:root {
  --primary-color: #2a2a2a;
  --secondary-color: #ffffff;
  --accent-color: #4169e1;
  --bg-gradient: linear-gradient(var(--primary-color) 0%, #000000 0%);
  --transition-speed: 0.3s;
  --container-width: 1200px;
}

html,
body {
  margin: 0;
  padding: 0;
  background: var(--bg-gradient);
  color: var(--secondary-color);
  font-family: "Inter", Arial, sans-serif;
  text-align: center;
  overflow-x: hidden;
  scroll-behavior: smooth;
  min-height: 100vh;
  width: 100%;
  /* Slide-up animation on page load */
  opacity: 0;
  transform: translateY(40px);
  animation: siteSlideUp 0.8s ease-out forwards;
}

/* Keyframes for the slide-up animation */
@keyframes siteSlideUp {
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* Enhanced Stars Background */
.stars {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: url("https://www.solarsystemscope.com/textures/download/2k_stars.jpg")
    repeat;
  background-size: cover;
  animation: moveStars 50s linear infinite;
  /* Augmentation de la visibilité des étoiles */
  opacity: 0.8;
  filter: brightness(1.25);
  z-index: 0;
  pointer-events: none;
}

@keyframes moveStars {
  from {
    background-position: 0 0;
  }
  to {
    background-position: -10000px 10000px;
  }
}

/* Modern Header Styles */
header {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  background: rgba(0, 0, 0, 0.9);
  padding: 1rem;
  z-index: 100;
  display: flex;
  align-items: center;
  justify-content: space-between;
  transition: all var(--transition-speed) ease;
  backdrop-filter: blur(10px);
  box-shadow: 0 2px 20px rgba(0, 0, 0, 0.2);
  gap: 1rem;
}

.lang-switch {
  background: var(--accent-color);
  color: var(--secondary-color);
  border: none;
  border-radius: 20px;
  padding: 0.5rem 1.2rem;
  font-size: 1rem;
  cursor: pointer;
  margin-left: 1rem;
  margin-right: 30px;
  transition: background var(--transition-speed) ease,
    color var(--transition-speed) ease;
  font-weight: bold;
}
.lang-switch:hover {
  background: var(--secondary-color);
  color: var(--accent-color);
}

header.hide {
  transform: translateY(-100%);
}

header h1 {
  margin: 0;
  font-size: 1.8rem;
  color: var(--secondary-color);
  text-shadow: 0 0 10px rgba(255, 255, 255, 0.2);
  transition: color var(--transition-speed) ease;
}

header h1:hover {
  color: var(--accent-color);
}

/* Navigation Styles */
/* Navigation Styles */
.nav-links {
  display: flex;
  align-items: center;
  gap: 2rem;
  padding-right: 2rem;
}

.nav-links a {
  color: var(--secondary-color);
  text-decoration: none;
  font-size: 1rem;
  transition: all var(--transition-speed) ease;
  position: relative;
  padding: 0.5rem 0;
  white-space: nowrap;
  min-width: max-content;
}

.nav-links a::after {
  content: "";
  position: absolute;
  width: 0;
  height: 2px;
  bottom: 0;
  left: 0;
  background-color: var(--accent-color);
  transition: width var(--transition-speed) ease;
}

.nav-links a:hover::after,
.nav-links a.active::after {
  width: 100%;
}

.nav-links a:hover,
.nav-links a.active {
  color: var(--accent-color);
}

/* Mobile Menu Styles */
.menu-toggle {
  display: none;
  flex-direction: column;
  gap: 6px;
  cursor: pointer;
  z-index: 101;
}

.menu-toggle span {
  display: block;
  height: 2px;
  width: 30px;
  background-color: var(--secondary-color);
  transition: all var(--transition-speed) ease;
}

/* Main Content Styles */
main {
  position: relative;
  z-index: 1;
  padding: 80px 20px;
  max-width: var(--container-width);
  margin: 0 auto;
}

/* Section Styles */
.intro-section {
  background: rgba(255, 255, 255, 0.05);
  padding: 100px 20px 80px;
  margin-top: 60px;
  border-radius: 20px;
  backdrop-filter: blur(10px);
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.2);
  transform: translateY(20px);
  opacity: 0;
  animation: fadeInUp 1s forwards;
}

@keyframes fadeInUp {
  to {
    transform: translateY(0);
    opacity: 1;
  }
}

.intro-section h2 {
  font-size: 2.5rem;
  margin-bottom: 1.5rem;
  color: var(--accent-color);
}

.intro-section p {
  font-size: 1.2rem;
  max-width: 800px;
  margin: 0 auto;
  line-height: 1.6;
}

/* Projects Section */

/* Toggle Buttons */
.project-toggle {
  display: flex;
  justify-content: center;
  gap: 1rem;
  margin-bottom: 2rem;
}

