/* ============================================================
   AIVANTA — Core Stylesheet
   Design system: ink/paper duotone, signal-blue + amber accents
   Type: Space Grotesk (display) + Inter (body)
   ============================================================ */

:root {
  /* Color tokens */
  --ink: #0b0f19;
  --ink-soft: #131a2b;
  --ink-line: #232c42;
  --paper: #f5f6f8;
  --paper-dim: #eceef2;
  --paper-line: #dde1e8;
  --signal: #3e5fdd;
  --signal-dim: #2c46ad;
  --amber: #e8a33d;
  --slate: #5b6474;
  --slate-dark: #aab2c5;
  --white: #ffffff;
  --danger: #d84a4a;
  --success: #2f9e6b;

  /* Type */
  --font-display: "Space Grotesk", "Helvetica Neue", Arial, sans-serif;
  --font-body: "Inter", "Helvetica Neue", Arial, sans-serif;

  /* Scale (major third-ish, hand tuned) */
  --fs-100: 0.8125rem;
  --fs-200: 0.9375rem;
  --fs-300: 1.0625rem;
  --fs-400: 1.25rem;
  --fs-500: 1.625rem;
  --fs-600: 2.125rem;
  --fs-700: 2.875rem;
  --fs-800: 3.75rem;

  --radius-sm: 4px;
  --radius-md: 8px;
  --max-w: 1180px;

  --ease: cubic-bezier(0.22, 1, 0.36, 1);
}

/* ---------- Reset ---------- */
*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; }
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { animation-duration: 0.001ms !important; animation-iteration-count: 1 !important; transition-duration: 0.001ms !important; }
}
body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--font-body);
  font-size: var(--fs-300);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}
img { max-width: 100%; display: block; }
a { color: inherit; text-decoration: none; }
ul { margin: 0; padding: 0; list-style: none; }
h1, h2, h3, h4 { font-family: var(--font-display); line-height: 1.15; margin: 0 0 0.5em; letter-spacing: -0.01em; }
p { margin: 0 0 1em; color: var(--slate); }
button { font-family: inherit; cursor: pointer; }
input, textarea, select { font-family: inherit; font-size: inherit; }

:focus-visible {
  outline: 2px solid var(--signal);
  outline-offset: 3px;
}

.container {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 24px;
}

.section {
  padding: 96px 0;
}
.section--tight { padding: 64px 0; }
.section--dark {
  background: var(--ink);
  color: var(--white);
}
.section--dark p { color: var(--slate-dark); }
.section--dim { background: var(--paper-dim); }

.section-head {
  max-width: 640px;
  margin-bottom: 56px;
}
.section-head .kicker {
  display: inline-block;
  font-family: var(--font-display);
  font-size: var(--fs-200);
  color: var(--signal);
  margin-bottom: 12px;
}
.section--dark .section-head .kicker { color: var(--amber); }
.section-head h2 {
  font-size: var(--fs-700);
}
.section-head p { font-size: var(--fs-300); }

/* ---------- Buttons ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 13px 26px;
  border-radius: var(--radius-sm);
  font-weight: 600;
  font-size: var(--fs-200);
  border: 1px solid transparent;
  transition: transform 0.2s var(--ease), background 0.2s var(--ease), border-color 0.2s var(--ease), color .2s var(--ease);
  white-space: nowrap;
}
.btn:hover { transform: translateY(-2px); }
.btn-primary {
  background: var(--signal);
  color: var(--white);
}
.btn-primary:hover { background: var(--signal-dim); }
.btn-outline {
  background: transparent;
  border-color: var(--ink-line);
  color: var(--ink);
}
.section--dark .btn-outline { border-color: var(--slate-dark); color: var(--white); }
.btn-outline:hover { border-color: var(--signal); color: var(--signal); }
.btn-ghost {
  background: transparent;
  color: var(--signal);
  padding: 8px 4px;
  border-bottom: 1px solid transparent;
  border-radius: 0;
}
.btn-ghost:hover { border-bottom-color: var(--signal); transform: none; }
.btn-block { width: 100%; }
.btn:disabled { opacity: 0.55; cursor: not-allowed; transform: none; }

