/* ═══════════════════════════════════════════════════════
   IDE Playground — Styles
   Uses global CSS vars from main.css (--gradient-start,
   --gradient-end, --text-color, --highlight-color, etc.)
   ═══════════════════════════════════════════════════════ */

/* IDE-specific color scheme variables */
[data-md-color-scheme="slate"] {
  --ide-bg-start: #1b2735;
  --ide-bg-end: #243b4a;
  --ide-container-shadow: 0 8px 32px rgba(0, 0, 0, 0.4);
  --ide-section-bg: rgba(0, 0, 0, 0.20);
  --ide-header-bg: rgba(0, 0, 0, 0.35);
  --ide-border: rgba(255, 255, 255, 0.08);
  --ide-border-accent: rgba(255, 255, 255, 0.15);
  --ide-border-strong: rgba(255, 255, 255, 0.22);
  --ide-code-inline-bg: rgba(0, 0, 0, 0.30);
  --ide-modal-bg: #151f2b;
  --ide-modal-bg-alt: #1a2c3c;
  --ide-modal-border: rgba(0, 180, 220, 0.30);
  --ide-dropdown-bg: #141e28;
  --ide-dropdown-bg-alt: #1a2a38;
  --ide-dropdown-text: #d4dce6;
  --ide-close-color: #aabbbb;
}

[data-md-color-scheme="light"] {
  --ide-bg-start: #e8f0f8;
  --ide-bg-end: #d0dfee;
  --ide-container-shadow: 0 8px 32px rgba(0, 50, 100, 0.12);
  --ide-section-bg: rgba(0, 50, 100, 0.06);
  --ide-header-bg: rgba(0, 50, 100, 0.09);
  --ide-border: rgba(0, 50, 100, 0.12);
  --ide-border-accent: rgba(0, 50, 100, 0.18);
  --ide-border-strong: rgba(0, 50, 100, 0.22);
  --ide-code-inline-bg: rgba(0, 50, 100, 0.08);
  --ide-modal-bg: #f0f4f8;
  --ide-modal-bg-alt: #e4ecf2;
  --ide-modal-border: rgba(0, 100, 150, 0.25);
  --ide-dropdown-bg: #d0dde8;
  --ide-dropdown-bg-alt: #bccad8;
  --ide-dropdown-text: #0f2a40;
  --ide-close-color: #556677;
}

/* ── Main container ── */
.ide-playground {
  background: linear-gradient(135deg, var(--ide-bg-start), var(--ide-bg-end));
  color: var(--text-color);
  overflow: hidden;
  min-height: 400px;
  width: 100%;
}

/* ═══════════  UNIFIED COMMAND BAR  ═══════════ */
.ide-command-bar {
  --cmd-h: 40px;
  --diff-easy: #34d399;                 /* emerald  */
  --diff-easy-dim: rgba(52,211,153,.12);
  --diff-medium: #fbbf24;               /* amber    */
  --diff-medium-dim: rgba(251,191,36,.12);
  --diff-hard: #f87171;                 /* rose     */
  --diff-hard-dim: rgba(248,113,113,.12);
  --bar-surface: var(--ide-header-bg);
  display: flex;
  align-items: center;
  padding: 8px 20px;
  background: var(--bar-surface);
  backdrop-filter: blur(14px) saturate(1.5);
  -webkit-backdrop-filter: blur(14px) saturate(1.5);
  border-bottom: 1px solid var(--ide-border-accent);
  box-shadow: 0 1px 0 0 rgba(255,255,255,.03) inset, 0 4px 16px -4px rgba(0,0,0,.25);
  gap: 0;
  flex-wrap: wrap;
  row-gap: 6px;
  position: relative;
  z-index: 2;
}

/* Normalise every interactive / measured element inside the bar */
.ide-command-bar button,
.ide-command-bar .challenge-counter,
.ide-command-bar .progress-label,
.ide-command-bar .progress-ring-wrap {
  box-sizing: border-box;
  height: var(--cmd-h);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  vertical-align: middle;
  margin: 0;
  line-height: 1;
}

.cmd-group {
  display: flex;
  align-items: center;
  gap: 8px;
}
.cmd-divider {
  width: 1px;
  height: calc(var(--cmd-h) - 10px);
  background: var(--ide-border-accent);
  margin: 0 14px;
  flex-shrink: 0;
  opacity: .5;
}

