/* ===========================
   ROOT & RESET
=========================== */
:root {
  --bg:       #0c0c0f;
  --bg2:      #13131a;
  --bg3:      #1a1a24;
  --border:   rgba(255,255,255,0.07);
  --border2:  rgba(255,255,255,0.12);
  --text:     #f4f3f0;
  --muted:    #6b6b80;
  --accent:   #c8ff57;
  --accent2:  #57c8ff;
  --danger:   #ff5757;
  --success:  #57ffb8;
  --warn:     #ffc857;
  --glow:     rgba(200,255,87,0.18);
  --radius:   18px;
  --font-disp: 'DM Serif Display', serif;
  --font-body: 'Outfit', sans-serif;
  --font-mono: 'DM Mono', monospace;
  --t: 0.25s cubic-bezier(0.4,0,0.2,1);
}

*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; }

body {
  background: var(--bg);
  color: var(--text);
  font-family: var(--font-body);
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
}

/* ===========================
   GRID BACKGROUND
=========================== */
.grid-bg {
  position: fixed;
  inset: 0;
  pointer-events: none;
  z-index: 0;
  background-image:
    linear-gradient(rgba(255,255,255,0.025) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255,255,255,0.025) 1px, transparent 1px);
  background-size: 48px 48px;
  mask-image: radial-gradient(ellipse 70% 70% at 50% 50%, black 40%, transparent 100%);
}

/* ===========================
   APP & SCREENS
=========================== */
.app {
  position: relative;
  z-index: 1;
  width: 100%;
  max-width: 560px;
  padding: 1.5rem;
}

.screen {
  display: none;
  animation: fadeSlide 0.4s cubic-bezier(0.34,1.2,0.64,1);
}

.screen.active { display: block; }

@keyframes fadeSlide {
  from { opacity: 0; transform: translateY(24px) scale(0.97); }
  to   { opacity: 1; transform: translateY(0)    scale(1); }
}

/* ===========================
   HOME SCREEN
=========================== */
.home-inner {
  background: var(--bg2);
  border: 1px solid var(--border2);
  border-radius: 28px;
  padding: 3rem 2.5rem;
  position: relative;
  overflow: hidden;
  box-shadow: 0 0 80px rgba(200,255,87,0.04), 0 32px 64px rgba(0,0,0,0.5);
}

.home-inner::before {
  content: '';
  position: absolute;
  top: -1px; left: 0; right: 0;
  height: 2px;
  background: linear-gradient(90deg, transparent, var(--accent), transparent);
}

.brand-tag {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  letter-spacing: 0.2em;
  color: var(--accent);
  margin-bottom: 1.2rem;
}

.home-title {
  font-family: var(--font-disp);
  font-size: 4rem;
  line-height: 1;
  letter-spacing: -1px;
  margin-bottom: 1rem;
  color: var(--text);
}

.home-title em {
  font-style: italic;
  color: var(--accent);
}

.home-sub {
  color: var(--muted);
  font-size: 0.9rem;
  line-height: 1.7;
  margin-bottom: 2rem;
  max-width: 340px;
}

/* Category Buttons */
.category-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 0.6rem;
  margin-bottom: 1.2rem;
}

.cat-btn {
  background: var(--bg3);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 0.65rem 0.3rem;
  font-family: var(--font-body);
  font-size: 0.78rem;
  font-weight: 600;
  color: var(--muted);
  cursor: pointer;
  transition: all var(--t);
  white-space: nowrap;
}

.cat-btn:hover  { border-color: var(--accent); color: var(--text); }
.cat-btn.active { background: rgba(200,255,87,0.1); border-color: var(--accent); color: var(--accent); }

/* Difficulty */
.difficulty-row {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  margin-bottom: 2rem;
}

.diff-label {
  font-size: 0.78rem;
  color: var(--muted);
  font-weight: 600;
  margin-right: 0.2rem;
}

