/* ==========================================================================
   EduSpace — learning.css
   Lesson page: topic sidebar + lesson panel.
   Motion here is limited to a low-velocity slide when the lesson changes.
   ========================================================================== */

.learning-main {
  padding-block: clamp(2rem, 1rem + 3vw, 3.5rem) clamp(3rem, 2rem + 4vw, 5.5rem);
  background: var(--surface);
}

.learning-shell {
  display: grid;
  grid-template-columns: 280px 1fr;
  align-items: start;
  gap: clamp(1.5rem, 1rem + 2vw, 3rem);
}

/* ==========================================================================
   Sidebar — the path
   ========================================================================== */

.learning-sidebar {
  position: sticky;
  top: 7rem;
  padding: var(--space-5);
  border: 1px solid var(--border);
  border-radius: var(--r-lg);
  background: var(--white);
  box-shadow: var(--sh-sm);
}

.learning-sidebar-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-3);
}

.ai-new-topic-btn {
  flex: none;
  font-family: var(--font-ui);
  font-size: var(--fs-micro);
  font-weight: 700;
  letter-spacing: 0.04em;
  color: var(--accent-ink);
  background: var(--accent-soft);
  border: 1px solid transparent;
  border-radius: var(--r-pill);
  padding: 0.3rem 0.7rem;
  cursor: pointer;
  transition: background-color var(--t-fast) var(--ease), transform var(--t-fast) var(--ease);
}

.ai-new-topic-btn:hover {
  background: var(--accent);
  color: var(--charcoal);
}

.ai-new-topic-btn:active {
  transform: scale(0.97);
}

.learning-sidebar h3 {
  margin-top: 0.6rem;
  margin-bottom: var(--space-4);
}

.topic-list {
  display: grid;
  gap: 0.25rem;
}

.topic-item {
  display: flex;
  align-items: center;
  gap: 0.7rem;
  padding: 0.62rem 0.7rem;
  border-radius: var(--r-sm);
  cursor: pointer;
  color: var(--text-muted);
  transition:
    background-color var(--t-fast) var(--ease),
    color var(--t-fast) var(--ease);
}

.topic-item:hover {
  background: var(--sand);
  color: var(--text);
}

.topic-item:focus-visible {
  outline: 2px solid var(--ink);
  outline-offset: 2px;
}

.topic-status {
  flex: none;
  display: grid;
  place-items: center;
  width: 20px;
  height: 20px;
  border-radius: 50%;
  border: 1px solid var(--border);
  background: var(--surface);
  font-size: 0.62rem;
  line-height: 1;
  color: var(--text-muted);
}

.topic-name {
  font-family: var(--font-ui);
  font-size: 0.9rem;
  font-weight: 500;
}

/* Completed */
.topic-item.done .topic-status {
  border-color: var(--ink);
  background: var(--ink);
  color: var(--white);
}
.topic-item.done .topic-name {
  color: var(--text);
}

/* Currently open — gold, because it is the system telling you where you are */
.topic-item.active {
  background: var(--sand);
  color: var(--text);
}
.topic-item.active .topic-status {
  border-color: var(--accent);
  background: var(--accent);
  color: var(--charcoal);
}
.topic-item.active .topic-name {
  font-weight: 600;
}

/* Marked for review */
.topic-item.flagged .topic-name::after {
  content: "· for review";
  margin-left: 0.4rem;
  font-size: 0.72rem;
  font-weight: 500;
  color: var(--accent-ink);
}

.sidebar-progress {
  margin-top: var(--space-5);
  padding-top: var(--space-4);
  border-top: 1px solid var(--border);
}

/* ==========================================================================
   Lesson panel
   ========================================================================== */

.lesson-head h1 {
  margin-top: var(--space-4);
  font-size: clamp(1.8rem, 1.3rem + 2vw, 2.75rem);
}

.lesson-head > p {
  max-width: 62ch;
  margin-top: var(--space-4);
  color: var(--text-muted);
  font-size: var(--fs-lead);
}

.lesson-body {
  margin-top: var(--space-6);
}

.lesson-body h3 {
  margin-top: var(--space-5);
}
.lesson-body h3:first-child {
  margin-top: 0;
}

