/* ============================================
   TACTUN brain4machinery.com — Main Stylesheet
   Mobile-first, responsive, Inter font
   ============================================ */

/* --- CSS Variables --- */
:root {
  --bg: #FFFFFF;
  --bg-alt: #F3F4F6;
  --bg-accent: #EDE9FE;
  --purple: #6D28D9;
  --purple-mid: #7C3AED;
  --purple-light: rgba(109, 40, 217, 0.07);
  --purple-border: rgba(109, 40, 217, 0.2);
  --text: #111827;
  --text-secondary: #374151;
  --text-muted: #6B7280;
  --border: #E5E7EB;
  --green: #059669;
  --red: #DC2626;
  --radius: 12px;
  --radius-sm: 8px;
  --shadow-sm: 0 1px 3px rgba(0,0,0,0.06);
  --shadow-md: 0 4px 16px rgba(0,0,0,0.08);
  --shadow-lg: 0 12px 40px rgba(0,0,0,0.12);
  --transition: 0.2s ease;
}

/* --- Reset & Base --- */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; -webkit-text-size-adjust: 100%; }
body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  font-size: 18px;
  line-height: 1.6;
  color: var(--text-secondary);
  background: var(--bg);
  -webkit-font-smoothing: antialiased;
}
img { max-width: 100%; height: auto; display: block; }
a { color: var(--purple); text-decoration: none; transition: color var(--transition); }
a:hover { color: var(--purple-mid); }
ul, ol { list-style: none; }

/* --- Typography --- */
h1, h2, h3, h4, h5, h6 { color: var(--text); line-height: 1.15; font-weight: 700; }
h1 { font-size: 2.5rem; font-weight: 800; letter-spacing: -0.025em; }
h2 { font-size: 2rem; font-weight: 700; letter-spacing: -0.02em; }
h3 { font-size: 1.5rem; }
h4 { font-size: 1.125rem; }
.accent { color: var(--purple); }
.text-muted { color: var(--text-muted); }
.text-center { text-align: center; }
.label {
  display: inline-block;
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--purple);
  background: var(--purple-light);
  padding: 5px 14px;
  border-radius: 20px;
  margin-bottom: 1rem;
}

/* --- Layout --- */
.container { width: 100%; max-width: 1200px; margin: 0 auto; padding: 0 1.25rem; }
.section { padding: 5rem 0; }
.section--alt { background: var(--bg-alt); }
.section--accent { background: var(--bg-accent); }
.section--white { background: var(--bg); }

/* --- Navigation --- */
.nav {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 1000;
  background: rgba(255,255,255,0.95);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  border-bottom: 1px solid transparent;
  transition: border-color var(--transition), box-shadow var(--transition);
}
.nav--scrolled {
  border-bottom-color: var(--border);
  box-shadow: 0 1px 8px rgba(0,0,0,0.05);
}
.nav__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 72px;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 1.25rem;
}
.nav__logo img { height: 36px; width: auto; }
.nav__links {
  display: none;
  align-items: center;
  gap: 2rem;
}
.nav__link {
  font-size: 0.9375rem;
  font-weight: 500;
  color: var(--text-secondary);
  transition: color var(--transition);
}
.nav__link:hover, .nav__link--active { color: var(--purple); }
.nav__cta {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.9375rem;
  font-weight: 600;
  color: #fff;
  background: var(--purple);
  padding: 0.625rem 1.5rem;
  border-radius: var(--radius-sm);
  transition: background var(--transition), transform var(--transition);
}
.nav__cta:hover { background: var(--purple-mid); color: #fff; transform: translateY(-1px); }

/* Hamburger */
.nav__hamburger {
  display: flex;
  flex-direction: column;
  gap: 5px;
  cursor: pointer;
  padding: 8px;
  background: none;
  border: none;
}
.nav__hamburger span {
  display: block;
  width: 24px;
  height: 2px;
  background: var(--text);
  border-radius: 2px;
  transition: transform var(--transition), opacity var(--transition);
}
.nav__hamburger--open span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.nav__hamburger--open span:nth-child(2) { opacity: 0; }
.nav__hamburger--open span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

