:root {
  --bg: #0a0e1a;
  --bg-2: #0f1525;
  --panel: #131a2e;
  --panel-2: #1a2340;
  --line: #243056;
  --ink: #e8edf7;
  --ink-dim: #8593b8;
  --ink-faint: #4d5a82;
  --gold: #d4a64a;
  --gold-2: #e8c378;
  --blue: #4a8fd4;
  --blue-2: #6fb0ec;
  --red: #e34a4a;
  --green: #4ad48b;
  --stripe-tan: #c9b896;
  --stripe-teal: #6dc9c9;
  --stripe-orange: #e8722f;
  --stripe-grey: #6e7381;
}

* { box-sizing: border-box; margin: 0; padding: 0; }
html, body { height: 100%; }
body {
  background: var(--bg);
  color: var(--ink);
  font-family: 'JetBrains Mono', monospace;
  font-size: 14px;
  line-height: 1.5;
  overflow-x: hidden;
  background-image:
    radial-gradient(ellipse 1200px 600px at 80% -10%, rgba(74, 143, 212, 0.08), transparent),
    radial-gradient(ellipse 800px 400px at -10% 110%, rgba(212, 166, 74, 0.06), transparent);
}

/* Grain overlay */
body::before {
  content: '';
  position: fixed;
  inset: 0;
  pointer-events: none;
  z-index: 1;
  opacity: 0.035;
  background-image: url("data:image/svg+xml,%3Csvg viewBox='0 0 200 200' xmlns='http://www.w3.org/2000/svg'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.85' numOctaves='3'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23n)'/%3E%3C/svg%3E");
}

/* HEADER */
header {
  position: relative;
  z-index: 5;
  border-bottom: 1px solid var(--line);
  background: linear-gradient(180deg, var(--bg-2), var(--bg));
  padding: 28px 40px 0;
}

.stripes {
  display: flex;
  height: 6px;
  margin-bottom: 24px;
  border-radius: 1px;
  overflow: hidden;
}
.stripes div { flex: 1; }
.stripes div:nth-child(1) { background: var(--stripe-tan); }
.stripes div:nth-child(2) { background: var(--stripe-teal); flex: 1.4; }
.stripes div:nth-child(3) { background: var(--stripe-orange); flex: 1.6; }
.stripes div:nth-child(4) { background: var(--stripe-grey); flex: 1.8; }

.head-row {
  display: flex;
  align-items: flex-end;
  justify-content: space-between;
  gap: 24px;
  flex-wrap: wrap;
  padding-bottom: 24px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 18px;
}

.badge {
  width: 56px;
  height: 64px;
  background: var(--ink);
  color: var(--bg);
  clip-path: polygon(50% 0%, 100% 18%, 100% 78%, 50% 100%, 0% 78%, 0% 18%);
  display: grid;
  place-items: center;
  font-family: 'Bebas Neue', sans-serif;
  font-size: 11px;
  letter-spacing: 0.1em;
  line-height: 1;
  text-align: center;
  box-shadow: 0 4px 16px rgba(0,0,0,0.4);
}

h1 {
  font-family: 'Bebas Neue', sans-serif;
  font-size: 38px;
  letter-spacing: 0.04em;
  line-height: 0.95;
  color: var(--ink);
}
h1 small {
  display: block;
  font-family: 'JetBrains Mono', monospace;
  font-size: 11px;
  font-weight: 400;
  letter-spacing: 0.3em;
  color: var(--gold);
  margin-top: 6px;
}

.stats {
  display: flex;
  gap: 18px;
  font-size: 11px;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  color: var(--ink-dim);
}
.stats div { text-align: right; }
.stats strong {
  display: block;
  font-family: 'Bebas Neue', sans-serif;
  font-size: 28px;
  font-weight: 400;
  color: var(--gold);
  letter-spacing: 0.02em;
  line-height: 1;
  margin-bottom: 2px;
}

