/* ===========================================================
   Code Olympiad 2081 - Demo questions page
   The practice set: core programs, output prediction and design
   tasks in the Night Shift world. Phosphor hero, a sticky mono
   tab bar, expandable code blocks and output answers.
   Token-driven only.
   =========================================================== */

/* ---------- Hero ---------- */
.hero {
  position: relative;
  padding-block: clamp(var(--space-4xl), 9vw, var(--space-6xl)) var(--space-4xl);
  overflow: hidden;
}

.hero::before {
  content: "";
  position: absolute;
  top: -240px;
  right: -180px;
  width: 560px;
  height: 560px;
  border-radius: var(--radius-full);
  background: radial-gradient(closest-side, var(--color-phosphor), transparent 72%);
  opacity: 0.07;
  pointer-events: none;
  z-index: -1;
}

.hero::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  height: 1px;
  background: linear-gradient(
    90deg,
    var(--color-border-hairline),
    var(--color-phosphor),
    var(--color-border-hairline)
  );
  opacity: 0.35;
  pointer-events: none;
}

.hero__brand {
  display: inline-flex;
  align-items: center;
  gap: var(--space-sm);
  font-family: var(--font-mono);
  font-size: var(--text-kicker);
  letter-spacing: 0.04em;
  color: var(--color-text-tertiary);
  padding: var(--space-2xs) var(--space-sm);
  border: 1px solid var(--color-border-hairline);
  border-radius: var(--radius-full);
  background: var(--color-surface);
  margin-bottom: var(--space-xl);
}

.hero__brand-logo {
  width: 28px;
  height: 28px;
  border-radius: var(--radius-full);
  object-fit: cover;
}

.hero__title {
  font-family: var(--font-display);
  font-size: var(--text-display);
  font-weight: 800;
  letter-spacing: -0.03em;
  line-height: 1.02;
  color: var(--color-text-primary);
}

.hero__accent {
  color: var(--color-phosphor);
}

.hero__lede {
  margin-top: var(--space-lg);
  max-width: 52ch;
  color: var(--color-text-secondary);
  font-size: 1.0625rem;
}

.hero__actions {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-sm);
  margin-top: var(--space-xl);
}

.hero__actions .btn {
  font-family: var(--font-mono);
  font-size: 0.875rem;
}

/* ---------- Stats ---------- */
.stats {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(130px, 1fr));
  gap: var(--space-xl);
  max-width: 460px;
  margin-top: var(--space-2xl);
  padding-top: var(--space-xl);
  border-top: 1px solid var(--color-border-hairline);
}

.stat__num {
  font-family: var(--font-mono);
  font-size: clamp(1.75rem, 4vw, 2.25rem);
  font-weight: 700;
  line-height: 1;
  color: var(--color-phosphor);
  font-variant-numeric: tabular-nums;
}

.stat__label {
  display: block;
  margin-top: var(--space-2xs);
  font-family: var(--font-mono);
  font-size: var(--text-caption);
  color: var(--color-text-tertiary);
}

.hero__note {
  margin-top: var(--space-xl);
  font-family: var(--font-mono);
  font-size: var(--text-caption);
  color: var(--color-text-tertiary);
}

/* ---------- Sticky tab bar ---------- */
.demo-toolbar {
  position: sticky;
  top: var(--nav-height);
  z-index: 800;
  background: var(--color-nav-material);
  backdrop-filter: saturate(180%) blur(20px);
  -webkit-backdrop-filter: saturate(180%) blur(20px);
  border-bottom: 1px solid var(--color-border-hairline);
  margin-bottom: var(--space-2xl);
}

.demo-toolbar__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-md);
  flex-wrap: wrap;
  padding-block: var(--space-sm);
}

.demo-toolbar__count {
  margin-left: auto;
  font-family: var(--font-mono);
  font-size: var(--text-caption);
  color: var(--color-text-tertiary);
  white-space: nowrap;
  font-variant-numeric: tabular-nums;
}

.demo-toolbar .segmented {
  background: transparent;
  padding: 0;
  gap: var(--space-lg);
  border-radius: 0;
  overflow-x: auto;
  scrollbar-width: none;
}

.demo-toolbar .segmented__thumb {
  display: none;
}

.demo-toolbar .segmented__btn {
  position: relative;
  min-height: 0;
  padding: var(--space-2xs) 0;
  border-radius: 0;
  background: transparent;
  font-family: var(--font-mono);
  font-size: var(--text-kicker);
  font-weight: 600;
  letter-spacing: 0.01em;
  color: var(--color-text-tertiary);
  transition: color var(--motion-instant) var(--ease-touch);
}

