:root {
  /* Light Modern Color Palette - Clean & Fresh */
  --primary-gradient: linear-gradient(
    135deg,
    #7c3aed 0%,
    #a78bfa 50%,
    #c4b5fd 100%
  );
  --secondary: #8b5cf6;
  --accent: rgba(139, 92, 246, 0.15);
  --glass-bg: rgba(255, 255, 255, 0.85);
  --glass-border: rgba(139, 92, 246, 0.2);
  --text-primary: #1e293b;
  --text-secondary: #475569;
  --shadow: 0 10px 40px rgba(0, 0, 0, 0.1);
  --nav-bg: rgba(255, 255, 255, 0.9);
  --bg-primary: linear-gradient(135deg, #f8fafc 0%, #f1f5f9 50%, #e2e8f0 100%);
  --card-bg: rgba(255, 255, 255, 0.95);
}

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

body {
  font-family: "Poppins", sans-serif;
  /* background: var(--bg-primary); */
  background: linear-gradient(
    rgba(255, 0, 0, 0.43),
    rgba(54, 54, 247, 0.419),
    pink
  );
  color: var(--text-primary);
  min-height: 100vh;
  overflow-x: hidden;
  transition: all 0.3s ease;
}

.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 1rem;
  min-height: 100vh;
  position: relative;
  padding-bottom: 80px;
  padding-top: 100px;
}

/* Back Button */
.back-button {
  position: fixed;
  top: 20px;
  left: 20px;
  z-index: 1001;
  background: var(--glass-bg);
  backdrop-filter: blur(20px);
  border: 1px solid var(--glass-border);
  border-radius: 20px;
  padding: 12px 20px;
  color: var(--text-primary);
  font-weight: 500;
  cursor: pointer;
  transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  display: flex;
  align-items: center;
  gap: 8px;
  box-shadow: var(--shadow);
  font-size: 0.95rem;
  min-height: 48px;
  text-decoration: none;
}

.back-button:hover {
  background: var(--primary-gradient);
  color: white;
  transform: translateY(-2px) scale(1.02);
  box-shadow: 0 15px 45px rgba(124, 58, 237, 0.3);
}

.back-button:active {
  transform: translateY(0) scale(0.98);
}

.back-button.hidden {
  display: none;
}

/* Glassmorphism Cards */
.glass-card {
  background: var(--card-bg);
  backdrop-filter: blur(20px);
  border: 1px solid var(--glass-border);
  border-radius: 24px;
  padding: 2rem;
  box-shadow: var(--shadow);
  transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

.glass-card:hover {
  transform: translateY(-8px);
  box-shadow: 0 20px 50px rgba(0, 0, 0, 0.15);
}

/* Home Dashboard */
.home-dashboard {
  text-align: center;
  padding-top: 2rem;
}

.daily-message {
  font-size: 1.5rem;
  font-weight: 600;
  margin-bottom: 2rem;
  background: var(--primary-gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.action-buttons {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 1.5rem;
  margin-top: 2rem;
}

.btn {
  padding: 1.2rem 2rem;
  border: none;
  border-radius: 20px;
  font-size: 1.1rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.3s ease;
  display: flex;
  align-items: center;
  gap: 0.8rem;
  justify-content: center;
  text-decoration: none;
  color: white;
  min-height: 64px;
  position: relative;
  overflow: hidden;
}

.btn-primary {
  background: var(--primary-gradient);
  box-shadow: 0 8px 25px rgba(124, 58, 237, 0.3);
}

.btn-primary:hover {
  transform: translateY(-4px);
  box-shadow: 0 15px 35px rgba(124, 58, 237, 0.4);
}

.btn-primary::before {
  content: "";
  position: absolute;
  top: 0;
  left: -100%;
  width: 100%;
  height: 100%;
  background: linear-gradient(
    90deg,
    transparent,
    rgba(255, 255, 255, 0.3),
    transparent
  );
  transition: left 0.5s;
}

.btn-primary:hover::before {
  left: 100%;
}

.btn-secondary {
  background: rgba(255, 255, 255, 0.9);
  color: var(--text-primary);
  border: 2px solid var(--glass-border);
  backdrop-filter: blur(20px);
}

.btn-secondary:hover {
  background: white;
  transform: translateY(-4px);
  box-shadow: 0 12px 30px rgba(0, 0, 0, 0.15);
}

/* Today's Words */
.words-list {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 1.5rem;
  margin-top: 2rem;
}

.word-card {
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.word-title {
  font-size: 1.8rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 0.5rem;
}

.word-pos {
  color: var(--secondary);
  font-weight: 500;
  text-transform: uppercase;
  font-size: 0.9rem;
  letter-spacing: 1px;
}

.word-meaning {
  font-size: 1.1rem;
  line-height: 1.6;
  color: var(--text-secondary);
}

