letter-spacing: 0.1em; margin-bottom: 0.3rem; font-weight: 500; }
.step-t { font-size: 0.82rem; color: var(--text); font-weight: 500; line-height: 1.4; }
.step-arrow { display: flex; align-items: center; padding: 0 0.5rem; color: var(--accent); font-size: 1.2rem; font-weight: 700; }

/* ── TOC ── */
.toc { display: grid; grid-template-columns: repeat(auto-fill, minmax(280px,1fr)); gap: 1px; background: var(--border); border: 1px solid var(--border); margin: 2rem 0; box-shadow: 0 2px 8px rgba(0,0,0,0.06); }
.toc-item { background: var(--white); padding: 1.25rem 1.5rem; display: flex; align-items: flex-start; gap: 1rem; text-decoration: none; transition: background 0.15s; border-left: 3px solid transparent; }
.toc-item:hover { background: var(--surface2); border-left-color: var(--accent); }
.toc-num { font-size: 0.7rem; color: var(--accent); letter-spacing: 0.08em; min-width: 2rem; padding-top: 0.1rem; font-weight: 500; }
.toc-title { font-size: 0.9rem; color: var(--text); font-weight: 500; margin-bottom: 0.2rem; }
.toc-sub { font-size: 0.75rem; color: var(--dim); line-height: 1.5; }

/* ── LAYER BADGE ── */
.layer {
  display: flex; align-items: flex-start; gap: 1rem;
  padding: 1.25rem; background: var(--white);
  border: 1px solid var(--border); margin-bottom: 1px;
  border-left: 4px solid var(--accent);
  box-shadow: 0 1px 4px rgba(0,0,0,0.05);
}
.layer.blue   { border-left-color: var(--blue); }
.layer.orange { border-left-color: var(--orange); }
.layer.red    { border-left-color: var(--red); }
.layer-num { font-size: 1.4rem; font-weight: 700; color: var(--accent); font-family: var(--serif); min-width: 2rem; line-height: 1; margin-top: 0.1rem; }
.layer.blue .layer-num   { color: var(--blue); }
.layer.orange .layer-num { color: var(--orange); }
.layer.red .layer-num    { color: var(--red); }
.layer-title { font-size: 0.9rem; color: var(--text); font-weight: 500; margin-bottom: 0.3rem; }
.layer-desc  { font-size: 0.82rem; color: var(--dim); line-height: 1.75; margin: 0; max-width: none; }

/* ── MISC ── */
hr { border: none; border-top: 1px solid var(--border); margin: 2.5rem 0; }
.copy-btn {
  background: none; border: 1px solid var(--border); color: var(--dim);
  font-family: var(--mono); font-size: 0.65rem; letter-spacing: 0.08em;
  text-transform: uppercase; padding: 0.25rem 0.6rem; cursor: pointer;
  transition: color 0.15s, border-color 0.15s; border-radius: 2px;
}
.copy-btn:hover, .copy-btn.copied { color: var(--accent); border-color: var(--accent); }

/* ── ANIMATIONS ── */
@keyframes fadeUp { from { opacity:0; transform:translateY(14px); } to { opacity:1; transform:translateY(0); } }
.anim    { animation: fadeUp 0.45s ease both; }
.anim-d1 { animation-delay: 0.08s; }
.anim-d2 { animation-delay: 0.16s; }
.anim-d3 { animation-delay: 0.24s; }
.anim-d4 { animation-delay: 0.32s; }
.anim-d5 { animation-delay: 0.40s; }
.anim-d6 { animation-delay: 0.48s; }

/* ── FLOW ANIMATION (forside) ── */
.flow-canvas { width:100%; aspect-ratio:16/9; background:var(--white); border:2px solid var(--border); position:relative; overflow:hidden; box-shadow:0 2px 8px rgba(0,0,0,0.08); }
.fnode { position:absolute; background:var(--white); border:2px solid var(--border); padding:0.4rem 0.7rem; font-size:0.68rem; letter-spacing:0.04em; color:var(--dim); white-space:nowrap; transition:border-color 0.3s, color 0.3s, box-shadow 0.3s; border-radius:3px; }
.fnode.lit        { border-color:var(--accent); color:var(--accent); box-shadow:0 0 0 3px rgba(10,110,85,0.12); }
.fnode.lit.blue   { border-color:var(--blue);   color:var(--blue);   box-shadow:0 0 0 3px rgba(26,79,191,0.12); }
.fnode.lit.orange { border-color:var(--orange);  color:var(--orange); box-shadow:0 0 0 3px rgba(184,78,5,0.12); }
.fnode.lit.red    { border-color:var(--red);     color:var(--red);    box-shadow:0 0 0 3px rgba(185,28,28,0.12); }
.fnode-sub { font-size:0.58rem; color:var(--muted); display:block; margin-bottom:0.1rem; }
.fpkt { position:absolute; width:9px; height:9px; border-radius:50%; transform:translate(-50%,-50%); opacity:0; pointer-events:none; }
.fpkt.g { background:var(--accent); box-shadow:0 0 8px rgba(10,110,85,0.6); }
.fpkt.b { background:var(--blue);   box-shadow:0 0 8px rgba(26,79,191,0.6); }
.fpkt.o { background:var(--orange); box-shadow:0 0 8px rgba(184,78,5,0.6); }
.fpkt.r { background:var(--red);    box-shadow:0 0 8px rgba(185,28,28,0.6); }

@media (max-width: 640px) {
  .g2 { grid-template-columns: 1fr; }
  .steps { flex-direction: column; }
  .step-arrow { transform: rotate(90deg); align-self: flex-start; padding: 0.25rem 1rem; }
}