/* ─── Google Fonts ─────────────────────────────────────────────────────────── */
@import url('https://fonts.googleapis.com/css2?family=Outfit:wght@400;500;600;700;800&family=Nunito+Sans:wght@400;600;700&display=swap');

/* ─── Design Tokens ────────────────────────────────────────────────────────── */
:root {
  --bg: #060a14;
  --bg-card: #0d1120;
  --bg-card-hover: #121828;
  --accent: #2563eb;
  --accent-2: #0ea5e9;
  --accent-soft: rgba(37,99,235,0.14);
  --text-main: #f0f4ff;
  --text-muted: #8b96b8;
  --border-soft: #1e2840;
  --tag-bg: #141d33;
  --tag-text: #c8d0e8;
  --focus-ring: 0 0 0 3px rgba(37,99,235,0.5);
  --shadow-soft: 0 18px 40px rgba(0,0,0,0.55);
  --radius-lg: 16px;
  --radius-xl: 22px;
  --transition-fast: 0.16s ease-out;
  --transition-med: 0.26s ease;
}

*, *::before, *::after { box-sizing: border-box; }

body {
  margin: 0;
  min-height: 100vh;
  font-family: 'Nunito Sans', system-ui, sans-serif;
  background: radial-gradient(ellipse at top, #111b38 0, #060a14 55%, #020308 100%);
  color: var(--text-main);
  display: flex;
  align-items: stretch;
  justify-content: center;
  -webkit-font-smoothing: antialiased;
}

.page {
  width: 100%;
  max-width: 1300px;
  padding: 28px 20px 48px;
  margin: 0 auto;
}

@media (min-width: 960px) {
  .page { padding: 32px 28px 56px; }
}

/* ─── Header (brand block below nav) ──────────────────────────────────────── */
header {
  display: flex;
  flex-direction: column;
  gap: 16px;
  margin-bottom: 28px;
}

@media (min-width: 840px) {
  header { margin-bottom: 36px; }
}

.brand {
  display: flex;
  align-items: center;
  gap: 14px;
}

.brand-logo {
  width: 52px;
  height: 52px;
  border-radius: 16px;
  background: linear-gradient(135deg, #1d4ed8, #0ea5e9);
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: var(--shadow-soft);
  flex-shrink: 0;
}

.brand-logo span {
  font-family: 'Outfit', sans-serif;
  font-weight: 800;
  font-size: 1.4rem;
}

.brand-text h1 {
  font-family: 'Outfit', system-ui, sans-serif;
  font-size: clamp(1.5rem, 2vw + 1rem, 2rem);
  font-weight: 800;
  margin: 0;
  letter-spacing: -0.02em;
  line-height: 1.15;
  color: #fff;
  display: flex;
  flex-wrap: wrap;
  gap: 0.3ch;
  align-items: baseline;
}

.brand-text h1 span.highlight { color: var(--accent-2); }
.brand-text p {
  margin: 5px 0 0;
  font-size: 0.88rem;
  color: var(--text-muted);
}

/* ─── Controls / Filters ───────────────────────────────────────────────────── */
.controls {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-top: 4px;
}

.filter-group {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
}

.pill {
  border-radius: 999px;
  border: 1px solid var(--border-soft);
  background: rgba(14,30,61,0.6);
  padding: 6px 14px;
  font-size: 0.8rem;
  color: var(--text-muted);
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-family: 'Nunito Sans', sans-serif;
}

.pill strong { color: var(--text-main); font-weight: 700; }

.filter-btn {
  border-radius: 8px;
  border: 1px solid var(--border-soft);
  padding: 7px 14px;
  font-size: 0.82rem;
  font-weight: 600;
  font-family: 'Nunito Sans', sans-serif;
  background: rgba(10,14,28,0.9);
  color: var(--text-muted);
  cursor: pointer;
  transition: background var(--transition-fast), color var(--transition-fast),
              border-color var(--transition-fast), transform 0.1s ease;
}

.filter-btn:hover {
  border-color: var(--accent);
  color: var(--text-main);
  transform: translateY(-1px);
}

.filter-btn.active {
  background: var(--accent-soft);
  color: #93c5fd;
  border-color: rgba(37,99,235,0.5);
}

.filter-btn:focus-visible,
.random-btn:focus-visible,
.play-btn:focus-visible {
  outline: none;
  box-shadow: var(--focus-ring);
}

.random-btn {
  border-radius: 10px;
  border: none;
  padding: 9px 20px;
  font-size: 0.88rem;
  font-weight: 700;
  font-family: 'Nunito Sans', sans-serif;
  letter-spacing: 0.01em;
  cursor: pointer;
  background: linear-gradient(135deg, #2563eb, #0ea5e9);
  color: #fff;
  display: inline-flex;
  align-items: center;
  gap: 8px;
  box-shadow: 0 4px 16px rgba(37,99,235,0.35);
  transition: transform var(--transition-med), box-shadow var(--transition-med), filter 0.18s ease;
}

