/* ═══════════════════════════════════════════════
   MATH ARENA – DESIGN SYSTEM v3 (Professional)
   ═══════════════════════════════════════════════ */

:root {
  /* Typography */
  --font-sans: 'Inter', system-ui, -apple-system, sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', monospace;
  /* Radii */
  --radius: 14px;
  --radius-sm: 8px;
  --radius-xs: 6px;
  /* Easing */
  --ease: cubic-bezier(0.4, 0, 0.2, 1);
  --spring: cubic-bezier(0.34, 1.56, 0.64, 1);
}

:root[data-theme="dark"],
:root:not([data-theme]) {
  /* Surfaces */
  --bg-primary: #0b0f1a;
  --bg-secondary: #111827;
  --bg-card: rgba(17, 24, 39, 0.55);
  --bg-card-border: rgba(99, 102, 241, 0.1);
  --bg-card-hover: rgba(99, 102, 241, 0.18);
  /* Accent */
  --accent: #818cf8;
  --accent-bright: #a5b4fc;
  --accent-glow: rgba(129, 140, 248, 0.25);
  --accent-gradient: linear-gradient(135deg, #818cf8 0%, #a78bfa 60%, #c084fc 100%);
  /* Text */
  --text-primary: #f1f5f9;
  --text-secondary: #94a3b8;
  --text-muted: #506080;
  /* Feedback */
  --correct: #34d399;
  --correct-glow: rgba(52, 211, 153, 0.25);
  --warn: #fbbf24;
  --danger: #f87171;
  /* Ambient */
  --ambient-1: rgba(129, 140, 248, 0.06);
  --ambient-2: rgba(167, 139, 250, 0.04);
}

:root[data-theme="midnight"] {
  --bg-primary: #040914;
  --bg-secondary: #0a1128;
  --bg-card: rgba(10, 17, 40, 0.55);
  --bg-card-border: rgba(45, 120, 230, 0.15);
  --bg-card-hover: rgba(45, 120, 230, 0.25);
  --accent: #3b82f6;
  --accent-bright: #60a5fa;
  --accent-glow: rgba(59, 130, 246, 0.25);
  --accent-gradient: linear-gradient(135deg, #3b82f6 0%, #2563eb 60%, #1d4ed8 100%);
  --text-primary: #f8fafc;
  --text-secondary: #94a3b8;
  --text-muted: #475569;
  --correct: #10b981;
  --correct-glow: rgba(16, 185, 129, 0.25);
  --warn: #fbbf24;
  --danger: #ef4444;
  --ambient-1: rgba(59, 130, 246, 0.06);
  --ambient-2: rgba(37, 99, 235, 0.04);
}

:root[data-theme="ocean"] {
  --bg-primary: #001219;
  --bg-secondary: #005f73;
  --bg-card: rgba(0, 95, 115, 0.25);
  --bg-card-border: rgba(10, 147, 150, 0.15);
  --bg-card-hover: rgba(10, 147, 150, 0.25);
  --accent: #0a9396;
  --accent-bright: #94d2bd;
  --accent-glow: rgba(10, 147, 150, 0.25);
  --accent-gradient: linear-gradient(135deg, #0a9396 0%, #005f73 60%, #001219 100%);
  --text-primary: #cae9ff;
  --text-secondary: #94d2bd;
  --text-muted: #6495a0;
  --correct: #e9d8a6;
  --correct-glow: rgba(233, 216, 166, 0.25);
  --warn: #ee9b00;
  --danger: #ae2012;
  --ambient-1: rgba(10, 147, 150, 0.08);
  --ambient-2: rgba(148, 210, 189, 0.05);
}