/* CATEGORY NAV */
.cat-nav {
  display: flex;
  gap: 0;
  padding: 0 40px;
  background: var(--bg-2);
  border-bottom: 1px solid var(--line);
  overflow-x: auto;
  position: sticky;
  top: 0;
  z-index: 4;
  backdrop-filter: blur(12px);
}
.cat-btn {
  background: none;
  border: none;
  color: var(--ink-dim);
  font-family: 'JetBrains Mono', monospace;
  font-size: 12px;
  font-weight: 500;
  letter-spacing: 0.1em;
  padding: 16px 22px;
  cursor: pointer;
  text-transform: uppercase;
  position: relative;
  white-space: nowrap;
  transition: color 0.2s;
  border-bottom: 2px solid transparent;
}
.cat-btn:hover { color: var(--ink); }
.cat-btn.active {
  color: var(--gold);
  border-bottom-color: var(--gold);
}
.cat-btn .count {
  color: var(--ink-faint);
  margin-left: 6px;
  font-size: 10px;
}
.cat-btn .icon {
  margin-right: 6px;
  opacity: 0.7;
}

/* MAIN */
main {
  position: relative;
  z-index: 2;
  padding: 40px;
  max-width: 1300px;
  margin: 0 auto;
  min-height: 60vh;
}

/* MODE SWITCHER */
.modes {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 14px;
  margin-bottom: 36px;
}
.mode-card {
  background: var(--panel);
  border: 1px solid var(--line);
  padding: 20px 22px;
  cursor: pointer;
  text-align: left;
  transition: all 0.2s;
  color: var(--ink);
  font-family: inherit;
  position: relative;
  overflow: hidden;
}
.mode-card::before {
  content: '';
  position: absolute;
  top: 0; left: 0;
  width: 4px;
  height: 100%;
  background: var(--gold);
  transform: scaleY(0);
  transform-origin: bottom;
  transition: transform 0.3s;
}
.mode-card:hover { border-color: var(--gold); background: var(--panel-2); }
.mode-card.active { border-color: var(--gold); background: var(--panel-2); }
.mode-card.active::before { transform: scaleY(1); }
.mode-card .num {
  font-family: 'Bebas Neue', sans-serif;
  font-size: 13px;
  color: var(--ink-faint);
  letter-spacing: 0.2em;
}
.mode-card .name {
  font-family: 'Bebas Neue', sans-serif;
  font-size: 24px;
  letter-spacing: 0.05em;
  margin: 6px 0 4px;
}
.mode-card .desc {
  font-size: 11px;
  color: var(--ink-dim);
  letter-spacing: 0.05em;
}

/* SECTION TITLE */
.section-title {
  font-family: 'Bebas Neue', sans-serif;
  font-size: 14px;
  letter-spacing: 0.3em;
  color: var(--gold);
  margin-bottom: 14px;
  display: flex;
  align-items: center;
  gap: 12px;
}
.section-title::after {
  content: '';
  flex: 1;
  height: 1px;
  background: linear-gradient(90deg, var(--line), transparent);
}

/* FLASHCARDS */
.fc-stage {
  perspective: 1500px;
  margin-bottom: 24px;
}
.flashcard {
  position: relative;
  width: 100%;
  min-height: 380px;
  transform-style: preserve-3d;
  transition: transform 0.6s cubic-bezier(0.4, 0, 0.2, 1);
  cursor: pointer;
}
.flashcard.flipped { transform: rotateY(180deg); }
.fc-face {
  position: absolute;
  inset: 0;
  backface-visibility: hidden;
  background: var(--panel);
  border: 1px solid var(--line);
  padding: 40px;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  text-align: center;
  overflow: auto;
}
.fc-back {
  transform: rotateY(180deg);
  background: linear-gradient(135deg, var(--panel-2), var(--panel));
  border-color: var(--gold);
}
.fc-label {
  font-size: 10px;
  letter-spacing: 0.3em;
  color: var(--ink-faint);
  text-transform: uppercase;
  position: absolute;
  top: 18px;
  left: 24px;
}
.fc-back .fc-label { color: var(--gold); }
.fc-face .term {
  font-family: 'Fraunces', serif;
  font-size: 32px;
  font-weight: 600;
  line-height: 1.2;
  max-width: 700px;
}
.fc-back .term {
  font-size: 16px;
  line-height: 1.6;
  color: var(--ink);
  font-family: 'JetBrains Mono', monospace;
  font-weight: 400;
  max-width: 800px;
}
.fc-meta {
  position: absolute;
  bottom: 18px;
  right: 24px;
  font-size: 10px;
  letter-spacing: 0.2em;
  color: var(--ink-faint);
}

