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

body {
  font-family: Arial, sans-serif;
  line-height: 1.6;
  background-color: #f0f2f5;
}

.container {
  max-width: 800px;
  margin: 2rem auto;
  padding: 0 1rem;
}

.study-controls {
  margin-bottom: 2rem;
  text-align: center;
}

.study-controls .know-it {
  background-color: #28a745;
}

.study-controls .know-it:hover {
  background-color: #218838;
}

.study-controls .reset-cards {
  background-color: #ffc107;
  color: #000;
}

.study-controls .reset-cards:hover {
  background-color: #e0a800;
}

button {
  padding: 0.5rem 1rem;
  margin: 0.5rem;
  border: none;
  border-radius: 4px;
  background-color: #4CAF50;
  color: white;
  cursor: pointer;
  transition: background-color 0.3s;
}

button:hover {
  background-color: #45a049;
}

.card-section {
  background-color: white;
  padding: 2rem;
  border-radius: 8px;
  box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
}

.card-input {
  display: flex;
  gap: 1rem;
  margin-bottom: 1rem;
  padding: 1rem;
  background-color: #f8f9fa;
  border-radius: 4px;
  animation: fadeIn 0.3s ease-in;
}

.card-input input {
  flex: 1;
  padding: 0.5rem;
  border: 1px solid #ddd;
  border-radius: 4px;
}

.card-input button {
  background-color: #dc3545;
}

.card-input button:hover {
  background-color: #c82333;
}

.study-card {
  min-height: 200px;
  perspective: 1000px;
  margin-bottom: 2rem;
}

.card-content {
  position: relative;
  width: 100%;
  height: 200px;
  cursor: pointer;
}

.card-front, .card-back {
  position: absolute;
  width: 100%;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: center;
  background-color: #fff;
  border-radius: 8px;
  box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
  padding: 1rem;
  text-align: center;
}

.hidden {
  display: none;
}

#exitStudy {
  background-color: #6c757d;
}

#exitStudy:hover {
  background-color: #5a6268;
}

#shuffleBtn {
  background-color: #007bff;
}

#shuffleBtn:hover {
  background-color: #0056b3;
}

.managed-card {
  display: flex;
  gap: 1rem;
  margin-bottom: 1rem;
  padding: 1rem;
  background-color: #f8f9fa;
  border-radius: 4px;
  animation: fadeIn 0.3s ease-in;
}

.managed-card input {
  flex: 1;
  padding: 0.5rem;
  border: 1px solid #ddd;
  border-radius: 4px;
}

.managed-card .edit-buttons {
  display: flex;
  gap: 0.5rem;
}

.managed-card .save-btn {
  background-color: #28a745;
}

.managed-card .save-btn:hover {
  background-color: #218838;
}

.managed-card .delete-btn {
  background-color: #dc3545;
}

.managed-card .delete-btn:hover {
  background-color: #c82333;
}

.managed-card .edit-btn {
  background-color: #ffc107;
  color: #000;
}

.managed-card .edit-btn:hover {
  background-color: #e0a800;
}

#exportCardsBtn {
  background-color: #17a2b8;
}

#exportCardsBtn:hover {
  background-color: #138496;
}

#importCardsBtn {
  background-color: #6610f2;
}

#importCardsBtn:hover {
  background-color: #520dc2;
}

.modal-overlay {
  display: none;
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background-color: rgba(0, 0, 0, 0.5);
  z-index: 1000;
  justify-content: center;
  align-items: center;
}

.modal {
  background-color: white;
  padding: 2rem;
  border-radius: 8px;
  width: 90%;
  max-width: 500px;
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
}

.modal textarea {
  width: 100%;
  height: 150px;
  margin: 1rem 0;
  padding: 0.5rem;
  border: 1px solid #ddd;
  border-radius: 4px;
  resize: vertical;
}

.modal-buttons {
  display: flex;
  gap: 1rem;
  justify-content: flex-end;
}

.modal-buttons .confirm-import {
  background-color: #28a745;
}

.modal-buttons .confirm-import:hover {
  background-color: #218838;
}

.modal-buttons .cancel-import {
  background-color: #dc3545;
}

.modal-buttons .cancel-import:hover {
  background-color: #c82333;
}

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