Voici ton `style.css` propre, complet, avec un seul bloc responsive premium.

```css
/* ================================
   ARNAUD SIMART — style.css
   Partagé par toutes les pages
   ================================ */

@import url('https://fonts.googleapis.com/css2?family=Poppins:wght@300;400;500;600;700;800&family=Patrick+Hand&display=swap');

:root {
  --bleu:    #1C3F60;
  --corail:  #FF6F61;
  --jaune:   #F7D774;
  --gris:    #F2F2F2;
  --noir:    #1A1A1A;
  --blanc:   #FFFFFF;
}

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

html {
  scroll-behavior:smooth;
}

body {
  font-family:'Poppins', sans-serif;
  background:#f6f6f6;
  color:var(--noir);
  line-height:1.6;
  overflow-x:hidden;
}

/* ---- NAVIGATION ---- */

nav {
  background:var(--bleu);
  padding:0 60px;
  display:flex;
  align-items:center;
  justify-content:space-between;
  position:sticky;
  top:0;
  z-index:1000;
  box-shadow:0 2px 20px rgba(0,0,0,0.15);
  height:70px;
}

.nav-logo {
  font-family:'Patrick Hand', cursive;
  color:var(--jaune);
  font-size:22px;
  text-decoration:none;
  white-space:nowrap;
}

.nav-links {
  display:flex;
  align-items:center;
  gap:8px;
  list-style:none;
}

.nav-links a {
  color:rgba(255,255,255,0.85);
  text-decoration:none;
  font-size:14px;
  font-weight:500;
  padding:8px 16px;
  border-radius:999px;
  transition:0.2s ease;
}

.nav-links a:hover,
.nav-links a.active {
  background:rgba(255,255,255,0.12);
  color:white;
}

.nav-links a.nav-cta {
  background:var(--corail);
  color:white;
  font-weight:600;
}

.nav-links a.nav-cta:hover {
  background:#e85d50;
}

.nav-toggle {
  display:none;
  flex-direction:column;
  gap:5px;
  cursor:pointer;
  background:none;
  border:none;
  padding:4px;
}

.nav-toggle span {
  display:block;
  width:24px;
  height:2px;
  background:white;
  border-radius:2px;
  transition:0.3s;
}

/* ---- UTILITAIRES ---- */

.section {
  max-width:1200px;
  margin:auto;
  padding:80px 40px;
}

.section-title {
  font-size:42px;
  color:var(--bleu);
  margin-bottom:15px;
  font-weight:800;
  line-height:1.15;
}

.section-sub {
  font-size:18px;
  color:#555;
  margin-bottom:50px;
  max-width:800px;
  line-height:1.7;
}

.badge {
  display:inline-block;
  background:var(--corail);
  padding:10px 18px;
  border-radius:999px;
  font-size:14px;
  font-weight:600;
  margin-bottom:25px;
  color:white;
}

.btn {
  display:inline-block;
  background:var(--corail);
  color:white;
  text-decoration:none;
  padding:16px 32px;
  border-radius:999px;
  font-weight:700;
  transition:0.2s ease;
  border:none;
  cursor:pointer;
  font-size:16px;
  font-family:'Poppins', sans-serif;
}

.btn:hover {
  transform:scale(1.04);
}

.btn-outline {
  background:transparent;
  border:2px solid var(--corail);
  color:var(--corail);
}

.btn-outline:hover {
  background:var(--corail);
  color:white;
  transform:scale(1.04);
}

/* ---- FOOTER ---- */

footer {
  background:var(--bleu);
  color:rgba(255,255,255,0.8);
  padding:50px 60px;
  margin-top:60px;
}

.footer-inner {
  max-width:1200px;
  margin:auto;
  display:grid;
  grid-template-columns:1fr 1fr 1fr;
  gap:40px;
  align-items:start;
}

.footer-logo {
  font-family:'Patrick Hand', cursive;
  color:var(--jaune);
  font-size:26px;
  margin-bottom:10px;
}

.footer-tagline {
  font-size:14px;
  opacity:0.7;
  line-height:1.7;
}

.footer-links {
  list-style:none;
}

.footer-links li {
  margin-bottom:10px;
}

.footer-links a {
  color:rgba(255,255,255,0.75);