.demo-toolbar .segmented__btn::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: -3px;
  height: 2px;
  background: var(--color-phosphor);
  transform: scaleX(0);
  transform-origin: 0 50%;
  transition: transform var(--motion-base) var(--ease-touch);
}

.demo-toolbar .segmented__btn[aria-selected="true"] {
  color: var(--color-phosphor);
}

.demo-toolbar .segmented__btn[aria-selected="true"]::after {
  transform: scaleX(1);
}

/* ---------- Sections ---------- */
.demo-section {
  padding-bottom: var(--space-3xl);
}

.demo-section[hidden] {
  display: none;
}

.demo-section__head {
  display: flex;
  align-items: baseline;
  gap: var(--space-md);
  flex-wrap: wrap;
  margin-bottom: var(--space-xs);
}

.demo-section__title {
  font-family: var(--font-display);
  font-size: var(--text-heading);
  font-weight: 800;
  letter-spacing: -0.02em;
  color: var(--color-text-primary);
}

.demo-section__tag {
  font-family: var(--font-mono);
  font-size: var(--text-caption);
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--color-text-tertiary);
}

.demo-section__intro {
  max-width: 56ch;
  color: var(--color-text-secondary);
  margin-bottom: var(--space-xl);
}

/* ---------- Question cards ---------- */
.demo__list {
  display: grid;
  gap: var(--space-md);
  max-width: 780px;
}

.q-card {
  display: flex;
  flex-direction: column;
  gap: var(--space-sm);
  padding: var(--space-md);
  background: var(--color-surface);
  border: 1px solid var(--color-border-hairline);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-card);
  transition: transform var(--motion-base) var(--ease-touch),
    box-shadow var(--motion-base) var(--ease-touch),
    border-color var(--motion-base) var(--ease-touch);
}

@media (hover: hover) {
  .q-card:hover {
    transform: translateY(-4px);
    border-color: var(--color-border-strong);
    box-shadow: var(--shadow-float);
  }
}

.q-card__head {
  display: flex;
  align-items: baseline;
  gap: var(--space-sm);
}

.q-card__index {
  flex-shrink: 0;
  font-family: var(--font-mono);
  font-size: var(--text-caption);
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--color-phosphor);
  padding: var(--space-hair) var(--space-xs);
  border: 1px solid color-mix(in srgb, var(--color-phosphor) 45%, transparent);
  border-radius: var(--radius-full);
}

.q-card__title {
  font-size: var(--text-sub);
  font-weight: 650;
  line-height: 1.4;
  color: var(--color-text-primary);
}

/* ---------- Toggle button ---------- */
.q-toggle {
  align-self: flex-start;
  display: inline-flex;
  align-items: center;
  gap: var(--space-xs);
  min-height: 38px;
  padding: 0 var(--space-md);
  border: 1px solid var(--color-border-hairline);
  border-radius: var(--radius-full);
  background: var(--color-surface-2);
  color: var(--color-text-primary);
  font-family: var(--font-mono);
  font-size: var(--text-kicker);
  font-weight: 600;
  cursor: pointer;
  transition: background-color var(--motion-instant) var(--ease-touch),
    border-color var(--motion-instant) var(--ease-touch),
    transform var(--motion-instant) var(--ease-touch);
}

.q-toggle svg {
  width: var(--icon-sm);
  height: var(--icon-sm);
  color: var(--color-text-tertiary);
  transition: transform var(--motion-base) var(--ease-touch);
}

.q-toggle:hover {
  background: var(--color-surface-hover);
  border-color: var(--color-border-strong);
}

.q-toggle:active {
  transform: scale(0.97);
}

.q-toggle[aria-expanded="true"] svg {
  transform: rotate(180deg);
}

/* ---------- Code block ---------- */
.code-block {
  margin-top: var(--space-2xs);
  border: 1px solid var(--color-border-hairline);
  border-radius: var(--radius-sm);
  background: var(--color-surface-2);
  overflow: hidden;
}

.code-block[hidden] {
  display: none;
}

.code-block__bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-sm);
  padding: var(--space-2xs) var(--space-sm);
  border-bottom: 1px solid var(--color-border-hairline);
  background: var(--color-surface);
}