/* Mobile Menu */
.nav__mobile {
  display: none;
  position: fixed;
  top: 72px; left: 0;
  width: 100vw;
  height: calc(100vh - 72px);
  height: calc(100dvh - 72px);
  background: #FFFFFF;
  padding: 2rem 1.25rem;
  flex-direction: column;
  gap: 0;
  z-index: 9999;
  overflow-y: auto;
  -webkit-overflow-scrolling: touch;
  box-shadow: 0 4px 20px rgba(0,0,0,0.1);
}
.nav__mobile--open { display: flex; }
.nav__mobile .nav__link {
  font-size: 1.25rem;
  padding: 0.75rem 0;
  display: block;
  border-bottom: 1px solid var(--border);
}
.nav__mobile .nav__cta {
  text-align: center;
  justify-content: center;
  margin-top: 1rem;
  padding: 1rem;
  font-size: 1.125rem;
}

/* --- Buttons --- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  font-family: inherit;
  font-size: 1rem;
  font-weight: 600;
  padding: 0.875rem 2rem;
  border-radius: var(--radius-sm);
  border: none;
  cursor: pointer;
  transition: background var(--transition), transform var(--transition), box-shadow var(--transition);
}
.btn--primary {
  color: #fff;
  background: var(--purple);
}
.btn--primary:hover { background: var(--purple-mid); color: #fff; transform: translateY(-1px); box-shadow: 0 4px 12px rgba(109,40,217,0.3); }
.btn--secondary {
  color: var(--purple);
  background: transparent;
  border: 2px solid var(--purple);
}
.btn--secondary:hover { background: var(--purple-light); color: var(--purple); }
.btn--ghost {
  color: var(--purple);
  background: transparent;
  padding: 0;
  font-weight: 600;
}
.btn--ghost:hover { color: var(--purple-mid); }
.btn--ghost::after { content: ' \2192'; }

/* --- Hero --- */
.hero {
  min-height: 100vh;
  display: flex;
  align-items: center;
  padding-top: 72px;
}
.hero--short {
  min-height: auto;
  padding-top: 72px;
  padding-bottom: 0;
}
.hero__inner {
  display: flex;
  flex-direction: column;
  gap: 2rem;
  padding: 3rem 0;
}
.hero__content { max-width: 640px; }
.hero__content h1 {
  font-size: 2.5rem;
  margin-bottom: 1rem;
}
.hero__content .sub {
  font-size: 1.25rem;
  color: var(--text-secondary);
  line-height: 1.5;
  margin-bottom: 2rem;
}
.hero__buttons { display: flex; flex-wrap: wrap; gap: 1rem; }
.hero__image {
  display: flex;
  justify-content: center;
}
.hero__image img {
  border-radius: var(--radius);
  box-shadow: var(--shadow-lg);
  max-height: 420px;
  object-fit: cover;
}

/* --- Section Headers --- */
.section-header {
  max-width: 720px;
  margin-bottom: 3rem;
}
.section-header h2 { margin-bottom: 1rem; }
.section-header p {
  font-size: 1.125rem;
  color: var(--text-secondary);
}
.section-header--center {
  text-align: center;
  margin-left: auto;
  margin-right: auto;
}

/* --- Cards --- */
.card {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 2rem;
  transition: transform var(--transition), box-shadow var(--transition);
}
.card:hover { transform: translateY(-2px); box-shadow: var(--shadow-md); }
.card--alt { background: var(--bg-alt); }
.card__icon {
  width: 48px;
  height: 48px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--purple-light);
  border-radius: var(--radius-sm);
  margin-bottom: 1rem;
  font-size: 1.5rem;
  color: var(--purple);
}
.card__title {
  font-size: 1.125rem;
  font-weight: 700;
  color: var(--text);
  margin-bottom: 0.5rem;
}
.card__text {
  font-size: 1rem;
  color: var(--text-secondary);
  line-height: 1.6;
}
.card__number {
  font-size: 2.5rem;
  font-weight: 800;
  color: var(--red);
  margin-bottom: 0.5rem;
}

/* --- Grid Layouts --- */
.grid { display: grid; gap: 1.5rem; }
.grid--2 { grid-template-columns: 1fr; }
.grid--3 { grid-template-columns: 1fr; }
.grid--4 { grid-template-columns: 1fr; }

/* --- Pain Points --- */
.pain__number {
  font-size: 2.5rem;
  font-weight: 800;
  color: var(--red);
  line-height: 1;
  margin-bottom: 0.25rem;
}
.pain__label {
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--text-muted);
  margin-bottom: 0.75rem;
}

/* --- Steps (Solution / How We Work) --- */
.steps { display: flex; flex-direction: column; gap: 2rem; }
.step {
  display: flex;
  gap: 1.5rem;
  align-items: flex-start;
}
.step__number {
  width: 48px;
  height: 48px;
  flex-shrink: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--purple);
  color: #fff;
  font-size: 1.25rem;
  font-weight: 800;
  border-radius: 50%;
}
.step__content h4 { margin-bottom: 0.25rem; }
.step__content p { color: var(--text-secondary); }