/* ── Language pills ── */
.lang-tab {
  background: transparent;
  color: var(--text-color);
  border: 1px solid var(--ide-border-accent);
  padding: 0 20px;
  border-radius: 24px;
  font-size: 15px;
  font-weight: 600;
  cursor: pointer;
  transition: all .2s cubic-bezier(.4,0,.2,1);
  text-transform: none;
  min-width: auto;
  letter-spacing: 0;
  position: relative;
}
.lang-tab:hover {
  background: var(--ide-section-bg);
  border-color: var(--ide-border-strong);
  color: var(--button-hover);
}
.lang-tab:active {
  transform: scale(.96);
  transition-duration: .08s;
}
.lang-tab.active {
  background: linear-gradient(135deg, var(--highlight-color), var(--button-hover));
  color: #fff;
  border-color: transparent;
  box-shadow: 0 2px 12px rgba(0,140,180,.35), 0 0 0 1px rgba(255,255,255,.06) inset;
  text-shadow: 0 1px 2px rgba(0,0,0,.2);
}

/* ── Difficulty chips ── */
.diff-tab {
  background: transparent;
  color: var(--text-color);
  border: 1px solid transparent;
  padding: 0 18px;
  border-radius: 20px;
  font-size: 13px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: .8px;
  cursor: pointer;
  transition: all .2s cubic-bezier(.4,0,.2,1);
  opacity: .5;
  position: relative;
}

/* Per-difficulty idle tint */
.diff-tab[data-difficulty="easy"]   { border-color: rgba(52,211,153,.2);  color: var(--diff-easy); }
.diff-tab[data-difficulty="medium"] { border-color: rgba(251,191,36,.2);  color: var(--diff-medium); }
.diff-tab[data-difficulty="hard"]   { border-color: rgba(248,113,113,.2); color: var(--diff-hard); }

/* Hover */
.diff-tab:hover { opacity: .85; }
.diff-tab:active {
  transform: scale(.95);
  transition-duration: .08s;
}
.diff-tab[data-difficulty="easy"]:hover {
  border-color: rgba(52,211,153,.4);
  background: var(--diff-easy-dim);
}
.diff-tab[data-difficulty="medium"]:hover {
  border-color: rgba(251,191,36,.4);
  background: var(--diff-medium-dim);
}
.diff-tab[data-difficulty="hard"]:hover {
  border-color: rgba(248,113,113,.4);
  background: var(--diff-hard-dim);
}

/* Active — solid, elevated, confident */
.diff-tab.active { opacity: 1; }
.diff-tab[data-difficulty="easy"].active {
  background: var(--diff-easy-dim);
  border-color: var(--diff-easy);
  color: var(--diff-easy);
  box-shadow: 0 0 12px rgba(52,211,153,.2);
}
.diff-tab[data-difficulty="medium"].active {
  background: var(--diff-medium-dim);
  border-color: var(--diff-medium);
  color: var(--diff-medium);
  box-shadow: 0 0 12px rgba(251,191,36,.2);
}
.diff-tab[data-difficulty="hard"].active {
  background: var(--diff-hard-dim);
  border-color: var(--diff-hard);
  color: var(--diff-hard);
  box-shadow: 0 0 14px rgba(248,113,113,.25);
}

/* ── Challenge navigator ── */
.nav-arrow {
  background: var(--ide-section-bg);
  color: var(--text-color);
  border: 1px solid var(--ide-border-accent);
  width: var(--cmd-h);
  border-radius: 50%;
  cursor: pointer;
  transition: all .2s cubic-bezier(.4,0,.2,1);
  flex-shrink: 0;
  padding: 0;
  position: relative;
  overflow: hidden;
  box-shadow: 0 1px 3px rgba(0,0,0,.25), inset 0 1px 0 rgba(255,255,255,.04);
}
.nav-arrow::before {
  content: '';
  position: absolute;
  inset: 0;
  border-radius: inherit;
  background: var(--highlight-color);
  opacity: 0;
  transition: opacity .2s ease;
}
.nav-arrow svg {
  display: block;
  position: relative;
  z-index: 1;
  transition: transform .18s cubic-bezier(.4,0,.2,1);
}
.nav-arrow:hover:not(:disabled) {
  border-color: var(--highlight-color);
  color: var(--highlight-color);
  box-shadow: 0 3px 10px rgba(0,140,180,.22), 0 1px 3px rgba(0,0,0,.2), inset 0 1px 0 rgba(255,255,255,.06);
}
.nav-arrow:hover:not(:disabled)::before {
  opacity: .1;
}
.nav-arrow:hover:not(:disabled) svg {
  transform: scale(1.18);
}
.nav-arrow.nav-prev:active:not(:disabled) svg {
  transform: translateX(-2px) scale(1.05);
}
.nav-arrow.nav-next:active:not(:disabled) svg {
  transform: translateX(2px) scale(1.05);
}
.nav-arrow:active:not(:disabled) {
  box-shadow: 0 1px 2px rgba(0,0,0,.3), inset 0 2px 4px rgba(0,0,0,.15);
  transition-duration: .06s;
}
.nav-arrow:active:not(:disabled)::before {
  opacity: .18;
}
.nav-arrow:disabled {
  opacity: .15;
  cursor: not-allowed;
  box-shadow: none;
}

