/* =========================================================
   Prevsenior — Design System
   Brand: navy #333366, disciplined BI-grade visual language
   ========================================================= */

:root {
  /* Brand */
  --navy-900: #21213f;
  --navy-800: #2a2a52;
  --navy-700: #333366; /* brand primary */
  --navy-600: #3f3f7d;
  --navy-500: #52529c;
  --navy-100: #e7e7f1;
  --navy-50:  #f3f3f9;

  /* Neutrals */
  --ink-900: #16161f;
  --ink-700: #3b3b46;
  --ink-500: #6a6a78;
  --ink-300: #a6a6b3;
  --line-200: #e3e3ea;
  --line-100: #ededf2;
  --surface-0: #ffffff;
  --surface-1: #f7f7fb;
  --surface-2: #f0f0f6;

  /* Accent — used sparingly, single highlight per IBCS "Unify" principle */
  --accent-amber: #c1791f;
  --accent-teal:  #1f7a6c;

  /* Type */
  --font-sans: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;

  /* Spacing scale */
  --sp-1: 4px;
  --sp-2: 8px;
  --sp-3: 12px;
  --sp-4: 16px;
  --sp-5: 24px;
  --sp-6: 32px;
  --sp-7: 48px;
  --sp-8: 64px;
  --sp-9: 96px;

  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;

  --shadow-sm: 0 1px 2px rgba(22,22,31,0.06), 0 1px 1px rgba(22,22,31,0.04);
  --shadow-md: 0 8px 24px rgba(22,22,31,0.08), 0 2px 6px rgba(22,22,31,0.05);
  --shadow-lg: 0 20px 48px rgba(22,22,31,0.14), 0 6px 16px rgba(22,22,31,0.08);

  --maxw: 1180px;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }

body {
  margin: 0;
  font-family: var(--font-sans);
  color: var(--ink-900);
  background: var(--surface-0);
  -webkit-font-smoothing: antialiased;
  line-height: 1.6;
}

img { max-width: 100%; display: block; }

a { color: inherit; text-decoration: none; }

.container {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 0 var(--sp-5);
}

/* ---------- Typography ---------- */
h1, h2, h3, h4 {
  font-family: var(--font-sans);
  color: var(--navy-900);
  line-height: 1.15;
  margin: 0 0 var(--sp-4);
  letter-spacing: -0.01em;
}
h1 { font-size: clamp(2.1rem, 3.4vw, 3.2rem); font-weight: 700; }
h2 { font-size: clamp(1.6rem, 2.4vw, 2.25rem); font-weight: 700; }
h3 { font-size: 1.25rem; font-weight: 600; }
h4 { font-size: 1rem; font-weight: 700; text-transform: uppercase; letter-spacing: 0.06em; color: var(--navy-700); }

p { margin: 0 0 var(--sp-4); color: var(--ink-700); }
.lede { font-size: 1.2rem; color: var(--ink-700); line-height: 1.65; }
.muted { color: var(--ink-500); }
.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: var(--sp-2);
  font-size: 0.78rem;
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--navy-700);
  margin-bottom: var(--sp-3);
}
.eyebrow::before {
  content: "";
  width: 18px;
  height: 2px;
  background: var(--accent-amber);
  display: inline-block;
}

/* ---------- Buttons ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--sp-2);
  padding: 13px 26px;
  border-radius: var(--radius-sm);
  font-weight: 600;
  font-size: 0.95rem;
  border: 1.5px solid transparent;
  cursor: pointer;
  transition: transform 0.15s ease, box-shadow 0.15s ease, background 0.15s ease, color 0.15s ease, border-color .15s ease;
  white-space: nowrap;
}
.btn-primary {
  background: var(--navy-700);
  color: #fff;
  box-shadow: var(--shadow-sm);
}
.btn-primary:hover { background: var(--navy-800); box-shadow: var(--shadow-md); transform: translateY(-1px); }
.btn-ghost {
  background: transparent;
  color: var(--navy-700);
  border-color: var(--navy-100);
}
.btn-ghost:hover { border-color: var(--navy-700); background: var(--navy-50); }
.btn-on-dark {
  background: #fff;
  color: var(--navy-800);
}
.btn-on-dark:hover { background: var(--navy-50); transform: translateY(-1px); }
.btn-ghost-on-dark {
  background: transparent;
  color: #fff;
  border-color: rgba(255,255,255,0.35);
}
.btn-ghost-on-dark:hover { border-color: #fff; background: rgba(255,255,255,0.08); }
.btn-sm { padding: 9px 18px; font-size: 0.85rem; }