/* ---------- Header / Nav ---------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(245, 246, 248, 0.88);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--paper-line);
}
.nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 76px;
}
.logo {
  font-family: var(--font-display);
  font-size: var(--fs-400);
  font-weight: 700;
  letter-spacing: -0.02em;
  display: flex;
  align-items: baseline;
  gap: 2px;
}
.logo .dot { color: var(--signal); }
.nav-links {
  display: flex;
  align-items: center;
  gap: 36px;
}
.nav-links a {
  font-size: var(--fs-200);
  font-weight: 500;
  color: var(--ink);
  position: relative;
  padding: 4px 0;
}
.nav-links a::after {
  content: "";
  position: absolute;
  left: 0; right: 100%;
  bottom: -2px;
  height: 2px;
  background: var(--signal);
  transition: right 0.25s var(--ease);
}
.nav-links a:hover::after,
.nav-links a.active::after { right: 0; }
.nav-links a.active { color: var(--signal); }
.nav-actions { display: flex; align-items: center; gap: 12px; }
.nav-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  padding: 6px;
}
.nav-toggle span {
  width: 24px; height: 2px; background: var(--ink); transition: transform .25s var(--ease), opacity .25s var(--ease);
}
.nav-toggle.open span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.nav-toggle.open span:nth-child(2) { opacity: 0; }
.nav-toggle.open span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

@media (max-width: 900px) {
  .nav-links { position: fixed; top: 76px; left: 0; right: 0; bottom: 0; background: var(--paper); flex-direction: column; justify-content: flex-start; align-items: flex-start; padding: 32px 24px; gap: 24px; transform: translateX(100%); transition: transform 0.3s var(--ease); overflow-y: auto; }
  .nav-links.open { transform: translateX(0); }
  .nav-links a { font-size: var(--fs-500); }
  .nav-actions .btn-outline { display: none; }
  .nav-toggle { display: flex; }
}

/* ---------- Hero ---------- */
.hero {
  position: relative;
  overflow: hidden;
  padding: 88px 0 96px;
  background: var(--ink);
  color: var(--white);
}
.hero-grid {
  display: grid;
  grid-template-columns: 1.1fr 0.9fr;
  gap: 48px;
  align-items: center;
}
.hero .eyebrow {
  font-family: var(--font-display);
  color: var(--amber);
  font-size: var(--fs-200);
  margin-bottom: 18px;
  display: flex;
  align-items: center;
  gap: 10px;
}
.hero .eyebrow::before {
  content: "";
  width: 28px; height: 1px; background: var(--amber);
}
.hero h1 {
  font-size: var(--fs-800);
  max-width: 620px;
}
.hero p.lead {
  font-size: var(--fs-400);
  color: var(--slate-dark);
  max-width: 500px;
  margin-bottom: 32px;
}
.hero-actions { display: flex; gap: 16px; flex-wrap: wrap; margin-bottom: 44px; }
.hero-stats { display: flex; gap: 40px; }
.hero-stats div strong { display: block; font-family: var(--font-display); font-size: var(--fs-600); }
.hero-stats div span { font-size: var(--fs-100); color: var(--slate-dark); }

.hero-visual {
  position: relative;
  aspect-ratio: 1/1;
  max-width: 460px;
  justify-self: end;
}
.hero-visual svg { width: 100%; height: 100%; }

@media (max-width: 960px) {
  .hero-grid { grid-template-columns: 1fr; }
  .hero-visual { justify-self: center; margin-top: 12px; max-width: 340px; }
  .hero h1 { font-size: var(--fs-700); }
}

/* ---------- Cards ---------- */
.grid {
  display: grid;
  gap: 28px;
}
.grid-3 { grid-template-columns: repeat(3, 1fr); }
.grid-2 { grid-template-columns: repeat(2, 1fr); }
@media (max-width: 900px) { .grid-3, .grid-2 { grid-template-columns: 1fr; } }

.card {
  background: var(--white);
  border: 1px solid var(--paper-line);
  border-left: 3px solid var(--signal);
  padding: 32px 28px;
  transition: border-color .25s var(--ease), transform .25s var(--ease), box-shadow .25s var(--ease);
}
.card:hover {
  transform: translateY(-4px);
  border-left-color: var(--amber);
  box-shadow: 0 18px 40px -24px rgba(11, 15, 25, 0.35);
}
.card .icon {
  width: 44px; height: 44px;
  color: var(--signal);
  margin-bottom: 20px;
}
.card h3 { font-size: var(--fs-400); margin-bottom: 10px; }
.card p { margin-bottom: 18px; font-size: var(--fs-200); }

.feature-row {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1px;
  background: var(--ink-line);
  border: 1px solid var(--ink-line);
}
@media (max-width: 900px) { .feature-row { grid-template-columns: repeat(2, 1fr); } }
@media (max-width: 600px) { .feature-row { grid-template-columns: 1fr; } }
.feature-item {
  background: var(--ink);
  padding: 32px 28px;
}
.feature-item .num { font-family: var(--font-display); color: var(--amber); font-size: var(--fs-200); margin-bottom: 14px; display: block; }
.feature-item h4 { color: var(--white); font-size: var(--fs-400); margin-bottom: 8px; }
.feature-item p { color: var(--slate-dark); font-size: var(--fs-200); margin: 0; }