.challenge-selector {
  position: relative;
}
.challenge-selector-btn {
  background: linear-gradient(160deg, var(--ide-dropdown-bg), var(--ide-dropdown-bg-alt));
  color: var(--ide-dropdown-text);
  border: 1px solid var(--ide-border-accent);
  padding: 0 36px 0 14px;
  justify-content: flex-start;
  border-radius: 10px;
  font-size: 15px;
  font-weight: 600;
  cursor: pointer;
  min-width: 240px;
  text-align: left;
  transition: all .2s cubic-bezier(.4,0,.2,1);
  position: relative;
}
.challenge-selector-btn:hover {
  border-color: var(--highlight-color);
  box-shadow: 0 2px 8px rgba(0,0,0,.15);
}

/* ── Awaiting-selection pulse ── */
.challenge-selector--awaiting .challenge-selector-btn {
  animation: selector-pulse 4.5s ease-in-out infinite;
  border-width: 2px;
}
.challenge-selector--awaiting .challenge-selector-btn::after {
  content: '';
  position: absolute;
  inset: -2px;
  border-radius: inherit;
  opacity: 0;
  pointer-events: none;
  animation: selector-ring 4.5s ease-in-out infinite;
  border: 2px solid var(--highlight-color);
}
@keyframes selector-pulse {
  0%, 100% { border-color: var(--ide-border-accent); box-shadow: none; }
  50%      { border-color: var(--highlight-color); box-shadow: 0 0 24px -2px rgba(0,180,220,.4); }
}
@keyframes selector-ring {
  0%       { opacity: 0; transform: scale(1); }
  30%      { opacity: .7; transform: scale(1); }
  80%      { opacity: 0; transform: scale(1.06, 1.3); }
  100%     { opacity: 0; transform: scale(1.06, 1.3); }
}
.challenge-selector-btn:active {
  transform: scale(.98);
  transition-duration: .08s;
}
.challenge-selector.open .challenge-selector-btn {
  border-color: var(--button-hover);
  box-shadow: 0 0 0 2px rgba(0,140,180,.12), 0 4px 12px rgba(0,0,0,.2);
}
.selector-text {
  display: block;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
  padding-right: 4px;
}
.selector-chevron {
  position: absolute;
  right: 12px;
  top: 50%;
  transform: translateY(-50%);
  color: var(--highlight-color);
  font-size: 14px;
  transition: transform .25s cubic-bezier(.4,0,.2,1);
  pointer-events: none;
}
.challenge-selector.open .selector-chevron {
  transform: translateY(-50%) rotate(180deg);
}

.challenge-list {
  display: none;
  position: absolute;
  top: calc(100% + 6px);
  left: 0;
  min-width: 100%;
  width: max-content;
  max-width: 360px;
  max-height: 340px;
  overflow-y: auto;
  background: var(--ide-modal-bg);
  border: 1px solid var(--ide-modal-border);
  border-radius: 12px;
  box-shadow: 0 8px 32px rgba(0,0,0,.4), 0 0 0 1px rgba(255,255,255,.03) inset;
  z-index: 500;
  padding: 6px;
}
.challenge-list.open {
  display: block;
  animation: cmd-dropdown-in .2s cubic-bezier(.16,1,.3,1);
}
@keyframes cmd-dropdown-in {
  from { opacity: 0; transform: translateY(-6px); }
  to   { opacity: 1; transform: translateY(0); }
}
.challenge-list::-webkit-scrollbar { width: 4px; }
.challenge-list::-webkit-scrollbar-track { background: transparent; margin: 6px 0; }
.challenge-list::-webkit-scrollbar-thumb { background: var(--ide-border-accent); border-radius: 4px; }
.challenge-list::-webkit-scrollbar-thumb:hover { background: var(--ide-border-strong); }

.challenge-list-item {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 8px 12px;
  border-radius: 8px;
  font-size: 13px;
  font-weight: 500;
  cursor: pointer;
  transition: background .15s ease, color .15s ease;
  color: var(--ide-dropdown-text);
}
.challenge-list-item:hover {
  background: var(--ide-section-bg);
}
.challenge-list-item.active {
  background: rgba(0,140,200,.12);
  color: var(--button-hover);
  font-weight: 700;
}
.challenge-list-item.completed .cl-title {
  opacity: .65;
}

.cl-number {
  font-size: 10px;
  font-weight: 700;
  opacity: .4;
  min-width: 16px;
  text-align: center;
  flex-shrink: 0;
}
.cl-title {
  flex: 1;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}
.cl-check {
  color: #2ecc71;
  font-weight: 700;
  font-size: 11px;
  flex-shrink: 0;
  width: 18px;
  height: 18px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: rgba(46,204,113,.12);
  border-radius: 50%;
}

