/* ============================================================
   CourserTech — Responsive (Desktop-first, breakpoints down)
   ============================================================ */

/* ---------- ≤ 1100px ---------- */
@media (max-width: 1100px) {
  .grid-4 { grid-template-columns: repeat(2, 1fr); }
  .grid-6 { grid-template-columns: repeat(3, 1fr); }
  .steps { grid-template-columns: repeat(3, 1fr); }
  .footer-main { grid-template-columns: 1fr 1fr; }
  .nav-link { padding-inline: 10px; }
  .intro-media .float-card { right: 10px; }
}

/* ---------- ≤ 992px (tablet) ---------- */
@media (max-width: 992px) {
  :root { --header-h: 66px; }

  /* Nav → burger */
  .nav-burger { display: flex; }
  .nav-cta { display: none; }

  .main-nav {
    position: fixed;
    inset: 0;
    z-index: 99;
    background: var(--c-white);
    padding: calc(var(--topbar-h) + 70px) 24px 40px;
    overflow-y: auto;
    opacity: 0;
    visibility: hidden;
    transition: opacity var(--transition), visibility var(--transition);
  }
  body.nav-open .main-nav { opacity: 1; visibility: visible; z-index: 101; }
  body.nav-open { overflow: hidden; }

  .nav-list {
    flex-direction: column;
    align-items: stretch;
    gap: 2px;
  }
  .nav-link {
    width: 100%;
    justify-content: space-between;
    font-size: var(--fs-base);
    padding: 13px 10px;
    border-bottom: 1px solid var(--c-line);
    border-radius: 0;
  }
  .nav-item.has-children::after { display: none; }
  .nav-item .chevron { transition: transform var(--transition); }
  .nav-item.is-open .chevron { transform: rotate(180deg); }

  /* Mobile accordion dropdowns */
  .dropdown {
    position: static;
    opacity: 1;
    visibility: visible;
    transform: none;
    border: 0;
    box-shadow: none;
    background: var(--c-bg-soft);
    border-radius: var(--radius);
    padding: 6px;
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.35s ease;
  }
  .nav-item.is-open .dropdown { max-height: 420px; padding: 8px; }
  .dropdown a { color: var(--c-body); }

  .mobile-cta {
    display: grid !important;
    gap: 12px;
    margin-top: 24px;
  }

  /* Layout */
  .intro,
  .split,
  .contact-grid { grid-template-columns: 1fr; }
  .intro-media { order: -1; }
  .intro-media .float-card { position: relative; margin-top: 16px; margin-inline: auto; width: fit-content; box-shadow: var(--shadow-lg); }
  .float-card strong { font-size: var(--fs-sm); }
  .float-card small { font-size: var(--fs-xs); }
  .grid-3 { grid-template-columns: repeat(2, 1fr); }
  .why-grid { grid-template-columns: 1fr; }
  .hero { min-height: 520px; }
  .hero-nav { display: none; }
  .cta-inner { flex-direction: column; align-items: flex-start; }
  .tl-item { grid-template-columns: 72px 1fr; gap: 18px; }
}

/* ---------- ≤ 640px (phone) ---------- */
@media (max-width: 640px) {
  :root { --section-pad: 56px; }

  .topbar-left .topbar-hide-sm { display: none; }
  .topbar .container { justify-content: center; }
  .topbar-left { display: none; }

  .grid-2,
  .grid-3,
  .grid-4 { grid-template-columns: 1fr; }
  .grid-3 > *,
  .grid-2 > * { min-width: 0; }
  .grid-6 { grid-template-columns: repeat(2, 1fr); }
  .stats-grid { grid-template-columns: 1fr 1fr; }
  .steps { grid-template-columns: 1fr 1fr; }

  .hero { min-height: 480px; }
  .slide-actions .btn { width: 100%; }
  .hero-trust { gap: 8px 18px; }
  .slide-content p { font-size: var(--fs-base); }
  .slide-content .slide-actions { flex-direction: column; }
  .slide-content .slide-actions .btn { width: 100%; }

  .card { padding: 22px; }
  .cta-band::before, .cta-band::after { display: none; }

  .doc-card { grid-template-columns: auto 1fr; }
  .doc-card .btn { grid-column: 1 / -1; }

  .footer-main { grid-template-columns: 1fr; gap: 34px; }
  .footer-bottom { flex-direction: column; text-align: center; }