  text-decoration:none;
  font-size:14px;
  transition:0.2s;
}

.footer-links a:hover {
  color:var(--jaune);
}

.footer-contact {
  font-size:14px;
  line-height:2;
}

.footer-contact a {
  color:var(--jaune);
  text-decoration:none;
}

.footer-linkedin {
  display:inline-flex;
  align-items:center;
  gap:8px;
  background:rgba(255,255,255,0.1);
  border:1px solid rgba(255,255,255,0.2);
  color:white;
  text-decoration:none;
  padding:10px 18px;
  border-radius:999px;
  font-size:13px;
  font-weight:600;
  margin-top:14px;
  transition:0.2s;
}

.footer-linkedin:hover {
  background:#0077b5;
  border-color:#0077b5;
}

.footer-bottom {
  max-width:1200px;
  margin:30px auto 0;
  padding-top:20px;
  border-top:1px solid rgba(255,255,255,0.1);
  font-size:12px;
  opacity:0.5;
  text-align:center;
}

/* =========================
   RESPONSIVE PREMIUM MOBILE
   ========================= */

@media (max-width:900px) {

  nav {
    height:auto;
    min-height:70px;
    padding:14px 18px;
  }

  .nav-logo {
    font-size:22px;
  }

  .nav-toggle {
    display:flex;
  }

  .nav-links {
    display:none;
    flex-direction:column;
    position:absolute;
    top:70px;
    left:0;
    right:0;
    background:var(--bleu);
    padding:20px 25px 30px;
    gap:8px;
    box-shadow:0 10px 30px rgba(0,0,0,0.2);
  }

  .nav-links.open {
    display:flex;
  }

  .nav-links a {
    border-radius:12px;
    padding:12px 16px;
    font-size:16px;
  }

  .section {
    padding:60px 20px;
  }

  .section-title {
    font-size:34px;
    line-height:1.15;
  }

  .section-sub {
    font-size:16px;
    line-height:1.7;
    margin-bottom:36px;
  }

  .hero {
    padding:50px 22px;
  }

  .hero-inner {
    grid-template-columns:1fr;
    gap:30px;
  }

  .hero-photo-wrap {
    order:-1;
  }

  .hero-photo {
    width:190px;
    height:190px;
  }

  .hero h1 {
    font-size:42px;
    line-height:1.08;
  }

  .hero-desc {
    font-size:17px;
    line-height:1.7;
  }

  .signature {
    font-size:24px;
  }

  .hero-btns {
    flex-direction:column;
    align-items:stretch;
  }

  .hero-btns .btn {
    width:100%;
    text-align:center;
  }

  .stats-inner {
    grid-template-columns:repeat(2,1fr);
    gap:18px;
  }

  .praticien {
    margin:0;
    border-radius:28px;
    padding:36px 22px;
  }

  .praticien-grid {
    grid-template-columns:1fr;
    gap:34px;
  }

  .praticien-text p {
    font-size:16px;
    line-height:1.8;
  }

  .praticien-cards {
    grid-template-columns:1fr;
  }

  .mini-card {
    padding:24px;
  }

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

  .formation-card {
    padding:28px;
  }

  .home-gallery {
    grid-template-columns:1fr;
  }

  .home-gallery .wide {
    grid-column:span 1;
  }

  .home-gallery img,
  .home-gallery .wide img {
    aspect-ratio:1;
  }

  .temoignage-vedette {
    padding:38px 24px;
    border-radius:26px;
  }

  .temoignage-vedette p {
    font-size:17px;
    line-height:1.8;
  }

  .cta-section {
    padding:60px 22px;
  }

  .cta-section h2 {
    font-size:34px;
    line-height:1.2;
  }

  footer {
    padding:40px 25px;
  }

  .footer-inner {
    grid-template-columns:1fr;
    gap:30px;
    text-align:center;
  }
}

@media (max-width:520px) {

  .section {
    padding:48px 18px;
  }

  .section-title {
    font-size:30px;
  }

  .hero h1 {
    font-size:36px;
  }

  .stats-inner {
    grid-template-columns:1fr;
  }

  .btn {
    width:100%;
    text-align:center;
  }
}
```