:root {
  --bg:     #080e1a;
  --panel:  #0c1424;
  --surf:   #101c30;
  --grid:   #0f1e35;
  --bord:   #1a3050;
  --bord2:  #254468;
  --text:   #8ab0d0;
  --bright: #d0e8ff;
  --muted:  #6888a8;
  --faded:  #7098c0;

  --ice:    #60d0ff;
  --mint:   #40f0b0;
  --gold:   #f0c040;
  --coral:  #f07060;
  --violet: #a060f0;
  --sky:    #40a0ff;
  --lime:   #a0e040;
}

*{ margin:0; padding:0; box-sizing:border-box; }

body {
  background: var(--bg);
  color: var(--text);
  font-family: 'Syne', sans-serif;
  min-height: 100vh;
  overflow-x: hidden;
}

/* Crystal grid background */
body::before {
  content:'';
  position:fixed; inset:0;
  background-image:
    linear-gradient(rgba(60,120,200,0.04) 1px, transparent 1px),
    linear-gradient(90deg, rgba(60,120,200,0.04) 1px, transparent 1px),
    linear-gradient(rgba(60,120,200,0.02) 1px, transparent 1px),
    linear-gradient(90deg, rgba(60,120,200,0.02) 1px, transparent 1px);
  background-size: 80px 80px, 80px 80px, 16px 16px, 16px 16px;
  pointer-events:none; z-index:0;
}

/* ═══ HEADER ═══ */
header {
  position: relative; z-index: 1;
  border-bottom: 1px solid var(--bord2);
}
.hdr-accent {
  background: linear-gradient(90deg, var(--ice) 0%, var(--sky) 100%);
  height: 3px;
}
.hdr-inner {
  padding: 32px 52px 24px;
  display: flex; align-items: flex-start;
  justify-content: space-between; gap: 40px;
}
.hdr-kicker {
  font-family: 'Source Code Pro', monospace;
  font-size: 9px; letter-spacing: 3px;
  color: var(--ice); margin-bottom: 12px;
  display: flex; align-items: center; gap: 8px;
}
.hdr-kicker::before { content:''; width:24px; height:1px; background:var(--ice); }
header h1 {
  font-family: 'DM Serif Display', serif;
  font-size: clamp(32px, 5vw, 68px);
  font-weight: 400; line-height: 1.05;
  color: var(--bright); margin-bottom: 8px;
}
header h1 em { color: var(--ice); font-style: italic; }
.hdr-sub {
  font-family: 'Source Code Pro', monospace;
  font-size: 10px; color: var(--faded); letter-spacing: 1px;
  line-height: 1.7;
}
.hdr-stats {
  display: grid; grid-template-columns: repeat(2,1fr);
  gap: 8px; min-width: 220px;
}
.hs-box {
  background: var(--panel); border: 1px solid var(--bord);
  padding: 12px 14px; text-align: center;
}
.hs-val {
  font-family: 'DM Serif Display', serif;
  font-size: 28px; color: var(--ice); line-height: 1;
  margin-bottom: 3px;
}
.hs-lbl {
  font-family: 'Source Code Pro', monospace;
  font-size: 8px; letter-spacing: 1px; color: var(--muted);
}
.topic-strip {
  display: flex; gap: 2px; padding: 0 52px 16px;
  overflow-x: auto;
}
.topic-pill {
  font-family: 'Source Code Pro', monospace;
  font-size: 8px; letter-spacing: 1px;
  padding: 4px 10px; border: 1px solid;
  white-space: nowrap; flex-shrink: 0;
}

/* ═══ NAV ═══ */
.nav {
  position: sticky; top: 0; z-index: 100;
  background: var(--panel); border-bottom: 1px solid var(--bord2);
  display: flex; overflow-x: auto;
}
.nav-tab {
  padding: 12px 16px;
  font-family: 'Source Code Pro', monospace;
  font-size: 9px; letter-spacing: 1.5px; text-transform: uppercase;
  color: var(--muted); cursor: pointer;
  border-bottom: 2px solid transparent;
  transition: all 0.12s; white-space: nowrap;
}
.nav-tab:hover { color: var(--text); }
.nav-tab.active { color: var(--ice); border-bottom-color: var(--ice); }

/* ═══ CONTENT ═══ */
.content { padding: 40px 52px; position: relative; z-index: 1; max-width: 1280px; }
.view { display: none; }
.view.active { display: block; }

/* Headings */
.sec-h {
  font-family: 'DM Serif Display', serif;
  font-size: 24px; color: var(--bright); margin-bottom: 4px;
}
.sec-sub {
  font-family: 'Source Code Pro', monospace;
  font-size: 9px; letter-spacing: 2px; color: var(--faded);
  margin-bottom: 18px; padding-bottom: 10px;
  border-bottom: 1px solid var(--bord);
}