/* ---------- Header / Nav ---------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(255,255,255,0.92);
  backdrop-filter: saturate(180%) blur(10px);
  border-bottom: 1px solid var(--line-200);
}
.nav-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 14px 0;
}
.brand { display: flex; align-items: center; gap: 10px; }
.brand img { height: 30px; width: auto; }
.nav-links {
  display: flex;
  align-items: center;
  gap: var(--sp-6);
  list-style: none;
  margin: 0;
  padding: 0;
}
.nav-links a {
  font-size: 0.93rem;
  font-weight: 600;
  color: var(--ink-700);
  padding: 6px 2px;
  border-bottom: 2px solid transparent;
  transition: color .15s ease, border-color .15s ease;
}
.nav-links a:hover, .nav-links a[aria-current="page"] {
  color: var(--navy-700);
  border-color: var(--accent-amber);
}
.nav-cta { display: flex; align-items: center; gap: var(--sp-4); }
.nav-toggle {
  display: none;
  background: none;
  border: 1px solid var(--line-200);
  border-radius: var(--radius-sm);
  padding: 8px 10px;
  cursor: pointer;
}
.nav-toggle span, .nav-toggle span::before, .nav-toggle span::after {
  content: "";
  display: block;
  width: 20px;
  height: 2px;
  background: var(--navy-800);
  position: relative;
  transition: all .2s ease;
}
.nav-toggle span::before { position: absolute; top: -6px; }
.nav-toggle span::after { position: absolute; top: 6px; }

@media (max-width: 900px) {
  .nav-links { display: none; }
  .nav-cta .btn-primary { display: none; }
  .nav-toggle { display: inline-flex; align-items: center; }
  .site-header.nav-open .nav-links {
    display: flex;
    flex-direction: column;
    align-items: flex-start;
    gap: var(--sp-4);
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background: #fff;
    padding: var(--sp-5);
    border-bottom: 1px solid var(--line-200);
    box-shadow: var(--shadow-md);
  }
  .site-header.nav-open .nav-cta .btn-primary { display: inline-flex; }
}

/* ---------- Hero ---------- */
.hero {
  background: linear-gradient(180deg, var(--navy-900) 0%, var(--navy-700) 100%);
  color: #fff;
  padding: var(--sp-9) 0 var(--sp-8);
  position: relative;
  overflow: hidden;
}
.hero::after {
  content: "";
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(rgba(255,255,255,0.05) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255,255,255,0.05) 1px, transparent 1px);
  background-size: 48px 48px;
  mask-image: radial-gradient(ellipse at top right, black, transparent 70%);
  pointer-events: none;
}
.hero .container { position: relative; z-index: 1; }
.hero-grid {
  display: grid;
  grid-template-columns: 1.1fr 0.9fr;
  gap: var(--sp-8);
  align-items: center;
}
.hero h1 { color: #fff; }
.hero .lede { color: rgba(255,255,255,0.82); }
.hero-actions { display: flex; gap: var(--sp-4); margin-top: var(--sp-6); flex-wrap: wrap; }
.hero-badges {
  display: flex;
  gap: var(--sp-5);
  margin-top: var(--sp-7);
  flex-wrap: wrap;
}
.hero-badge {
  display: flex;
  align-items: center;
  gap: var(--sp-2);
  font-size: 0.85rem;
  color: rgba(255,255,255,0.75);
}
.hero-badge strong { color: #fff; }

@media (max-width: 880px) {
  .hero-grid { grid-template-columns: 1fr; }
}

/* ---------- Page header (non-home) ---------- */
.page-hero {
  background: linear-gradient(180deg, var(--navy-900) 0%, var(--navy-700) 100%);
  color: #fff;
  padding: var(--sp-8) 0 var(--sp-7);
}
.page-hero h1 { color: #fff; margin-bottom: var(--sp-3); }
.page-hero .lede { color: rgba(255,255,255,0.82); max-width: 62ch; }
.breadcrumb { font-size: 0.82rem; color: rgba(255,255,255,0.6); margin-bottom: var(--sp-4); }
.breadcrumb a { color: rgba(255,255,255,0.85); }

/* ---------- Sections ---------- */
section { padding: var(--sp-8) 0; }
.section-tight { padding: var(--sp-7) 0; }
.section-alt { background: var(--surface-1); }
.section-navy { background: var(--navy-900); color: #fff; }
.section-navy h2, .section-navy h3 { color: #fff; }
.section-navy p { color: rgba(255,255,255,0.78); }
.section-head { max-width: 68ch; margin-bottom: var(--sp-7); }
.section-head.center { margin-left: auto; margin-right: auto; text-align: center; }

