:root {
  --bleu: #064f97;
  --turquoise: #18a6a0;
  --clair: #f5f8fb;
  --texte: #1f2933;
  --gold: #d9a441;
  --ombre: 0 18px 45px rgba(6,79,151,.12);
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: Arial, Helvetica, sans-serif;
  color: var(--texte);
  line-height: 1.6;
  background:
    radial-gradient(circle at 50% 18%, rgba(127,227,218,.18), transparent 32%),
    linear-gradient(135deg, #f8fbfc, #ffffff);
}

.prepa-header {
  background:
    radial-gradient(circle at 50% 0%, rgba(127,227,218,.35), transparent 35%),
    linear-gradient(135deg, var(--bleu), var(--turquoise));
  color: #fff;
  padding: 55px 20px 65px;
  text-align: center;
}

.prepa-header img {
  max-width: 220px;
  background: #fff;
  padding: 15px;
  border-radius: 18px;
  box-shadow: var(--ombre);
}

.prepa-header h1 {
  font-size: clamp(2.2rem, 5vw, 3.6rem);
  margin: 22px 0 12px;
  line-height: 1.05;
}

.prepa-header p {
  max-width: 900px;
  margin: auto;
  font-size: 1.18rem;
}

.small-header {
  padding: 38px 20px 45px;
}

.small-header img {
  max-width: 170px;
}

main {
  max-width: 1200px;
  margin: auto;
  padding: 55px 20px;
}

section {
  margin-bottom: 42px;
}

h2 {
  color: var(--bleu);
  font-size: clamp(1.7rem, 3vw, 2.4rem);
  line-height: 1.15;
  margin-top: 0;
}

h3 {
  color: var(--bleu);
  font-size: 1.3rem;
  margin-top: 0;
}

.intro,
.highlight,
.card,
.form-card,
.validation-card {
  background: rgba(255,255,255,.96);
  border-radius: 26px;
  padding: 34px 40px;
  box-shadow: var(--ombre);
  border-left: 5px solid var(--turquoise);
  border-bottom: 4px solid var(--turquoise);
}

.grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 24px;
}

.card {
  border-left: none;
  border-bottom: 4px solid var(--gold);
}

.highlight {
  background:
    radial-gradient(circle at top right, rgba(127,227,218,.24), transparent 40%),
    rgba(255,255,255,.96);
}

.carousel img {
  width: 100%;
  height: 500px;
  object-fit: cover;
  border-radius: 26px;
  box-shadow: var(--ombre);
  border-bottom: 5px solid var(--gold);
}

.cta {
  background:
    radial-gradient(circle at top right, rgba(127,227,218,.30), transparent 38%),
    linear-gradient(135deg, var(--bleu), var(--turquoise));
  color: #fff;
  padding: 45px;
  border-radius: 26px;
  text-align: center;
  box-shadow: var(--ombre);
}

.cta h2 {
  color: #fff;
}

.btn,
.btn-submit,
.btn-secondary {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  margin-top: 25px;
  padding: 15px 28px;
  border-radius: 999px;
  text-decoration: none;
  font-weight: 900;
  border: none;
  cursor: pointer;
  transition: .22s ease;
}

.btn {
  background: #fff;
  color: var(--bleu);
}

.btn-light {
  background: #fff;
  color: var(--bleu);
}

.btn-submit {
  background: linear-gradient(135deg, var(--turquoise), var(--bleu));
  color: #fff;
  font-size: 1rem;
}

.btn-secondary {
  background: #eef2f7;
  color: var(--bleu);
}

.btn:hover,
.btn-submit:hover,
.btn-secondary:hover {
  transform: translateY(-3px);
  box-shadow: 0 16px 30px rgba(6,79,151,.20);
}

.form-card section {
  margin-bottom: 36px;
}

.form-card h2 {
  border-bottom: 1px solid rgba(6,79,151,.12);
  padding-bottom: 12px;
  margin-bottom: 24px;
}

.form-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 20px 24px;
}

label {
  display: block;
  color: var(--bleu);
  font-weight: 800;
  margin-bottom: 18px;
}

input,
select,
textarea {
  width: 100%;
  margin-top: 8px;
  padding: 14px 16px;
  border: 1px solid rgba(6,79,151,.18);
  border-radius: 14px;
  font-size: 1rem;
  font-family: inherit;
  color: var(--texte);
  background: #fff;
}

textarea {
  resize: vertical;
}

input:focus,
select:focus,
textarea:focus {
  outline: none;
  border-color: var(--turquoise);
  box-shadow: 0 0 0 4px rgba(24,166,160,.14);
}

.note-form {
  background: rgba(127,227,218,.16);
  border-radius: 16px;
  padding: 14px 18px;
  color: var(--bleu);
  font-weight: 700;
}

.consentement {
  background: rgba(217,164,65,.14);
  padding: 20px;
  border-radius: 18px;
}

.consentement label {
  color: var(--texte);
  margin: 0;
}

.consentement input {
  width: auto;
  margin-right: 8px;
}

.form-actions {
  display: flex;
  justify-content: space-between;
  gap: 18px;
  flex-wrap: wrap;
}

.validation-card {
  max-width: 800px;
  margin: 0 auto;
  text-align: center;
}

.check {
  width: 82px;
  height: 82px;
  margin: 0 auto 24px;
  border-radius: 999px;
  background: linear-gradient(135deg, var(--turquoise), var(--bleu));
  color: #fff;
  font-size: 3rem;
  font-weight: 900;
  display: flex;
  align-items: center;
  justify-content: center;
}

.reference {
  font-size: 1.2rem;
  color: var(--bleu);
}

.reference strong {
  font-size: 1.8rem;
}

@media (max-width: 760px) {
  main {
    padding: 35px 16px;
  }

  .intro,
  .highlight,
  .card,
  .form-card,
  .validation-card {
    padding: 26px;
  }

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

  .carousel img {
    height: 320px;
  }

  .form-actions {
    flex-direction: column;
  }

  .btn,
  .btn-submit,
  .btn-secondary {
    width: 100%;
  }
}