.code-block__lang {
  font-family: var(--font-mono);
  font-size: var(--text-caption);
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--color-text-tertiary);
}

.code-block__copy {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2xs);
  min-height: 28px;
  padding: 0 var(--space-sm);
  border: 1px solid var(--color-border-hairline);
  border-radius: var(--radius-full);
  background: transparent;
  color: var(--color-text-secondary);
  font-family: var(--font-mono);
  font-size: var(--text-caption);
  font-weight: 600;
  cursor: pointer;
  transition: color var(--motion-instant) var(--ease-touch),
    border-color var(--motion-instant) var(--ease-touch);
}

.code-block__copy svg {
  width: 14px;
  height: 14px;
}

.code-block__copy:hover {
  color: var(--color-accent-strong);
  border-color: var(--color-accent-strong);
}

.code-block__copy:active {
  transform: scale(0.96);
}

.code-block pre {
  margin: 0;
  padding: var(--space-md);
  overflow-x: auto;
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  line-height: 1.65;
  tab-size: 4;
  color: var(--color-text-secondary);
}

.code-block code {
  font: inherit;
  white-space: pre;
}

/* ---------- Output answer ---------- */
.q-answer {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  padding: var(--space-xs) var(--space-md);
  border: 1px solid var(--color-accent-soft);
  border-radius: var(--radius-sm);
  background: var(--color-accent-soft);
}

.q-answer[hidden] {
  display: none;
}

.q-answer__label {
  flex-shrink: 0;
  font-family: var(--font-mono);
  font-size: var(--text-caption);
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--color-accent-strong);
}

.q-answer__value {
  font-family: var(--font-mono);
  font-size: var(--text-sub);
  font-weight: 700;
  color: var(--color-text-primary);
}

/* ---------- Design cards ---------- */
.design-grid {
  max-width: none;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  align-items: start;
}

.d-card {
  display: flex;
  flex-direction: column;
  gap: var(--space-sm);
  padding: var(--space-md);
  background: var(--color-surface);
  border: 1px solid var(--color-border-hairline);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-card);
  transition: transform var(--motion-base) var(--ease-touch),
    box-shadow var(--motion-base) var(--ease-touch),
    border-color var(--motion-base) var(--ease-touch);
}

@media (hover: hover) {
  .d-card:hover {
    transform: translateY(-4px);
    border-color: var(--color-border-strong);
    box-shadow: var(--shadow-float);
  }
}

.d-card__media {
  position: relative;
  border-radius: var(--radius-sm);
  overflow: hidden;
  border: 1px solid var(--color-border-hairline);
  aspect-ratio: 16 / 10;
  background: var(--color-surface-2);
}

.d-card__media img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.d-card__head {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: var(--space-sm);
}

.d-card__index + .d-card__title {
  flex: 1 1 auto;
}

.d-card__index {
  flex-shrink: 0;
  font-family: var(--font-mono);
  font-size: var(--text-caption);
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--color-phosphor);
  padding: var(--space-hair) var(--space-xs);
  border: 1px solid color-mix(in srgb, var(--color-phosphor) 45%, transparent);
  border-radius: var(--radius-full);
}

.d-card__title {
  font-size: var(--text-title);
  font-weight: 700;
  color: var(--color-text-primary);
  overflow-wrap: anywhere;
}

.d-card__preview {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2xs);
  flex-shrink: 0;
  font-family: var(--font-mono);
  font-size: var(--text-caption);
  font-weight: 600;
  color: var(--color-accent-strong);
  padding: var(--space-2xs) var(--space-sm);
  border: 1px solid color-mix(in srgb, var(--color-accent) 45%, transparent);
  border-radius: var(--radius-full);
  transition: background-color var(--motion-instant) var(--ease-touch),
    border-color var(--motion-instant) var(--ease-touch);
}

.d-card__preview:hover {
  background: var(--color-accent-soft);
  border-color: var(--color-accent-strong);
}

.d-card__preview svg {
  width: 14px;
  height: 14px;
}

/* ---------- Responsive ---------- */
@media (max-width: 520px) {
  .stats {
    gap: var(--space-lg);
  }

  .demo-toolbar__count {
    display: none;
  }

  .q-card__head {
    flex-direction: column;
    align-items: flex-start;
    gap: var(--space-xs);
  }

  .d-card__head {
    flex-wrap: wrap;
  }
}