.fc-controls {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
}
.nav-btn {
  background: var(--panel);
  border: 1px solid var(--line);
  color: var(--ink);
  padding: 12px 20px;
  cursor: pointer;
  font-family: inherit;
  font-size: 12px;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  transition: all 0.2s;
}
.nav-btn:hover:not(:disabled) {
  border-color: var(--gold);
  color: var(--gold);
}
.nav-btn:disabled { opacity: 0.4; cursor: not-allowed; }
.progress-text {
  font-size: 11px;
  letter-spacing: 0.2em;
  color: var(--ink-dim);
}
.progress-text strong { color: var(--gold); font-family: 'Bebas Neue'; font-size: 18px; }

.progress-bar {
  height: 2px;
  background: var(--line);
  margin-top: 16px;
  overflow: hidden;
}
.progress-fill {
  height: 100%;
  background: var(--gold);
  transition: width 0.3s;
}

/* QUIZ */
.quiz-card {
  background: var(--panel);
  border: 1px solid var(--line);
  padding: 36px;
  margin-bottom: 18px;
}
.q-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 22px;
  padding-bottom: 14px;
  border-bottom: 1px dashed var(--line);
}
.q-num {
  font-family: 'Bebas Neue';
  font-size: 14px;
  letter-spacing: 0.2em;
  color: var(--gold);
}
.q-score {
  font-size: 11px;
  letter-spacing: 0.15em;
  color: var(--ink-dim);
}
.q-text {
  font-family: 'Fraunces', serif;
  font-size: 22px;
  font-weight: 600;
  line-height: 1.4;
  margin-bottom: 26px;
  white-space: pre-wrap;
}
.q-options {
  display: grid;
  gap: 10px;
}
.q-opt {
  background: var(--bg-2);
  border: 1px solid var(--line);
  padding: 16px 20px;
  cursor: pointer;
  text-align: left;
  color: var(--ink);
  font-family: inherit;
  font-size: 13px;
  line-height: 1.5;
  transition: all 0.2s;
  display: flex;
  gap: 14px;
  align-items: flex-start;
}
.q-opt:hover:not(:disabled) {
  border-color: var(--gold);
  background: var(--panel-2);
}
.q-opt .letter {
  font-family: 'Bebas Neue';
  font-size: 18px;
  color: var(--gold);
  letter-spacing: 0.05em;
  min-width: 22px;
}
.q-opt.correct {
  border-color: var(--green);
  background: rgba(74, 212, 139, 0.1);
}
.q-opt.correct .letter { color: var(--green); }
.q-opt.wrong {
  border-color: var(--red);
  background: rgba(227, 74, 74, 0.1);
}
.q-opt.wrong .letter { color: var(--red); }
.q-opt:disabled { cursor: default; }

.q-feedback {
  margin-top: 18px;
  padding: 14px 18px;
  border-left: 3px solid var(--gold);
  background: var(--bg-2);
  font-size: 12px;
  color: var(--ink-dim);
  line-height: 1.6;
  display: none;
}
.q-feedback.show { display: block; }
.q-feedback strong { color: var(--gold); }

.quiz-summary {
  text-align: center;
  padding: 60px 40px;
  background: var(--panel);
  border: 1px solid var(--gold);
}
.quiz-summary .pct {
  font-family: 'Bebas Neue';
  font-size: 96px;
  color: var(--gold);
  line-height: 1;
  letter-spacing: 0.02em;
}
.quiz-summary .label {
  font-size: 12px;
  letter-spacing: 0.3em;
  color: var(--ink-dim);
  margin-bottom: 24px;
}
.quiz-summary .verdict {
  font-family: 'Fraunces', serif;
  font-size: 22px;
  font-weight: 600;
  margin-bottom: 8px;
}
.quiz-summary .breakdown {
  font-size: 12px;
  color: var(--ink-dim);
  margin-bottom: 32px;
  letter-spacing: 0.1em;
}

