:root {
  --background: #f8f7ff;

  --card-background: rgba(255, 255, 255, 0.96);
  --card-border: rgba(91, 33, 182, 0.12);

  --text: #252238;
  --text-muted: #68637a;

  --primary: #6d28d9;
  --primary-hover: #5b21b6;

  --secondary: #ede9fe;
  --secondary-hover: #ddd6fe;
  --secondary-text: #5b21b6;

  --tertiary: #f5f5f7;
  --tertiary-hover: #e9e9ee;
  --tertiary-text: #45414f;
  --tertiary-border: #ddddE5;

  --shadow:
    0 8px 24px rgba(46, 16, 101, 0.07),
    0 2px 6px rgba(46, 16, 101, 0.04);
}


/* =========================
   Réglages généraux
   ========================= */

* {
  box-sizing: border-box;
}

html {
  font-family:
    Inter,
    system-ui,
    -apple-system,
    BlinkMacSystemFont,
    "Segoe UI",
    sans-serif;

  color: var(--text);
}

body {
  margin: 0;
  min-height: 100vh;

  background-color: var(--background);

  background-image:
    linear-gradient(
      30deg,
      rgba(109, 40, 217, 0.05) 12%,
      transparent 12.5%,
      transparent 87%,
      rgba(109, 40, 217, 0.05) 87.5%
    ),
    linear-gradient(
      150deg,
      rgba(109, 40, 217, 0.05) 12%,
      transparent 12.5%,
      transparent 87%,
      rgba(109, 40, 217, 0.05) 87.5%
    ),
    linear-gradient(
      30deg,
      rgba(109, 40, 217, 0.05) 12%,
      transparent 12.5%,
      transparent 87%,
      rgba(109, 40, 217, 0.05) 87.5%
    ),
    linear-gradient(
      150deg,
      rgba(109, 40, 217, 0.05) 12%,
      transparent 12.5%,
      transparent 87%,
      rgba(109, 40, 217, 0.05) 87.5%
    ),
    linear-gradient(
      60deg,
      rgba(109, 40, 217, 0.03) 25%,
      transparent 25.5%,
      transparent 75%,
      rgba(109, 40, 217, 0.03) 75%
    ),
    linear-gradient(
      60deg,
      rgba(109, 40, 217, 0.03) 25%,
      transparent 25.5%,
      transparent 75%,
      rgba(109, 40, 217, 0.03) 75%
    );

  background-size: 80px 140px;

  background-position:
    0 0,
    0 0,
    40px 70px,
    40px 70px,
    0 0,
    40px 70px;

  background-attachment: fixed;
}


/* =========================
   Conteneur principal
   ========================= */

.page {
  width: min(100% - 40px, 860px);

  margin-left: max(20px, calc((100vw - 1100px) / 2));
  margin-right: auto;

  padding-block: 50px;
}


/* =========================
   En-tête
   ========================= */

.hero {
  margin-bottom: 32px;

  text-align: left;
}

.eyebrow {
  margin: 0 0 7px;

  color: var(--primary);

  font-size: 0.76rem;
  font-weight: 700;

  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.hero h1 {
  margin: 0;

  font-size: clamp(1.9rem, 4vw, 2.8rem);
  line-height: 1.08;

  letter-spacing: -0.035em;
}

.subtitle {
  /*max-width: 580px;*/

  margin: 12px 0 0;

  color: var(--text-muted);

  font-size: 1rem;
  line-height: 1.5;
}


/* =========================
   Liste des chapitres
   ========================= */

.chapters {
  display: grid;

  gap: 16px;
}


/* =========================
   Container d'un chapitre
   ========================= */

.chapter-card {
  display: flex;
  align-items: center;

  gap: 20px;

  padding: 18px;

  background: var(--card-background);

  border: 1px solid var(--card-border);
  border-radius: 0;

  box-shadow: var(--shadow);

  backdrop-filter: blur(6px);
  -webkit-backdrop-filter: blur(6px);
}


/* =========================
   Image du chapitre
   ========================= */

.chapter-image {
  width: 130px;
  height: 130px;

  flex-shrink: 0;

  object-fit: cover;

  border-radius: 8px;
}


/* =========================
   Contenu du chapitre
   ========================= */