/* --- Brain vs Spine Diagram --- */
.bvs {
  display: flex;
  flex-direction: column;
  gap: 1rem;
  max-width: 960px;
  margin: 0 auto;
}
.bvs__panel {
  flex: 1;
  padding: 2rem;
  border-radius: var(--radius);
}
.bvs__panel--brain {
  background: var(--bg-alt);
  border: 1px solid var(--border);
}
.bvs__panel--spine {
  background: var(--bg-accent);
  border: 1px solid var(--purple-border);
}
.bvs__owner {
  font-size: 0.6875rem;
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  margin-bottom: 0.25rem;
}
.bvs__panel--brain .bvs__owner { color: var(--text-muted); }
.bvs__panel--spine .bvs__owner { color: var(--purple); }
.bvs__panel h3 { margin-bottom: 1rem; }
.bvs__panel li {
  font-size: 1rem;
  color: var(--text-secondary);
  padding: 0.375rem 0 0.375rem 1.375rem;
  position: relative;
}
.bvs__panel li::before {
  content: '';
  position: absolute;
  left: 0;
  top: 0.75rem;
  width: 6px;
  height: 6px;
  border-radius: 50%;
}
.bvs__panel--brain li::before { background: var(--text-muted); }
.bvs__panel--spine li::before { background: var(--purple); }
.bvs__connector {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 0.5rem;
  font-size: 1.5rem;
  color: var(--purple);
  padding: 0.5rem;
}
.bvs__connector span { font-size: 0.75rem; color: var(--text-muted); }

/* --- Testimonials --- */
.testimonial {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 2rem;
}
.testimonial__quote {
  font-size: 1.125rem;
  font-style: italic;
  color: var(--text-secondary);
  line-height: 1.6;
  margin-bottom: 1.5rem;
  position: relative;
  padding-left: 1.5rem;
  border-left: 3px solid var(--purple);
}
.testimonial__author { font-weight: 700; color: var(--text); }
.testimonial__role { font-size: 0.875rem; color: var(--text-muted); }

/* --- CTA Section --- */
.cta-section {
  background: var(--bg-accent);
  padding: 5rem 0;
  text-align: center;
}
.cta-section h2 { margin-bottom: 1rem; }
.cta-section p {
  font-size: 1.125rem;
  color: var(--text-secondary);
  max-width: 600px;
  margin: 0 auto 2rem;
}
.cta-section .cta-alt {
  display: block;
  margin-top: 1rem;
  font-size: 0.9375rem;
  color: var(--text-muted);
}

/* --- Proof Line --- */
.proof-line {
  font-size: 0.9375rem;
  color: var(--text-muted);
  text-align: center;
  padding: 1.5rem 0;
}

/* --- Use Cases Vertical --- */
.vertical {
  padding: 3rem 0;
  border-bottom: 1px solid var(--border);
}
.vertical:last-child { border-bottom: none; }
.vertical__header {
  margin-bottom: 1.5rem;
}
.vertical__header h3 {
  font-size: 1.5rem;
  margin-bottom: 0.5rem;
}
.vertical__challenge {
  color: var(--text-secondary);
  margin-bottom: 1.5rem;
  line-height: 1.6;
}
.vertical__grid {
  display: grid;
  gap: 1.5rem;
  grid-template-columns: 1fr;
}
.vertical__what h4 {
  font-size: 1rem;
  font-weight: 700;
  color: var(--purple);
  margin-bottom: 0.5rem;
}
.vertical__what li {
  padding: 0.25rem 0 0.25rem 1.25rem;
  position: relative;
  font-size: 0.9375rem;
}
.vertical__what li::before {
  content: '';
  position: absolute;
  left: 0;
  top: 0.625rem;
  width: 5px;
  height: 5px;
  background: var(--purple);
  border-radius: 50%;
}
.vertical__reqs {
  background: var(--bg-alt);
  border-radius: var(--radius-sm);
  padding: 1.25rem;
}
.vertical__reqs h4 {
  font-size: 0.875rem;
  font-weight: 700;
  color: var(--text);
  margin-bottom: 0.5rem;
}
.vertical__reqs p {
  font-size: 0.875rem;
  color: var(--text-muted);
}

/* Vertical nav (anchor links) */
.vertical-nav {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-bottom: 3rem;
  justify-content: center;
}
.vertical-nav a {
  font-size: 0.8125rem;
  font-weight: 600;
  color: var(--text-secondary);
  background: var(--bg-alt);
  padding: 0.5rem 1rem;
  border-radius: 20px;
  border: 1px solid var(--border);
  transition: all var(--transition);
}
.vertical-nav a:hover {
  background: var(--purple-light);
  color: var(--purple);
  border-color: var(--purple-border);
}

