/* ==========================================================================
   Cards — feature cards, filesystem tree, challenge cards, cheat sheet
   ========================================================================== */

/* ---------------------------- Feature card (home) ---------------------------- */

.feature-card {
  background: var(--bg-panel);
  border: 1px solid var(--border-hairline);
  border-radius: var(--radius-lg);
  padding: var(--space-5);
  transition: transform var(--dur-fast) var(--ease-out), border-color var(--dur-fast) var(--ease-out), box-shadow var(--dur-fast) var(--ease-out), background var(--dur-fast) var(--ease-out);
}
.feature-card:hover {
  transform: translateY(-4px);
  border-color: rgba(255,176,0,0.35);
  box-shadow: var(--shadow-panel);
  background: var(--bg-elevated);
}
.feature-card .feature-icon {
  width: 40px; height: 40px;
  border-radius: var(--radius-sm);
  background: var(--bg-inset);
  border: 1px solid var(--border-hairline);
  display: flex; align-items: center; justify-content: center;
  color: var(--amber-500);
  margin-bottom: var(--space-4);
  transition: background var(--dur-fast) var(--ease-out), border-color var(--dur-fast) var(--ease-out);
}
.feature-card:hover .feature-icon {
  background: linear-gradient(160deg, rgba(255,176,0,0.16), rgba(255,176,0,0.04));
  border-color: rgba(255,176,0,0.3);
}
.feature-card h3 { margin-bottom: 6px; }
.feature-card p { font-size: 0.88rem; margin-bottom: 0; }

/* ---------------------------- Filesystem tree ---------------------------- */

.fs-tree {
  font-family: var(--font-mono);
  font-size: 0.85rem;
}

.fs-node-btn {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  width: 100%;
  text-align: left;
  background: transparent;
  border: 1px solid transparent;
  border-radius: var(--radius-sm);
  padding: 7px 8px;
  color: var(--text-secondary);
  cursor: pointer;
}
.fs-node-btn:hover { background: var(--bg-elevated); color: var(--text-primary); }
.fs-node-btn.selected { background: rgba(255,176,0,0.1); border-color: rgba(255,176,0,0.25); color: var(--amber-300); }
.fs-node-btn .fs-icon { flex-shrink: 0; opacity: 0.8; width: 16px; height: 16px; }
.fs-node-btn .fs-name { flex: 1; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.fs-node-btn .fs-perm-chip {
  font-size: 0.68rem;
  color: var(--text-tertiary);
  flex-shrink: 0;
}
.fs-group { margin-left: 18px; border-left: 1px dashed var(--border-hairline); padding-left: 8px; }
.fs-node-btn.is-risky .fs-perm-chip { color: var(--crit-500); }

/* ---------------------------- Special bits explainer cards ---------------------------- */

.bit-card {
  background: var(--bg-inset);
  border: 1px solid var(--border-hairline);
  border-radius: var(--radius-md);
  padding: var(--space-4);
  cursor: pointer;
}
.bit-card summary { list-style: none; display: flex; align-items: center; justify-content: space-between; cursor: pointer; font-family: var(--font-mono); font-weight: 600; color: var(--text-primary); }
.bit-card summary::-webkit-details-marker { display: none; }
.bit-card summary .chev { transition: transform var(--dur-fast) var(--ease-out); color: var(--text-tertiary); }
.bit-card[open] summary .chev { transform: rotate(90deg); }
.bit-card .bit-body { margin-top: var(--space-3); font-size: 0.88rem; }
.bit-card .bit-body dt { color: var(--amber-300); font-family: var(--font-mono); font-size: 0.72rem; text-transform: uppercase; letter-spacing: 0.04em; margin-top: var(--space-3); }
.bit-card .bit-body dt:first-child { margin-top: 0; }
.bit-card .bit-body dd { margin: 4px 0 0; color: var(--text-secondary); }

/* ---------------------------- Challenge cards ---------------------------- */

.challenge-tabs { display: flex; gap: var(--space-2); margin-bottom: var(--space-5); flex-wrap: wrap; }

.challenge-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: var(--space-4);
}