/* ---------- Grid / Cards ---------- */
.grid { display: grid; gap: var(--sp-5); }
.grid-2 { grid-template-columns: repeat(2, 1fr); }
.grid-3 { grid-template-columns: repeat(3, 1fr); }
.grid-4 { grid-template-columns: repeat(4, 1fr); }
@media (max-width: 980px) {
  .grid-3 { grid-template-columns: repeat(2, 1fr); }
  .grid-4 { grid-template-columns: repeat(2, 1fr); }
}
@media (max-width: 640px) {
  .grid-2, .grid-3, .grid-4 { grid-template-columns: 1fr; }
}

.card {
  background: var(--surface-0);
  border: 1px solid var(--line-200);
  border-radius: var(--radius-md);
  padding: var(--sp-6);
  transition: box-shadow .18s ease, transform .18s ease, border-color .18s ease;
}
.card:hover { box-shadow: var(--shadow-md); transform: translateY(-2px); border-color: var(--navy-100); }
.card .icon {
  width: 44px;
  height: 44px;
  border-radius: var(--radius-sm);
  background: var(--navy-50);
  color: var(--navy-700);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: var(--sp-4);
}
.card h3 { margin-bottom: var(--sp-2); }
.card p { margin-bottom: 0; font-size: 0.95rem; }

.card-flat {
  background: var(--surface-1);
  border-radius: var(--radius-md);
  padding: var(--sp-6);
}

/* Numbered list for principles (SUCCESS) */
.principle {
  display: grid;
  grid-template-columns: 56px 1fr;
  gap: var(--sp-4);
  padding: var(--sp-5) 0;
  border-top: 1px solid var(--line-200);
}
.principle:first-child { border-top: none; padding-top: 0; }
.principle .num {
  font-size: 1.6rem;
  font-weight: 700;
  color: var(--navy-100);
  font-variant-numeric: tabular-nums;
}
.principle h3 { margin-bottom: var(--sp-1); }
.principle p { margin-bottom: 0; }

/* ---------- Stats ---------- */
.stat-row { display: grid; grid-template-columns: repeat(4, 1fr); gap: var(--sp-5); }
@media (max-width: 780px) { .stat-row { grid-template-columns: repeat(2, 1fr); } }
.stat { text-align: left; }
.stat .value {
  font-size: 2.1rem;
  font-weight: 700;
  color: var(--navy-800);
  font-variant-numeric: tabular-nums;
  line-height: 1;
  margin-bottom: var(--sp-2);
}
.section-navy .stat .value { color: #fff; }
.stat .label { font-size: 0.88rem; color: var(--ink-500); }
.section-navy .stat .label { color: rgba(255,255,255,0.65); }

/* ---------- Vocabulary chips (chart-selection-by-purpose) ---------- */
.vocab-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: var(--sp-5); }
@media (max-width: 880px) { .vocab-grid { grid-template-columns: repeat(2, 1fr); } }
@media (max-width: 560px) { .vocab-grid { grid-template-columns: 1fr; } }
.vocab-card {
  border: 1px solid var(--line-200);
  border-radius: var(--radius-md);
  padding: var(--sp-5);
  background: #fff;
}
.vocab-card .q { font-size: 0.82rem; color: var(--ink-500); margin-bottom: var(--sp-2); }
.vocab-card h3 { margin-bottom: var(--sp-3); }
.vocab-card .mini-chart { margin-bottom: var(--sp-3); }
.vocab-card ul { margin: 0; padding-left: 18px; color: var(--ink-500); font-size: 0.85rem; }
.vocab-card li { margin-bottom: 4px; }

/* ---------- Before/After comparison ---------- */
.compare {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--sp-5);
  align-items: stretch;
}
@media (max-width: 760px) { .compare { grid-template-columns: 1fr; } }
.compare-panel {
  border-radius: var(--radius-md);
  padding: var(--sp-5);
  border: 1.5px solid var(--line-200);
  background: #fff;
  display: flex;
  flex-direction: column;
}
.compare-panel.bad { border-color: #e7d3c4; background: #fdfaf7; }
.compare-panel.good { border-color: var(--navy-100); background: var(--navy-50); }
.compare-tag {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  padding: 4px 10px;
  border-radius: 100px;
  margin-bottom: var(--sp-4);
  width: fit-content;
}
.compare-panel.bad .compare-tag { background: #f3e3d4; color: var(--accent-amber); }
.compare-panel.good .compare-tag { background: var(--navy-100); color: var(--navy-700); }
.compare-panel figure { margin: 0 0 var(--sp-4); }
.compare-panel ul { margin: 0; padding-left: 18px; font-size: 0.88rem; color: var(--ink-500); }
.compare-panel li { margin-bottom: 4px; }