  .flow { flex-direction: column; }
  .flow-arrow { transform: rotate(90deg); }
  .flow-node { width: 100%; max-width: 320px; }

  .timeline { max-width: 100%; }
  .tl-item {
    grid-template-columns: 1fr;
    gap: 8px;
    padding-bottom: 28px;
  }
  .tl-item:last-child { padding-bottom: 0; }
  .tl-item .tl-year {
    text-align: left;
    padding-top: 0;
    font-size: var(--fs-h4);
  }
  .tl-item .tl-dot-col {
    flex-direction: row;
    align-items: flex-start;
    gap: 12px;
  }
  .tl-item:not(:last-child) .tl-dot-col::after {
    top: 18px;
    bottom: -12px;
    left: 7px;
    transform: none;
  }
  .tl-item .tl-dot { margin-top: 4px; }
  .tl-item .tl-dot-col > div { padding-top: 0; }

  .partner-block .partner-top {
    flex-wrap: wrap;
  }
  .partner-block .p-name {
    font-size: 1.05rem;
  }

  .flow { flex-direction: column; }
  .flow-arrow { transform: rotate(90deg); }
  .flow-node { width: 100%; max-width: 320px; }

  .vflow-step { grid-template-columns: 40px 1fr; gap: 12px; }
  .vflow-step .vflow-dot { width: 40px; height: 40px; }
  .vflow-step:not(:last-child)::before { left: 19px; top: 40px; }

  .to-top { right: 14px; bottom: 14px; }
}

/* ---------- Client logos ---------- */
.client-logo {
  aspect-ratio: 3/2;
  background: var(--c-white);
  border: 1px solid var(--c-line);
  border-radius: var(--radius);
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 16px;
  transition: border-color var(--transition), box-shadow var(--transition);
}
.client-logo:hover {
  border-color: rgba(0,169,206,.4);
  box-shadow: var(--shadow-sm);
}
.client-logo-inner {
  font-weight: 900;
  font-size: var(--fs-sm);
  color: var(--c-muted);
  text-align: center;
  letter-spacing: 0.04em;
}
.client-logo img {
  max-width: 100%;
  max-height: 100%;
  object-fit: contain;
}
.client-grid { grid-template-columns: repeat(4, 1fr); }
@media (max-width: 1100px) { .client-grid { grid-template-columns: repeat(3, 1fr); } }
@media (max-width: 640px) { .client-grid { grid-template-columns: repeat(2, 1fr); } }

/* ---------- Mobile nav close ---------- */
.nav-close {
  display: none;
  position: absolute;
  top: 16px;
  right: 16px;
  width: 44px;
  height: 44px;
  align-items: center;
  justify-content: center;
  background: var(--c-bg-soft);
  border: 1px solid var(--c-line);
  border-radius: var(--radius);
  color: var(--c-ink);
  cursor: pointer;
}
@media (max-width: 992px) {
  .nav-close { display: flex; }
}

/* ---------- Partners owl-carousel overrides ---------- */
.partners-carousel.owl-carousel { display: block; }
.partners-carousel .partner-slide { min-width: 0; }
.partners-carousel .partner-block {
  margin: 0 8px;
  height: 100%;
}
@media (max-width: 640px) {
  .partners-carousel .partner-block { margin: 0 4px; }
  .partner-block .partner-top {
    flex-direction: column;
    align-items: flex-start;
    gap: 4px;
  }
}

/* ---------- Product gallery ---------- */
@media (max-width: 992px) {
  .product-grid { grid-template-columns: 1fr; }
  .product-gallery { position: static; }
  .gallery-thumb { flex: 0 0 calc(25% - 8px); }
  .gallery-arrow { width: 32px; height: 32px; }
  .gallery-arrow svg { width: 16px; height: 16px; }
}

@media (max-width: 640px) {
  .gallery-thumb { flex: 0 0 calc(20% - 8px); }
  .gallery-thumbs { gap: 8px; }
  .gallery-thumbs-wrap { gap: 8px; }
}

@media (max-width: 400px) {
  .gallery-thumb { flex: 0 0 calc(33.333% - 7px); }
  .gallery-main { aspect-ratio: 4 / 3; }
}

/* ---------- ≤ 400px ---------- */
@media (max-width: 400px) {
  .steps { grid-template-columns: 1fr; }
  .logo-text { font-size: 1.15rem; }
  .case-study-grid { gap: 16px; }
  .case-study-grid .card { padding: 18px; }
  .case-study-grid .p-link { margin-top: 10px; }
}