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

:root {
  --primary: #4f46e5;
  --primary-hover: #4338ca;
  --correct: #22c55e;
  --correct-hover: #16a34a;
  --wrong: #ef4444;
  --wrong-hover: #dc2626;
  --bg: #f8fafc;
  --card-bg: #ffffff;
  --card-back: #e0e7ff;
  --text: #1e293b;
  --text-muted: #64748b;
  --border: #e2e8f0;
  --shadow: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
  --shadow-lg:
    0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
}

[data-theme="dark"] {
  --bg: #0f172a;
  --card-bg: #1e293b;
  --text: #f1f5f9;
  --text-muted: #94a3b8;
  --border: #334155;
  --card-back: #334155;
  --shadow: 0 4px 6px -1px rgb(0 0 0 / 0.3), 0 2px 4px -2px rgb(0 0 0 / 0.3);
  --shadow-lg:
    0 10px 15px -3px rgb(0 0 0 / 0.4), 0 4px 6px -4px rgb(0 0 0 / 0.4);
}

body {
  font-family:
    -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Oxygen, Ubuntu,
    sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  min-height: 100vh;
  transition:
    background-color 0.3s ease,
    color 0.3s ease;
}

body * {
  transition:
    background-color 0.3s ease,
    color 0.3s ease,
    border-color 0.3s ease,
    box-shadow 0.3s ease;
}

/* Header */
.header {
  background: var(--card-bg);
  border-bottom: 1px solid var(--border);
  padding: 1rem 2rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 1rem;
}

.header h1,
.header-title {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--primary);
  text-decoration: none;
}

.header-title:hover {
  opacity: 0.9;
}

.nav {
  display: flex;
  gap: 0.5rem;
  flex-wrap: wrap;
}

.nav-btn {
  padding: 0.5rem 1rem;
  border: none;
  background: transparent;
  color: var(--text-muted);
  cursor: pointer;
  border-radius: 0.5rem;
  font-size: 0.875rem;
  font-weight: 500;
  transition: all 0.2s;
}

.nav-btn:hover {
  background: var(--bg);
  color: var(--text);
}

.nav-btn.active {
  background: var(--primary);
  color: white;
}

.theme-toggle {
  display: flex;
  align-items: center;
  justify-content: center;
  min-width: 2.5rem;
}

.theme-icon {
  font-size: 1.1rem;
}

/* Main */
.main {
  max-width: 800px;
  margin: 0 auto;
  padding: 2rem;
}

.view {
  display: none;
}

.view.active {
  display: block;
}

.view h2 {
  margin-bottom: 1.5rem;
  font-size: 1.5rem;
}

/* Buttons */
.btn {
  padding: 0.75rem 1.5rem;
  border: 1px solid var(--border);
  background: var(--card-bg);
  color: var(--text);
  cursor: pointer;
  border-radius: 0.5rem;
  font-size: 0.875rem;
  font-weight: 500;
  transition: all 0.2s;
}

.btn:hover {
  background: var(--bg);
}

.btn-primary {
  background: var(--primary);
  border-color: var(--primary);
  color: white;
}

.btn-primary:hover {
  background: var(--primary-hover);
}

.btn-correct {
  background: var(--correct);
  border-color: var(--correct);
  color: white;
}

.btn-correct:hover {
  background: var(--correct-hover);
}

.btn-wrong {
  background: var(--wrong);
  border-color: var(--wrong);
  color: white;
}

.btn-wrong:hover {
  background: var(--wrong-hover);
}

/* Home */
.home-content {
  text-align: center;
  padding: 3rem 0;
}

.home-content h2 {
  font-size: 2rem;
  margin-bottom: 0.5rem;
}

.home-content p {
  color: var(--text-muted);
  margin-bottom: 2rem;
}

.card-count {
  font-size: 1.25rem;
  margin-bottom: 2rem;
  padding: 1rem;
  background: var(--card-bg);
  border-radius: 0.5rem;
  display: inline-block;
  box-shadow: var(--shadow);
}

.home-actions {
  display: flex;
  gap: 1rem;
  justify-content: center;
  flex-wrap: wrap;
}

/* Forms */
.create-form {
  background: var(--card-bg);
  padding: 1.5rem;
  border-radius: 0.5rem;
  box-shadow: var(--shadow);
}

.form-group {
  margin-bottom: 1rem;
}

.form-group label {
  display: block;
  margin-bottom: 0.5rem;
  font-weight: 500;
}

.form-group textarea,
.form-group input {
  width: 100%;
  padding: 0.75rem;
  border: 1px solid var(--border);
  border-radius: 0.5rem;
  font-size: 1rem;
  font-family: inherit;
  resize: vertical;
}

.form-group textarea {
  min-height: 100px;
}

.form-group textarea:focus,
.form-group input:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgb(79 70 229 / 0.1);
}