.lesson-body p {
  margin-top: 0.6rem;
  color: var(--text-muted);
  max-width: 68ch;
}

.lesson-body strong {
  color: var(--text);
  font-weight: 600;
}

/* Tutor note — the one place gold appears in the lesson body, because it
   marks something the system worked out about this student. */
.tutor-note {
  margin-top: var(--space-6);
  padding: var(--space-4) var(--space-5);
  border: 1px solid var(--border);
  border-left: 3px solid var(--accent);
  border-radius: var(--r-md);
  background: var(--sand);
}

.tutor-note p {
  margin-top: 0.5rem;
  color: var(--text);
}

.tutor-tag {
  font-family: var(--font-ui);
  font-size: var(--fs-micro);
  font-weight: 700;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--accent-ink);
}

/* Shown when no tutor analysis exists for the open topic. */
.tutor-note.is-empty {
  border-left-color: var(--sand-deep);
  background: var(--surface-alt);
}
.tutor-note.is-empty .tutor-tag {
  color: var(--text-muted);
}
.tutor-note.is-empty p {
  color: var(--text-muted);
}

.lesson-actions {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-3);
  margin-top: var(--space-6);
}

/* ==========================================================================
   Lesson change — a single low-velocity slide, nothing more
   ========================================================================== */

.lesson-panel {
  transition:
    opacity var(--t-mid) var(--ease),
    transform var(--t-mid) var(--ease);
}

.lesson-panel.is-swapping {
  opacity: 0;
  transform: translate3d(0, 10px, 0);
}

@media (prefers-reduced-motion: reduce) {
  .lesson-panel,
  .lesson-panel.is-swapping {
    transition: none;
    opacity: 1;
    transform: none;
  }
}

/* ==========================================================================
   AI lesson cards — Quick summary / Understand it, rendered by
   assets/js/ai-learning.js. The tutor note keeps its own existing look
   (.tutor-note, defined above) so all three read as one family.
   ========================================================================== */

.ai-lesson-card {
  display: grid;
  gap: 0.6rem;
}

.ai-lesson-card + .ai-lesson-card,
.ai-lesson-card + .tutor-note {
  margin-top: var(--space-5);
}

.ai-lesson-card-label {
  font-family: var(--font-ui);
  font-size: var(--fs-micro);
  font-weight: 700;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--text-muted);
}

.ai-lesson-summary .ai-lesson-card-label {
  color: var(--accent-ink);
}

.ai-lesson-card-content p {
  color: var(--text-muted);
  max-width: 68ch;
}
.ai-lesson-card-content p + p {
  margin-top: 0.6rem;
}
.ai-lesson-card-content strong {
  color: var(--text);
  font-weight: 600;
}
.ai-lesson-card-content code {
  font-family: ui-monospace, "SFMono-Regular", Consolas, monospace;
  font-size: 0.88em;
  background: var(--surface-alt);
  padding: 0.1em 0.4em;
  border-radius: 5px;
  color: var(--ink-deep);
}
.ai-lesson-card-content pre {
  margin-top: 0.6rem;
  padding: var(--space-4);
  border-radius: var(--r-md);
  background: var(--grad-deep);
  overflow-x: auto;
}
.ai-lesson-card-content pre code {
  background: none;
  padding: 0;
  color: #eaf2ff;
  font-size: 0.86em;
  line-height: 1.6;
}

.ai-lesson-loading,
.ai-lesson-error {
  align-items: start;
  text-align: left;
}
.ai-lesson-loading {
  display: flex;
  flex-direction: row;
  align-items: center;
  gap: var(--space-3);
}
.ai-lesson-loading p {
  color: var(--text-muted);
}
.ai-lesson-error p {
  color: var(--text);
  margin-bottom: var(--space-3);
}

/* The "what would you like to learn today?" AI topic modal (.ai-topic-*)
   moved to base.css — it is a shared component, also used by quiz.html's
   AI quiz topic modal. See base.css for its rules. */

/* ==========================================================================
   Responsive
   ========================================================================== */

@media (max-width: 900px) {
  .learning-shell {
    grid-template-columns: 1fr;
  }
  .learning-sidebar {
    position: static;
  }
  .topic-list {
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    display: grid;
  }
}