/* ── Practice page layout ─────────────────────────────── */
.main-content--practice {
  padding: 0;
  display: flex;
  flex-direction: column;
  height: 100vh;
  overflow: hidden;
}

@media (max-width: 900px) {
  .main-content--practice {
    height: calc(100vh - 52px);
    margin-top: 52px;
  }
}

/* ── Problem List View ────────────────────────────────── */
.practice-list {
  flex: 1;
  overflow-y: auto;
  padding: 36px 40px 64px;
}

@media (max-width: 600px) {
  .practice-list { padding: 20px 16px 48px; }
}

.practice-list__header {
  margin-bottom: 28px;
  padding-bottom: 24px;
  border-bottom: 1px solid var(--border);
}

.practice-list__title {
  font-size: 1.6rem;
  font-weight: 700;
  color: var(--text);
  letter-spacing: -0.025em;
  margin-bottom: 6px;
}

@media (min-width: 901px) {
  .practice-list__title { font-size: 2rem; }
}

.practice-list__sub {
  font-size: 0.9rem;
  color: var(--text-secondary);
  margin-bottom: 20px;
}

/* ── Filters ──────────────────────────────────────────── */
.practice-filters {
  display: flex;
  gap: 6px;
  flex-wrap: wrap;
}

.filter-btn {
  padding: 5px 14px;
  font-size: 0.8rem;
  font-weight: 500;
  font-family: var(--font-ui);
  border: 1px solid var(--border);
  border-radius: 20px;
  background: var(--surface);
  color: var(--text-secondary);
  cursor: pointer;
  transition: all var(--transition);
}

.filter-btn:hover {
  border-color: var(--accent-border);
  color: var(--accent);
  background: var(--accent-bg);
}

.filter-btn.active {
  background: var(--accent);
  border-color: var(--accent);
  color: #fff;
}

.filter-btn.active-easy  { background: var(--easy);   border-color: var(--easy);   color: #fff; }
.filter-btn.active-medium { background: var(--medium); border-color: var(--medium); color: #fff; }
.filter-btn.active-hard  { background: var(--hard);  border-color: var(--hard);   color: #fff; }

/* ── Search ───────────────────────────────────────────── */
.practice-search {
  margin-top: 12px;
}

.search-input {
  width: 100%;
  padding: 8px 14px;
  font-size: 0.88rem;
  font-family: var(--font-ui);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--surface);
  color: var(--text);
  outline: none;
  transition: border-color var(--transition);
  box-sizing: border-box;
}

.search-input:focus {
  border-color: var(--accent);
}

.search-input::placeholder {
  color: var(--text-muted);
}

/* ── Category filters ─────────────────────────────────── */
.practice-categories {
  display: flex;
  gap: 6px;
  flex-wrap: wrap;
  margin-top: 10px;
}

/* ── Stats bar ────────────────────────────────────────── */
.practice-stats {
  display: flex;
  align-items: center;
  gap: 14px;
  margin-bottom: 16px;
  padding: 10px 16px;
  background: var(--surface-2);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-sm);
}

.practice-stats__bar {
  flex: 1;
  height: 5px;
  background: var(--surface-3);
  border-radius: 3px;
  overflow: hidden;
}

.practice-stats__fill {
  height: 100%;
  background: var(--accent);
  border-radius: 3px;
  transition: width 0.4s ease;
}

.practice-stats__label {
  font-size: 0.8rem;
  color: var(--text-secondary);
  white-space: nowrap;
}

/* ── Challenge table ──────────────────────────────────── */
.challenge-table {
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  overflow: hidden;
}

.challenge-row {
  display: grid;
  grid-template-columns: 40px 1fr auto auto 32px;
  align-items: center;
  gap: 12px;
  padding: 13px 16px;
  border-bottom: 1px solid var(--border-light);
  cursor: pointer;
  transition: background var(--transition);
  text-decoration: none;
  color: inherit;
}