/* ---------- Course cards ---------- */
.course-card {
  background: var(--white);
  border: 1px solid var(--paper-line);
  display: flex;
  flex-direction: column;
  transition: transform .25s var(--ease), box-shadow .25s var(--ease);
}
.course-card:hover { transform: translateY(-4px); box-shadow: 0 18px 40px -24px rgba(11,15,25,0.35); }
.course-card .thumb {
  height: 148px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-display);
  font-size: var(--fs-600);
  color: var(--white);
}
.course-card .body { padding: 24px; display: flex; flex-direction: column; gap: 10px; flex: 1; }
.course-card .tag-row { display: flex; gap: 8px; }
.course-card .tag {
  font-size: var(--fs-100);
  padding: 3px 10px;
  border: 1px solid var(--paper-line);
  color: var(--slate);
}
.course-card h3 { font-size: var(--fs-400); margin: 0; }
.course-card .meta { display: flex; justify-content: space-between; font-size: var(--fs-100); color: var(--slate); border-top: 1px solid var(--paper-line); padding-top: 14px; margin-top: auto; }
.course-card .price { font-family: var(--font-display); font-size: var(--fs-400); color: var(--ink); }
.course-card .footer-row { display: flex; align-items: center; justify-content: space-between; gap: 12px; margin-top: 4px; }

.course-filters {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-bottom: 36px;
  align-items: center;
  justify-content: space-between;
}
.filter-pills { display: flex; gap: 8px; flex-wrap: wrap; }
.filter-pill {
  background: transparent;
  border: 1px solid var(--paper-line);
  padding: 8px 18px;
  border-radius: 999px;
  font-size: var(--fs-200);
  font-weight: 500;
  transition: all .2s var(--ease);
}
.filter-pill.active, .filter-pill:hover { background: var(--ink); color: var(--white); border-color: var(--ink); }
.search-box {
  position: relative;
  min-width: 260px;
}
.search-box input {
  width: 100%;
  padding: 10px 16px 10px 40px;
  border: 1px solid var(--paper-line);
  border-radius: var(--radius-sm);
  background: var(--white);
}
.search-box svg { position: absolute; left: 12px; top: 50%; transform: translateY(-50%); width: 16px; height: 16px; color: var(--slate); }

.empty-state {
  padding: 64px 24px;
  text-align: center;
  color: var(--slate);
  border: 1px dashed var(--paper-line);
  grid-column: 1 / -1;
}

/* ---------- CTA band ---------- */
.cta-band {
  background: var(--signal);
  color: var(--white);
  padding: 72px 0;
}
.cta-band-inner { display: flex; align-items: center; justify-content: space-between; gap: 32px; flex-wrap: wrap; }
.cta-band h2 { font-size: var(--fs-600); margin-bottom: 6px; }
.cta-band p { color: rgba(255,255,255,0.85); margin: 0; max-width: 460px; }
.cta-band .btn-primary { background: var(--ink); }
.cta-band .btn-primary:hover { background: #000; }
.cta-band .btn-outline { border-color: rgba(255,255,255,0.5); color: var(--white); }
.cta-band .btn-outline:hover { border-color: var(--white); color: var(--white); }
.cta-actions { display: flex; gap: 14px; flex-wrap: wrap; }

/* ---------- Footer ---------- */
.site-footer {
  background: var(--ink);
  color: var(--slate-dark);
  padding: 64px 0 28px;
}
.footer-grid {
  display: grid;
  grid-template-columns: 1.4fr 1fr 1fr 1fr;
  gap: 32px;
  padding-bottom: 40px;
  border-bottom: 1px solid var(--ink-line);
}
@media (max-width: 800px) { .footer-grid { grid-template-columns: 1fr 1fr; } }
.footer-grid h5 { color: var(--white); font-family: var(--font-display); font-size: var(--fs-200); margin-bottom: 16px; letter-spacing: 0.02em; }
.footer-grid li { margin-bottom: 10px; font-size: var(--fs-200); }
.footer-grid a:hover { color: var(--white); }
.footer-brand .logo { color: var(--white); margin-bottom: 14px; }
.footer-brand p { max-width: 280px; font-size: var(--fs-200); }
.footer-bottom { display: flex; justify-content: space-between; align-items: center; padding-top: 24px; font-size: var(--fs-100); flex-wrap: wrap; gap: 12px; }

