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

body {
  font-family: serif, 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  line-height: 1.7;
  background: linear-gradient(135deg, #0d1b2a 0%, #1a1a2e 100%);
  color: #e0e7ff;
  min-height: 100vh;
  overflow-x: hidden;
}


header {
  background: linear-gradient(135deg, rgba(15, 52, 96, 0.95), rgba(26, 26, 46, 0.95));
  padding: 14px 20px; 
  text-align: center;
  position: sticky;
  top: 0;
  z-index: 1000;
  box-shadow: 0 4px 20px rgba(0, 255, 157, 0.2);
  backdrop-filter: blur(10px);
}

h1 {
  font-size: 1.8rem; 
  color: #00ff9d;
  text-shadow: 0 0 10px #00ff9d;
  margin-bottom: 8px;
}

#main-nav {
  position: relative;
}

#nav-list {
  display: flex;
  justify-content: center;
  flex-wrap: wrap;
  gap: 1px; 
  margin-top: 0px;
  list-style: none;
  border-radius: 9px;
  transition: all 0.4s ease;
  font-size: 0.95rem;
}

.nav-link {
  color: #a5b4fc;
  text-decoration: none;
  font-weight: 600;
  padding: 8px 9px;
  border-radius: 30px;
  border: #899db2;
  transition: all 0.3s ease;
  position: relative;
}

.nav-link:hover {
  background: rgba(0, 255, 157, 0.25);
  color: #00ff9d;
  box-shadow: 0 0 15px rgba(0, 0, 0, 0.4);
  transform: translateY(-2px);
}

.nav-link.active {
  background: rgba(0, 255, 157, 0.35);
  color: #00ff9d;
  box-shadow: 0 0 20px rgba(0, 255, 157, 0.5);
  font-weight: 700;
}

/* Menu Button */
#menu-toggle {
  display: none;
  background: none;
  border: none;
  color: #00ff9d;
  font-size: 1rem;
  cursor: pointer;
  padding: 12px;
}

#search {
  margin: 14px auto;
  display: block;
  width: 70%;
  max-width: 700px;
  padding: 7px;
  border: 1px solid #00ff9d;
  border-radius: 30px;
  background: rgba(255,255,255,0.1);
  color: #e0e7ff;
  font-size: 1.1rem;
  outline: none;
}

main {
  max-width: 1200px;
  margin: 23px auto;
  padding: 0 20px;
}

section {
  margin-bottom: 35px;
  padding: 30px;
  background: rgba(26, 26, 46, 0.6);
  border-radius: 20px;
  border: 1px solid rgba(0, 255, 157, 0.3);
  backdrop-filter: blur(10px);
  box-shadow: 0 10px 30px rgba(0, 255, 157, 0.1);
  transition: transform 0.4s;
}

.des {
  font-style: italic; 
  margin-top: 0.8em; 
  margin-bottom: 1.5em; 
  color: #888; 
  font-size: 0.95em;
} 

.highlight {
  font-size: 1.8em; 
  text-align: center; 
  margin: 1em 0; 
  font-weight: bold; 
  color: #00ffcc;
}

.introPoint {
  font-size: 0.95em; 
  line-height: 1.6; 
  margin-left: 2em;
}

.points {
  margin-left: 2em; 
  margin-bottom: 1.5em; 
  line-height: 1.6;
}

section:hover {
  transform: translateY(-10px);
  box-shadow: 0 20px 40px rgba(0, 255, 157, 0.2);
}

h2 {
  color: #00ff9d;
  font-size: 1.5rem;
  margin-bottom: 20px;
  text-shadow: 0 0 8px rgba(0, 255, 157, 0.5);
}

img { 
  max-width: 55%; 
  border-radius: 12px;
  margin: 20px auto;
  box-shadow: 0 8px 20px rgba(0, 0, 0, 0.4);
  display: block; 
}

details {
  margin-top: 20px;
  cursor: pointer;
}

summary {
  color: #00ff9d;
  font-weight: 600;
  font-size: 1.2rem;
  padding: 10px;
  border-radius: 10px;
  background: rgba(0, 255, 157, 0.1);
  transition: 0.3s;
}

summary:hover {
  background: rgba(0, 255, 157, 0.3);
}

.animation-demo {
  width: 100%;
  height: 250px;
  background: rgba(0, 255, 157, 0.1);
  border-radius: 15px;
  position: relative;
  overflow: hidden;
  margin: 20px 0;
}

.particle {
  position: absolute;
  width: 8px;
  height: 8px;
  background: #00ff9d;
  border-radius: 50%;
  box-shadow: 0 0 15px #00ff9d;
  animation: float 10s infinite linear;
}

/* Light Mode */
body.light-mode {
  background: linear-gradient(135deg, #c2c0d7 0%, #f1f5f9 100%);
  color: #000000;
}

body.light-mode header {
  background: rgba(135, 154, 173, 0.98);
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.1);
}

body.light-mode h1,
body.light-mode h2 {
  color: #161357;
  text-shadow: none;
}

body.light-mode section {
  background: white;
  border: 1px solid #cbd5e1;
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.08);
}

body.light-mode .des{
  color: #1f212e;
}

body.light-mode #search {
  background: white;
  color: #1e293b;
  border-color: #0ea5e9;
}

body.light-mode .nav-link {
  color: #161357;
}

body.light-mode .nav-link:hover {
  background: rgba(13, 51, 63, 0.15);
  color: #0f1e25;
}

body.light-mode .nav-link.active {
  background: #a7e3ff;
  color: rgb(6, 53, 70);
  box-shadow: 0 0 15px rgba(14, 165, 233, 0.4);
}

body.light-mode .highlight {
  color: #1a1a2e;
}

body.light-mode summary {
  color: #0c394adf;
  background: rgba(15, 107, 193, 0.192);
}

body.light-mode summary:hover {
  color: #09232ddf;
  background: rgba(135, 154, 173, 0.98);
}

body.light-mode #nav-list {
  background: rgba(135, 154, 173, 0.92);
}

body.light-mode #menu-toggle {
  color: #1e3460;
}

body.light-mode footer {
  background: rgba(135, 154, 173, 0.98);
  color: #161357;
}