/* --- Team --- */
.team-grid {
  display: grid;
  gap: 2rem;
  grid-template-columns: 1fr;
}
.team-member {
  text-align: center;
}
.team-member img {
  width: 140px;
  height: 140px;
  border-radius: 50%;
  object-fit: cover;
  border: 3px solid var(--purple-border);
  margin: 0 auto 1rem;
}
.team-member__name {
  font-size: 1.125rem;
  font-weight: 700;
  color: var(--text);
}
.team-member__role {
  font-size: 0.875rem;
  color: var(--purple);
  font-weight: 600;
  margin-bottom: 0.5rem;
}
.team-member__bio {
  font-size: 0.9375rem;
  color: var(--text-secondary);
  max-width: 320px;
  margin: 0 auto;
}

/* --- Credibility Stats --- */
.stats-row {
  display: grid;
  gap: 1rem;
  grid-template-columns: repeat(2, 1fr);
}
.stat-item {
  text-align: center;
  padding: 1.5rem;
  background: var(--bg-alt);
  border: 1px solid var(--border);
  border-radius: var(--radius);
}
.stat-item__number {
  font-size: 2rem;
  font-weight: 800;
  color: var(--purple);
  line-height: 1.2;
}
.stat-item__label {
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-muted);
  margin-top: 0.25rem;
}

/* --- Contact Form --- */
.contact-split {
  display: grid;
  gap: 3rem;
  grid-template-columns: 1fr;
}
.contact-info h1 { margin-bottom: 1rem; }
.contact-info p {
  font-size: 1.125rem;
  color: var(--text-secondary);
  margin-bottom: 2rem;
}
.contact-alt {
  padding-top: 2rem;
  border-top: 1px solid var(--border);
}
.contact-alt p {
  font-size: 0.9375rem;
  color: var(--text-muted);
  margin-bottom: 0.5rem;
}

.form__group { margin-bottom: 1.5rem; }
.form__label {
  display: block;
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--text);
  margin-bottom: 0.5rem;
}
.form__input,
.form__textarea {
  width: 100%;
  font-family: inherit;
  font-size: 1rem;
  padding: 0.875rem 1rem;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--bg);
  color: var(--text);
  transition: border-color var(--transition), box-shadow var(--transition);
}
.form__input:focus,
.form__textarea:focus {
  outline: none;
  border-color: var(--purple);
  box-shadow: 0 0 0 3px rgba(109,40,217,0.1);
}
.form__textarea { min-height: 140px; resize: vertical; }
.form__optional {
  font-size: 0.75rem;
  color: var(--text-muted);
  font-weight: 400;
}
.form__submit { width: 100%; justify-content: center; font-size: 1.0625rem; }
.form__status {
  padding: 1rem;
  border-radius: var(--radius-sm);
  margin-top: 1rem;
  font-size: 0.9375rem;
  display: none;
}
.form__status--success {
  display: block;
  background: rgba(5,150,105,0.08);
  color: var(--green);
  border: 1px solid rgba(5,150,105,0.2);
}
.form__status--error {
  display: block;
  background: rgba(220,38,38,0.08);
  color: var(--red);
  border: 1px solid rgba(220,38,38,0.2);
}

/* --- Capabilities Grid --- */
.cap-group { margin-bottom: 3rem; }
.cap-group__title {
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.12em;
  color: var(--purple);
  margin-bottom: 1rem;
  padding-bottom: 0.5rem;
  border-bottom: 2px solid var(--purple-light);
}
.cap-item {
  padding: 0.625rem 0 0.625rem 1.25rem;
  position: relative;
  font-size: 1rem;
  color: var(--text-secondary);
}
.cap-item::before {
  content: '';
  position: absolute;
  left: 0;
  top: 0.875rem;
  width: 5px;
  height: 5px;
  background: var(--purple);
  border-radius: 50%;
}

/* --- Process Timeline --- */
.process { counter-reset: process-step; }
.process__step {
  display: flex;
  gap: 1.5rem;
  padding: 1.5rem 0;
  border-bottom: 1px solid var(--border);
}
.process__step:last-child { border-bottom: none; }
.process__num {
  width: 40px;
  height: 40px;
  flex-shrink: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--purple);
  color: #fff;
  font-weight: 800;
  font-size: 1rem;
  border-radius: 50%;
}
.process__content h4 { margin-bottom: 0.25rem; }
.process__content p { font-size: 0.9375rem; color: var(--text-secondary); }