/* ---------- Breadcrumb / page header ---------- */
.page-hero {
  background: var(--ink);
  color: var(--white);
  padding: 64px 0 56px;
}
.page-hero .kicker { color: var(--amber); font-family: var(--font-display); font-size: var(--fs-200); margin-bottom: 10px; display:block; }
.page-hero h1 { font-size: var(--fs-700); max-width: 700px; }
.page-hero p { color: var(--slate-dark); max-width: 560px; font-size: var(--fs-300); }

/* ---------- Service detail blocks ---------- */
.service-detail {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 56px;
  align-items: start;
  padding: 64px 0;
  border-bottom: 1px solid var(--paper-line);
}
.service-detail:last-child { border-bottom: none; }
.service-detail.reverse .service-copy { order: 2; }
.service-detail .service-visual {
  aspect-ratio: 4/3;
  border: 1px solid var(--paper-line);
  display: flex; align-items: center; justify-content: center;
  font-family: var(--font-display);
  color: var(--slate);
  background: var(--white);
}
.service-copy .service-index { font-family: var(--font-display); color: var(--signal); font-size: var(--fs-200); margin-bottom: 12px; display:block; }
.service-copy h2 { font-size: var(--fs-600); }
.spec-list { display: grid; grid-template-columns: 1fr 1fr; gap: 12px 24px; margin: 24px 0; padding: 20px 0; border-top: 1px solid var(--paper-line); border-bottom: 1px solid var(--paper-line); }
.spec-list div span { display: block; font-size: var(--fs-100); color: var(--slate); }
.spec-list div strong { font-family: var(--font-display); font-size: var(--fs-300); }
.feature-list li { position: relative; padding-left: 22px; margin-bottom: 10px; font-size: var(--fs-200); color: var(--slate); }
.feature-list li::before { content: "—"; position: absolute; left: 0; color: var(--signal); }
@media (max-width: 860px) { .service-detail { grid-template-columns: 1fr; } .service-detail.reverse .service-copy { order: 0; } }

/* ---------- Forms ---------- */
.form-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 20px; }
.form-grid .full { grid-column: 1 / -1; }
@media (max-width: 700px) { .form-grid { grid-template-columns: 1fr; } }
.field { display: flex; flex-direction: column; gap: 6px; }
.field label { font-size: var(--fs-200); font-weight: 600; }
.field .req { color: var(--danger); }
.field input, .field select, .field textarea {
  padding: 12px 14px;
  border: 1px solid var(--paper-line);
  border-radius: var(--radius-sm);
  background: var(--white);
  color: var(--ink);
  transition: border-color .2s var(--ease);
}
.field input:focus, .field select:focus, .field textarea:focus { border-color: var(--signal); }
.field textarea { resize: vertical; min-height: 110px; }
.field.invalid input, .field.invalid textarea, .field.invalid select { border-color: var(--danger); }
.field .error-msg { font-size: var(--fs-100); color: var(--danger); min-height: 16px; }
.form-note { font-size: var(--fs-100); color: var(--slate); margin-top: 8px; }

.form-success {
  display: none;
  align-items: flex-start;
  gap: 14px;
  background: rgba(47, 158, 107, 0.08);
  border: 1px solid var(--success);
  color: var(--success);
  padding: 18px 20px;
  border-radius: var(--radius-sm);
  margin-bottom: 20px;
  font-size: var(--fs-200);
}
.form-success.show { display: flex; }
.form-success svg { flex-shrink: 0; width: 20px; height: 20px; margin-top: 2px; }

/* ---------- Modal ---------- */
.modal-overlay {
  position: fixed; inset: 0;
  background: rgba(11, 15, 25, 0.6);
  display: none;
  align-items: flex-start;
  justify-content: center;
  padding: 48px 20px;
  overflow-y: auto;
  z-index: 200;
}
.modal-overlay.open { display: flex; }
.modal {
  background: var(--paper);
  max-width: 640px;
  width: 100%;
  padding: 40px;
  position: relative;
  border-top: 3px solid var(--signal);
}
.modal-close {
  position: absolute; top: 18px; right: 18px;
  background: none; border: none;
  width: 32px; height: 32px;
  display: flex; align-items: center; justify-content: center;
  color: var(--slate);
}
.modal-close:hover { color: var(--ink); }
.modal h3 { font-size: var(--fs-500); margin-bottom: 4px; }
.modal .modal-sub { color: var(--slate); font-size: var(--fs-200); margin-bottom: 24px; }