.challenge-counter {
  margin-left: 10px;
  font-size: 12px;
  opacity: .4;
  font-weight: 600;
  white-space: nowrap;
  letter-spacing: .3px;
  font-variant-numeric: tabular-nums;
}

/* ═══════════  CHALLENGE CONTENT  ═══════════ */
.challenge-content {
  padding: 10px 14px;
  animation: ide-fade-in .25s ease;
}
@keyframes ide-fade-in {
  from { opacity: 0; transform: translateY(6px); }
  to   { opacity: 1; transform: translateY(0); }
}

/* ── Collapsible Problem Card ── */
.problem-card {
  background: var(--ide-section-bg);
  border: 1px solid var(--ide-border);
  border-radius: 10px;
  margin-bottom: 10px;
  overflow: hidden;
  transition: all .25s ease;
}
.problem-card-header {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 8px 14px;
  cursor: pointer;
  user-select: none;
  transition: background .2s ease;
}
.problem-card-header:hover {
  background: rgba(255,255,255,.03);
}
[data-md-color-scheme="light"] .problem-card-header:hover {
  background: rgba(0,50,100,.03);
}
.problem-card-icon {
  font-size: 14px;
  flex-shrink: 0;
}
.problem-card-header h3 {
  margin: 0;
  color: var(--button-hover);
  font-size: 15px;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

/* ── Challenge skill tags ── */
.challenge-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 5px;
  flex: 1;
  min-width: 0;
}
.challenge-tag {
  display: inline-block;
  padding: 2px 9px;
  font-size: 10.5px;
  font-weight: 600;
  letter-spacing: .3px;
  text-transform: uppercase;
  border-radius: 20px;
  background: rgba(0, 140, 200, .12);
  color: var(--button-hover);
  border: 1px solid rgba(0, 140, 200, .2);
  white-space: nowrap;
  line-height: 1.5;
}
[data-md-color-scheme="light"] .challenge-tag {
  background: rgba(0, 100, 160, .08);
  border-color: rgba(0, 100, 160, .18);
}

.problem-card-toggle {
  background: transparent;
  border: 1px solid var(--ide-border-accent);
  color: var(--text-color);
  width: 26px;
  height: 26px;
  border-radius: 6px;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all .2s ease;
  flex-shrink: 0;
  opacity: .6;
}
.problem-card-toggle:hover {
  opacity: 1;
  background: var(--ide-section-bg);
}
.toggle-chevron {
  transition: transform .25s ease;
}
.problem-card.collapsed .toggle-chevron {
  transform: rotate(-90deg);
}
.problem-card-body {
  display: flex;
  gap: 0;
  padding: 0 14px 10px;
  max-height: 400px;
  overflow: hidden;
  transition: max-height .3s ease, padding .3s ease, opacity .2s ease;
  opacity: 1;
}
.problem-card.collapsed .problem-card-body {
  max-height: 0;
  padding-top: 0;
  padding-bottom: 0;
  opacity: 0;
}
.problem-col {
  min-width: 0;
}
.problem-col-desc {
  flex: 1 1 55%;
  padding-right: 14px;
}
.problem-col-divider {
  width: 1px;
  background: var(--ide-border-accent);
  opacity: .4;
  flex-shrink: 0;
  align-self: stretch;
}
.problem-col-cases {
  flex: 1 1 40%;
  padding-left: 14px;
  display: flex;
  flex-direction: column;
  gap: 6px;
}
.cases-label {
  font-size: 10px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: .6px;
  color: var(--highlight-color);
  opacity: .75;
  margin-bottom: 2px;
}
.problem-card-body p {
  line-height: 1.7;
  margin: 0 0 10px;
  font-size: 14.5px;
  color: var(--text-color);
}
.problem-card-body code {
  background: var(--ide-code-inline-bg);
  padding: 2px 6px;
  border-radius: 4px;
  font-size: 13px;
}

/* ── Vertical test-case rows ── */
.case-rows {
  display: flex;
  flex-direction: column;
  gap: 5px;
}
.case-row {
  display: flex;
  align-items: center;
  gap: 8px;
  background: var(--ide-header-bg);
  border: 1px solid var(--ide-border);
  border-radius: 6px;
  padding: 5px 10px;
  font-size: 12px;
  transition: border-color .2s ease;
}
.case-row:hover {
  border-color: var(--ide-border-accent);
}
.case-row code {
  background: var(--ide-code-inline-bg);
  padding: 1px 5px;
  border-radius: 3px;
  font-size: 11px;
  white-space: nowrap;
}
.case-arrow {
  color: var(--highlight-color);
  font-weight: 700;
  font-size: 11px;
  flex-shrink: 0;
}

/* ═══════════  EDITOR PANEL  ═══════════ */
.editor-panel {
  border: 1px solid var(--ide-border);
  border-radius: 10px;
  overflow: hidden;
  margin-bottom: 14px;
}
.editor-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 8px 16px;
  background: var(--ide-header-bg);
  border-bottom: 1px solid var(--ide-border);
  font-size: 13px;
  font-weight: 700;
}
#editor-language-label {
  letter-spacing: .4px;
}

