/* Global Reset & Basics */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  transition: all 0.25s ease;

}

body {
  background: linear-gradient(135deg, #0f2027, #203a43, #2c5364);
  color: #f8f9fa;
  font-family: "Poppins", sans-serif;
  min-height: 100vh;
  overflow-x: hidden;
}

h1, h2, h3, .btn {
    font-family: 'Quicksand', sans-serif;
    font-weight: 600;
  }
  body, p, input, textarea {
    font-family: 'Quicksand', sans-serif;
    font-weight: 400;
  }

.navbar {
  background: rgba(15, 32, 39, 0.6); 
  backdrop-filter: blur(10px);       
  -webkit-backdrop-filter: blur(10px);
  color: white;
  box-shadow: 0 4px 10px rgba(0, 0, 0, 0.3);
  position: sticky; 
  top: 0;
  z-index: 100;
}

.navbar-nav .nav-link {
  color: #e0e0e0;
  font-weight: 500;
  letter-spacing: 0.5px;
  position: relative;
  transition: all 0.3s ease;
  padding: 10px 18px;
  margin-right: 5px;
}

/* Underline for link */
.navbar-nav .nav-link::after {
  content: "";
  position: absolute;
  left: 50%;
  bottom: 4px;
  width: 0;
  height: 2px;
  background: linear-gradient(90deg, #00c6ff, #0072ff);
  transition: all 0.3s ease;
  transform: translateX(-50%);
  border-radius: 2px;
}
.navbar-nav .nav-link:hover::after,
.navbar-nav .nav-link.active::after {
  width: 80%;
}

.navbar-nav .nav-link.active {
  color: #00ffff;
  text-shadow: 0 0 6px #00ffff;
}

/* Links in expanded (vertical) menu state */
.navbar-collapse .nav-link {
  display: block;
  text-align: center;
  padding: 12px 0;
  font-size: 1.1rem;
  border-bottom: 1px solid rgba(255, 255, 255, 0.1);
}

/* Hover effect in expanded menu */
.navbar-collapse .nav-link:hover {
  background: rgba(0, 255, 255, 0.1);
  border-radius: 8px;
}

.section {
  display: none;
  padding: 20px 0;
  background-color: transparent !important;
    animation: fadeIn 0.5s ease forwards;
}

.active-section {
  display: block;
}

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(10px); }
  to { opacity: 1; transform: translateY(0); }
}

/* Display cards in the Library section */
#library {
  row-gap: 1.5rem; 
  column-gap: 1.5rem; 
}

/* Carts */
.card {
  border-radius: 14px;
  background: #1e1f25;
  border: none;
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}

/* Quiz */
.quiz-card {
  background: #1e1f25;
  border: 1px solid #198754;
  padding: 15px;
  border-radius: 10px;
}

.quiz-card input {
  background: #2c2f33;
  color: #fff;
  border: none;
  border-radius: 6px;
  padding: 8px 12px;
  width: 100%;
}

.quiz-card input::placeholder {
  color: #aaa;
}

/* Learn */
.learn-pane {
  display: none;
}

.active-pane {
  display: block;
}

@media (max-width: 576px) {
  body {
    font-size: 14px;
  }

  .section {
    padding: 10px 0;
  }

  .tab-content {
    padding: 12px;
  }

  h2,
  h3 {
    font-size: 1.25rem;
  }

  .btn {
    font-size: 0.9rem;
  }
}

/* Navigation buttons */
.nav-btn {
  background: transparent;
  border: none;
  color: #ccc;
  font-size: 1.6rem;
  cursor: pointer;
  padding: 0 12px;
  transition: color 0.2s;
}

.nav-btn:hover {
  color: #fff;
}

/* fashcarts */
.flashcard {
  width: 320px;
  height: 200px;
  position: relative;
  transform-style: preserve-3d;
  transition: transform 0.6s;
  cursor: pointer;
}

.flashcard.flipped {
  transform: rotateY(180deg);
}

.flashcard .front,
.flashcard .back {
  position: absolute;
  width: 100%;
  height: 100%;
  top: 0;
  left: 0;
  backface-visibility: hidden;
  border: 1px solid rgba(255,255,255,0.1);
  border-radius: 10px;
  display: flex;
  justify-content: center;
  align-items: center;
  font-size: 1.4rem;
  padding: 20px;
  box-shadow: 0 0 15px rgba(0,0,0,0.3);
}

/* Front side of the card */
.flashcard .front {
  background: linear-gradient(145deg, #04394e, #06657c);
  color: #fff;
}

/* Back side of the card */
.flashcard .back {
  background: linear-gradient(145deg, #023141, #034f62);
  color: #9fc191;
  transform: rotateY(180deg);
}

.quiz-question {
  font-size: 1.3rem;
  margin-bottom: 15px;
  font-weight: 600;
}

/* quiz section */
.quiz-options {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.quiz-options button {
  background: rgba(255, 255, 255, 0.08);
  border: 1px solid rgba(255, 255, 255, 0.1);
  border-radius: 8px;
  padding: 10px;
  color: #fff;
  text-align: left;
  transition: background 0.3s;
}

.quiz-options button:hover {
  background: rgba(0, 255, 150, 0.2);
}

.quiz-options button.correct {
  background: rgba(0, 200, 100, 0.3);
}

.quiz-options button.wrong {
  background: rgba(255, 0, 80, 0.3);
}