.chapter-content {
  flex: 1;

  min-width: 0;

  text-align: left;
}

.chapter-number {
  margin: 0 0 5px;

  color: var(--primary);

  font-size: 0.72rem;
  font-weight: 750;

  letter-spacing: 0.08em;

  text-transform: uppercase;
}

.chapter-content h2 {
  margin: 0 0 18px;

  font-size: clamp(1.2rem, 3vw, 1.55rem);
  line-height: 1.2;
}


/* =========================
   Boutons
   ========================= */

.chapter-actions {
  display: flex;
  flex-wrap: wrap;

  gap: 8px;

  justify-content: flex-start;
}

.button {
  display: inline-flex;

  align-items: center;
  justify-content: center;

  min-width: 105px;

  padding: 8px 14px;

  border: 1px solid transparent;
  border-radius: 6px;

  font-size: 0.86rem;
  font-weight: 650;

  text-decoration: none;

  cursor: pointer;

  transition:
    background-color 0.2s ease,
    color 0.2s ease,
    border-color 0.2s ease;
}

/* =========================
   Boutons désactivés
   ========================= */

.button.disabled,
.button[aria-disabled="true"] {
  background-color: #eeeeF1;
  color: #99999f;

  border-color: #ddddE2;

  cursor: not-allowed;

  opacity: 0.75;

  box-shadow: none;

  text-shadow: none;
}


/* Neutralise aussi les styles hover éventuels */

.button.disabled:hover,
.button[aria-disabled="true"]:hover {
  background-color: #eeeeF1;
  color: #99999f;

  border-color: #ddddE2;
}


/* =========================
   Bouton principal
   ========================= */

.button-primary {
  color: white;

  background-color: var(--primary);
}

.button-primary:hover {
  background-color: var(--primary-hover);
}


/* =========================
   Bouton secondaire
   ========================= */

.button-secondary {
  color: var(--secondary-text);

  background-color: var(--secondary);

  border-color: rgba(91, 33, 182, 0.1);
}

.button-secondary:hover {
  background-color: var(--secondary-hover);
}


/* =========================
   Bouton tertiary
   ========================= */

.button-tertiary {
  color: var(--tertiary-text);

  background-color: var(--tertiary);

  border-color: var(--tertiary-border);
}

.button-tertiary:hover {
  background-color: var(--tertiary-hover);
}


/* =========================
   Focus clavier
   ========================= */

.button:focus-visible {
  outline: 3px solid rgba(109, 40, 217, 0.25);

  outline-offset: 2px;
}


/* =========================
   Responsive : tablette
   ========================= */

@media (max-width: 650px) {

  .page {
    width: min(100% - 28px, 860px);

    margin-inline: auto;

    padding-block: 36px;
  }

  .hero {
    margin-bottom: 26px;
  }

  .chapter-card {
    align-items: flex-start;

    gap: 15px;

    padding: 14px;
  }

  .chapter-image {
    width: 95px;
    height: 95px;
  }

  .chapter-content h2 {
    margin-bottom: 14px;
  }

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

  .button {
    width: 100%;
  }

}


/* =========================
   Responsive : smartphone
   ========================= */

@media (max-width: 460px) {

  .page {
    width: min(100% - 20px, 860px);

    padding-block: 28px;
  }

  .chapter-card {
    flex-direction: column;

    padding: 14px;
  }

  .chapter-image {
    width: 100%;
    height: auto;

    aspect-ratio: 16 / 7;

    border-radius: 0;
  }

  .chapter-content {
    width: 100%;
  }

  .chapter-actions {
    width: 100%;
  }

}

/* =========================
   Layout principal
   ========================= */

.page {
  width: min(100% - 40px, 1100px);

  margin-inline: auto;

  padding-block: 50px;
}

.layout {
  display: grid;

  grid-template-columns:
    minmax(0, 1fr)
    260px;

  gap: 24px;

  align-items: start;
}


/* =========================
   Chapitres
   ========================= */

.chapters {
  display: grid;

  gap: 16px;
}


/* =========================
   Sidebar
   ========================= */

.sidebar {
  position: sticky;
  top: 24px;
}


/* =========================
   Compteur
   ========================= */

.countdown {
  padding: 18px 16px;

  background:
    linear-gradient(
      180deg,
      #181a12 0%,
      #050604 100%
    );

  border: 1px solid #353929;