.message {
  margin-top: 1rem;
  padding: 0.75rem;
  border-radius: 0.5rem;
  display: none;
}

.message.show {
  display: block;
}

.message.success {
  background: #dcfce7;
  color: #166534;
}

.message.error {
  background: #fee2e2;
  color: #991b1b;
}

.message.warning {
  background: #fef3c7;
  color: #92400e;
}

/* CSV Import */
.csv-import {
  margin-top: 1.5rem;
}

.csv-import-divider {
  display: flex;
  align-items: center;
  text-align: center;
  margin: 1.5rem 0;
  color: var(--text-muted);
}

.csv-import-divider::before,
.csv-import-divider::after {
  content: "";
  flex: 1;
  border-bottom: 1px solid var(--border);
}

.csv-import-divider span {
  padding: 0 0.75rem;
  font-size: 0.875rem;
}

.csv-import-section {
  background: var(--card-bg);
  padding: 1.5rem;
  border-radius: 0.5rem;
  box-shadow: var(--shadow);
  text-align: center;
}

.csv-import-section h3 {
  font-size: 1rem;
  margin-bottom: 0.5rem;
}

.csv-hint {
  color: var(--text-muted);
  font-size: 0.875rem;
  margin-bottom: 1rem;
}

.csv-file-input {
  display: block;
  margin: 0 auto;
  padding: 0.5rem;
  border: 1px dashed var(--border);
  border-radius: 0.5rem;
  background: var(--bg);
  cursor: pointer;
  width: 100%;
  max-width: 300px;
}

.csv-file-input:hover {
  border-color: var(--primary);
  background: var(--bg);
}

/* Checkbox */
.checkbox-label {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  cursor: pointer;
  user-select: none;
}

.checkbox-label input {
  width: 1rem;
  height: 1rem;
  cursor: pointer;
}

/* View Header */
.view-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 1.5rem;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.view-header h2 {
  margin-bottom: 0;
}

/* View Options */
.view-options {
  display: flex;
  gap: 1.5rem;
  align-items: center;
  flex-wrap: wrap;
}

.card-count-inline {
  margin-left: auto;
  font-weight: 500;
  color: var(--text-muted);
}

/* Cards Grid */
.cards-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 1rem;
}

.card-item {
  background: var(--card-bg);
  padding: 1.25rem;
  border-radius: 0.5rem;
  box-shadow: var(--shadow);
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
  transition: box-shadow 0.2s;
}

.card-item:hover {
  box-shadow: var(--shadow-lg);
}

.card-item .front {
  font-weight: 600;
  color: var(--primary);
  font-size: 0.95rem;
  line-height: 1.5;
  word-break: break-word;
}

.card-item .back {
  color: var(--text-muted);
  font-size: 0.9rem;
  line-height: 1.5;
  word-break: break-word;
  flex: 1;
}

.card-item-actions {
  display: flex;
  gap: 0.5rem;
  justify-content: flex-end;
  margin-top: auto;
  padding-top: 0.75rem;
  border-top: 1px solid var(--border);
}

.card-item-actions .btn {
  padding: 0.4rem 0.75rem;
  font-size: 0.8rem;
}

/* Empty State */
.empty-state {
  text-align: center;
  padding: 3rem 1rem;
  color: var(--text-muted);
  background: var(--card-bg);
  border-radius: 0.5rem;
  box-shadow: var(--shadow);
}

/* Flashcard */
.card-display {
  perspective: 1000px;
  margin: 2rem 0;
}

.flashcard {
  width: 100%;
  min-height: 300px;
  cursor: pointer;
}

.flashcard-inner {
  position: relative;
  width: 100%;
  height: 100%;
  transition: transform 0.6s;
  transform-style: preserve-3d;
}

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

.flashcard-front,
.flashcard-back {
  position: absolute;
  width: 100%;
  min-height: 300px;
  backface-visibility: hidden;
  background: var(--card-bg);
  border-radius: 0.5rem;
  box-shadow: var(--shadow-lg);
  padding: 2rem;
  display: flex;
  align-items: center;
  justify-content: center;
}

.flashcard-front {
  border: 2px solid var(--border);
}

.flashcard-back {
  transform: rotateY(180deg);
  background: var(--card-back);
  color: var(--text);
}

.flashcard-front p,
.flashcard-back p {
  font-size: 1.25rem;
  text-align: center;
  line-height: 1.8;
}

/* Cram & Learn Setup */
.cram-setup,
.learn-setup {
  background: var(--card-bg);
  padding: 1.5rem;
  border-radius: 0.5rem;
  box-shadow: var(--shadow);
  text-align: center;
}

.cram-setup p,
.learn-setup p {
  color: var(--text-muted);
  margin-bottom: 1rem;
}

.cram-setup label,
.learn-setup label {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 0.5rem;
  margin-bottom: 1rem;
}

