:root {
  --ink: #d8fff2;
  --muted: #8bcab7;
  --bg: #06120f;
  --panel: rgba(9, 31, 26, 0.84);
  --panel-strong: rgba(13, 48, 40, 0.96);
  --line: rgba(108, 255, 202, 0.22);
  --accent: #4cffb3;
  --cyan: #63dbff;
  --amber: #ffd36a;
  --danger: #ff6d86;
  --shadow: 0 18px 70px rgba(0, 0, 0, 0.42);
  color-scheme: dark;
}

* { box-sizing: border-box; }

html, body {
  height: 100%;
  margin: 0;
  overflow: hidden;
}

body {
  color: var(--ink);
  font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", monospace;
  background:
    radial-gradient(circle at 16% 8%, rgba(99, 219, 255, 0.18), transparent 31rem),
    radial-gradient(circle at 88% 0%, rgba(76, 255, 179, 0.16), transparent 28rem),
    linear-gradient(135deg, #020706, #082018 58%, #03100d);
}

body::before,
body::after {
  content: "";
  position: fixed;
  inset: 0;
  pointer-events: none;
}

body::before {
  background:
    linear-gradient(rgba(255,255,255,0.035) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255,255,255,0.025) 1px, transparent 1px);
  background-size: 36px 36px;
  mask-image: linear-gradient(to bottom, black, transparent 88%);
}

body::after {
  background: repeating-linear-gradient(0deg, rgba(255,255,255,0.035) 0 1px, transparent 1px 5px);
  mix-blend-mode: overlay;
  opacity: 0.14;
}

.shell {
  width: min(1240px, calc(100% - 24px));
  height: 100dvh;
  margin: 0 auto;
  padding: 10px 0;
  display: grid;
  grid-template-rows: auto auto minmax(150px, 0.86fr) minmax(250px, 1.44fr);
  gap: 8px;
  min-height: 0;
}

.hero {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 14px;
  align-items: center;
  min-height: 0;
}

.eyebrow, .panel-label {
  margin: 0 0 6px;
  color: var(--cyan);
  font-size: 0.72rem;
  letter-spacing: 0.15em;
  text-transform: uppercase;
}

h1 {
  margin: 0;
  font-size: clamp(2rem, 4.4vw, 4.4rem);
  line-height: 0.86;
  letter-spacing: -0.075em;
  text-shadow: 0 0 28px rgba(76,255,179,0.3);
}

h2 { margin: 0 0 8px; line-height: 1.1; font-size: 1.05rem; }

.lede {
  max-width: 760px;
  margin: 7px 0 0;
  color: var(--muted);
  line-height: 1.35;
  font-size: 0.86rem;
}

kbd {
  border: 1px solid var(--line);
  border-bottom-color: rgba(76,255,179,0.55);
  border-radius: 6px;
  padding: 0.1rem 0.33rem;
  background: rgba(255,255,255,0.06);
  color: var(--ink);
}

.category-status, .panel, .terminal-wrap {
  border: 1px solid var(--line);
  background: var(--panel);
  box-shadow: var(--shadow);
  backdrop-filter: blur(14px);
}

.category-status {
  display: grid;
  grid-template-columns: repeat(3, max-content);
  align-items: center;
  gap: 10px;
  min-width: 230px;
  padding: 9px 11px;
  border-radius: 16px;
}

button {
  border: 1px solid rgba(76,255,179,0.42);
  border-radius: 11px;
  padding: 7px 10px;
  color: var(--bg);
  background: linear-gradient(135deg, var(--accent), var(--cyan));
  font: inherit;
  font-size: 0.86rem;
  font-weight: 800;
  cursor: pointer;
  transition: transform 150ms ease, filter 150ms ease, border-color 150ms ease;
}

button:hover { transform: translateY(-1px); filter: brightness(1.07); }
button:active { transform: translateY(0); }

.panel {
  border-radius: 17px;
  padding: 10px;
  min-height: 0;
}

.category-panel {
  display: grid;
  grid-template-columns: max-content 1fr;
  gap: 10px;
  align-items: center;
  overflow: hidden;
}

.category-panel .panel-label { margin: 0; }

.category-list {
  display: grid;
  grid-template-columns: repeat(5, minmax(0, 1fr));
  gap: 7px;
}

.category-button {
  color: var(--ink);
  background: rgba(255,255,255,0.04);
  border-color: var(--line);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.category-button.active {
  color: var(--bg);
  background: linear-gradient(135deg, var(--amber), var(--accent));
  border-color: rgba(255, 211, 106, 0.6);
}

.learning-grid {
  display: grid;
  grid-template-columns: 1fr 0.85fr 1.35fr;
  gap: 8px;
  min-height: 0;
}

.task-panel {
  background:
    linear-gradient(135deg, rgba(76,255,179,0.1), transparent 42%),
    var(--panel-strong);
  display: grid;
  grid-template-rows: auto auto auto auto auto auto;
  overflow: hidden;
}

#task-copy, .explanation-content, .task-feedback {
  color: var(--muted);
  line-height: 1.32;
}