.btn-action {
  background: transparent;
  color: var(--text-color);
  border: 1px solid var(--ide-border-accent);
  padding: 4px 12px;
  border-radius: 6px;
  font-size: 12px;
  cursor: pointer;
  transition: all .2s ease;
  font-weight: 600;
}
.btn-action:hover {
  background: var(--ide-section-bg);
  border-color: var(--ide-border-strong);
}

/* CodeMirror overrides */
.editor-panel .CodeMirror {
  height: auto;
  min-height: 140px;
  max-height: 400px;
  font-size: 14px;
  line-height: 1.5;
  padding: 6px 0;
}

/* ── Button bar ── */
.button-bar {
  display: flex;
  gap: 10px;
  padding: 10px 16px;
  background: var(--ide-section-bg);
  border-top: 1px solid var(--ide-border);
  align-items: center;
}

.btn-run {
  background: linear-gradient(145deg, #0a8f5c, #06c77f);
  color: #fff;
  border: none;
  padding: 9px 26px;
  border-radius: 8px;
  font-size: 14px;
  font-weight: 700;
  cursor: pointer;
  transition: all .3s ease;
  letter-spacing: .3px;
}
.btn-run:hover:not(:disabled) {
  background: linear-gradient(145deg, #06c77f, #0a8f5c);
  box-shadow: 0 4px 16px rgba(6,199,127,.35);
  transform: translateY(-1px);
}
.btn-run:disabled {
  opacity: .6;
  cursor: not-allowed;
}

.btn-hints, .btn-solution, .btn-docs {
  background: linear-gradient(145deg, var(--button-bg), var(--button-bg-hover));
  color: var(--text-color);
  border: 1px solid var(--ide-border-accent);
  padding: 9px 18px;
  border-radius: 8px;
  font-size: 13px;
  font-weight: 600;
  cursor: pointer;
  transition: all .3s ease;
}
.btn-hints:hover, .btn-solution:hover, .btn-docs:hover {
  background: linear-gradient(145deg, var(--button-bg-hover), var(--highlight-color));
  border-color: var(--ide-border-strong);
  transform: translateY(-1px);
}
.btn-docs.active {
  background: linear-gradient(145deg, var(--highlight-color), var(--button-bg-hover));
  border-color: var(--button-hover);
  color: #fff;
}

/* ═══════════  CONSOLE OUTPUT PANEL  ═══════════ */
.console-output-panel {
  background: #0d1117;
  border: 1px solid var(--ide-border-accent);
  border-radius: 10px;
  padding: 10px 14px;
  margin-bottom: 10px;
  animation: ide-fade-in .25s ease;
}
.console-output-panel h4 {
  margin: 0 0 6px;
  font-size: 13px;
  text-transform: uppercase;
  letter-spacing: .5px;
  opacity: .7;
  color: #8b949e;
}
.console-output-panel pre {
  margin: 0;
  padding: 8px 10px;
  background: #000000;
  color: #58d68d;
  font-family: 'Consolas', 'Monaco', 'Courier New', monospace;
  font-size: 13px;
  line-height: 1.45;
  border-radius: 6px;
  white-space: pre-wrap;
  word-break: break-word;
  max-height: 160px;
  overflow-y: auto;
}

/* ═══════════  RESULTS PANEL (inline, below editor)  ═══════════ */
.results-panel {
  background: var(--ide-section-bg);
  border: 1px solid var(--ide-border);
  border-radius: 10px;
  padding: 14px 18px;
  margin-bottom: 10px;
  animation: ide-fade-in .25s ease;
}
.results-panel h4 {
  margin: 0 0 10px;
  font-size: 14px;
  text-transform: uppercase;
  letter-spacing: .5px;
  opacity: .75;
}

.result-summary {
  padding: 8px 14px;
  border-radius: 8px;
  font-weight: 700;
  font-size: 14px;
  margin-bottom: 10px;
  text-align: center;
}
.summary-pass {
  background: rgba(6,199,127,.15);
  border: 1px solid rgba(6,199,127,.35);
  color: #06c77f;
}
.summary-fail {
  background: rgba(220,60,60,.12);
  border: 1px solid rgba(220,60,60,.3);
  color: #f06060;
}

.result-row {
  padding: 6px 12px;
  border-radius: 6px;
  margin-bottom: 4px;
  font-size: 13px;
  display: flex;
  align-items: center;
  gap: 8px;
  flex-wrap: wrap;
}
.result-row.pass { background: rgba(6,199,127,.06); }
.result-row.fail { background: rgba(220,60,60,.06); }

