@import url('https://fonts.googleapis.com/css2?family=Poppins:wght@300;400;500;600;700&display=swap');

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

body {
  font-family: 'Poppins', sans-serif;
  background: linear-gradient(135deg, #0a0e27 0%, #1a1a2e 50%, #16213e 100%);
  min-height: 100vh;
  color: #eaeaea;
}

.navbar {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  background: #0a0e27f2;
  -webkit-backdrop-filter: blur(10px);
  backdrop-filter: blur(10px);
  box-shadow: 0 4px 20px rgba(0, 212, 255, 0.302);
  border-bottom: 1px solid rgba(0, 212, 255, 0.2);
  z-index: 1000;
  padding: 1rem 2rem;
  transition: all 0.3s ease;
}

.navbar-content {
  display: flex;
  justify-content: flex-start;
  align-items: center;
  max-width: 1200px;
  margin: 0 auto;
  gap: 3rem;
}

.navbar-title {
  font-size: 1.5rem;
  font-weight: 700;
  background: linear-gradient(135deg, #00d4ff 0%, #7b2cbf 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  text-decoration: none;
  filter: drop-shadow(0 2px 4px rgba(0, 212, 255, 0.4));
}

.navbar-links {
  display: flex;
  list-style: none;
  gap: 1.5rem;
}

.navbar-links a {
  text-decoration: none;
  color: #b8b8b8;
  font-weight: 500;
  padding: 0.5rem 1rem;
  border-radius: 8px;
  transition: all 0.3s ease;
}

.navbar-links a:hover {
  background: linear-gradient(135deg, #00d4ff 0%, #7b2cbf 100%);
  color: white;
  transform: translateY(-2px);
  box-shadow: 0 4px 15px rgba(0, 212, 255, 0.4);
}

.navbar-links a.active {
  background: linear-gradient(135deg, #00d4ff 0%, #7b2cbf 100%);
  color: white;
  font-weight: 600;
  box-shadow: 0 4px 15px rgba(0, 212, 255, 0.4);
}

.container {
  margin-top: 80px;
  padding: 2rem;
  min-height: calc(100vh - 80px);
}

.main-container {
  margin-top: 80px;
  padding: 2rem;
  min-height: calc(100vh - 80px);
}

.content-wrapper {
  max-width: 1200px;
  margin: 0 auto;
  background: rgba(10, 30, 60, 0.7);
  -webkit-backdrop-filter: blur(10px);
  backdrop-filter: blur(10px);
  border-radius: 20px;
  padding: 2rem;
  box-shadow: 0 15px 50px rgba(0, 212, 255, 0.2), 0 0 100px rgba(123, 44, 191, 0.1);
  border: 1px solid rgba(0, 212, 255, 0.3);
}

h1 {
  font-size: 2.5rem;
  background: linear-gradient(135deg, #00d4ff 0%, #7b2cbf 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  margin-bottom: 1.5rem;
  text-align: center;
}

h2 {
  font-size: 2rem;
  color: #eaeaea;
  margin-bottom: 1rem;
}

h3 {
  font-size: 1.5rem;
  color: #b8b8b8;
  margin-bottom: 0.8rem;
}

h4 {
  font-size: 1.2rem;
  color: #333;
  margin-bottom: 0.5rem;
}

p {
  line-height: 1.6;
  margin-bottom: 1rem;
  color: #b8b8b8;
}

button {
  padding: 0.8rem 1.5rem;
  font-size: 1rem;
  font-weight: 600;
  border: none;
  border-radius: 10px;
  cursor: pointer;
  background: linear-gradient(135deg, #00d4ff 0%, #7b2cbf 100%);
  color: white;
  transition: all 0.3s ease;
  box-shadow: 0 4px 15px rgba(0, 212, 255, 0.4);
}

button:hover {
  transform: translateY(-3px);
  box-shadow: 0 8px 25px rgba(0, 212, 255, 0.6);
  background: linear-gradient(135deg, #7b2cbf 0%, #00d4ff 100%);
}

button:active {
  transform: translateY(-1px);
}

.sudoku-cell {
  aspect-ratio: 1;
  border: 1px solid #cccccc;
  display: flex;
  align-items: center;
  justify-content: center;
  background-color: white;
  position: relative;
}

.sudoku-cell input {
  width: 100%;
  height: 100%;
  border: none;
  text-align: center;
  font-weight: 600;
  color: #1a1a2e;
  background-color: transparent;
}

.sudoku-cell.prefilled {
  background-color: rgba(255, 255, 255, 0.9);
}

.sudoku-cell.prefilled input {
  color: #1e40af;
  font-weight: 700;
}

.sudoku-cell input:focus,
.sudoku-cell.selected input {
  outline: 2px solid #1e40af;
  background-color: rgba(30, 64, 175, 0.1);
  box-shadow: 0 0 10px rgba(30, 64, 175, 0.5);
}

.sudoku-cell.incorrect {
  border: 2px solid rgba(255, 75, 75, 0.8);
}

.sudoku-cell.incorrect input {
  background-color: rgba(255, 0, 0, 0.07);
}

.sudoku-cell:not(.prefilled):hover {
  cursor: pointer;
  box-shadow: 0 0 8px rgba(0, 212, 255, 0.6);
}

.sudoku-cell input[readonly] {
  cursor: default;
  background-color: rgba(16, 185, 129, 0.08);
}

.sudoku-congrats {
  margin-top: 1rem;
  text-align: center;
  font-weight: 600;
  color: #4ade80;
  text-shadow: 0 0 8px rgba(34, 197, 94, 0.6);
}

@media (max-width: 768px) {
  .navbar {
      top: auto;
      bottom: 0;
      padding: 0.5rem 0.5rem 0.8rem 0.5rem;
      box-shadow: 0 -4px 20px rgba(0, 212, 255, 0.3);
      border-bottom: none;
      border-top: 1px solid rgba(0, 212, 255, 0.2);
  }

  .navbar-content {
      flex-direction: column;
      gap: 0.5rem;
      align-items: center;
  }

  .navbar-title {
      font-size: 1.1rem;
      order: -1;
  }

  .navbar-links {
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      gap: 0.3rem;
      width: 100%;
      max-width: 500px;
  }

  .navbar-links li {
      width: 100%;
  }

  .navbar-links a {
      display: block;
      padding: 0.5rem 0.3rem;
      font-size: 0.7rem;
      text-align: center;
      white-space: nowrap;
      overflow: hidden;
      text-overflow: ellipsis;
  }

  .main-container {
      margin-top: 0;
      margin-bottom: 110px;
      padding: 1rem;
  }

  .container {
      margin-top: 0;
      margin-bottom: 110px;
      padding: 1rem;
  }

  .content-wrapper {
      padding: 1.5rem;
  }

  h1 {
      font-size: 2rem;
  }

  h2 {
      font-size: 1.5rem;
  }
}

@media (max-width: 480px) {
  .navbar {
      padding: 0.4rem 0.3rem 0.6rem 0.3rem;
  }

  .navbar-title {
      font-size: 1rem;
  }

  .navbar-links {
      grid-template-columns: repeat(4, 1fr);
      gap: 0.2rem;
  }

  .navbar-links a {
      padding: 0.4rem 0.2rem;
      font-size: 0.65rem;
  }

  h1 {
      font-size: 1.5rem;
  }

  h2 {
      font-size: 1.3rem;
  }

  .content-wrapper {
      padding: 1rem;
  }

  .main-container {
      margin-bottom: 100px;
  }

  .container {
      margin-bottom: 100px;
  }
}