.diff-btn {
  background: var(--bg3);
  border: 1px solid var(--border);
  border-radius: 100px;
  padding: 0.35rem 1rem;
  font-family: var(--font-body);
  font-size: 0.78rem;
  font-weight: 600;
  color: var(--muted);
  cursor: pointer;
  transition: all var(--t);
}

.diff-btn:hover  { border-color: var(--accent2); color: var(--text); }
.diff-btn.active { background: rgba(87,200,255,0.12); border-color: var(--accent2); color: var(--accent2); }

/* Start Button */
.start-btn {
  width: 100%;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.8rem;
  background: var(--accent);
  color: #0c0c0f;
  border: none;
  border-radius: var(--radius);
  padding: 1rem 2rem;
  font-family: var(--font-body);
  font-size: 1.05rem;
  font-weight: 700;
  cursor: pointer;
  transition: all var(--t);
  box-shadow: 0 0 32px rgba(200,255,87,0.25);
  margin-bottom: 2rem;
  letter-spacing: 0.02em;
}

.start-btn:hover {
  transform: translateY(-2px);
  box-shadow: 0 0 48px rgba(200,255,87,0.4);
}

.start-btn:active { transform: scale(0.97); }

.btn-arrow {
  font-size: 1.2rem;
  transition: transform var(--t);
}

.start-btn:hover .btn-arrow { transform: translateX(4px); }

/* Home Stats */
.home-stats {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  border-top: 1px solid var(--border);
  padding-top: 1.5rem;
  gap: 1rem;
}

.hs {
  text-align: center;
}

.hs span {
  display: block;
  font-family: var(--font-disp);
  font-size: 1.8rem;
  color: var(--accent);
  line-height: 1;
  margin-bottom: 0.3rem;
}

.hs small {
  font-size: 0.7rem;
  color: var(--muted);
  text-transform: uppercase;
  letter-spacing: 0.1em;
  font-family: var(--font-mono);
}

/* ===========================
   QUIZ SCREEN
=========================== */
.quiz-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 1rem;
}

.q-meta { display: flex; align-items: center; gap: 0.7rem; }

.q-num {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  color: var(--muted);
  font-weight: 500;
}

.q-cat-tag {
  font-size: 0.7rem;
  font-weight: 600;
  font-family: var(--font-mono);
  color: var(--accent2);
  border: 1px solid rgba(87,200,255,0.3);
  border-radius: 100px;
  padding: 0.2rem 0.7rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
}

.quiz-top-right {
  display: flex;
  align-items: center;
  gap: 0.8rem;
}

.score-live {
  font-size: 0.85rem;
  color: var(--muted);
  font-family: var(--font-mono);
}

.score-live strong { color: var(--text); }

.streak-badge {
  font-size: 0.8rem;
  font-weight: 700;
  background: rgba(255,200,87,0.1);
  border: 1px solid rgba(255,200,87,0.25);
  border-radius: 100px;
  padding: 0.2rem 0.7rem;
  color: var(--warn);
  font-family: var(--font-mono);
  transition: all var(--t);
}

.streak-badge.fire {
  background: rgba(255,200,87,0.2);
  box-shadow: 0 0 16px rgba(255,200,87,0.25);
}

/* Progress */
.progress-track {
  height: 3px;
  background: var(--bg3);
  border-radius: 100px;
  margin-bottom: 1.8rem;
  overflow: hidden;
}

.progress-fill {
  height: 100%;
  width: 0%;
  background: linear-gradient(90deg, var(--accent2), var(--accent));
  border-radius: 100px;
  transition: width 0.5s ease;
}

/* Timer */
.timer-wrap {
  position: relative;
  width: 80px;
  height: 80px;
  margin: 0 auto 1.5rem;
}

.timer-svg { width: 80px; height: 80px; transform: rotate(-90deg); }

.timer-bg {
  fill: none;
  stroke: var(--bg3);
  stroke-width: 5;
}

.timer-ring {
  fill: none;
  stroke: var(--accent);
  stroke-width: 5;
  stroke-linecap: round;
  stroke-dasharray: 213.6;
  stroke-dashoffset: 0;
  transition: stroke-dashoffset 1s linear, stroke 0.3s;
}

