:root {
  --bg:        #0a0e1a;
  --surface:   #111827;
  --surface2:  #1e293b;
  --border:    #1e293b;
  --blue:      #3b82f6;
  --amber:     #f59e0b;
  --text:      #e2e8f0;
  --muted:     #64748b;
  --tension:   #ef4444;
  --compress:  #3b82f6;
  --green:     #22c55e;
  --radius:    8px;
  --nav-h:     60px;
}

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

body {
  background: var(--bg);
  color: var(--text);
  font-family: 'Segoe UI', system-ui, sans-serif;
  line-height: 1.6;
  min-height: 100vh;
}

/* ── NAV ── */
nav {
  position: sticky; top: 0; z-index: 100;
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  height: var(--nav-h);
  display: flex; align-items: center;
  padding: 0 2rem; gap: 2rem;
}
nav .logo { font-weight: 700; color: var(--blue); font-size: 1.1rem; text-decoration: none; }
nav a { color: var(--muted); text-decoration: none; font-size: 0.9rem; transition: color 0.2s; }
nav a:hover, nav a.active { color: var(--text); }
nav .spacer { flex: 1; }

/* ── HERO ── */
.hero {
  min-height: calc(100vh - var(--nav-h));
  display: flex; flex-direction: column;
  align-items: center; justify-content: center;
  text-align: center; padding: 4rem 2rem;
}
.hero h1 { font-size: clamp(2.5rem, 6vw, 5rem); font-weight: 800; line-height: 1.1; }
.hero h1 span { color: var(--blue); }
.hero p { max-width: 600px; color: var(--muted); font-size: 1.1rem; margin: 1.5rem auto; }
.hero-svg { width: min(700px, 90vw); margin: 2rem auto; }

/* ── CARDS ── */
.cards { display: grid; grid-template-columns: repeat(auto-fit, minmax(220px, 1fr)); gap: 1.5rem; padding: 1rem 0; }
.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.5rem;
  text-decoration: none; color: var(--text);
  transition: border-color 0.2s, transform 0.2s;
  display: block;
}
.card:hover { border-color: var(--blue); transform: translateY(-2px); }
.card h3 { color: var(--blue); margin-bottom: 0.5rem; }
.card p { color: var(--muted); font-size: 0.9rem; }

/* ── CONTENT PAGES ── */
.page { max-width: 900px; margin: 0 auto; padding: 3rem 2rem; }
.page h1 { font-size: 2.2rem; font-weight: 800; margin-bottom: 0.5rem; }
.page .hook { color: var(--muted); font-size: 1.05rem; margin-bottom: 3rem; border-left: 3px solid var(--blue); padding-left: 1rem; }
.page h2 { font-size: 1.35rem; font-weight: 700; margin: 2.5rem 0 1rem; color: var(--amber); }
.page p { color: var(--muted); margin-bottom: 1rem; }
.page ul { color: var(--muted); padding-left: 1.5rem; margin-bottom: 1rem; }
.page li { margin-bottom: 0.4rem; }

/* ── CALCULATOR BOX ── */
.calc-box {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 2rem; margin: 2rem 0;
}
.calc-box h3 { color: var(--blue); margin-bottom: 1.5rem; font-size: 1.05rem; }
.calc-row { display: grid; grid-template-columns: repeat(auto-fit, minmax(180px, 1fr)); gap: 1rem; margin-bottom: 1rem; }
label { display: block; color: var(--muted); font-size: 0.82rem; margin-bottom: 0.3rem; }
input[type=range] { width: 100%; accent-color: var(--blue); }
input[type=number], select {
  width: 100%; padding: 0.45rem 0.6rem;
  background: var(--surface2); border: 1px solid var(--border);
  color: var(--text); border-radius: 4px; font-size: 0.9rem;
}
button.calc-btn {
  background: var(--blue); color: #fff;
  border: none; border-radius: var(--radius);
  padding: 0.65rem 1.4rem; cursor: pointer;
  font-size: 0.95rem; font-weight: 600;
  transition: opacity 0.2s; margin-top: 0.5rem;
}
button.calc-btn:hover { opacity: 0.85; }
.calc-result {
  margin-top: 1.5rem; padding: 1rem;
  background: var(--surface2); border-radius: var(--radius);
  font-size: 1rem; color: var(--muted);
}
.calc-result .big { font-size: 1.9rem; font-weight: 700; color: var(--amber); }
canvas { display: block; width: 100%; border-radius: 4px; margin-top: 1rem; }

/* ── TABLE ── */
table { width: 100%; border-collapse: collapse; margin: 1.5rem 0; font-size: 0.88rem; }
th { background: var(--surface2); color: var(--blue); padding: 0.65rem 1rem; text-align: left; }
td { padding: 0.65rem 1rem; border-bottom: 1px solid var(--border); color: var(--muted); }
tr:hover td { background: var(--surface); }

/* ── GO DEEPER ── */
.go-deeper {
  background: var(--surface);
  border: 1px solid var(--amber);
  border-radius: var(--radius);
  padding: 1.2rem 1.5rem; margin: 2.5rem 0;
  color: var(--muted); font-size: 0.95rem;
}
.go-deeper a { color: var(--amber); font-weight: 600; text-decoration: none; }
.go-deeper a:hover { text-decoration: underline; }

/* ── BADGES ── */
.badge { display: inline-block; padding: 0.2rem 0.7rem; border-radius: 99px; font-size: 0.75rem; font-weight: 600; }
.badge-blue { background: rgba(59,130,246,0.15); color: var(--blue); }
.badge-amber { background: rgba(245,158,11,0.15); color: var(--amber); }

/* ── HIGHLIGHT BOX ── */
.highlight-box {
  background: linear-gradient(135deg, rgba(59,130,246,0.07), rgba(245,158,11,0.07));
  border: 1px solid var(--blue); border-radius: var(--radius);
  padding: 1.5rem; margin: 1.5rem 0;
}

/* ── RESPONSIVE ── */
@media (max-width: 600px) {
  nav { gap: 1rem; padding: 0.7rem 1rem; flex-wrap: wrap; height: auto; }
  .page { padding: 2rem 1rem; }
  .page h1 { font-size: 1.8rem; }
}