@keyframes float {
  0% { transform: translateY(0) translateX(0); opacity: 1; }
  50% { transform: translateY(-200px) translateX(100px); opacity: 0.7; }
  100% { transform: translateY(0) translateX(200px); opacity: 1; }
}

#mode-toggle {
  position: fixed;
  bottom: 20px;
  right: 20px;
  width: 50px; /* Slightly smaller default */
  height: 50px;
  background: linear-gradient(45deg, #7b2cbf, #00b4d8);
  color: white;
  border: none;
  border-radius: 50%;
  font-size: 1.4rem; /* Balanced size */
  cursor: pointer;
  box-shadow: 0 4px 15px rgba(0, 0, 0, 0.3);
  z-index: 2000;
  transition: all 0.3s ease;
  display: flex;
  align-items: center;
  justify-content: center;
}

#mode-toggle:hover {
  transform: scale(1.1);
}

footer {
  text-align: center;
  padding: 40px 20px;
  background: rgba(13, 27, 42, 0.8);
  color: #a5b4fc;
  font-size: 1.1rem;
}

/* Mobile Styles */
@media (max-width: 768px) {

  body {
    line-height: 1.8;
  }

  header {
    padding: 9px 10px;
  }
  

  h1 {
    font-size: 1.4rem;
  }

  h2 {
    font-size: 1.2rem;
  }

  h3 {
    font-size: 0.9rem;
  }

  p, ul {
    font-size: 0.8rem;
    line-height: 1.6;
  }

  #menu-toggle {
    display: inline-block;
    position: absolute;
    right: 95%;
    bottom: -37px;
    /* top: 2%; */
    transform: translateY(-100%);
  }

  #mode-toggle {
    width: 45px;
    height: 45px;
    font-size: 1.2rem;
    bottom: 15px;
    right: 15px;
  }

  #search {
    padding: 3px;
    font-size: 0.9rem;
  }

  main {
    margin: 20px auto;
    padding: 0 9px;
    line-height: 1.5rem;
  }

  section {
    margin-bottom: 15px;
    border-radius: 10px;
  }

  .des {
    margin-top: 0.5em; 
    margin-bottom: 1.5em; 
    font-size: 0.8rem;
    line-height: 1.6;
  } 
  
  .highlight {
    font-size: 1.3em; 
    text-align: center; 
    margin: 0.6em 0;
  }
  
  .introPoint {
    font-size: 0.8rem; 
    line-height: 1.6; 
    margin-left: 2em;
  }

  .points {
    font-size: 0.8rem;
    line-height: 1.6;
    margin-left: 2em; 
    margin-bottom: 1.5em;
  }

  img {
    max-width: 70%;
    /* border-radius: 12px; */
  }
  
  summary {
    font-size: 0.8rem;
    line-height: 1.6;
    padding: 3px;
    border-radius: 5px;
  }

  #nav-list {
    display: none;
    flex-direction: column;
    background: rgba(26, 26, 46, 0.98);
    position: absolute;
    top: 100%;
    left: 0;
    width: 100%;
    padding: 15px 0;
    border-radius: 0 0 20px 20px;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.5);
  }

  #nav-list.open {
    display: flex;
  }

  .nav-link {
    padding: 12px 20px;
    text-align: center;
    border-radius: 0;
    font-size: 1rem;
  }

  .nav-link:hover {
    background: rgba(0, 255, 157, 0.2);
  }

  footer {
    padding: 9px 10px;
    font-size: 0.4rem;
  }

}

@media (max-width: 400px) {

  body {
    line-height: 1.2;
  }

  header {
    padding: 6px 8px;
  }
  

  h1 {
    font-size: 1.2rem;
  }

  h2 {
    font-size: 1rem;
  }

  h3 {
    font-size: 0.7rem;
  }

  p, ul {
    font-size: 0.8rem;
  }

  #menu-toggle {
    display: inline-block;
    position: absolute;
    right: 88%;
    bottom: -43px;
    top: 2%; 
    transform: translateY(-100%);
  }

  #mode-toggle {
    width: 30px;
    height: 30px;
    font-size: 1rem;
    bottom: 15px;
    right: 15px;
  }

  #search {
    padding: 2px;
    font-size: 0.8rem;
  }

  main {
    margin: 20px auto;
    padding: 0 9px;
  }
  
  .highlight {
    font-size: 1.1em; 
    margin: 0.3em 0;
  }
  
  .introPoint {
    margin-left: 1em;
  }

  .points {
    font-size: 0.8rem;
    margin-left: 1em; 
  }

  img {
    max-width: 100%;
    border-radius: 9px;
  }

  .nav-link {
    padding: 9px 20px;
    border-radius: 4px;
    font-size: 0.7rem;
  }

  footer {
    padding: 9px 10px;
    font-size: 0.3rem;
  }

}

@media (max-width: 288px) {
  #menu-toggle {
    right: -8%;
    bottom: -30px;
    top: 2%;
    transform: translateY(-100%);
  }
}

@media (max-width: 768px) {
  section { padding: 20px; }
}