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

body {
  font-family: 'Inter', sans-serif;
  background-color: #f4f4f9;
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
  margin: 0;
}

.container {
  text-align: center;
  width: 640px;
  max-width: calc(100% - 40px);
  margin: 20px auto;
}

h1 {
  margin-bottom: 12px;
  font-size: 30px;
}

.login-box {
  background: white;
  padding: 18px;
  border-radius: 8px;
  box-shadow: 0 6px 18px rgba(0,0,0,0.06);
  width: 560px;
  max-width: calc(100% - 40px);
  text-align: center;
}

.mode-box {
  margin-bottom: 14px;
}

.mode-box button {
  padding: 8px 12px;
  margin: 0 6px;
  border-radius: 6px;
  border: 1px solid #ccc;
  background: #fff;
  cursor: pointer;
}

.mode-box button:disabled {
  opacity: 0.55;
  cursor: default;
}

.form-box {
  margin: 8px 0 22px 0;
  display: flex;
  gap: 12px;
  justify-content: center;
  align-items: center;
}

.form-box input {
  flex: 1 1 55%;
  min-width: 260px;
  padding: 14px 16px;
  border: 1px solid #d0d0d5;
  border-radius: 8px;
  font-size: 16px;
}

.form-box button {
  padding: 12px 18px;
  background-color: #28a745;
  color: white;
  border: none;
  border-radius: 8px;
  cursor: pointer;
}

.flashcard {
  width: 100%;
  height: 300px;
  perspective: 1000px;
  cursor: pointer;
  margin: 18px 0 42px 0; /* increased bottom space */
}

.nav-box {
  margin-top: 12px;
  display: flex;
  justify-content: center;
  gap: 20px;
  padding-bottom: 24px; /* give breathing room under nav */
}

.card-inner {
  position: relative;
  width: 100%;
  height: 100%;
  text-align: center;
  transition: transform 0.45s;
  transform-style: preserve-3d;
}

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

.card-front, .card-back {
  position: absolute;
  width: 100%;
  height: 100%;
  backface-visibility: hidden;
  display: flex;
  justify-content: center;
  align-items: center;
  font-size: 28px;
  border-radius: 12px;
  box-shadow: 0 8px 24px rgba(0,0,0,0.08);
  padding: 18px;
}

.card-front {
  background-color: white;
  color: #111;
}

.card-back {
  background-color: #007bff;
  color: white;
  transform: rotateY(180deg);
}

.nav-box {
  margin-top: 8px;
  display: flex;
  justify-content: center;
  gap: 20px;
  padding-bottom: 12px; /* give breathing room under nav */
}

.nav-box button {
  padding: 12px 22px;
  margin: 0 8px;
  cursor: pointer;
  border-radius: 8px;
  border: 1px solid #ccc;
  background: #fff;
}

.practice-box input {
  width: 100%;
  padding: 12px;
  margin-top: 8px;
  border-radius: 6px;
  border: 1px solid #d0d0d5;
  font-size: 15px;
}

.practice-controls button {
  margin-top: 8px;
  margin-right: 8px;
  padding: 8px 12px;
  border-radius: 6px;
}

#practiceFeedback {
  color: #333;
}

@media (max-width: 720px) {
  .container { width: 92%; }
  .form-box { flex-direction: column; gap: 10px; }
  .form-box input { min-width: auto; width: 100%; }
  .card-front, .card-back { font-size: 22px; }
}

@media (max-width: 480px) {
  .card-front, .card-back { font-size: 20px; }
}