.timer-ring.warn  { stroke: var(--warn); }
.timer-ring.danger { stroke: var(--danger); }

.timer-text {
  position: absolute;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-mono);
  font-size: 1.4rem;
  font-weight: 500;
  color: var(--text);
}

/* Question Card */
.question-card {
  background: var(--bg2);
  border: 1px solid var(--border2);
  border-radius: var(--radius);
  padding: 2rem;
  margin-bottom: 1.2rem;
  min-height: 100px;
  display: flex;
  align-items: center;
  box-shadow: 0 8px 32px rgba(0,0,0,0.3);
  position: relative;
  overflow: hidden;
}

.question-card::before {
  content: '';
  position: absolute;
  top: -1px; left: 0; right: 0;
  height: 1px;
  background: linear-gradient(90deg, transparent, var(--accent2), transparent);
}

.question-text {
  font-family: var(--font-disp);
  font-size: 1.25rem;
  line-height: 1.5;
  color: var(--text);
}

/* Options */
.options-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0.75rem;
  margin-bottom: 1rem;
}

.option-btn {
  background: var(--bg2);
  border: 1px solid var(--border2);
  border-radius: var(--radius);
  padding: 1rem 1.2rem;
  font-family: var(--font-body);
  font-size: 0.9rem;
  font-weight: 500;
  color: var(--text);
  cursor: pointer;
  text-align: left;
  transition: all var(--t);
  display: flex;
  align-items: center;
  gap: 0.8rem;
  line-height: 1.4;
}

.option-btn:hover:not(:disabled) {
  border-color: var(--accent);
  background: rgba(200,255,87,0.05);
  transform: translateY(-2px);
  box-shadow: 0 8px 24px rgba(0,0,0,0.3);
}

.option-btn .opt-label {
  width: 26px;
  height: 26px;
  min-width: 26px;
  border-radius: 8px;
  background: var(--bg3);
  border: 1px solid var(--border2);
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-mono);
  font-size: 0.7rem;
  font-weight: 500;
  color: var(--muted);
  transition: all var(--t);
}

.option-btn:hover:not(:disabled) .opt-label {
  background: var(--accent);
  border-color: var(--accent);
  color: #0c0c0f;
}

.option-btn.correct {
  border-color: var(--success);
  background: rgba(87,255,184,0.08);
  color: var(--success);
}

.option-btn.correct .opt-label {
  background: var(--success);
  border-color: var(--success);
  color: #0c0c0f;
}

.option-btn.wrong {
  border-color: var(--danger);
  background: rgba(255,87,87,0.08);
  color: var(--danger);
}

.option-btn.wrong .opt-label {
  background: var(--danger);
  border-color: var(--danger);
  color: white;
}

.option-btn.revealed {
  opacity: 0.45;
}

.option-btn:disabled { cursor: default; }

/* Feedback Bar */
.feedback-bar {
  text-align: center;
  font-size: 0.85rem;
  font-weight: 600;
  font-family: var(--font-mono);
  min-height: 1.5rem;
  transition: all var(--t);
  padding: 0.5rem;
  border-radius: 10px;
}

.feedback-bar.correct-fb {
  color: var(--success);
  background: rgba(87,255,184,0.06);
}

.feedback-bar.wrong-fb {
  color: var(--danger);
  background: rgba(255,87,87,0.06);
}

.feedback-bar.timeout-fb {
  color: var(--warn);
  background: rgba(255,200,87,0.06);
}

/* ===========================
   RESULT SCREEN
=========================== */
.result-inner {
  background: var(--bg2);
  border: 1px solid var(--border2);
  border-radius: 28px;
  padding: 3rem 2.5rem;
  text-align: center;
  position: relative;
  overflow: hidden;
  box-shadow: 0 32px 64px rgba(0,0,0,0.5);
}

.result-inner::before {
  content: '';
  position: absolute;
  top: -1px; left: 0; right: 0;
  height: 2px;
  background: linear-gradient(90deg, transparent, var(--accent), transparent);
}