.mark-known {
  background: rgba(139, 92, 246, 0.1);
  border: 2px solid var(--glass-border);
  padding: 0.8rem 1.5rem;
  border-radius: 50px;
  font-weight: 500;
  transition: all 0.3s ease;
  color: var(--text-primary);
}

.mark-known:hover {
  background: var(--primary-gradient);
  color: white;
  transform: scale(1.05);
}

/* Flashcard Mode */
.flashcard-container {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  min-height: 70vh;
  perspective: 1000px;
}

.flashcard {
  width: 100%;
  max-width: 400px;
  height: 500px;
  position: relative;
  cursor: pointer;
}

.flashcard-inner {
  position: relative;
  width: 100%;
  height: 100%;
  text-align: center;
  transition: transform 0.8s cubic-bezier(0.25, 0.46, 0.45, 0.94);
  transform-style: preserve-3d;
}

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

.flashcard-front,
.flashcard-back {
  position: absolute;
  width: 100%;
  height: 100%;
  backface-visibility: hidden;
  border-radius: 24px;
  padding: 3rem 2rem;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  background: var(--glass-bg);
  backdrop-filter: blur(20px);
  border: 1px solid var(--glass-border);
  box-shadow: var(--shadow);
}

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

.flashcard-title {
  font-size: 3rem;
  font-weight: 700;
  margin-bottom: 1rem;
  background: var(--primary-gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.flashcard-content {
  font-size: 1.4rem;
  line-height: 1.6;
  color: var(--text-secondary);
}

.progress-indicator {
  margin-top: 2rem;
  font-size: 1.2rem;
  color: var(--secondary);
}

/* Quiz Mode */
.quiz-options {
  display: grid;
  gap: 1rem;
  margin: 2rem 0;
}

.quiz-option {
  padding: 1.5rem;
  border-radius: 20px;
  cursor: pointer;
  transition: all 0.3s ease;
  font-size: 1.1rem;
  border: 2px solid var(--glass-border);
  background: var(--glass-bg);
}

.quiz-option:hover {
  background: rgba(255, 255, 255, 0.95);
  transform: translateX(8px);
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.1);
}

.quiz-option.correct {
  background: rgba(34, 197, 94, 0.15);
  border-color: #22c55e;
  color: #166534;
  animation: pulse 0.6s ease;
}

.quiz-option.incorrect {
  background: rgba(239, 68, 68, 0.1);
  border-color: #ef4444;
  color: #991b1b;
}

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

/* Progress Tracker */
.stats-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 1.5rem;
  margin-top: 2rem;
}

.stat-card {
  text-align: center;
  padding: 2rem;
  background: var(--glass-bg);
  border-radius: 20px;
  border: 1px solid var(--glass-border);
}

.stat-number {
  font-size: 2.5rem;
  font-weight: 700;
  background: var(--primary-gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

/* Navigation */
.bottom-nav {
  position: fixed;
  bottom: 0;
  left: 0;
  right: 0;
  background: var(--nav-bg);
  backdrop-filter: blur(20px);
  border-top: 1px solid var(--glass-border);
  padding: 1rem 0;
  display: none;
  justify-content: space-around;
  z-index: 1000;
  box-shadow: 0 -4px 20px rgba(0, 0, 0, 0.08);
}

.bottom-nav.active {
  display: flex;
}

.nav-item {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.3rem;
  color: var(--text-secondary);
  text-decoration: none;
  padding: 0.5rem;
  border-radius: 12px;
  transition: all 0.3s ease;
  min-width: 60px;
}

.nav-item.active,
.nav-item:hover {
  color: var(--secondary);
  background: rgba(139, 92, 246, 0.1);
  transform: translateY(-2px);
}

.nav-icon {
  font-size: 1.5rem;
}

/* Responsive Design */
@media (max-width: 768px) {
  .container {
    padding: 1rem;
    padding-bottom: 100px;
    padding-top: 120px;
  }

  .back-button {
    top: 15px;
    left: 15px;
    padding: 10px 16px;
    font-size: 0.9rem;
  }

  .bottom-nav {
    display: flex;
  }

  .action-buttons {
    grid-template-columns: 1fr;
  }

  .flashcard {
    height: 400px;
  }

  .flashcard-title {
    font-size: 2.2rem;
  }
}

@media (max-width: 480px) {
  .glass-card {
    padding: 1.5rem;
  }

  .word-title {
    font-size: 1.5rem;
  }

  .back-button {
    padding: 12px 18px;
    font-size: 0.95rem;
  }
}

@media (min-width: 1200px) {
  .back-button {
    top: 25px;
    left: 25px;
  }
}

/* Screen Hiding */
.screen {
  display: none;
}

.screen.active {
  display: block;
}

.screen-title {
  font-size: 2rem;
  font-weight: 700;
  margin-bottom: 1rem;
  text-align: center;
  background: var(--primary-gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}