@import url("https://fonts.googleapis.com/css2?family=Inter:wght@300;400;600;700&display=swap");
* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
  font-family: "Inter", sans-serif;
}
body {
  display: flex;
  flex-direction: column;
  min-height: 100vh;
  background: linear-gradient(135deg, #c850c0, #4158d0);
  color: #333;
  transition: background 0.5s ease-in-out;
}
header {
  padding: 20px;
  background: #333;
  color: #fff;
  display: flex;
  justify-content: space-between;
  align-items: center;
  position: sticky;
  top: 0;
  z-index: 1000;
}
header h1 {
  font-size: 24px;
  margin: 0;
  letter-spacing: 1px;
  font-weight: 700;
}
header nav button {
  background: #fff;
  color: #333;
  border: none;
  border-radius: 20px;
  padding: 10px 20px;
  cursor: pointer;
  transition: all 0.3s ease;
  outline: none;
  font-size: 14px;
  font-weight: 600;
}
header nav button:hover {
  background: #f0f0f0;
  color: #333;
  transform: translateY(-1px);
}
main {
  flex: 1;
  display: flex;
  flex-direction: column;
  max-width: 1200px;
  width: 100%;
  margin: auto;
  padding: 20px;
  gap: 20px;
  transition: all 0.3s ease;
}
form {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}
form input,
form select {
  padding: 10px;
  border: 1px solid #ccc;
  border-radius: 6px;
  min-width: 150px;
  outline: none;
  transition: border-color 0.3s ease;
}
form input:focus,
form select:focus {
  border-color: #4158d0;
}
form button {
  padding: 10px 20px;
  background: #333;
  color: #fff;
  border: none;
  border-radius: 20px;
  cursor: pointer;
  transition: all 0.3s ease;
  font-weight: 600;
}
form button:hover {
  background: #4158d0;
}
.deck-list,
.study-container,
.test-container,
.create-container,
.edit-deck-container,
.edit-card-container {
  background: #fff;
  padding: 20px;
  border-radius: 12px;
  box-shadow: 0 8px 20px rgba(0, 0, 0, 0.1);
  transition: transform 0.3s ease, box-shadow 0.3s ease;
  flex-direction: column;
  gap: 20px;
}
.deck-list {
  display: block;
}
.study-container,
.test-container,
.create-container,
.edit-deck-container,
.edit-card-container {
  display: none;
}
.deck-list:hover,
.study-container:hover,
.test-container:hover,
.create-container:hover,
.edit-deck-container:hover,
.edit-card-container:hover {
  transform: translateY(-1px);
  box-shadow: 0 12px 24px rgba(0, 0, 0, 0.15);
}
.deck-list h2,
.study-container h2,
.test-container h2,
.create-container h2,
.edit-deck-container h2,
.edit-card-container h2 {
  margin-bottom: 10px;
  color: #333;
  font-weight: 700;
  letter-spacing: 0.5px;
}
.decks {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 20px;
}
.deck {
  background: #fafafa;
  padding: 20px;
  border: 1px solid #eee;
  border-radius: 12px;
  display: flex;
  flex-direction: column;
  gap: 10px;
  position: relative;
  transition: box-shadow 0.3s ease, transform 0.3s ease;
}
.deck h3 {
  margin: 0;
  font-size: 18px;
  font-weight: 600;
  color: #333;
}
.deck p {
  color: #666;
  font-size: 14px;
}
.deck:hover {
  box-shadow: 0 8px 20px rgba(0, 0, 0, 0.1);
  transform: translateY(-1px);
}
.deck-actions {
  display: flex;
  gap: 10px;
  justify-content: flex-end;
  flex-wrap: wrap;
}
.deck-actions button {
  padding: 8px 16px;
  background: #333;
  color: #fff;
  border: none;
  border-radius: 20px;
  cursor: pointer;
  font-size: 14px;
  font-weight: 500;
  transition: all 0.3s ease;
}
.deck-actions button:hover {
  background: #4158d0;
}
.study-container {
  align-items: center;
  gap: 20px;
}
.study-card {
  position: relative;
  width: 300px;
  height: 200px;
  perspective: 1000px;
  will-change: transform;
}
.study-card-inner {
  position: relative;
  width: 100%;
  height: 100%;
  transition: transform 0.4s ease;
  transform-style: preserve-3d;
  will-change: transform;