#task-copy { margin: 0; }

.task-feedback {
  min-height: 1.3em;
  margin-top: 7px;
  font-size: 0.86rem;
}

.task-feedback.good { color: var(--accent); }
.task-feedback.warn { color: var(--amber); }
.task-feedback.bad { color: var(--danger); }

body[data-run-state="correct"] .task-panel,
body[data-run-state="correct"] .terminal-output,
body[data-run-state="correct"] .terminal-input-row {
  border-color: rgba(76, 255, 179, 0.72);
  box-shadow: inset 0 0 0 1px rgba(76, 255, 179, 0.22), 0 0 28px rgba(76, 255, 179, 0.18);
}

body[data-run-state="correct"] .terminal-output,
body[data-run-state="correct"] .terminal-input-row {
  background-color: rgba(76, 255, 179, 0.055);
}

body[data-run-state="valid"] .task-panel,
body[data-run-state="valid"] .terminal-output,
body[data-run-state="valid"] .terminal-input-row {
  border-color: rgba(255, 211, 106, 0.78);
  box-shadow: inset 0 0 0 1px rgba(255, 211, 106, 0.22), 0 0 28px rgba(255, 211, 106, 0.15);
}

body[data-run-state="valid"] .terminal-output,
body[data-run-state="valid"] .terminal-input-row {
  background-color: rgba(255, 211, 106, 0.055);
}

body[data-run-state="error"] .task-panel,
body[data-run-state="error"] .terminal-output,
body[data-run-state="error"] .terminal-input-row {
  border-color: rgba(255, 109, 134, 0.78);
  box-shadow: inset 0 0 0 1px rgba(255, 109, 134, 0.23), 0 0 28px rgba(255, 109, 134, 0.16);
}

body[data-run-state="error"] .terminal-output,
body[data-run-state="error"] .terminal-input-row {
  background-color: rgba(255, 109, 134, 0.055);
}

.path-pill {
  display: inline-flex;
  gap: 8px;
  align-items: center;
  justify-self: start;
  margin-top: 7px;
  padding: 5px 8px;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: rgba(0,0,0,0.22);
  color: var(--muted);
  font-size: 0.86rem;
}

code { color: var(--amber); }

.choices {
  display: grid;
  gap: 6px;
}

.choice {
  display: grid;
  grid-template-columns: 1.8rem 1fr;
  gap: 7px;
  width: 100%;
  text-align: left;
  color: var(--ink);
  background: rgba(255,255,255,0.035);
  border-color: var(--line);
}

.choice-number {
  display: inline-grid;
  place-items: center;
  width: 1.42rem;
  height: 1.42rem;
  border-radius: 50%;
  background: rgba(99,219,255,0.16);
  color: var(--cyan);
}

.explanation-panel {
  display: grid;
  grid-template-rows: auto auto minmax(0, 1fr);
  overflow: hidden;
}

.explanation-content {
  overflow-y: auto;
  padding-right: 4px;
}

.explanation-content p { margin: 0 0 8px; }
.explanation-content ul { margin: 6px 0 0; padding-left: 18px; }
.explanation-content strong { color: var(--ink); }

.terminal-wrap {
  overflow: hidden;
  border-radius: 20px;
  background: #020807;
  display: grid;
  grid-template-rows: auto auto minmax(0, 1fr);
  min-height: 0;
}

.terminal-topbar {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 8px 14px;
  background: linear-gradient(180deg, #16382f, #0b1f1a);
  border-bottom: 1px solid var(--line);
}

.dot { width: 12px; height: 12px; border-radius: 50%; display: inline-block; }
.red { background: #ff5f57; }
.yellow { background: #ffbd2e; }
.green { background: #28c840; }
.terminal-title { margin-left: 8px; color: var(--muted); font-size: 0.82rem; }

.terminal-output {
  min-height: 0;
  max-height: none;
  overflow-y: auto;
  padding: 8px 14px 12px;
  line-height: 1.36;
  white-space: pre-wrap;
  border: 1px solid transparent;
  border-left: 0;
  border-right: 0;
  transition: border-color 180ms ease, box-shadow 180ms ease, background-color 180ms ease;
}

.line { margin: 0 0 4px; }
.line.command { color: var(--ink); }
.line.good { color: var(--accent); }
.line.warn { color: var(--amber); }
.line.bad { color: var(--danger); }
.line.system { color: var(--cyan); }

.terminal-input-row {
  display: grid;
  grid-template-columns: max-content 1fr;
  gap: 8px;
  align-items: center;
  padding: 12px 14px 8px;
  border: 1px solid transparent;
  border-bottom: 0;
  border-left: 0;
  border-right: 0;
  transition: border-color 180ms ease, box-shadow 180ms ease, background-color 180ms ease;
}

#prompt-label { color: var(--accent); }
#terminal-input {
  width: 100%;
  border: 0;
  outline: none;
  color: var(--ink);
  background: transparent;
  font: inherit;
  caret-color: var(--accent);
}

@media (max-width: 920px) {
  .shell { grid-template-rows: auto auto minmax(185px, 1fr) minmax(250px, 1.35fr); }
  .hero { grid-template-columns: 1fr; }
  .category-status { grid-template-columns: repeat(3, 1fr); }
  .category-panel { grid-template-columns: 1fr; }
  .category-list { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .learning-grid { grid-template-columns: 1fr 1fr; }
  .explanation-panel { grid-column: 1 / -1; }
}

@media (max-width: 560px) {
  .shell {
    width: min(100% - 12px, 1220px);
    padding: 6px 0;
    gap: 6px;
    grid-template-rows: auto auto minmax(0, 1fr) minmax(0, 1.1fr);
  }
  .eyebrow, .lede { display: none; }
  h1 { font-size: 2rem; }
  h2 { font-size: 0.98rem; margin-bottom: 5px; }
  .panel { padding: 8px; border-radius: 14px; }
  .category-list { grid-template-columns: 1fr; max-height: 82px; overflow-y: auto; }
  .learning-grid { grid-template-columns: 1fr; gap: 6px; overflow: hidden; }
  .choices-panel, .explanation-panel { min-height: 0; overflow: hidden; }
  .terminal-input-row { grid-template-columns: 1fr; }
  .category-status { font-size: 0.76rem; }
}