.result-emoji {
  font-size: 3.5rem;
  margin-bottom: 0.8rem;
  animation: bounce 0.6s cubic-bezier(0.34,1.56,0.64,1);
}

@keyframes bounce {
  from { transform: scale(0) rotate(-15deg); }
  to   { transform: scale(1) rotate(0deg); }
}

.result-title {
  font-family: var(--font-disp);
  font-size: 2rem;
  margin-bottom: 2rem;
  color: var(--text);
}

/* Score Ring */
.result-score-ring {
  position: relative;
  width: 140px;
  height: 140px;
  margin: 0 auto 2rem;
}

.result-score-ring svg {
  width: 140px;
  height: 140px;
  transform: rotate(-90deg);
}

.rs-bg {
  fill: none;
  stroke: var(--bg3);
  stroke-width: 8;
}

.rs-fill {
  fill: none;
  stroke: var(--accent);
  stroke-width: 8;
  stroke-linecap: round;
  stroke-dasharray: 314.2;
  stroke-dashoffset: 314.2;
  transition: stroke-dashoffset 1.2s cubic-bezier(0.4,0,0.2,1);
}

.rs-inner {
  position: absolute;
  inset: 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
}

.rs-num {
  font-family: var(--font-disp);
  font-size: 3rem;
  line-height: 1;
  color: var(--accent);
}

.rs-label {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--muted);
}

/* Result Stats */
.result-stats {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1rem;
  margin-bottom: 2rem;
}

.rs-stat span {
  display: block;
  font-family: var(--font-disp);
  font-size: 1.6rem;
  color: var(--text);
  margin-bottom: 0.2rem;
}

.rs-stat small {
  font-size: 0.7rem;
  color: var(--muted);
  text-transform: uppercase;
  letter-spacing: 0.1em;
  font-family: var(--font-mono);
}

/* Breakdown */
.result-breakdown {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  margin-bottom: 2rem;
  max-height: 180px;
  overflow-y: auto;
  text-align: left;
  scrollbar-width: thin;
  scrollbar-color: var(--border2) transparent;
}

.bd-item {
  display: flex;
  align-items: flex-start;
  gap: 0.7rem;
  padding: 0.7rem 0.9rem;
  border-radius: 12px;
  font-size: 0.8rem;
  line-height: 1.4;
}

.bd-item.correct { background: rgba(87,255,184,0.05); border: 1px solid rgba(87,255,184,0.12); }
.bd-item.wrong   { background: rgba(255,87,87,0.05);  border: 1px solid rgba(255,87,87,0.12); }

.bd-icon { font-size: 0.9rem; margin-top: 1px; flex-shrink: 0; }
.bd-q    { color: var(--muted); }
.bd-a    { font-weight: 600; color: var(--text); }

/* Action Buttons */
.result-actions {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0.75rem;
}

.action-btn {
  padding: 0.9rem 1.5rem;
  border-radius: var(--radius);
  font-family: var(--font-body);
  font-size: 0.95rem;
  font-weight: 700;
  cursor: pointer;
  transition: all var(--t);
  border: 2px solid transparent;
}

.action-btn.primary {
  background: var(--accent);
  color: #0c0c0f;
  box-shadow: 0 0 24px rgba(200,255,87,0.2);
}

.action-btn.primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 0 40px rgba(200,255,87,0.35);
}

.action-btn.ghost {
  background: transparent;
  border-color: var(--border2);
  color: var(--muted);
}

.action-btn.ghost:hover {
  border-color: var(--text);
  color: var(--text);
}

/* ===========================
   RESPONSIVE
=========================== */
@media (max-width: 500px) {
  .home-inner, .result-inner { padding: 2rem 1.5rem; }
  .home-title { font-size: 3rem; }
  .category-grid { grid-template-columns: repeat(2, 1fr); }
  .options-grid { grid-template-columns: 1fr; }
  .result-stats { grid-template-columns: repeat(3, 1fr); }
}