CSS Avancé

1. Animations & Transitions

Transitions

/* ── Transition simple ── */
.btn {
  background: #3b82f6;
  transition: background 0.2s ease, transform 0.15s ease;
}
.btn:hover {
  background: #1d4ed8;
  transform: translateY(-2px);
}

/* ── Transition complète ── */
/* transition: propriété durée timing-function délai */
transition: all 0.3s ease;
transition: opacity 0.4s ease-in-out, transform 0.3s cubic-bezier(0.34, 1.56, 0.64, 1);

/* ── Timing functions ── */
transition-timing-function: linear;
transition-timing-function: ease;            /* défaut */
transition-timing-function: ease-in;         /* commence lentement */
transition-timing-function: ease-out;        /* finit lentement */
transition-timing-function: ease-in-out;     /* commence et finit lentement */
transition-timing-function: cubic-bezier(0.25, 0.1, 0.25, 1);

Animations @keyframes

/* ── Définir une animation ── */
@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes pulse {
  0%, 100% { transform: scale(1); }
  50%       { transform: scale(1.05); }
}

@keyframes gradientShift {
  0%   { background-position: 0% 50%; }
  50%  { background-position: 100% 50%; }
  100% { background-position: 0% 50%; }
}

/* ── Appliquer une animation ── */
.card {
  animation: fadeInUp 0.5s ease forwards;
  /* animation: nom durée timing délai iterations direction fill-mode */
}

/* ── Propriétés d'animation ── */
.loader {
  animation-name: spin;
  animation-duration: 1s;
  animation-timing-function: linear;
  animation-delay: 0s;
  animation-iteration-count: infinite;   /* ou nombre */
  animation-direction: normal;           /* reverse | alternate | alternate-reverse */
  animation-fill-mode: forwards;         /* none | forwards | backwards | both */
  animation-play-state: running;         /* ou paused */
}

/* ── Accessibilité : respecter prefers-reduced-motion ── */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    transition-duration: 0.01ms !important;
  }
}

2. Transformations 2D & 3D

/* ── 2D ── */
.el {
  transform: translateX(50px);
  transform: translateY(-20px);
  transform: translate(50px, -20px);    /* x, y */
  transform: scale(1.2);               /* uniforme */
  transform: scaleX(2) scaleY(0.5);
  transform: rotate(45deg);
  transform: skewX(15deg);
  transform: skewY(10deg);

  /* Combinaisons (de droite à gauche) */
  transform: translateY(-4px) scale(1.02);

  /* Origine de la transformation */
  transform-origin: center center;    /* défaut */
  transform-origin: top left;
  transform-origin: 50% 50%;
}

/* ── 3D ── */
.scene {
  perspective: 1000px;             /* sur le parent */
  perspective-origin: 50% 50%;
}
.card-3d {
  transform-style: preserve-3d;   /* sur le parent 3D */
  transform: rotateY(30deg);
  transform: rotateX(15deg) translateZ(50px);
}

/* ── Flip card (exemple complet) ── */
.flip-container {
  perspective: 1000px;
  width: 300px; height: 200px;
}
.flipper {
  transform-style: preserve-3d;
  transition: transform 0.6s;
  position: relative; width: 100%; height: 100%;
}
.flip-container:hover .flipper {
  transform: rotateY(180deg);
}
.front, .back {
  position: absolute; inset: 0;
  backface-visibility: hidden;     /* cache la face inversée */
  border-radius: 12px;
  display: flex; align-items: center; justify-content: center;
}
.back { transform: rotateY(180deg); background: #3b82f6; color: white; }

3. Pseudo-éléments avancés

/* ── ::before et ::after ── */
.badge {
  position: relative;
}
.badge::before {
  content: '';
  position: absolute;
  inset: -2px;
  background: linear-gradient(135deg, #f78166, #d2a8ff);
  border-radius: inherit;
  z-index: -1;         /* derrière l'élément */
}

/* ── Effet underline animé ── */
.nav-link {
  position: relative;
  text-decoration: none;
}
.nav-link::after {
  content: '';
  position: absolute;
  bottom: -2px; left: 0;
  width: 0; height: 2px;
  background: #3b82f6;
  transition: width 0.3s ease;
}
.nav-link:hover::after { width: 100%; }

/* ── Compteur CSS ── */
ol.fancy {
  counter-reset: item;
  list-style: none;
}
ol.fancy li {
  counter-increment: item;
}
ol.fancy li::before {
  content: counter(item, decimal-leading-zero) '.';
  color: #3b82f6;
  font-weight: 700;
  margin-right: 0.5rem;
}

/* ── Sélection de texte ── */
::selection {
  background: rgba(59, 130, 246, 0.3);
  color: inherit;
}

4. Glassmorphism

Le glassmorphism crée un effet de verre dépoli — très utilisé dans les interfaces modernes.