}
.study-card.flipped .study-card-inner {
  transform: rotateY(180deg);
}
.study-card-face {
  position: absolute;
  width: 100%;
  height: 100%;
  backface-visibility: hidden;
  display: flex;
  flex-direction: column;
  font-size: 24px;
  font-weight: 600;
  color: #333;
  background: #fff;
  border: 1px solid #ccc;
  border-radius: 12px;
  padding: 20px;
  text-align: left;
  will-change: transform;
  overflow-y: auto;
  word-break: break-word;
  white-space: normal;
}
.study-card-back {
  transform: rotateY(180deg);
  background: #f8f8f8;
}
.study-controls {
  display: flex;
  gap: 10px;
}
.study-controls button {
  padding: 10px 20px;
  background: #333;
  color: #fff;
  border: none;
  border-radius: 20px;
  cursor: pointer;
  transition: all 0.3s ease;
  font-weight: 600;
}
.study-controls button:hover {
  background: #4158d0;
}
.test-question {
  font-size: 20px;
  margin-bottom: 10px;
  color: #333;
  font-weight: 600;
}
.test-choices {
  display: flex;
  flex-direction: column;
  gap: 10px;
}
.test-choices button {
  padding: 10px;
  background: #f0f0f0;
  color: #333;
  border: none;
  border-radius: 6px;
  cursor: pointer;
  text-align: left;
  font-size: 16px;
  font-weight: 500;
  transition: all 0.3s ease;
}
.test-choices button:hover {
  background: #e0e0e0;
}
.test-result {
  font-size: 18px;
  margin-top: 20px;
  font-weight: 600;
  color: #333;
}
.test-controls {
  display: flex;
  gap: 10px;
}
.test-controls button {
  padding: 10px 20px;
  background: #333;
  color: #fff;
  border: none;
  border-radius: 20px;
  cursor: pointer;
  transition: all 0.3s ease;
  font-weight: 600;
}
.test-controls button:hover {
  background: #4158d0;
}
.create-container {
  gap: 20px;
}
.create-deck-form,
.create-card-form {
  display: flex;
  gap: 10px;
  align-items: center;
  flex-wrap: wrap;
}
.create-deck-form input,
.create-card-form input,
.create-card-form select {
  flex: 0 0 auto;
}
.edit-deck-actions {
  display: flex;
  gap: 10px;
}
.edit-deck-add-card-form input {
  flex: 0 0 auto;
}
.edit-deck-cards {
  display: flex;
  flex-direction: column;
  gap: 10px;
}
.edit-deck-card {
  display: flex;
  justify-content: space-between;
  align-items: center;
  background: #fafafa;
  border: 1px solid #eee;
  padding: 10px;
  border-radius: 6px;
}
.edit-deck-card-content {
  display: flex;
  flex-direction: column;
  gap: 5px;
}
.edit-deck-card-content span {
  font-size: 14px;
}
.edit-deck-card-actions {
  display: flex;
  gap: 10px;
}
.edit-deck-card-actions button {
  padding: 5px 10px;
  background: #333;
  color: #fff;
  border: none;
  border-radius: 20px;
  cursor: pointer;
  font-size: 14px;
  font-weight: 500;
  transition: all 0.3s ease;
}
.edit-deck-card-actions button:hover {
  background: #4158d0;
}
.edit-card-form {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
}
.edit-card-form input {
  flex: 1;
  padding: 10px;
  border: 1px solid #ccc;
  border-radius: 6px;
  outline: none;
  transition: border-color 0.3s ease;
}
.edit-card-form button {
  padding: 10px 20px;
  background: #333;
  color: #fff;
  border: none;
  border-radius: 20px;
  cursor: pointer;
  transition: all 0.3s ease;
  font-weight: 600;
}
.edit-card-form button:hover {
  background: #4158d0;
}
.correct-choice {
  background: #4caf50 !important;
  color: #fff !important;
  transition: background-color 0.5s ease, color 0.5s ease;
}
.incorrect-choice {
  background: #f44336 !important;
  color: #fff !important;
  transition: background-color 0.5s ease, color 0.5s ease;
}
.danger-button,
.close-button {
  background: #333;
  color: #fff;
  border: none;
  border-radius: 20px;
  padding: 10px 20px;
  cursor: pointer;
  transition: all 0.3s ease;
  font-weight: 600;
}
.danger-button:hover,
.close-button:hover {
  background: #4158d0;
}