:root[data-theme="sunset"] {
  --bg-primary: #210b05;
  --bg-secondary: #3b0918;
  --bg-card: rgba(59, 9, 24, 0.55);
  --bg-card-border: rgba(239, 68, 68, 0.15);
  --bg-card-hover: rgba(239, 68, 68, 0.25);
  --accent: #f97316;
  --accent-bright: #fb923c;
  --accent-glow: rgba(249, 115, 22, 0.25);
  --accent-gradient: linear-gradient(135deg, #f97316 0%, #ef4444 60%, #b91c1c 100%);
  --text-primary: #fff1f2;
  --text-secondary: #fecdd3;
  --text-muted: #881337;
  --correct: #4ade80;
  --correct-glow: rgba(74, 222, 128, 0.25);
  --warn: #facc15;
  --danger: #ef4444;
  --ambient-1: rgba(249, 115, 22, 0.08);
  --ambient-2: rgba(239, 68, 68, 0.06);
}

:root[data-theme="light"] {
  --bg-primary: #f8fafc;
  --bg-secondary: #e2e8f0;
  --bg-card: rgba(255, 255, 255, 0.85);
  --bg-card-border: rgba(148, 163, 184, 0.3);
  --bg-card-hover: rgba(99, 102, 241, 0.4);
  --accent: #4f46e5;
  --accent-bright: #6366f1;
  --accent-glow: rgba(79, 70, 229, 0.2);
  --accent-gradient: linear-gradient(135deg, #4f46e5 0%, #6366f1 60%, #818cf8 100%);
  --text-primary: #0f172a;
  --text-secondary: #334155;
  --text-muted: #64748b;
  --correct: #10b981;
  --correct-glow: rgba(16, 185, 129, 0.25);
  --warn: #f59e0b;
  --danger: #ef4444;
  --ambient-1: rgba(79, 70, 229, 0.04);
  --ambient-2: rgba(99, 102, 241, 0.02);
}

:root[data-theme="mint"] {
  --bg-primary: #f0fdf4;
  --bg-secondary: #dcfce7;
  --bg-card: rgba(255, 255, 255, 0.85);
  --bg-card-border: rgba(16, 185, 129, 0.2);
  --bg-card-hover: rgba(16, 185, 129, 0.35);
  --accent: #10b981;
  --accent-bright: #34d399;
  --accent-glow: rgba(16, 185, 129, 0.2);
  --accent-gradient: linear-gradient(135deg, #10b981 0%, #34d399 60%, #6ee7b7 100%);
  --text-primary: #064e3b;
  --text-secondary: #065f46;
  --text-muted: #115e59;
  --correct: #3b82f6;
  --correct-glow: rgba(59, 130, 246, 0.25);
  --warn: #f59e0b;
  --danger: #ef4444;
  --ambient-1: rgba(16, 185, 129, 0.04);
  --ambient-2: rgba(52, 211, 153, 0.03);
}

:root[data-theme="peach"] {
  --bg-primary: #fff1f2;
  --bg-secondary: #ffe4e6;
  --bg-card: rgba(255, 255, 255, 0.85);
  --bg-card-border: rgba(244, 63, 94, 0.2);
  --bg-card-hover: rgba(244, 63, 94, 0.35);
  --accent: #f43f5e;
  --accent-bright: #fb7185;
  --accent-glow: rgba(244, 63, 94, 0.2);
  --accent-gradient: linear-gradient(135deg, #f43f5e 0%, #fb7185 60%, #fda4af 100%);
  --text-primary: #4c0519;
  --text-secondary: #881337;
  --text-muted: #9f1239;
  --correct: #10b981;
  --correct-glow: rgba(16, 185, 129, 0.25);
  --warn: #f59e0b;
  --danger: #ef4444;
  --ambient-1: rgba(244, 63, 94, 0.04);
  --ambient-2: rgba(251, 113, 133, 0.03);
}