/* ── Fond nécessaire (gradient ou image) ── */
body {
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  min-height: 100vh;
}

/* ── Verre de base ── */
.glass {
  background: rgba(255, 255, 255, 0.15);
  backdrop-filter: blur(16px) saturate(180%);
  -webkit-backdrop-filter: blur(16px) saturate(180%);
  border: 1px solid rgba(255, 255, 255, 0.2);
  border-radius: 16px;
}

/* ── Variante sombre ── */
.glass-dark {
  background: rgba(10, 14, 26, 0.72);
  backdrop-filter: blur(14px);
  border: 1px solid rgba(255, 255, 255, 0.08);
  border-radius: 14px;
}

/* ── Carte glassmorphisme complète ── */
.glass-card {
  background: rgba(255, 255, 255, 0.12);
  backdrop-filter: blur(20px);
  border: 1px solid rgba(255, 255, 255, 0.25);
  border-radius: 20px;
  padding: 2rem;
  box-shadow:
    0 8px 32px rgba(0, 0, 0, 0.2),
    inset 0 1px 0 rgba(255, 255, 255, 0.3);
}

/* ── Bouton glassmorphisme ── */
.glass-btn {
  background: rgba(255, 255, 255, 0.15);
  border: 1px solid rgba(255, 255, 255, 0.3);
  backdrop-filter: blur(8px);
  color: white;
  transition: background 0.2s;
}
.glass-btn:hover {
  background: rgba(255, 255, 255, 0.25);
}

5. Scrollbar personnalisée

/* ── Webkit (Chrome, Safari, Edge) ── */
::-webkit-scrollbar {
  width: 8px;
  height: 8px;
}
::-webkit-scrollbar-track {
  background: transparent;
}
::-webkit-scrollbar-thumb {
  background: rgba(255, 255, 255, 0.2);
  border-radius: 4px;
}
::-webkit-scrollbar-thumb:hover {
  background: rgba(255, 255, 255, 0.35);
}

/* ── Standard CSS (Firefox) ── */
* {
  scrollbar-width: thin;
  scrollbar-color: rgba(255,255,255,0.2) transparent;
}

/* ── Scroll snap ── */
.carousel {
  display: flex;
  overflow-x: auto;
  scroll-snap-type: x mandatory;
  gap: 1rem;
  scrollbar-width: none; /* cacher la scrollbar */
}
.carousel::-webkit-scrollbar { display: none; }
.carousel-item {
  flex-shrink: 0;
  width: 80%;
  scroll-snap-align: start;
}

6. Clip-path & Mask

/* ── clip-path ── */
.circle    { clip-path: circle(50%); }
.triangle  { clip-path: polygon(50% 0%, 0% 100%, 100% 100%); }
.hexagon   { clip-path: polygon(25% 0%, 75% 0%, 100% 50%, 75% 100%, 25% 100%, 0% 50%); }
.diagonal  { clip-path: polygon(0 0, 100% 0, 100% 80%, 0 100%); }

/* Inset (rectangle avec marges et radius) */
.card-clip { clip-path: inset(0 round 12px); }

/* Animation de clip-path */
.reveal-clip {
  clip-path: inset(0 100% 0 0);
  transition: clip-path 0.6s cubic-bezier(0.76, 0, 0.24, 1);
}
.reveal-clip.visible { clip-path: inset(0 0% 0 0); }

/* ── mask-image ── */
.gradient-fade {
  mask-image: linear-gradient(to right, black 60%, transparent 100%);
  -webkit-mask-image: linear-gradient(to right, black 60%, transparent 100%);
}

/* Mask avec image */
.masked {
  mask-image: url('mask-shape.svg');
  mask-size: cover;
  -webkit-mask-image: url('mask-shape.svg');
}

7. Filtres CSS

/* ── filter ── */
img.effect {
  filter: blur(4px);
  filter: brightness(1.5);
  filter: contrast(200%);
  filter: grayscale(100%);
  filter: hue-rotate(90deg);
  filter: invert(100%);
  filter: opacity(50%);
  filter: saturate(300%);
  filter: sepia(100%);
  filter: drop-shadow(4px 4px 8px rgba(0,0,0,0.5));

  /* Combinaison */
  filter: contrast(150%) brightness(1.1) saturate(120%);
}

/* Hover effet cinématique */
.photo {
  filter: grayscale(80%) contrast(110%);
  transition: filter 0.4s ease;
}
.photo:hover { filter: none; }

/* ── backdrop-filter ── */
.frosted-glass {
  backdrop-filter: blur(16px) saturate(1.8) brightness(1.1);
  /* uniquement sur l'arrière-plan derrière l'élément */
}

/* ── mix-blend-mode ── */
.text-overlay {
  mix-blend-mode: multiply;  /* screen | overlay | difference | exclusion */
  color: white;
}

8. Container Queries (CSS moderne)

Les Container Queries permettent de styler un composant en fonction de la taille de son conteneur plutôt que de la fenêtre.

