:root {
  --bg: #0f1419;
  --surface: #1a2332;
  --surface-2: #243044;
  --text: #e8eef7;
  --muted: #9fb0c7;
  --accent: #5b9cff;
  --accent-2: #7c5cff;
  --success: #3ecf8e;
  --danger: #ff6b6b;
  --border: rgba(255, 255, 255, 0.08);
  --shadow: 0 18px 50px rgba(0, 0, 0, 0.35);
  --radius: 16px;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: "Segoe UI", system-ui, sans-serif;
  background: radial-gradient(circle at top, #1b2740 0%, var(--bg) 45%);
  color: var(--text);
  min-height: 100vh;
}

.container {
  width: min(1100px, calc(100% - 2rem));
  margin: 0 auto;
  padding: 2rem 0 4rem;
}

.hero {
  display: grid;
  gap: 0.75rem;
  margin-bottom: 1.5rem;
}

.hero h1 {
  margin: 0;
  font-size: clamp(1.8rem, 4vw, 2.6rem);
}

.hero p {
  margin: 0;
  color: var(--muted);
  max-width: 70ch;
}

.card {
  background: rgba(26, 35, 50, 0.92);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 1.25rem;
}

.upload-card {
  display: grid;
  gap: 1rem;
}

.file-input {
  border: 1px dashed rgba(91, 156, 255, 0.45);
  border-radius: 12px;
  padding: 1.25rem;
  background: rgba(91, 156, 255, 0.05);
}

.file-input input {
  width: 100%;
}

.actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
}

button,
.btn {
  appearance: none;
  border: none;
  border-radius: 999px;
  padding: 0.75rem 1.2rem;
  font: inherit;
  cursor: pointer;
  transition: transform 0.15s ease, opacity 0.15s ease;
}

button:disabled {
  opacity: 0.55;
  cursor: not-allowed;
}

button:not(:disabled):hover {
  transform: translateY(-1px);
}

.btn-primary {
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  color: white;
}

.btn-secondary {
  background: var(--surface-2);
  color: var(--text);
  border: 1px solid var(--border);
}

.status {
  min-height: 1.5rem;
  color: var(--muted);
}

.status.error {
  color: var(--danger);
}

.hidden {
  display: none !important;
}

.section {
  margin-top: 1.25rem;
}

.section h2,
.section h3 {
  margin-top: 0;
}

.section-grid {
  display: grid;
  gap: 1rem;
}

.meta-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  gap: 0.75rem;
}

.meta-item {
  background: var(--surface-2);
  border-radius: 12px;
  padding: 0.85rem 1rem;
}

.meta-item span {
  display: block;
  color: var(--muted);
  font-size: 0.85rem;
}

.note-block,
.list-block,
.glossary-item,
.flashcard,
.mcq-card {
  background: var(--surface-2);
  border-radius: 12px;
  padding: 1rem;
}

.structured-item {
  display: grid;
  gap: 0.5rem;
}

.structured-item__title {
  color: var(--text);
  font-size: 1rem;
}

.structured-item__description {
  margin: 0;
  color: var(--muted);
}

.structured-item__section {
  display: grid;
  gap: 0.4rem;
}

.structured-item__meta {
  margin: 0;
  display: grid;
  gap: 0.5rem;
}

.structured-item__meta div {
  display: grid;
  grid-template-columns: minmax(7rem, auto) 1fr;
  gap: 0.5rem;
}

.structured-item__meta dt {
  color: var(--muted);
  font-weight: 600;
}

.structured-item__meta dd {
  margin: 0;
  color: var(--text);
}

.note-block + .note-block,
.mcq-card + .mcq-card,
.flashcard + .flashcard {
  margin-top: 0.75rem;
}

ul,
ol {
  padding-left: 1.2rem;
}

.mcq-options {
  display: grid;
  gap: 0.5rem;
  margin-top: 0.75rem;
}

.mcq-option {
  text-align: left;
  width: 100%;
  border-radius: 10px;
  padding: 0.75rem 0.9rem;
  background: rgba(255, 255, 255, 0.04);
  border: 1px solid var(--border);
  color: var(--text);
}

.mcq-option.selected-correct {
  border-color: var(--success);
  background: rgba(62, 207, 142, 0.12);
}

.mcq-option.selected-wrong {
  border-color: var(--danger);
  background: rgba(255, 107, 107, 0.12);
}

.mcq-option.reveal-correct {
  border-color: rgba(62, 207, 142, 0.55);
}

.mcq-feedback {
  margin-top: 0.75rem;
  padding: 0.75rem;
  border-radius: 10px;
  background: rgba(255, 255, 255, 0.04);
}

.mcq-feedback.correct {
  color: var(--success);
}

.mcq-feedback.incorrect {
  color: var(--danger);
}

.flashcard {
  cursor: pointer;
  min-height: 110px;
  display: grid;
  place-content: center;
  text-align: center;
}

.flashcard .back {
  display: none;
  color: var(--muted);
}

.flashcard.flipped .front {
  display: none;
}

.flashcard.flipped .back {
  display: block;
}

.mind-map ul {
  list-style: none;
  padding-left: 1rem;
}

.pill-list {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  padding: 0;
  list-style: none;
}

.pill-list li {
  background: rgba(91, 156, 255, 0.12);
  border: 1px solid rgba(91, 156, 255, 0.25);
  border-radius: 999px;
  padding: 0.45rem 0.8rem;
}

.toolbar {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 1rem;
}

@media (max-width: 640px) {
  .container {
    width: min(100%, calc(100% - 1rem));
    padding-top: 1rem;
  }
}