.random-btn span.icon { font-size: 1rem; }

.random-btn:hover {
  transform: translateY(-1px) scale(1.02);
  filter: brightness(1.08);
  box-shadow: 0 8px 28px rgba(37,99,235,0.45);
}

/* ─── Main game area ───────────────────────────────────────────────────────── */
main {
  background: linear-gradient(145deg,
    rgba(8,14,28,0.98),
    rgba(12,18,36,0.98));
  border-radius: var(--radius-xl);
  border: 1px solid rgba(30,40,64,0.9);
  padding: 22px 16px 20px;
  box-shadow: var(--shadow-soft);
}

@media (min-width: 720px) {
  main { padding: 26px 22px 24px; }
}

.grid-header {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 12px;
  margin-bottom: 16px;
}

.grid-header h2 {
  margin: 0;
  font-family: 'Outfit', sans-serif;
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--text-muted);
}

.grid-header small {
  font-size: 0.8rem;
  color: var(--text-muted);
}

.game-menu { margin: 10px 0 18px; }
.game-menu .controls { margin: 0; }

/* ─── Game Grid & Cards ────────────────────────────────────────────────────── */
.game-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 12px;
}

@media (min-width: 640px) {
  .game-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

@media (min-width: 1000px) {
  .game-grid { grid-template-columns: repeat(3, minmax(0, 1fr)); }
}

.game-card {
  position: relative;
  overflow: hidden;
  border-radius: var(--radius-lg);
  border: 1px solid var(--border-soft);
  background: linear-gradient(145deg,
    rgba(9,13,26,0.97),
    rgba(14,20,40,0.98));
  padding: 16px 16px 14px;
  display: flex;
  flex-direction: column;
  gap: 8px;
  min-height: 145px;
  transition: transform var(--transition-med), box-shadow var(--transition-med),
              border-color var(--transition-med), background 0.24s ease;
}

.game-card::before {
  content: '';
  position: absolute;
  inset: -40%;
  background: radial-gradient(circle at top left, rgba(37,99,235,0.14), transparent 60%);
  opacity: 0;
  pointer-events: none;
  transition: opacity var(--transition-med);
}

.game-card:hover {
  transform: translateY(-3px);
  box-shadow: 0 16px 36px rgba(0,0,0,0.75);
  border-color: rgba(37,99,235,0.5);
  background: linear-gradient(145deg, rgba(12,18,34,1), rgba(18,26,50,1));
}

.game-card:hover::before { opacity: 1; }

.game-topic {
  font-family: 'Outfit', sans-serif;
  font-size: 0.7rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--text-muted);
}

.game-title {
  margin: 0;
  font-family: 'Outfit', system-ui, sans-serif;
  font-size: 1rem;
  font-weight: 700;
  color: var(--text-main);
}

.game-title span { color: var(--accent-2); }

.game-desc {
  margin: 0;
  font-size: 0.84rem;
  color: var(--text-muted);
  line-height: 1.5;
}

.tag-row {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin-top: 2px;
}

.tag {
  background: var(--tag-bg);
  border-radius: 6px;
  padding: 3px 8px;
  font-size: 0.7rem;
  font-weight: 600;
  color: var(--tag-text);
}

.tag.exam {
  background: rgba(37,99,235,0.15);
  color: #93c5fd;
  border: 1px solid rgba(37,99,235,0.35);
}

.card-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 8px;
  margin-top: auto;
  padding-top: 10px;
  border-top: 1px solid rgba(30,40,64,0.9);
}

.skill-text {
  font-size: 0.76rem;
  color: var(--text-muted);
  font-weight: 600;
}

.play-btn {
  border-radius: 8px;
  border: 1px solid rgba(37,99,235,0.4);
  padding: 7px 14px;
  font-size: 0.82rem;
  font-weight: 700;
  font-family: 'Nunito Sans', sans-serif;
  letter-spacing: 0.02em;
  background: var(--accent-soft);
  color: #93c5fd;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  gap: 5px;
  text-decoration: none;
  transition: background var(--transition-fast), color var(--transition-fast),
              transform 0.1s ease, border-color var(--transition-fast);
}

.play-btn span.icon { font-size: 0.88rem; }

.game-card:hover .play-btn {
  background: rgba(37,99,235,0.28);
  border-color: rgba(37,99,235,0.65);
  color: #fff;
  transform: translateY(-1px);
}

/* ─── Collapsible sections ─────────────────────────────────────────────────── */
.collapsible {
  margin: 18px 0;
  border: 1px solid var(--border-soft);
  border-radius: var(--radius-lg);
  background: rgba(0,0,0,0.1);
  overflow: hidden;
}