/* ---------- Toast ---------- */
.toast {
  position: fixed;
  bottom: 24px; right: 24px;
  background: var(--ink);
  color: var(--white);
  padding: 16px 20px;
  border-radius: var(--radius-sm);
  border-left: 3px solid var(--success);
  display: flex; align-items: center; gap: 12px;
  transform: translateY(120%);
  opacity: 0;
  transition: transform .35s var(--ease), opacity .35s var(--ease);
  z-index: 300;
  max-width: 340px;
  font-size: var(--fs-200);
}
.toast.error { border-left-color: var(--danger); }
.toast.show { transform: translateY(0); opacity: 1; }

/* ---------- Back to top ---------- */
.back-to-top {
  position: fixed;
  bottom: 24px; left: 24px;
  width: 44px; height: 44px;
  background: var(--ink);
  color: var(--white);
  border: none;
  display: flex; align-items: center; justify-content: center;
  opacity: 0; visibility: hidden;
  transform: translateY(8px);
  transition: opacity .25s var(--ease), transform .25s var(--ease), visibility .25s;
  z-index: 90;
}
.back-to-top.show { opacity: 1; visibility: visible; transform: translateY(0); }
.back-to-top:hover { background: var(--signal); }

/* ---------- Reveal on scroll ---------- */
.reveal { opacity: 0; transform: translateY(18px); transition: opacity .6s var(--ease), transform .6s var(--ease); }
.reveal.in-view { opacity: 1; transform: translateY(0); }

/* ---------- Values / About ---------- */
.values-grid { display: grid; grid-template-columns: repeat(5, 1fr); gap: 1px; background: var(--paper-line); border: 1px solid var(--paper-line); }
@media (max-width: 900px) { .values-grid { grid-template-columns: repeat(2, 1fr); } }
.value-item { background: var(--white); padding: 28px 20px; text-align: left; }
.value-item h4 { font-size: var(--fs-300); margin-bottom: 6px; }
.value-item p { font-size: var(--fs-100); margin: 0; }

.story-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 32px; }
@media (max-width: 900px) { .story-grid { grid-template-columns: 1fr; } }
.story-card { border-top: 3px solid var(--signal); padding-top: 20px; }
.story-card:nth-child(2) { border-top-color: var(--amber); }
.story-card:nth-child(3) { border-top-color: var(--ink); }
.story-card h3 { font-size: var(--fs-400); }

/* ---------- Team / contact ---------- */
.contact-grid { display: grid; grid-template-columns: 0.9fr 1.1fr; gap: 56px; }
@media (max-width: 900px) { .contact-grid { grid-template-columns: 1fr; } }
.contact-info-item { display: flex; gap: 16px; padding: 20px 0; border-bottom: 1px solid var(--paper-line); }
.contact-info-item .icon { width: 22px; height: 22px; color: var(--signal); flex-shrink: 0; margin-top: 2px; }
.contact-info-item h4 { font-size: var(--fs-300); margin-bottom: 4px; }
.contact-info-item p { margin: 0; font-size: var(--fs-200); }

.map-block {
  margin-top: 24px;
  border: 1px solid var(--paper-line);
  padding: 20px;
  font-size: var(--fs-100);
  color: var(--slate);
}

/* ---------- Course details page ---------- */
.course-detail-layout { display: grid; grid-template-columns: 1.6fr 1fr; gap: 48px; align-items: start; }
@media (max-width: 960px) { .course-detail-layout { grid-template-columns: 1fr; } }
.syllabus-item { border: 1px solid var(--paper-line); padding: 18px 20px; margin-bottom: 12px; }
.syllabus-item .week { font-family: var(--font-display); color: var(--signal); font-size: var(--fs-100); display: block; margin-bottom: 4px; }
.skill-chip-row { display: flex; flex-wrap: wrap; gap: 8px; }
.skill-chip { background: var(--paper-dim); border: 1px solid var(--paper-line); padding: 6px 14px; font-size: var(--fs-100); border-radius: 999px; }
.enroll-card { border: 1px solid var(--paper-line); padding: 28px; position: sticky; top: 100px; background: var(--white); }
.enroll-card .price-big { font-family: var(--font-display); font-size: var(--fs-700); margin-bottom: 2px; }
.enroll-card .meta-list { list-style: none; padding: 0; margin: 20px 0; }
.enroll-card .meta-list li { display: flex; justify-content: space-between; padding: 10px 0; border-bottom: 1px solid var(--paper-line); font-size: var(--fs-200); }

/* Utility */
.text-center { text-align: center; }
.mt-0 { margin-top: 0; }
.hidden { display: none !important; }
.skip-link {
  position: absolute; left: -999px; top: 0;
  background: var(--ink); color: var(--white); padding: 12px 20px; z-index: 999;
}
.skip-link:focus { left: 12px; top: 12px; }