.challenge-card {
  background: var(--bg-panel);
  border: 1px solid var(--border-hairline);
  border-radius: var(--radius-lg);
  padding: var(--space-5);
  display: flex;
  flex-direction: column;
  gap: var(--space-3);
  transition: transform var(--dur-fast) var(--ease-out), border-color var(--dur-fast) var(--ease-out);
}
.challenge-card:hover { transform: translateY(-3px); border-color: var(--border-strong); }
.challenge-card.completed { border-color: rgba(61,220,132,0.35); }
.challenge-card-head { display: flex; justify-content: space-between; align-items: flex-start; gap: var(--space-2); }
.challenge-card h3 { font-size: 1rem; margin-bottom: 2px; }
.challenge-card .xp-tag { font-family: var(--font-mono); font-size: 0.72rem; color: var(--amber-300); white-space: nowrap; }
.challenge-card p { font-size: 0.85rem; margin-bottom: 0; }
.challenge-card .challenge-foot { margin-top: auto; display: flex; justify-content: space-between; align-items: center; }

/* ---------------------------- Cheat sheet table ---------------------------- */

.cheat-search { margin-bottom: var(--space-5); max-width: 340px; }

.cheat-table-wrap { overflow-x: auto; border: 1px solid var(--border-hairline); border-radius: var(--radius-lg); }
table.cheat-table { width: 100%; border-collapse: collapse; font-size: 0.86rem; }
table.cheat-table th, table.cheat-table td { padding: 10px 16px; text-align: left; border-bottom: 1px solid var(--border-hairline); white-space: nowrap; }
table.cheat-table th { font-family: var(--font-mono); font-size: 0.68rem; text-transform: uppercase; letter-spacing: 0.06em; color: var(--text-tertiary); background: var(--bg-inset); position: sticky; top: 0; }
table.cheat-table td { color: var(--text-secondary); font-family: var(--font-mono); }
table.cheat-table td.desc { font-family: var(--font-body); white-space: normal; color: var(--text-primary); }
table.cheat-table tbody tr:hover { background: var(--bg-elevated); }
table.cheat-table tbody tr[hidden] { display: none; }

.cheat-example-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(180px,1fr)); gap: var(--space-3); margin: var(--space-5) 0; }
.cheat-example { background: var(--bg-inset); border: 1px solid var(--border-hairline); border-radius: var(--radius-md); padding: var(--space-3) var(--space-4); font-family: var(--font-mono); }
.cheat-example .ce-octal { color: var(--amber-300); font-size: 1.1rem; }
.cheat-example .ce-desc { font-family: var(--font-body); font-size: 0.78rem; color: var(--text-tertiary); }

.best-practice-list { display: grid; gap: var(--space-2); }
.best-practice-list li { list-style: none; padding-left: var(--space-5); position: relative; color: var(--text-secondary); font-size: 0.9rem; }
.best-practice-list li::before { content: "→"; position: absolute; left: 0; color: var(--amber-500); font-family: var(--font-mono); }

/* ---------------------------- Learn cards ---------------------------- */

.learn-card {
  background: var(--bg-panel);
  border: 1px solid var(--border-hairline);
  border-radius: var(--radius-lg);
  padding: var(--space-4) var(--space-5);
}
.learn-card summary {
  list-style: none;
  display: flex;
  align-items: center;
  justify-content: space-between;
  cursor: pointer;
  font-family: var(--font-display);
  font-weight: 600;
  font-size: 1.02rem;
  color: var(--text-primary);
  padding: 4px 0;
}
.learn-card summary::-webkit-details-marker { display: none; }
.learn-card summary .chev { color: var(--text-tertiary); transition: transform var(--dur-fast) var(--ease-out); }
.learn-card[open] summary .chev { transform: rotate(90deg); }
.learn-card-title { display: inline-flex; align-items: center; gap: 8px; }
.learn-read-dot {
  display: inline-block;
  width: 6px; height: 6px;
  border-radius: 50%;
  background: var(--safe-500);
  box-shadow: 0 0 5px var(--safe-500);
  flex-shrink: 0;
}
.learn-card .learn-body { margin-top: var(--space-4); display: flex; flex-direction: column; gap: var(--space-4); }
.learn-diagram {
  background: var(--bg-inset);
  border: 1px solid var(--border-hairline);
  border-radius: var(--radius-md);
  padding: var(--space-4);
  overflow-x: auto;
}
.learn-diagram svg { width: 100%; height: auto; min-width: 320px; display: block; margin: 0 auto; }
.learn-block-label {
  display: block;
  font-family: var(--font-mono);
  font-size: 0.68rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--text-tertiary);
  margin-bottom: 6px;
}
.learn-example { font-size: 0.88rem; margin-bottom: 0; }
.learn-commands { display: flex; flex-direction: column; gap: 6px; }
.learn-commands code {
  display: block;
  font-family: var(--font-mono);
  font-size: 0.82rem;
  color: var(--amber-300);
  background: var(--bg-inset);
  border: 1px solid var(--border-hairline);
  border-radius: 6px;
  padding: 7px 10px;
  width: fit-content;
}
.learn-tips-warnings { display: grid; grid-template-columns: 1fr 1fr; gap: var(--space-4); }
.learn-tips ul, .learn-warnings ul { margin: 0; padding-left: 1.1em; }
.learn-tips li { color: var(--text-secondary); font-size: 0.85rem; margin-bottom: 4px; }
.learn-warnings li { color: var(--warn-500); font-size: 0.85rem; margin-bottom: 4px; }