  box-shadow:
    inset 0 0 20px rgba(190, 255, 70, 0.04),
    0 8px 24px rgba(0, 0, 0, 0.15);

  color: #d8ff68;
}

.sidebar .countdown {
  opacity: 0;
  /*visibility: hidden;*/

  transition:
    opacity 0.35s ease,
    visibility 0.35s ease;
}

.sidebar .countdown:hover {
  opacity: 1;
  /*visibility: visible;*/
}

/* Petit titre */

.countdown-title {
  margin: 0 0 12px;

  color: #abb886;

  font-family:
    "Courier New",
    Courier,
    monospace;

  font-size: 0.7rem;
  font-weight: 700;

  letter-spacing: 0.18em;

  text-transform: uppercase;
}


/* Chiffres */

.countdown-display {
  display: grid;

  grid-template-columns:
    3fr
    auto
    2fr
    auto
    2fr
    auto
    2fr;

  align-items: center;

  font-family:
    "Courier New",
    Courier,
    monospace;

  font-size: 1.55rem;
  font-weight: 700;

  line-height: 1;

  letter-spacing: 0.03em;

  color: #dfff67;

  text-shadow:
    0 0 5px rgba(204, 255, 88, 0.8),
    0 0 12px rgba(204, 255, 88, 0.35);
}


/* Deux-points */

.separator {
  padding-inline: 2px;

  color: #91a453;
}


/* Labels */

.countdown-labels {
  display: grid;

  grid-template-columns:
    3fr
    2fr
    2fr
    2fr;

  gap: 7px;

  margin-top: 8px;

  color: #777f65;

  font-family:
    "Courier New",
    Courier,
    monospace;

  font-size: 0.58rem;

  letter-spacing: 0.06em;

  text-transform: uppercase;
}


/* Date */

.countdown-date {
  margin: 15px 0 0;

  padding-top: 11px;

  border-top: 1px solid #303426;

  color: #9ca47e;

  font-family:
    "Courier New",
    Courier,
    monospace;

  font-size: 0.68rem;

  letter-spacing: 0.04em;
}


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

@media (max-width: 850px) {

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

  .sidebar {
    position: static;

    margin-top: 8px;
  }

  .countdown {
    max-width: 100%;
  }

}


@media (max-width: 460px) {

  .page {
    width: min(100% - 20px, 1100px);

    padding-block: 28px;
  }

  .countdown-display {
    font-size: clamp(1.25rem, 7vw, 1.7rem);
  }

}



/* =========================
   Sidebar
   ========================= */

.sidebar {
  position: sticky;
  top: 24px;

  display: grid;
  gap: 16px;
}


/* =========================
   Carte Cahier de calcul
   ========================= */

.sidebar-card {
  background-color: rgba(255, 255, 255, 0.96);

  border: 1px solid var(--card-border);

  box-shadow: var(--shadow);
}


/* Image */

.cahier-image-wrapper {
  padding: 10%;

  background-color: white;
}

.cahier-image {
  display: block;

  width: 100%;
  height: auto;

  object-fit: contain;
}


/* Contenu */

.cahier-content {
  padding: 15px;
}


/* Petit label */

.sidebar-card-label {
  margin: 0 0 5px;

  color: var(--primary);

  font-size: 0.68rem;
  font-weight: 700;

  letter-spacing: 0.08em;

  text-transform: uppercase;
}


/* Titre */

.sidebar-card-title {
  margin: 0 0 8px;

  font-size: 1.05rem;
  line-height: 1.2;
}


/* Description */

.sidebar-card-text {
  margin: 0 0 14px;

  color: var(--text-muted);

  font-size: 0.82rem;
  line-height: 1.45;
}


/* Bouton */

.cahier-button {
  width: 100%;
}


/* =========================
   Mobile
   ========================= */

@media (max-width: 850px) {

  .sidebar {
    position: static;

    margin-top: 8px;
  }

  .cahier-card {
    display: grid;

    grid-template-columns: 120px 1fr;
  }

  .cahier-image {
    width: 120px;
    height: 100%;

    aspect-ratio: auto;

    object-fit: cover;
  }

}


@media (max-width: 460px) {

  .cahier-card {
    display: block;
  }

  .cahier-image {
    width: 100%;
    height: auto;

    aspect-ratio: 4 / 5;

    object-fit: cover;
  }

}