/* ── Définir un conteneur ── */
.card-wrapper {
  container-type: inline-size;
  container-name: card;        /* optionnel */
}

/* ── Styler selon la taille du conteneur ── */
@container card (min-width: 400px) {
  .card {
    display: flex;
    flex-direction: row;
  }
}
@container card (max-width: 300px) {
  .card h2 { font-size: 0.9rem; }
  .card img { display: none; }
}

/* ── Utilisation avec sidebar ── */
.sidebar-widget { container-type: inline-size; }

@container (min-width: 250px) {
  .widget-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
  }
}

/* ── Container query units ── */
.element {
  font-size: 3cqi;     /* cqi = 1% de la taille inline du conteneur */
  padding: 2cqb;       /* cqb = 1% de la taille block */
  width: 50cqw;        /* cqw = 1% de la largeur du conteneur */
}

9. :has() :is() :where()

/* ── :is() — groupe de sélecteurs ── */
:is(h1, h2, h3, h4) { margin-bottom: 1rem; }
/* équivalent à : h1, h2, h3, h4 { ... } */

:is(article, section, aside) p { color: #64748b; }
/* équivalent à : article p, section p, aside p */

/* ── :where() — comme :is() mais spécificité 0 ── */
:where(h1, h2, h3) { font-weight: 700; }
/* Utile dans les resets — facile à écraser */

/* ── :has() — parent selector ── */
/* Styler un parent selon son contenu */
.card:has(img) {
  /* La carte a une image → padding différent */
  padding: 0;
}
.card:has(img) .card-body {
  padding: 1rem;
}

/* Styler un label selon son input */
label:has(input:checked) {
  font-weight: 700;
  color: #3b82f6;
}

/* Formulaire valide / invalide */
form:has(input:invalid) button[type="submit"] {
  opacity: 0.5;
  pointer-events: none;
}

/* Section sans image */
.hero:not(:has(img)) { text-align: center; }

/* ── :not() avancé ── */
.card:not(:last-child) { border-bottom: 1px solid #e2e8f0; }
a:not([href^="http"]):not([href^="mailto"]) { color: inherit; }

10. Architecture CSS moderne

Méthodes BEM

/* ── BEM (Block Element Modifier) ── */
/* block__element--modifier */

/* Block */
.card { ... }

/* Elements (appartiennent au block) */
.card__header { ... }
.card__body   { ... }
.card__footer { ... }
.card__title  { ... }
.card__image  { ... }

/* Modifiers (variantes) */
.card--featured   { border-color: gold; }
.card--dark       { background: #1e293b; }
.card__title--sm  { font-size: 0.9rem; }

/* Usage HTML */
/* <div class="card card--featured">
     <div class="card__header">
       <h2 class="card__title">Titre</h2>
     </div>
     <div class="card__body">...</div>
   </div> */

Architecture en couches (Cascade Layers)

/* ── @layer ── */
@layer reset, base, components, utilities;

@layer reset {
  *, *::before, *::after { box-sizing: border-box; margin: 0; }
}

@layer base {
  body { font-family: system-ui; color: #1e293b; }
  h1, h2, h3 { font-weight: 700; line-height: 1.2; }
}

@layer components {
  .btn { padding: 0.5rem 1rem; border-radius: 6px; }
  .card { background: white; border-radius: 12px; padding: 1.5rem; }
}

@layer utilities {
  .text-center { text-align: center; }
  .flex        { display: flex; }
  .hidden      { display: none; }
}

/* ── Nesting CSS (natif, sans Sass) ── */
.card {
  background: white;
  border-radius: 12px;

  & h2 { font-size: 1.1rem; }        /* .card h2 */
  & .card-body { padding: 1rem; }     /* .card .card-body */
  &:hover { box-shadow: 0 4px 16px rgba(0,0,0,0.1); }

  @media (max-width: 768px) {
    padding: 1rem;                    /* media query nested */
  }
}