.collapsible-summary {
  display: grid;
  grid-template-columns: 1fr auto;
  grid-template-rows: auto auto;
  gap: 2px 10px;
  padding: 16px 18px;
  cursor: pointer;
  list-style: none;
}

.collapsible-summary::-webkit-details-marker { display: none; }

.collapsible-title {
  grid-column: 1 / 2;
  grid-row: 1;
  font-family: 'Outfit', sans-serif;
  font-weight: 800;
  font-size: 1.05rem;
  letter-spacing: 0.01em;
  color: #fff;
}

.collapsible-sub {
  grid-column: 1 / 2;
  grid-row: 2;
  font-size: 0.86rem;
  color: var(--text-muted);
}

.collapsible-chevron {
  grid-column: 2 / 3;
  grid-row: 1 / 3;
  align-self: center;
  font-size: 1rem;
  color: var(--text-muted);
  transition: transform 180ms ease;
}

.collapsible[open] .collapsible-chevron { transform: rotate(180deg); }
.collapsible-body { padding: 0 0 14px; }
.collapsible .game-menu { margin-top: 10px; }
.collapsible .game-grid { margin-top: 10px; }

/* ─── Topic guide section ──────────────────────────────────────────────────── */
.topic-section {
  margin-top: 32px;
  margin-bottom: 32px;
}

.topic-section-header {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 12px;
  margin-bottom: 18px;
}

.topic-section-header h2 {
  font-family: 'Outfit', sans-serif;
  font-size: 1rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--text-muted);
  margin: 0;
}

.topic-section-header .hint {
  font-size: 0.84rem;
  color: var(--text-muted);
}

.topic-layout {
  display: flex;
  flex-direction: column;
  gap: 14px;
}

.topic-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

.random-topic-btn {
  border-radius: 10px;
  border: none;
  padding: 9px 20px;
  font-size: 0.88rem;
  font-weight: 700;
  font-family: 'Nunito Sans', sans-serif;
  background: linear-gradient(135deg, #2563eb, #0ea5e9);
  color: #fff;
  display: inline-flex;
  align-items: center;
  gap: 6px;
  cursor: pointer;
  box-shadow: 0 4px 16px rgba(37,99,235,0.3);
  transition: transform 0.12s ease-out, box-shadow 0.12s ease-out, filter 0.12s ease-out;
}

.random-topic-btn .icon { font-size: 1rem; }

.random-topic-btn:hover {
  transform: translateY(-1px);
  filter: brightness(1.08);
  box-shadow: 0 8px 24px rgba(37,99,235,0.4);
}

/* ─── Topic Grid ───────────────────────────────────────────────────────────── */
.topic-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 8px;
}

@media (min-width: 900px) {
  .topic-grid { grid-template-columns: repeat(4, minmax(0, 1fr)); }
}

.topic-card {
  border-radius: 10px;
  border: 1px solid var(--border-soft);
  background: rgba(10,14,28,0.92);
  padding: 9px 14px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 8px;
  text-decoration: none;
  color: var(--text-main);
  font-size: 0.83rem;
  transition: background var(--transition-fast), border-color var(--transition-fast),
              transform var(--transition-fast), box-shadow var(--transition-fast);
}

.topic-card:hover,
.topic-card:focus-visible {
  background: rgba(37,99,235,0.12);
  border-color: rgba(37,99,235,0.45);
  transform: translateY(-1px);
  box-shadow: 0 6px 20px rgba(0,0,0,0.5);
  outline: none;
}

.topic-card-label {
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.topic-card-label span:first-child {
  font-family: 'Outfit', sans-serif;
  font-weight: 700;
  font-size: 0.82rem;
}

.topic-card-label span:last-child {
  font-size: 0.76rem;
  color: var(--text-muted);
}

.topic-number {
  font-family: 'Outfit', sans-serif;
  font-size: 0.76rem;
  font-weight: 700;
  padding: 3px 8px;
  border-radius: 6px;
  background: rgba(37,99,235,0.12);
  border: 1px solid rgba(37,99,235,0.2);
  color: #93c5fd;
  flex-shrink: 0;
}

/* ─── Footer ───────────────────────────────────────────────────────────────── */
footer {
  margin-top: 16px;
  text-align: center;
  font-size: 0.8rem;
  color: var(--text-muted);
}

.footer-note {
  margin-top: 4px;
  font-size: 0.74rem;
  opacity: 0.7;
}

.hint { opacity: 0.85; }
.hidden { display: none !important; }

/* ─── Homepage hero image ──────────────────────────────────────────────────── */
.homepage-hero {
  width: 100%;
  max-width: 1400px;
  margin: 0 auto 28px;
  border-radius: var(--radius-xl);
  overflow: hidden;
  border: 1px solid var(--border-soft);
  box-shadow: var(--shadow-soft);
}

.homepage-hero-img {
  display: block;
  width: 100%;
  height: auto;
}