.result-input {
  opacity: .5;
  font-size: 12px;
}
.result-detail {
  margin-left: auto;
  font-size: 12px;
  opacity: .8;
}
.result-detail code {
  background: var(--ide-code-inline-bg);
  padding: 1px 5px;
  border-radius: 3px;
}
.result-error pre {
  background: rgba(220,60,60,.1);
  border: 1px solid rgba(220,60,60,.25);
  border-radius: 8px;
  padding: 12px;
  font-size: 13px;
  white-space: pre-wrap;
  word-break: break-word;
  margin: 6px 0 0;
}

/* ═══════════  DOCS SLIDE-OUT PANEL  ═══════════ */
.docs-panel {
  position: fixed;
  top: 0;
  right: 0;
  width: 40%;
  height: 100vh;
  background: linear-gradient(180deg, var(--ide-modal-bg), var(--ide-modal-bg-alt));
  border-left: 1px solid var(--ide-modal-border);
  box-shadow: -6px 0 30px rgba(0,0,0,.35);
  z-index: 1100;
  transform: translateX(100%);
  transition: transform .35s cubic-bezier(.4,0,.2,1);
  display: flex;
  flex-direction: column;
  overflow: hidden;
}
.docs-panel.open {
  transform: translateX(0);
}
.docs-panel-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 14px 20px;
  border-bottom: 1px solid var(--ide-modal-border);
  flex-shrink: 0;
}
.docs-panel-header h3 {
  margin: 0;
  font-size: 16px;
  font-weight: 700;
  color: var(--button-hover);
}
.docs-panel-close {
  background: transparent;
  border: 1px solid var(--ide-border-accent);
  color: var(--text-color);
  width: 30px;
  height: 30px;
  border-radius: 6px;
  font-size: 18px;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all .2s ease;
  opacity: .7;
}
.docs-panel-close:hover {
  opacity: 1;
  background: rgba(220,60,60,.15);
  border-color: rgba(220,60,60,.4);
  color: #e44;
}
.docs-panel-body {
  flex: 1;
  overflow-y: auto;
  padding: 20px 24px;
  font-size: 14px;
  line-height: 1.75;
  color: var(--text-color);
}
.docs-panel-body h4 {
  font-size: 14px;
  font-weight: 700;
  color: var(--button-hover);
  margin: 18px 0 8px;
  padding-bottom: 4px;
  border-bottom: 1px solid var(--ide-border);
}
.docs-panel-body h4:first-child {
  margin-top: 0;
}
.docs-panel-body p {
  margin: 0 0 12px;
}
.docs-panel-body code {
  background: var(--ide-code-inline-bg);
  padding: 2px 6px;
  border-radius: 4px;
  font-size: 13px;
}
.docs-panel-body pre {
  background: var(--ide-header-bg);
  border: 1px solid var(--ide-border);
  border-radius: 8px;
  padding: 12px 14px;
  font-size: 12.5px;
  line-height: 1.6;
  overflow-x: auto;
  margin: 8px 0 14px;
}
.docs-panel-body pre code {
  background: none;
  padding: 0;
  font-size: inherit;
}
.docs-panel-body ul {
  margin: 0 0 12px;
  padding-left: 20px;
}
.docs-panel-body li {
  margin-bottom: 4px;
}

/* ═══════════  POPUP (hints & solution — non-blocking)  ═══════════ */
.ide-modal-overlay {
  display: none;
  position: fixed;
  top: 0; left: 0;
  width: 0; height: 0;
  background: none;
  z-index: 9999;
  pointer-events: none;
}
.ide-modal-overlay.active {
  display: block;
}

.ide-modal {
  pointer-events: auto;
  position: fixed;
  background: linear-gradient(145deg, var(--ide-modal-bg), var(--ide-modal-bg-alt));
  border: 1px solid var(--ide-modal-border);
  border-radius: 14px;
  padding: 0;
  width: 520px;
  max-width: 92vw;
  max-height: 60vh;
  overflow: hidden;
  box-shadow: 0 12px 40px rgba(0,0,0,.35), 0 0 20px rgba(0,140,180,.06);
  animation: ide-popup-in .2s cubic-bezier(.4,0,.2,1);
}
@keyframes ide-popup-in {
  from { opacity: 0; transform: translateY(8px); }
  to   { opacity: 1; transform: translateY(0); }
}

.ide-modal-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 14px 20px;
  background: var(--ide-header-bg);
  border-bottom: 1px solid var(--ide-modal-border);
}
.ide-modal-header h3 {
  margin: 0;
  font-size: 16px;
  font-weight: 700;
  color: var(--button-hover);
}
.ide-modal-close {
  background: transparent;
  border: 1px solid var(--ide-border-accent);
  color: var(--ide-close-color);
  font-size: 18px;
  width: 32px; height: 32px;
  border-radius: 8px;
  cursor: pointer;
  transition: all .2s ease;
  display: flex;
  align-items: center;
  justify-content: center;
  line-height: 1;
}
.ide-modal-close:hover {
  background: rgba(220,60,60,.2);
  border-color: rgba(220,60,60,.4);
  color: #f06060;
}