:root[data-theme="lavender"] {
  --bg-primary: #faf5ff;
  --bg-secondary: #f3e8ff;
  --bg-card: rgba(255, 255, 255, 0.85);
  --bg-card-border: rgba(139, 92, 246, 0.2);
  --bg-card-hover: rgba(139, 92, 246, 0.35);
  --accent: #8b5cf6;
  --accent-bright: #a78bfa;
  --accent-glow: rgba(139, 92, 246, 0.2);
  --accent-gradient: linear-gradient(135deg, #8b5cf6 0%, #a78bfa 60%, #c4b5fd 100%);
  --text-primary: #2e1065;
  --text-secondary: #4c1d95;
  --text-muted: #5b21b6;
  --correct: #10b981;
  --correct-glow: rgba(16, 185, 129, 0.25);
  --warn: #f59e0b;
  --danger: #ef4444;
  --ambient-1: rgba(139, 92, 246, 0.04);
  --ambient-2: rgba(167, 139, 250, 0.03);
}

:root[data-theme="frost"] {
  --bg-primary: #f0f9ff;
  --bg-secondary: #e0f2fe;
  --bg-card: rgba(255, 255, 255, 0.85);
  --bg-card-border: rgba(14, 165, 233, 0.2);
  --bg-card-hover: rgba(14, 165, 233, 0.35);
  --accent: #0ea5e9;
  --accent-bright: #38bdf8;
  --accent-glow: rgba(14, 165, 233, 0.2);
  --accent-gradient: linear-gradient(135deg, #0ea5e9 0%, #38bdf8 60%, #7dd3fc 100%);
  --text-primary: #082f49;
  --text-secondary: #0c4a6e;
  --text-muted: #0369a1;
  --correct: #10b981;
  --correct-glow: rgba(16, 185, 129, 0.25);
  --warn: #f59e0b;
  --danger: #ef4444;
  --ambient-1: rgba(14, 165, 233, 0.04);
  --ambient-2: rgba(56, 189, 248, 0.03);
}

/* ── Reset ── */
*,
*::before,
*::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  font-size: 16px;
}

body {
  font-family: var(--font-sans);
  background: var(--bg-primary);
  color: var(--text-primary);
  min-height: 100vh;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* Ambient light */
body::before {
  content: '';
  position: fixed;
  inset: 0;
  background:
    radial-gradient(ellipse 650px 450px at 25% 25%, var(--ambient-1) 0%, transparent 70%),
    radial-gradient(ellipse 500px 400px at 75% 75%, var(--ambient-2) 0%, transparent 70%);
  pointer-events: none;
  z-index: 0;
}

.particles-canvas {
  position: fixed;
  inset: 0;
  pointer-events: none;
  z-index: 50;
}

/* ── Views ── */
.view {
  display: none;
  min-height: 100vh;
  position: relative;
  z-index: 1;
}

.view.active {
  display: flex;
  align-items: center;
  justify-content: center;
  animation: viewIn 0.5s var(--ease);
}

@keyframes viewIn {
  from {
    opacity: 0;
    transform: translateY(12px);
  }

  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* ── Glass Card ── */
.glass-card {
  background: var(--bg-card);
  backdrop-filter: blur(24px);
  -webkit-backdrop-filter: blur(24px);
  border: 1px solid var(--bg-card-border);
  border-radius: var(--radius);
  padding: 24px;
  transition: border-color 0.3s var(--ease), box-shadow 0.3s var(--ease);
}

.glass-card:hover {
  border-color: var(--bg-card-hover);
}

/* ── Buttons ── */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 13px 28px;
  border: none;
  border-radius: var(--radius-sm);
  font-family: var(--font-sans);
  font-weight: 600;
  font-size: 0.92rem;
  cursor: pointer;
  transition: all 0.2s var(--ease);
  outline: none;
  letter-spacing: 0.01em;
}

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

.btn-primary {
  background: var(--accent-gradient);
  color: #fff;
  box-shadow: 0 2px 16px var(--accent-glow);
}

.btn-primary:hover {
  box-shadow: 0 4px 24px rgba(129, 140, 248, 0.4);
  transform: translateY(-1px);
}