.challenge-row:last-child { border-bottom: none; }

.challenge-row:hover { background: var(--surface-2); }

.challenge-row.solved { background: var(--surface-2); }

.challenge-row__num {
  font-size: 0.72rem;
  color: var(--text-muted);
  font-family: var(--font-mono);
  font-weight: 600;
  text-align: center;
}

.challenge-row__title {
  font-size: 0.9rem;
  font-weight: 500;
  color: var(--text);
  transition: color var(--transition);
}

.challenge-row:hover .challenge-row__title { color: var(--accent); }
.challenge-row.solved .challenge-row__title { color: var(--text-secondary); }

.challenge-row__cat {
  font-size: 0.75rem;
  color: var(--text-muted);
  white-space: nowrap;
}

.challenge-row__badge {
  font-size: 0.68rem;
  font-weight: 600;
  padding: 2px 8px;
  border-radius: 20px;
  border: 1px solid;
  white-space: nowrap;
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

.challenge-row__badge--easy   { color: var(--easy);   background: var(--easy-bg);   border-color: var(--easy-border); }
.challenge-row__badge--medium { color: var(--medium); background: var(--medium-bg); border-color: var(--medium-border); }
.challenge-row__badge--hard   { color: var(--hard);   background: var(--hard-bg);   border-color: var(--hard-border); }

.challenge-row__status {
  font-size: 0.85rem;
  color: var(--success);
  text-align: center;
}

@media (max-width: 500px) {
  .challenge-row {
    grid-template-columns: 32px 1fr auto 24px;
  }
  .challenge-row__cat { display: none; }
}

/* ── Detail View ──────────────────────────────────────── */
.practice-detail {
  flex: 1;
  display: flex;
  flex-direction: column;
  overflow: hidden;
}

/* Top bar */
.practice-topbar {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 10px 16px;
  border-bottom: 1px solid var(--border);
  background: var(--surface);
  flex-shrink: 0;
}

.practice-topbar__back {
  display: inline-flex;
  align-items: center;
  gap: 5px;
  font-size: 0.83rem;
  color: var(--text-muted);
  background: none;
  border: none;
  cursor: pointer;
  font-family: var(--font-ui);
  padding: 4px 8px;
  border-radius: var(--radius-xs);
  transition: color var(--transition), background var(--transition);
  flex-shrink: 0;
}

.practice-topbar__back:hover {
  color: var(--accent);
  background: var(--accent-bg);
}

.practice-topbar__title {
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--text);
  flex: 1;
  min-width: 0;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

/* Split layout */
.practice-split {
  flex: 1;
  display: flex;
  overflow: hidden;
}

.practice-split__desc {
  width: 45%;
  min-width: 300px;
  overflow-y: auto;
  padding: 24px 28px;
  border-right: 1px solid var(--border);
  flex-shrink: 0;
}

.practice-split__editor-pane {
  flex: 1;
  display: flex;
  flex-direction: column;
  overflow: hidden;
  min-width: 0;
}

/* Mobile: stack vertically with tabs */
@media (max-width: 800px) {
  .practice-split {
    flex-direction: column;
  }

  .practice-split__desc {
    width: 100%;
    min-width: 0;
    border-right: none;
    border-bottom: 1px solid var(--border);
    padding: 16px;
    max-height: 40vh;
    flex-shrink: 0;
  }

  .practice-split__editor-pane {
    flex: 1;
  }
}

/* ── Description content ──────────────────────────────── */
.prob-title {
  font-size: 1.2rem;
  font-weight: 700;
  color: var(--text);
  margin-bottom: 10px;
  line-height: 1.3;
}

.prob-meta {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 20px;
}

.prob-desc {
  font-size: 0.9rem;
  color: var(--text);
  line-height: 1.8;
}

.prob-desc p { margin-bottom: 12px; }
.prob-desc p:last-child { margin-bottom: 0; }

.prob-desc code {
  font-family: var(--font-mono);
  font-size: 0.85em;
  background: var(--surface-2);
  border: 1px solid var(--border);
  padding: 1px 5px;
  border-radius: 3px;
  color: var(--accent);
}