/* MATCHING */
.match-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 14px;
  margin-bottom: 24px;
}
.match-col {
  display: grid;
  gap: 8px;
}
.match-col h3 {
  font-family: 'Bebas Neue';
  font-size: 14px;
  letter-spacing: 0.25em;
  color: var(--gold);
  margin-bottom: 4px;
}
.match-item {
  background: var(--panel);
  border: 1px solid var(--line);
  padding: 14px 16px;
  cursor: pointer;
  font-size: 13px;
  line-height: 1.5;
  transition: all 0.2s;
  color: var(--ink);
  font-family: inherit;
  text-align: left;
}
.match-item:hover:not(:disabled) {
  border-color: var(--gold);
  background: var(--panel-2);
}
.match-item.selected {
  border-color: var(--gold);
  background: var(--panel-2);
  color: var(--gold);
}
.match-item.matched {
  border-color: var(--green);
  background: rgba(74, 212, 139, 0.08);
  color: var(--ink-dim);
  cursor: default;
  opacity: 0.6;
}
.match-item.flash-wrong {
  animation: shake 0.4s;
  border-color: var(--red);
}
@keyframes shake {
  0%, 100% { transform: translateX(0); }
  25% { transform: translateX(-6px); }
  75% { transform: translateX(6px); }
}

.match-status {
  text-align: center;
  font-size: 12px;
  letter-spacing: 0.2em;
  color: var(--ink-dim);
  margin-bottom: 18px;
}
.match-status strong { color: var(--gold); font-family: 'Bebas Neue'; font-size: 16px; }

/* BROWSE */
.browse-list {
  display: grid;
  gap: 10px;
}
.browse-item {
  background: var(--panel);
  border: 1px solid var(--line);
  padding: 18px 22px;
  display: grid;
  grid-template-columns: 1fr 2fr;
  gap: 24px;
  transition: border-color 0.2s;
}
.browse-item:hover { border-color: var(--gold); }
.browse-term {
  font-family: 'Fraunces', serif;
  font-weight: 600;
  font-size: 16px;
  color: var(--gold);
}
.browse-def { font-size: 13px; line-height: 1.6; color: var(--ink-dim); }

.search-bar {
  width: 100%;
  background: var(--panel);
  border: 1px solid var(--line);
  color: var(--ink);
  padding: 12px 18px;
  font-family: inherit;
  font-size: 13px;
  letter-spacing: 0.05em;
  margin-bottom: 18px;
  outline: none;
  transition: border-color 0.2s;
}
.search-bar:focus { border-color: var(--gold); }
.search-bar::placeholder { color: var(--ink-faint); letter-spacing: 0.15em; text-transform: uppercase; font-size: 11px; }

/* button row */
.action-row {
  display: flex;
  gap: 10px;
  margin-bottom: 24px;
  flex-wrap: wrap;
}
.btn-primary {
  background: var(--gold);
  border: 1px solid var(--gold);
  color: var(--bg);
  padding: 12px 22px;
  cursor: pointer;
  font-family: inherit;
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  transition: all 0.2s;
}
.btn-primary:hover { background: var(--gold-2); border-color: var(--gold-2); }
.btn-ghost {
  background: transparent;
  border: 1px solid var(--line);
  color: var(--ink-dim);
  padding: 12px 22px;
  cursor: pointer;
  font-family: inherit;
  font-size: 11px;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  transition: all 0.2s;
}
.btn-ghost:hover { border-color: var(--gold); color: var(--gold); }

/* footer */
footer {
  border-top: 1px solid var(--line);
  padding: 24px 40px;
  margin-top: 60px;
  color: var(--ink-faint);
  font-size: 10px;
  letter-spacing: 0.25em;
  text-transform: uppercase;
  text-align: center;
}

/* responsive */
@media (max-width: 720px) {
  header { padding: 20px 20px 0; }
  main { padding: 24px 20px; }
  h1 { font-size: 28px; }
  .modes { grid-template-columns: 1fr; }
  .match-grid { grid-template-columns: 1fr; }
  .browse-item { grid-template-columns: 1fr; gap: 8px; }
  .cat-nav { padding: 0 20px; }
  .cat-btn { padding: 14px 14px; font-size: 11px; }
  .quiz-summary .pct { font-size: 64px; }
  .fc-face .term { font-size: 22px; }
  .q-text { font-size: 18px; }
}

/* scrollbar */
::-webkit-scrollbar { width: 10px; height: 10px; }
::-webkit-scrollbar-track { background: var(--bg); }
::-webkit-scrollbar-thumb { background: var(--line); border: 2px solid var(--bg); }
::-webkit-scrollbar-thumb:hover { background: var(--gold); }