.btn-ghost {
  background: transparent;
  color: var(--text-secondary);
  border: 1px solid rgba(148, 163, 184, 0.15);
}

.btn-ghost:hover {
  color: var(--text-primary);
  background: rgba(255, 255, 255, 0.04);
  border-color: rgba(148, 163, 184, 0.3);
}

.btn-sm {
  padding: 8px 16px;
  font-size: 0.82rem;
}

/* Link button (inline text button) */
.link-btn {
  background: none;
  border: none;
  color: var(--accent);
  font-family: var(--font-sans);
  font-size: 0.82rem;
  font-weight: 600;
  cursor: pointer;
  padding: 4px 0;
  opacity: 0.8;
  transition: opacity 0.2s;
}

.link-btn:hover {
  opacity: 1;
}

/* ── Chips ── */
.chip-group {
  display: flex;
  gap: 6px;
  flex-wrap: wrap;
}

.chip {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 7px 16px;
  border-radius: 999px;
  border: 1px solid rgba(148, 163, 184, 0.12);
  background: rgba(255, 255, 255, 0.02);
  color: var(--text-muted);
  font-family: var(--font-sans);
  font-size: 0.82rem;
  font-weight: 500;
  cursor: pointer;
  transition: all 0.2s var(--ease);
  letter-spacing: 0.02em;
}

.theme-dot {
  display: inline-block;
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background-color: var(--chip-color, transparent);
  box-shadow: 0 0 8px var(--chip-color, transparent);
  opacity: 0.6;
  transition: opacity 0.2s;
}

.chip:hover .theme-dot {
  opacity: 0.8;
}

.chip.active .theme-dot {
  opacity: 1;
}

.chip:hover {
  border-color: rgba(148, 163, 184, 0.3);
  color: var(--text-secondary);
}

.chip.active {
  background: rgba(129, 140, 248, 0.12);
  border-color: rgba(129, 140, 248, 0.3);
  color: var(--accent-bright);
}

/* ═══════════════════════════════════════════════
   LANDING
   ═══════════════════════════════════════════════ */
.landing-container {
  width: 100%;
  max-width: 440px;
  padding: 48px 24px;
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.landing-header {
  text-align: center;
  margin-bottom: 4px;
}

.logo {
  font-size: 2.6rem;
  font-weight: 900;
  letter-spacing: -1.5px;
  line-height: 1;
}

.logo-accent {
  background: var(--accent-gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.tagline {
  color: var(--text-muted);
  font-size: 0.95rem;
  font-weight: 400;
  margin-top: 6px;
  letter-spacing: 0.02em;
}

/* Card header with inline link */
.card-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 16px;
}

.card-header .card-title {
  margin-bottom: 0;
}

.card-title {
  font-size: 0.72rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 1.8px;
  color: var(--text-muted);
  margin-bottom: 16px;
}

/* Stats Grid */
.stats-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 8px;
  text-align: center;
}

.stat-item {
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.stat-value {
  font-family: var(--font-mono);
  font-size: 1.8rem;
  font-weight: 700;
  color: var(--text-primary);
  line-height: 1.2;
}

.stat-value--accent {
  color: var(--accent-bright);
}

.stat-label {
  font-size: 0.68rem;
  text-transform: uppercase;
  letter-spacing: 1.2px;
  color: var(--text-muted);
  font-weight: 500;
}

/* Settings */
.setting-group {
  margin-bottom: 18px;
}

.setting-group:last-child {
  margin-bottom: 0;
}

.setting-label {
  display: block;
  font-size: 0.72rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 1.5px;
  color: var(--text-muted);
  margin-bottom: 8px;
}