.prob-desc pre {
  background: var(--code-bg);
  border: 1px solid var(--code-border);
  border-radius: var(--radius-sm);
  padding: 12px 14px;
  font-family: var(--font-mono);
  font-size: 0.83rem;
  line-height: 1.65;
  overflow-x: auto;
  margin: 12px 0;
}

.prob-desc pre code {
  background: none;
  border: none;
  padding: 0;
  color: var(--text);
  font-size: inherit;
}

/* ── Editor pane ──────────────────────────────────────── */
.editor-pane__toolbar {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 10px 16px;
  border-bottom: 1px solid var(--border);
  background: var(--surface-2);
  flex-shrink: 0;
  flex-wrap: wrap;
}

.editor-pane__body {
  flex: 1;
  overflow-y: auto;
  padding: 16px;
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.editor-pane__body .CodeMirror {
  flex: 1;
  min-height: 180px;
}

/* ── Test results ─────────────────────────────────────── */
.test-results {
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  overflow: hidden;
  flex-shrink: 0;
}

.test-results__header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 7px 14px;
  background: var(--surface-2);
  border-bottom: 1px solid var(--border);
}

.test-results__label {
  font-size: 0.72rem;
  font-weight: 600;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.06em;
}

.test-results__summary {
  font-size: 0.78rem;
  font-weight: 600;
}

.test-results__summary--pass { color: var(--success); }
.test-results__summary--fail { color: var(--error); }

.test-results__list {
  background: var(--code-bg);
}

.test-case {
  display: flex;
  align-items: flex-start;
  gap: 10px;
  padding: 8px 14px;
  border-bottom: 1px solid var(--border-light);
  font-size: 0.82rem;
  font-family: var(--font-mono);
  line-height: 1.5;
}

.test-case:last-child { border-bottom: none; }

.test-case__icon {
  font-size: 0.75rem;
  flex-shrink: 0;
  margin-top: 2px;
}

.test-case--pass .test-case__icon { color: var(--success); }
.test-case--fail .test-case__icon { color: var(--error); }

.test-case__label { color: var(--text-secondary); }
.test-case__got   { color: var(--error); }
.test-case__exp   { color: var(--success); }
.test-case__err   { color: var(--error); }

/* ── Timer ────────────────────────────────────────────── */
.timer-display {
  margin-left: auto;
  font-size: 0.8rem;
  font-family: var(--font-mono);
  color: var(--text-muted);
  background: var(--surface-3);
  padding: 3px 10px;
  border-radius: var(--radius-xs);
  border: 1px solid var(--border);
  min-width: 44px;
  text-align: center;
}

/* ── Solution panel ───────────────────────────────────── */
.btn-show-solution {
  margin-left: 12px;
  padding: 3px 10px;
  font-size: 0.78rem;
  font-family: var(--font-ui);
  border: 1px solid var(--easy-border);
  border-radius: var(--radius-xs);
  background: none;
  color: var(--easy);
  cursor: pointer;
  transition: background var(--transition);
}

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

.solution-panel {
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  overflow: hidden;
  flex-shrink: 0;
}

.solution-panel__header {
  padding: 7px 14px;
  background: var(--surface-2);
  border-bottom: 1px solid var(--border);
  font-size: 0.72rem;
  font-weight: 600;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.06em;
}

.solution-panel__code {
  background: var(--code-bg);
  padding: 14px;
  font-family: var(--font-mono);
  font-size: 0.83rem;
  line-height: 1.65;
  color: var(--text);
  white-space: pre;
  overflow-x: auto;
}

/* ── Practice nav item in sidebar ─────────────────────── */
.nav-item--practice .nav-item__num {
  font-size: 0.85rem;
}

/* ── Congratulation banner ────────────────────────────── */
.prob-solved-banner {
  padding: 10px 14px;
  background: var(--easy-bg);
  border: 1px solid var(--easy-border);
  border-radius: var(--radius-sm);
  font-size: 0.85rem;
  color: var(--easy);
  font-weight: 500;
  display: none;
}

.prob-solved-banner.visible { display: block; }