.ide-modal-body {
  padding: 18px 22px;
  overflow-y: auto;
  max-height: calc(80vh - 60px);
}

/* Modal adapts via CSS vars — no scheme-specific overrides needed */

/* ── Hint items inside modal ── */
.hint-item {
  padding: 10px 14px;
  margin-bottom: 10px;
  background: rgba(255,193,7,.08);
  border-left: 3px solid rgba(255,193,7,.55);
  border-radius: 0 8px 8px 0;
  font-size: 14px;
  line-height: 1.55;
}
.hint-item code {
  background: var(--ide-code-inline-bg);
  padding: 1px 5px;
  border-radius: 3px;
}
[data-md-color-scheme="light"] .hint-item {
  background: rgba(255,193,7,.1);
}

/* ── Solution inside modal ── */
.solution-warning {
  padding: 8px 14px;
  margin-bottom: 12px;
  background: rgba(220,60,60,.08);
  border: 1px solid rgba(220,60,60,.2);
  border-radius: 8px;
  font-size: 13px;
  font-weight: 600;
  text-align: center;
}
.ide-modal-body pre {
  background: var(--ide-header-bg);
  border-radius: 8px;
  padding: 14px;
  font-size: 14px;
  line-height: 1.5;
  overflow-x: auto;
  margin: 0;
  position: relative;
}
.ide-modal-body code {
  font-family: 'Fira Code', 'Cascadia Code', 'JetBrains Mono', monospace;
}

/* ── Copy button inside solution ── */
.solution-code-wrap {
  position: relative;
}
.solution-code-wrap .btn-copy-solution {
  display: block;
  margin-left: auto;
  margin-bottom: 6px;
  background: var(--ide-section-bg);
  color: var(--text-color);
  border: 1px solid var(--ide-border-accent);
  padding: 4px 12px;
  border-radius: 6px;
  font-size: 12px;
  font-weight: 600;
  cursor: pointer;
  transition: all .2s ease;
}
.solution-code-wrap .btn-copy-solution:hover {
  background: var(--highlight-color);
  color: #fff;
  border-color: var(--highlight-color);
}

/* ═══════════  LOADING INDICATOR  ═══════════ */
.loading-indicator {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  padding: 20px;
  font-size: 14px;
  font-weight: 600;
  opacity: .7;
}
.spinner {
  width: 18px; height: 18px;
  border: 3px solid var(--ide-border-accent);
  border-top-color: var(--highlight-color);
  border-radius: 50%;
  animation: ide-spin .8s linear infinite;
}
@keyframes ide-spin { to { transform: rotate(360deg); } }

/* All light-theme overrides handled by CSS vars in main.css */

/* ═══════════  PROGRESS DASHBOARD  ═══════════ */
.cmd-divider-progress { margin-left: auto; }

.cmd-progress {
  position: relative;
  cursor: pointer;
  user-select: none;
}

/* Ring container */
.progress-ring-wrap {
  position: relative;
  width: var(--cmd-h);
  transition: transform .2s cubic-bezier(.4,0,.2,1);
}
.cmd-progress:hover .progress-ring-wrap {
  transform: scale(1.08);
}
.progress-ring {
  position: absolute;
  top: 0;
  left: 0;
}
.progress-ring-bg {
  stroke: var(--ide-border-accent);
  opacity: .15;
}
/* Subtle shimmer trail behind the fill */
.progress-ring-trail {
  stroke: var(--highlight-color);
  opacity: .08;
}
.progress-ring-fill {
  transition: stroke-dashoffset .9s cubic-bezier(.4,0,.2,1), filter .4s ease;
  filter: drop-shadow(0 0 2px rgba(4,113,128,.3));
}
.progress-ring-text {
  font-size: 11px;
  font-weight: 800;
  letter-spacing: -.3px;
  color: var(--text-color);
  z-index: 1;
  pointer-events: none;
  transition: color .3s ease;
}
.cmd-progress:hover .progress-ring-text {
  color: var(--highlight-color);
}

/* Idle subtle pulse — very gentle breathing effect */
@keyframes progress-breathe {
  0%, 100% { filter: drop-shadow(0 0 2px rgba(4,113,128,.25)); }
  50%      { filter: drop-shadow(0 0 5px rgba(4,113,128,.45)); }
}
.progress-ring-fill {
  animation: progress-breathe 3.5s ease-in-out infinite;
}