/* ---------------------------- Achievement badges ---------------------------- */

.achievement-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: var(--space-4);
  margin-top: var(--space-4);
}

.achievement-badge {
  display: flex;
  align-items: flex-start;
  gap: var(--space-3);
  background: var(--bg-panel);
  border: 1px solid var(--border-hairline);
  border-radius: var(--radius-lg);
  padding: var(--space-4);
}
.achievement-badge.locked { opacity: 0.55; }
.achievement-badge.earned { border-color: rgba(255,176,0,0.3); }
.achievement-icon {
  width: 40px; height: 40px;
  border-radius: var(--radius-sm);
  background: var(--bg-inset);
  border: 1px solid var(--border-hairline);
  display: flex; align-items: center; justify-content: center;
  color: var(--amber-500);
  flex-shrink: 0;
}
.achievement-badge.earned .achievement-icon { color: var(--amber-300); border-color: rgba(255,176,0,0.3); }
.achievement-icon svg { width: 20px; height: 20px; }
.achievement-info { flex: 1; min-width: 0; }
.achievement-info h4 { margin: 0 0 4px; font-size: 0.9rem; }
.achievement-info p { font-size: 0.8rem; margin: 0 0 6px; }

/* ---------------------------- Guided Path (v2.3) ---------------------------- */

.path-steps {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: var(--space-3);
}
.path-step {
  border: 1px solid var(--border-hairline);
  border-radius: var(--radius-md);
  padding: var(--space-3) var(--space-3) var(--space-4);
  background: var(--bg-inset);
  transition: border-color var(--dur-fast) var(--ease-out);
}
.path-step-head { display: flex; align-items: center; gap: 8px; margin-bottom: var(--space-3); }
.path-step-index {
  width: 20px; height: 20px;
  flex-shrink: 0;
  border-radius: 50%;
  display: flex; align-items: center; justify-content: center;
  font-family: var(--font-mono);
  font-size: 0.68rem;
  font-weight: 700;
  background: var(--bg-elevated);
  color: var(--text-tertiary);
  border: 1px solid var(--border-hairline);
}
.path-step-label { font-size: 0.82rem; font-weight: 600; color: var(--text-secondary); }
.path-step-bar { height: 4px; border-radius: 3px; background: var(--bg-elevated); overflow: hidden; margin-bottom: 6px; }
.path-step-bar-fill { height: 100%; border-radius: 3px; background: var(--border-strong); transition: width var(--dur-slow) var(--ease-out); }
.path-step-count { font-family: var(--font-mono); font-size: 0.68rem; color: var(--text-tertiary); }

.path-step-done { border-color: rgba(61,220,132,0.3); }
.path-step-done .path-step-index { background: var(--safe-glow); color: var(--safe-500); border-color: rgba(61,220,132,0.4); }
.path-step-done .path-step-bar-fill { background: var(--safe-500); }
.path-step-done .path-step-label { color: var(--text-primary); }

.path-step-current { border-color: rgba(255,176,0,0.35); box-shadow: 0 0 0 1px rgba(255,176,0,0.12); }
.path-step-current .path-step-index { background: var(--amber-glow); color: var(--amber-300); border-color: rgba(255,176,0,0.4); }
.path-step-current .path-step-bar-fill { background: linear-gradient(90deg, var(--amber-600), var(--amber-300)); }
.path-step-current .path-step-label { color: var(--text-primary); }

.path-complete-banner {
  border: 1px solid rgba(61,220,132,0.3);
  background: var(--safe-glow);
  color: var(--safe-500);
  border-radius: var(--radius-md);
  padding: var(--space-3) var(--space-4);
  font-size: 0.86rem;
  font-weight: 600;
}