.toggle-btn {
  background: transparent;
  color: var(--secondary-color);
  border: 2px solid var(--accent-color);
  padding: 0.6rem 1.5rem;
  cursor: pointer;
  font-size: 1rem;
  transition: background var(--transition-speed) ease,
    color var(--transition-speed) ease;
}

.toggle-btn.active,
.toggle-btn:hover {
  background: var(--accent-color);
  color: var(--secondary-color);
}

/* Project lists and animation */
.project-area {
  position: relative;
}

.project-list {
  transition: opacity 0.5s ease, transform 0.5s ease;
  /* assure un fondu régulier entre les deux listes */
  position: relative;
}

.project-list.hidden {
  opacity: 0;
  transform: translateX(40px);
  pointer-events: none;
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
}
.content {
  padding: 80px 20px;
}

.title {
  font-size: 2.5rem;
  color: var(--accent-color);
  margin-bottom: 2rem;
}

.links {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 2rem;
  width: 100%;
}

.link-container {
  background: rgba(255, 255, 255, 0.05);
  border-radius: 0;
  padding: 2rem;
  transition: all var(--transition-speed) ease;
  backdrop-filter: blur(5px);
  border: 1px solid rgba(255, 255, 255, 0.1);
}

.link-container:hover {
  transform: translateY(-5px);
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.3);
  border-color: var(--accent-color);
}

.link {
  color: var(--secondary-color);
  text-decoration: none;
  font-size: 1.2rem;
  display: block;
}

.link-description {
  margin-top: 1rem;
  font-size: 0.9rem;
  color: rgba(255, 255, 255, 0.7);
}

/* Skills and Certifications */
.competence-section,
.certification-section {
  padding: 80px 20px;
}

.skill,
.certification {
  background: rgba(255, 255, 255, 0.05);
  border-radius: 0;
  padding: 2rem;
  margin-bottom: 2rem;
  transition: all var(--transition-speed) ease;
  display: flex;
  align-items: center;
  gap: 2rem;
  backdrop-filter: blur(5px);
}

.skill:hover,
.certification:hover {
  transform: translateX(10px);
  background: rgba(255, 255, 255, 0.1);
}

.skill img,
.certification img {
  width: 100px;
  height: 100px;
  object-fit: cover;
  border-radius: 50%;
  border: 2px solid var(--accent-color);
}

/* Footer Styles */
footer {
  background: rgba(0, 0, 0, 0.9);
  padding: 2rem;
  margin-top: 4rem;
  backdrop-filter: blur(10px);
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 2rem;
  flex-wrap: wrap;
}

footer span {
  margin-right: 1rem;
}

footer a {
  color: var(--secondary-color);
  text-decoration: none;
  display: inline-flex;
  align-items: center;
  transition: transform var(--transition-speed) ease;
}

footer a:hover {
  transform: translateY(-3px);
}

footer img {
  width: 20px;
  height: 20px;
  filter: brightness(0) invert(1);
  transition: filter var(--transition-speed) ease;
}

footer a:hover img {
  filter: brightness(0) invert(1) drop-shadow(0 0 3px rgba(255, 255, 255, 0.8));
}

/* Responsive Design */
@media (max-width: 1024px) {
  header h1 {
    font-size: 1.5rem;
  }

  .nav-links {
    gap: 1.5rem;
  }

  .nav-links a {
    font-size: 0.95rem;
  }
}
@media (max-width: 768px) {
  .lang-switch {
    position: static;
    padding: 0.4rem 1rem;
    font-size: 0.95rem;
    z-index: 102;
    margin-right: 100px;
  }
  .menu-toggle {
    display: flex;
    position: absolute;
    right: 1rem;
    top: 50%;
    transform: translateY(-50%);
    left: 82%;
  }

  header {
    padding-right: 1.2rem;
    gap: 0.5rem;
  }

  header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding-right: 1rem;
    padding-left: 1rem;
  }

  .header-actions {
    display: flex;
    align-items: center;
    gap: 0.5rem;
  }

  .nav-links {
    position: fixed;
    top: 0;
    right: -100%;
    height: 100vh;
    width: 100%;
    background: rgba(0, 0, 0, 0.95);
    flex-direction: column;
    justify-content: center;
    padding-right: 1.2rem;
    transition: right var(--transition-speed) ease;
    padding: 2rem;
  }

  .nav-links.active {
    right: 0;
  }

  .nav-links a {
    font-size: 1.1rem;
    padding: 1rem;
    width: auto;
    text-align: center;
  }

  .skill,
  .certification {
    flex-direction: column;
    text-align: center;
    gap: 1rem;
  }

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

  footer {
    padding: 1.5rem;
    gap: 1rem;
  }

  footer span {
    width: 100%;
    margin: 0 0 1rem 0;
  }
}

@media (max-width: 480px) {
  header h1 {
    font-size: 1.1rem;
  }

  .nav-links a {
    font-size: 1rem;
  }
}