/* ---------- Process steps ---------- */
.steps {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: var(--sp-5);
  counter-reset: step;
}
@media (max-width: 900px) { .steps { grid-template-columns: repeat(2, 1fr); } }
@media (max-width: 560px) { .steps { grid-template-columns: 1fr; } }
.step { position: relative; padding-top: var(--sp-6); }
.step::before {
  counter-increment: step;
  content: counter(step, decimal-leading-zero);
  font-size: 0.85rem;
  font-weight: 700;
  color: var(--accent-amber);
  letter-spacing: 0.08em;
  display: block;
  margin-bottom: var(--sp-2);
}
.step h3 { margin-bottom: var(--sp-2); font-size: 1.05rem; }
.step p { font-size: 0.92rem; margin-bottom: 0; }

/* ---------- Quote / testimonial style block ---------- */
.pull-quote {
  border-left: 3px solid var(--accent-amber);
  padding-left: var(--sp-5);
  font-size: 1.25rem;
  color: var(--navy-900);
  font-weight: 500;
  line-height: 1.5;
}

/* ---------- CTA band ---------- */
.cta-band {
  background: linear-gradient(120deg, var(--navy-800), var(--navy-700));
  color: #fff;
  border-radius: var(--radius-lg);
  padding: var(--sp-8);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--sp-6);
  flex-wrap: wrap;
}
.cta-band h2 { color: #fff; margin-bottom: var(--sp-2); }
.cta-band p { color: rgba(255,255,255,0.78); margin-bottom: 0; }

/* ---------- Table ---------- */
table { width: 100%; border-collapse: collapse; font-size: 0.92rem; }
th, td { text-align: left; padding: 12px 14px; border-bottom: 1px solid var(--line-200); }
th { color: var(--navy-700); font-weight: 700; font-size: 0.8rem; text-transform: uppercase; letter-spacing: 0.04em; }
td { color: var(--ink-700); }

/* ---------- Badge / pill ---------- */
.pill {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 6px 14px;
  border-radius: 100px;
  font-size: 0.8rem;
  font-weight: 600;
  background: var(--navy-50);
  color: var(--navy-700);
  border: 1px solid var(--navy-100);
}

/* ---------- Footer ---------- */
.site-footer {
  background: var(--navy-900);
  color: rgba(255,255,255,0.7);
  padding: var(--sp-8) 0 var(--sp-6);
}
.footer-grid {
  display: grid;
  grid-template-columns: 1.4fr 1fr 1fr 1fr;
  gap: var(--sp-6);
  padding-bottom: var(--sp-7);
  border-bottom: 1px solid rgba(255,255,255,0.12);
}
@media (max-width: 780px) { .footer-grid { grid-template-columns: 1fr 1fr; } }
@media (max-width: 480px) { .footer-grid { grid-template-columns: 1fr; } }
.footer-grid img { height: 26px; margin-bottom: var(--sp-4); }
.footer-grid p { font-size: 0.88rem; color: rgba(255,255,255,0.6); }
.footer-grid h4 { color: rgba(255,255,255,0.9); font-size: 0.78rem; margin-bottom: var(--sp-4); }
.footer-grid ul { list-style: none; margin: 0; padding: 0; }
.footer-grid li { margin-bottom: var(--sp-3); }
.footer-grid a { font-size: 0.9rem; color: rgba(255,255,255,0.68); }
.footer-grid a:hover { color: #fff; }
.footer-bottom {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: var(--sp-3);
  padding-top: var(--sp-5);
  font-size: 0.82rem;
  color: rgba(255,255,255,0.5);
}
.footer-legal-note {
  font-size: 0.78rem;
  color: rgba(255,255,255,0.42);
  max-width: 74ch;
  margin-top: var(--sp-3);
}

/* ---------- Utility ---------- */
.mt-0 { margin-top: 0; }
.mb-0 { margin-bottom: 0; }
.text-center { text-align: center; }
.flex { display: flex; }
.flex-center { display: flex; align-items: center; }
.gap-3 { gap: var(--sp-3); }
.gap-4 { gap: var(--sp-4); }
.visually-hidden {
  position: absolute; width: 1px; height: 1px; overflow: hidden;
  clip: rect(0,0,0,0); white-space: nowrap;
}

@media (prefers-reduced-motion: reduce) {
  * { transition: none !important; scroll-behavior: auto !important; }
}