.setup-actions {
  display: flex;
  gap: 1rem;
  justify-content: center;
  flex-wrap: wrap;
}

/* Cram & Learn Progress */
.cram-progress,
.learn-progress {
  display: flex;
  justify-content: space-around;
  padding: 1rem;
  background: var(--card-bg);
  border-radius: 0.5rem;
  box-shadow: var(--shadow);
  margin-bottom: 1rem;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.cram-progress span,
.learn-progress span {
  font-size: 0.875rem;
  color: var(--text-muted);
}

/* Cram Controls */
.cram-controls {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 1rem;
}

.cram-controls .btn {
  min-width: 150px;
}

/* Multiple Choice Options */
.mc-options {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1rem;
  margin-top: 1rem;
}

.mc-option {
  padding: 1rem;
  text-align: left;
  white-space: normal;
  word-wrap: break-word;
  min-height: 80px;
  display: flex;
  align-items: center;
}

.mc-option.correct {
  background: var(--correct) !important;
  border-color: var(--correct) !important;
  color: white !important;
}

.mc-option.incorrect {
  background: var(--wrong) !important;
  border-color: var(--wrong) !important;
  color: white !important;
}

.mc-option.disabled {
  pointer-events: none;
  opacity: 0.6;
}

.mc-feedback {
  text-align: center;
  padding: 1rem;
  margin-top: 1rem;
  border-radius: 0.5rem;
  font-weight: 500;
}

.mc-feedback.correct {
  background: #dcfce7;
  color: #166534;
}

.mc-feedback.incorrect {
  background: #fee2e2;
  color: #991b1b;
}

/* Written Input */
.written-input {
  display: flex;
  gap: 1rem;
  margin-top: 1rem;
}

.written-input input {
  flex: 1;
  padding: 0.75rem;
  border: 1px solid var(--border);
  border-radius: 0.5rem;
  font-size: 1rem;
}

.written-input input:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgb(79 70 229 / 0.1);
}

/* Flip Controls */
.flip-controls {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 1rem;
  margin-top: 1rem;
}

/* Complete States */
.cram-complete,
.learn-complete {
  text-align: center;
  padding: 3rem 0;
}

.cram-complete h3,
.learn-complete h3 {
  font-size: 1.5rem;
  margin-bottom: 0.5rem;
}

.cram-complete p,
.learn-complete p {
  color: var(--text-muted);
  margin-bottom: 1.5rem;
}

/* Utility */
.hidden {
  display: none !important;
}

/* Modal */
.modal {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  z-index: 1000;
  display: flex;
  align-items: center;
  justify-content: center;
}

.modal-overlay {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(0, 0, 0, 0.5);
}

.modal-content {
  position: relative;
  background: var(--card-bg);
  border-radius: 0.5rem;
  box-shadow: var(--shadow-lg);
  width: 90%;
  max-width: 500px;
  max-height: 90vh;
  overflow-y: auto;
  animation: modalSlideIn 0.2s ease-out;
}

.modal-small {
  max-width: 400px;
}

@keyframes modalSlideIn {
  from {
    opacity: 0;
    transform: translateY(-20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.modal-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 1rem 1.25rem;
  border-bottom: 1px solid var(--border);
}

.modal-header h3 {
  font-size: 1.1rem;
  font-weight: 600;
}

.modal-close {
  background: transparent;
  border: none;
  font-size: 1.5rem;
  cursor: pointer;
  color: var(--text-muted);
  line-height: 1;
  padding: 0;
  width: 2rem;
  height: 2rem;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 0.25rem;
  transition: all 0.2s;
}

.modal-close:hover {
  background: var(--bg);
  color: var(--text);
}

.modal-body {
  padding: 1.25rem;
}

.modal-actions {
  display: flex;
  justify-content: flex-end;
  gap: 0.5rem;
  padding: 1rem 1.25rem;
  border-top: 1px solid var(--border);
}

.edit-form {
  display: flex;
  flex-direction: column;
  gap: 1rem;
  padding: 1.25rem;
}

.edit-form .form-group {
  margin-bottom: 0;
}

/* Responsive */
@media (max-width: 600px) {
  .header {
    padding: 1rem;
  }

  .header h1 {
    font-size: 1.25rem;
  }

  .nav {
    width: 100%;
    justify-content: center;
  }

  .main {
    padding: 1rem;
  }

  .home-actions {
    flex-direction: column;
  }

  .mc-options {
    grid-template-columns: 1fr;
  }

  .written-input {
    flex-direction: column;
  }

  .cram-progress,
  .learn-progress {
    flex-direction: column;
    align-items: center;
  }

  .cards-grid {
    grid-template-columns: 1fr;
  }

  .view-header {
    flex-direction: column;
    align-items: flex-start;
  }

  .card-count-inline {
    margin-left: 0;
  }

  .modal-actions {
    flex-direction: column;
  }

  .modal-actions .btn {
    width: 100%;
  }
}