/* Code blocks */
.code-wrap {
  background: #050a12; border: 1px solid var(--bord2);
  border-radius: 3px; overflow: hidden; margin: 14px 0;
}
.code-top {
  display: flex; justify-content: space-between;
  padding: 6px 14px; background: var(--panel);
  border-bottom: 1px solid var(--bord);
  font-family: 'Source Code Pro', monospace;
  font-size: 8px; color: var(--faded); letter-spacing: 1px;
}
.code-lang { color: var(--ice); }
pre.code {
  padding: 14px 16px;
  font-family: 'Source Code Pro', monospace;
  font-size: 11.5px; line-height: 1.9;
  color: var(--faded); overflow-x: auto; white-space: pre;
}
.kw  { color: var(--sky); }
.cls { color: var(--ice); }
.fn  { color: var(--mint); }
.cm  { color: var(--muted); }
.str { color: var(--gold); }
.ok  { color: var(--mint); }
.no  { color: var(--coral); }
.hl  { color: var(--bright); }
.och { color: var(--gold); }

/* Main comparison table */
.big-table {
  width: 100%; border-collapse: collapse; margin: 14px 0;
  font-size: 12px;
}
.big-table th {
  background: var(--surf);
  padding: 9px 13px;
  font-family: 'Source Code Pro', monospace;
  font-size: 8px; letter-spacing: 2px; color: var(--ice);
  font-weight: 400; text-align: left;
  border-bottom: 1px solid var(--bord2);
}
.big-table td {
  padding: 9px 13px; border-bottom: 1px solid var(--bord);
  color: var(--faded); vertical-align: top; line-height: 1.5;
}
.big-table td:first-child {
  font-family: 'Source Code Pro', monospace;
  color: var(--ice); font-size: 11px;
}
.big-table tr:hover td { background: rgba(60,160,255,0.03); }
.yes { color: var(--mint) !important; }
.noo { color: var(--coral) !important; }

/* Index visual */
.idx-grid { display: grid; grid-template-columns: repeat(3,1fr); gap: 10px; margin: 14px 0; }
.idx-card {
  background: var(--panel); border: 1px solid var(--bord);
  border-top: 2px solid; padding: 14px 16px;
}
.idx-name { font-family: 'DM Serif Display', serif; font-size: 16px; color: var(--bright); margin-bottom: 6px; }
.idx-body { font-size: 12px; color: var(--faded); line-height: 1.55; }
.idx-use  { font-family: 'Source Code Pro', monospace; font-size: 9px; margin-top: 8px; }

/* ACID / BASE cards */
.ab-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 14px; margin: 14px 0; }
.ab-card { background: var(--panel); border: 1px solid var(--bord2); border-radius: 3px; overflow: hidden; }
.ab-hdr  { padding: 12px 16px; border-bottom: 1px solid var(--bord); }
.ab-title { font-family: 'DM Serif Display', serif; font-size: 22px; color: var(--bright); }
.ab-tag   { font-family: 'Source Code Pro', monospace; font-size: 9px; color: var(--faded); letter-spacing: 1px; }
.ab-body  { padding: 14px 16px; }
.ab-row   { display: flex; gap: 10px; margin: 8px 0; font-size: 12px; line-height: 1.5; }
.ab-letter { font-family: 'DM Serif Display', serif; font-size: 20px; color: var(--ice); flex-shrink: 0; width: 20px; }
.ab-def   { color: var(--faded); }
.ab-def strong { color: var(--bright); font-family: 'Source Code Pro', monospace; font-size: 11px; }

/* Sharding visual */
.shard-grid { display: grid; grid-template-columns: repeat(3,1fr); gap: 12px; margin: 14px 0; }
.shard-card { background: var(--panel); border: 1px solid var(--bord2); border-radius: 3px; overflow: hidden; }
.shard-hdr  { padding: 10px 14px; border-bottom: 1px solid var(--bord); display: flex; justify-content: space-between; align-items: center; }
.shard-name { font-family: 'DM Serif Display', serif; font-size: 15px; color: var(--bright); }
.shard-tag  { font-family: 'Source Code Pro', monospace; font-size: 8px; color: var(--faded); }
.shard-body { padding: 12px 14px; font-size: 12px; color: var(--faded); line-height: 1.55; }
.shard-pro  { color: var(--mint); font-family: 'Source Code Pro', monospace; font-size: 10px; line-height: 1.7; }
.shard-con  { color: var(--coral); font-family: 'Source Code Pro', monospace; font-size: 10px; line-height: 1.7; }

/* Replication diagram */
.rep-diagram {
  background: var(--panel); border: 1px solid var(--bord2);
  padding: 24px; margin: 14px 0; border-radius: 3px;
}
.rep-row { display: flex; align-items: center; gap: 10px; margin: 6px 0; flex-wrap: wrap; }
.rep-node {
  padding: 8px 14px; border: 1px solid; border-radius: 2px;
  font-family: 'Source Code Pro', monospace; font-size: 11px;
  text-align: center; flex-shrink: 0;
}
.rep-arrow { color: var(--faded); font-size: 14px; font-family: 'Source Code Pro', monospace; }
.rep-label { font-family: 'Source Code Pro', monospace; font-size: 9px; color: var(--muted); }