/* --- Footer --- */
.footer {
  background: var(--text);
  color: rgba(255,255,255,0.7);
  padding: 4rem 0 2rem;
  font-size: 0.875rem;
}
.footer__grid {
  display: grid;
  gap: 2rem;
  grid-template-columns: 1fr;
  margin-bottom: 3rem;
}
.footer__brand img { height: 36px; width: auto; margin-bottom: 0.75rem; filter: brightness(10); }
.footer__brand p { color: rgba(255,255,255,0.5); font-size: 0.875rem; }
.footer__col h4 {
  color: #fff;
  font-size: 0.8125rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  margin-bottom: 1rem;
}
.footer__col a {
  display: block;
  color: rgba(255,255,255,0.6);
  font-size: 0.875rem;
  padding: 0.25rem 0;
  transition: color var(--transition);
}
.footer__col a:hover { color: #fff; }
.footer__tactun-link {
  text-align: center;
  padding: 1.5rem 0;
  border-top: 1px solid rgba(255,255,255,0.1);
  border-bottom: 1px solid rgba(255,255,255,0.1);
  margin-bottom: 1.5rem;
}
.footer__tactun-link a { color: var(--purple-mid); }
.footer__bottom {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  align-items: center;
  font-size: 0.8125rem;
  color: rgba(255,255,255,0.4);
}
.footer__bottom a { color: rgba(255,255,255,0.5); }

/* --- Privacy Page --- */
.privacy-content {
  max-width: 720px;
  margin: 0 auto;
  padding-top: 72px;
}
.privacy-content h1 { margin-bottom: 0.5rem; }
.privacy-content .date { color: var(--text-muted); margin-bottom: 2rem; }
.privacy-content h2 {
  font-size: 1.375rem;
  margin-top: 2.5rem;
  margin-bottom: 0.75rem;
}
.privacy-content p, .privacy-content li {
  margin-bottom: 0.75rem;
  font-size: 1rem;
  line-height: 1.7;
}
.privacy-content ul { padding-left: 1.5rem; list-style: disc; }

/* --- Animations --- */
.fade-in {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}
.fade-in--visible {
  opacity: 1;
  transform: translateY(0);
}

/* ============================================
   Responsive Breakpoints
   ============================================ */

/* Tablet (768px+) */
@media (min-width: 768px) {
  h1 { font-size: 3.25rem; }
  h2 { font-size: 2.5rem; }

  .nav__links { display: flex; }
  .nav__hamburger { display: none; }

  .hero__inner {
    flex-direction: row;
    align-items: center;
    padding: 4rem 0;
  }
  .hero__content { flex: 1; }
  .hero__content h1 { font-size: 3.25rem; }
  .hero__image { flex: 1; }

  .grid--2 { grid-template-columns: repeat(2, 1fr); }
  .grid--3 { grid-template-columns: repeat(2, 1fr); }

  .bvs { flex-direction: row; gap: 0; }
  .bvs__panel--brain { border-radius: var(--radius) 0 0 var(--radius); }
  .bvs__panel--spine { border-radius: 0 var(--radius) var(--radius) 0; }
  .bvs__connector {
    flex-direction: column;
    width: 56px;
    margin: 0 -28px;
    z-index: 2;
  }

  .team-grid { grid-template-columns: repeat(3, 1fr); }
  .stats-row { grid-template-columns: repeat(4, 1fr); }

  .contact-split { grid-template-columns: 1fr 1fr; }

  .footer__grid { grid-template-columns: 2fr 1fr 1fr 1fr; }
  .footer__bottom { flex-direction: row; justify-content: space-between; }

  .vertical__grid { grid-template-columns: 1fr 1fr; }
}

/* Desktop (1024px+) */
@media (min-width: 1024px) {
  h1 { font-size: 3.75rem; }
  h2 { font-size: 3rem; }

  .hero__content h1 { font-size: 3.75rem; }

  .grid--3 { grid-template-columns: repeat(3, 1fr); }
  .grid--4 { grid-template-columns: repeat(2, 1fr); }

  .section { padding: 6rem 0; }
}

/* Wide (1280px+) */
@media (min-width: 1280px) {
  .grid--4 { grid-template-columns: repeat(4, 1fr); }
  .container { padding: 0 2rem; }
}

/* Print */
@media print {
  .nav, .footer, .nav__mobile { display: none !important; }
  .hero { min-height: auto; padding-top: 0; }
  .section { padding: 2rem 0; }
}