/* Celebrate pulse — triggered briefly by JS on new completion */
@keyframes progress-celebrate {
  0%   { transform: scale(1);   filter: drop-shadow(0 0 2px rgba(46,204,113,.3)); }
  30%  { transform: scale(1.18); filter: drop-shadow(0 0 12px rgba(46,204,113,.6)); }
  60%  { transform: scale(0.95); filter: drop-shadow(0 0 6px rgba(46,204,113,.4)); }
  100% { transform: scale(1);   filter: drop-shadow(0 0 3px rgba(46,204,113,.3)); }
}
.progress-ring-wrap.celebrate {
  animation: progress-celebrate .65s cubic-bezier(.4,0,.2,1) forwards;
}

/* Glow when fully complete */
.progress-ring-wrap.complete .progress-ring-fill {
  stroke: url(#prog-grad-complete);
  animation: progress-complete-glow 2.5s ease-in-out infinite;
}
@keyframes progress-complete-glow {
  0%, 100% { filter: drop-shadow(0 0 3px rgba(46,204,113,.4)); }
  50%      { filter: drop-shadow(0 0 10px rgba(46,204,113,.7)); }
}
.progress-ring-wrap.complete .progress-ring-text {
  color: #2ecc71;
}

/* Fraction label */
.progress-label {
  font-size: 12px;
  font-weight: 600;
  opacity: .45;
  white-space: nowrap;
  margin-left: 4px;
  letter-spacing: .3px;
  font-variant-numeric: tabular-nums;
  transition: opacity .2s ease;
}
.cmd-progress:hover .progress-label { opacity: .8; }

/* ── Progress dropdown ── */
.progress-dropdown {
  display: none;
  position: absolute;
  top: calc(100% + 10px);
  right: 0;
  width: 280px;
  background: var(--ide-modal-bg);
  border: 1px solid var(--ide-modal-border);
  border-radius: 12px;
  box-shadow: 0 8px 32px rgba(0,0,0,.4), 0 0 0 1px rgba(255,255,255,.03) inset;
  z-index: 600;
  overflow: hidden;
}
.progress-dropdown.open {
  display: block;
  animation: cmd-dropdown-in .2s cubic-bezier(.16,1,.3,1);
}

.progress-dropdown-title {
  padding: 10px 14px 8px;
  font-size: 13px;
  font-weight: 700;
  color: var(--button-hover);
  border-bottom: 1px solid var(--ide-border);
}

.progress-dropdown-body {
  padding: 10px 14px 14px;
}

/* Language section */
.progress-lang-section {
  margin-bottom: 10px;
}
.progress-lang-section:last-child { margin-bottom: 0; }
.progress-lang-label {
  font-size: 12px;
  font-weight: 700;
  margin-bottom: 6px;
  opacity: .85;
}

/* Bar rows */
.progress-bar-row {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 5px;
}
.progress-bar-row:last-child { margin-bottom: 0; }

.progress-diff-label {
  font-size: 10px;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: .4px;
  width: 48px;
  flex-shrink: 0;
  opacity: .6;
}

.progress-bar-track {
  flex: 1;
  height: 6px;
  background: var(--ide-border-accent);
  border-radius: 3px;
  overflow: hidden;
  opacity: .5;
}
.progress-bar-fill {
  height: 100%;
  border-radius: 3px;
  background: linear-gradient(90deg, var(--highlight-color), #2ecc71);
  transition: width .6s cubic-bezier(.4,0,.2,1);
  min-width: 0;
}

.progress-bar-count {
  font-size: 10px;
  font-weight: 700;
  width: 22px;
  text-align: right;
  flex-shrink: 0;
  opacity: .7;
}

/* ═══════════  RESPONSIVE  ═══════════ */
@media (max-width: 768px) {
  .ide-command-bar { --cmd-h: 32px; padding: 4px 10px; }
  .cmd-divider { margin: 0 8px; }
  .cmd-group { gap: 4px; }
  .lang-tab { padding: 0 14px; font-size: 13px; }
  .diff-tab { padding: 0 12px; font-size: 11px; }
  .challenge-selector-btn { min-width: 150px; font-size: 13px; }
  .nav-arrow { width: var(--cmd-h); box-shadow: 0 1px 2px rgba(0,0,0,.2); }
  .nav-arrow svg { width: 13px; height: 13px; }
  .button-bar { flex-wrap: wrap; }
  .result-row { font-size: 12px; }
  .challenge-content { padding: 8px; }
  .ide-modal { width: 92vw; max-width: 92vw; max-height: 60vh; }
  .problem-card-body { flex-direction: column; gap: 8px; }
  .problem-col-desc { padding-right: 0; }
  .problem-col-divider { width: auto; height: 1px; align-self: auto; }
  .problem-col-cases { padding-left: 0; }
  .problem-card-header h3 { font-size: 13px; }
  .docs-panel { width: 85%; }
  .cmd-divider-progress { margin-left: 0; }
  .progress-dropdown { width: 240px; }
  .progress-label { display: none; }
}