/* DB selection table */
.db-select { display: grid; grid-template-columns: repeat(2,1fr); gap: 10px; margin: 14px 0; }
.dbs-card { background: var(--panel); border: 1px solid var(--bord); padding: 12px 14px; }
.dbs-q    { font-family: 'Source Code Pro', monospace; font-size: 11px; color: var(--text); margin-bottom: 4px; }
.dbs-a    { font-family: 'DM Serif Display', serif; font-size: 15px; color: var(--ice); }

/* Alert */
.alert {
  padding: 12px 16px; margin: 14px 0;
  border-left: 3px solid; font-size: 12px; line-height: 1.7;
  font-family: 'Source Code Pro', monospace;
}
.alert.ice   { border-color: var(--ice);   color: var(--ice);   background: rgba(96,208,255,0.04); }
.alert.gold  { border-color: var(--gold);  color: var(--gold);  background: rgba(240,192,64,0.04); }
.alert.coral { border-color: var(--coral); color: var(--coral); background: rgba(240,112,96,0.04); }
.alert em    { color: var(--bright); font-style: normal; font-weight: 600; font-family: 'Syne', sans-serif; }

/* Tasks */
.task-list { display: flex; flex-direction: column; gap: 10px; }
.task-card { background: var(--panel); border: 1px solid var(--bord); overflow: hidden; }
.task-hd   { display: flex; align-items: center; gap: 14px; padding: 14px 18px; cursor: pointer; transition: background 0.12s; border-bottom: 1px solid var(--bord); }
.task-hd:hover { background: var(--surf); }
.t-num   { font-family: 'DM Serif Display', serif; font-size: 30px; color: var(--bord2); flex-shrink:0; line-height:1; }
.t-label { font-size: 14px; font-weight: 700; color: var(--bright); flex: 1; }
.t-meta  { font-family: 'Source Code Pro', monospace; font-size: 9px; color: var(--faded); white-space: nowrap; }
.t-arr   { color: var(--faded); font-size: 18px; transition: transform 0.2s; }
.t-arr.open { transform: rotate(90deg); }
.task-bd { display: none; padding: 14px 18px; font-size: 12px; color: var(--faded); line-height: 1.7; }
.task-bd.open { display: block; }
.task-bd pre { background: #050a12; border: 1px solid var(--bord); padding: 10px 12px; font-family: 'Source Code Pro', monospace; font-size: 10.5px; line-height: 1.75; overflow-x: auto; margin: 8px 0; color: var(--faded); white-space: pre; }
.task-bd ol, .task-bd ul { margin-left: 20px; margin-top: 8px; }
.task-bd li { margin-bottom: 4px; }

/* Checklist */
.chk-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 8px; }
.chk { display: flex; align-items: flex-start; gap: 10px; padding: 10px 14px; background: var(--panel); border: 1px solid var(--bord); cursor: pointer; transition: all 0.12s; }
.chk:hover { border-color: var(--bord2); }
.chk.done { border-color: rgba(64,240,176,0.3); }
.chk-box { width: 14px; height: 14px; border: 1px solid var(--bord); flex-shrink: 0; margin-top: 2px; display: flex; align-items: center; justify-content: center; font-size: 9px; font-family: 'Source Code Pro', monospace; transition: all 0.12s; }
.chk.done .chk-box { background: var(--mint); border-color: var(--mint); color: #000; }
.chk-lbl { font-size: 12px; color: var(--faded); line-height: 1.4; }
.chk.done .chk-lbl { color: var(--mint); text-decoration: line-through; text-decoration-color: rgba(64,240,176,0.4); }
.prog-row { display: flex; justify-content: space-between; font-family: 'Source Code Pro', monospace; font-size: 10px; color: var(--faded); margin-bottom: 8px; }
.prog-track { height: 2px; background: var(--bord); margin-bottom: 24px; }
.prog-fill  { height: 100%; background: var(--ice); transition: width 0.3s; width: 0%; box-shadow: 0 0 8px var(--ice); }

@media(max-width:900px){
  .content { padding: 28px 20px; }
  .hdr-inner { padding: 28px 20px 18px; flex-direction: column; }
  .topic-strip { padding: 0 20px 14px; }
  .idx-grid { grid-template-columns: 1fr 1fr; }
  .ab-grid  { grid-template-columns: 1fr; }
  .shard-grid { grid-template-columns: 1fr; }
  .db-select { grid-template-columns: 1fr; }
  .chk-grid { grid-template-columns: 1fr; }
}

/* ===== BOTTOM NAV ===== */
.b2-bottom-nav {
  display: flex;
  gap: 1rem;
  justify-content: center;
  flex-wrap: wrap;
  padding: 2rem 1rem;
  margin-top: 2rem;
  border-top: 1px solid rgba(255,255,255,0.15);
}
.b2-nav-footer-btn {
  display: inline-block;
  padding: 0.6rem 1.4rem;
  border-radius: 6px;
  font-size: 0.85rem;
  font-weight: 600;
  text-decoration: none;
  background: rgba(0,212,170,0.1);
  color: #00d4aa;
  border: 1px solid rgba(0,212,170,0.3);
  transition: all 0.2s;
  font-family: inherit;
}
.b2-nav-footer-btn:hover {
  background: rgba(0,212,170,0.2);
  transform: translateY(-2px);
}