.range-row {
  display: flex;
  align-items: center;
  gap: 10px;
}

.range-field {
  flex: 1;
}

.range-field input {
  width: 100%;
  padding: 10px 14px;
  border-radius: var(--radius-xs);
  border: 1px solid rgba(148, 163, 184, 0.12);
  background: rgba(255, 255, 255, 0.03);
  color: var(--text-primary);
  font-family: var(--font-mono);
  font-size: 0.95rem;
  outline: none;
  transition: border-color 0.2s, box-shadow 0.2s;
}

.range-field input:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px rgba(129, 140, 248, 0.08);
}

.range-sep {
  color: var(--text-muted);
  font-size: 0.85rem;
  user-select: none;
}

.btn-start {
  width: 100%;
  padding: 16px 32px;
  font-size: 1rem;
  letter-spacing: 0.02em;
}

.hint-text {
  text-align: center;
  font-size: 0.72rem;
  color: var(--text-muted);
  letter-spacing: 0.02em;
}

.hint-text kbd {
  display: inline-block;
  padding: 1px 6px;
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid rgba(255, 255, 255, 0.08);
  border-radius: 3px;
  font-family: var(--font-mono);
  font-size: 0.68rem;
  color: var(--text-secondary);
}

/* ═══════════════════════════════════════════════
   GAME
   ═══════════════════════════════════════════════ */
.game-container {
  width: 100%;
  max-width: 560px;
  padding: 48px 24px;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 56px;
  position: relative;
}

.game-hud {
  display: flex;
  align-items: center;
  justify-content: space-between;
  width: 100%;
  max-width: 380px;
}

.hud-item {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 4px;
  min-width: 56px;
}

.hud-label {
  font-size: 0.65rem;
  text-transform: uppercase;
  letter-spacing: 1.8px;
  color: var(--text-muted);
  font-weight: 600;
}

.hud-value {
  font-family: var(--font-mono);
  font-size: 2rem;
  font-weight: 700;
  line-height: 1;
  transition: transform 0.15s var(--spring);
}

.hud-value.bump {
  transform: scale(1.25);
}

.hud-value--muted {
  color: var(--text-muted);
  font-size: 1.5rem;
}

/* Timer */
.hud-timer-ring {
  position: relative;
  width: 96px;
  height: 96px;
}

.hud-timer-ring svg {
  width: 100%;
  height: 100%;
  transform: rotate(-90deg);
}

.ring-bg {
  fill: none;
  stroke: rgba(148, 163, 184, 0.08);
  stroke-width: 4;
}

.ring-fg {
  fill: none;
  stroke: var(--accent);
  stroke-width: 4;
  stroke-linecap: round;
  stroke-dasharray: 276.46;
  stroke-dashoffset: 0;
  transition: stroke-dashoffset 1s linear, stroke 0.5s;
}

.hud-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: 700;
}

/* Equation */
.equation-area {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 28px;
  width: 100%;
}

.equation {
  display: flex;
  align-items: center;
  gap: 14px;
  font-family: var(--font-mono);
  font-size: 3.2rem;
  font-weight: 700;
  color: var(--text-primary);
  animation: eqIn 0.2s var(--ease);
}

@keyframes eqIn {
  from {
    opacity: 0;
    transform: scale(0.92);
  }

  to {
    opacity: 1;
    transform: scale(1);
  }
}

.eq-op {
  color: var(--accent);
}

.eq-equals {
  color: var(--text-muted);
}

.answer-input {
  width: 180px;
  padding: 14px 20px;
  border-radius: var(--radius-sm);
  border: 2px solid rgba(129, 140, 248, 0.2);
  background: rgba(255, 255, 255, 0.03);
  color: var(--text-primary);
  font-family: var(--font-mono);
  font-size: 2rem;
  font-weight: 700;
  text-align: center;
  outline: none;
  caret-color: var(--accent);
  transition: border-color 0.2s, box-shadow 0.2s;
  appearance: textfield;
  -webkit-appearance: textfield;
  -moz-appearance: textfield;
}

.answer-input:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 4px rgba(129, 140, 248, 0.1);
}

.answer-input.correct {
  border-color: var(--correct);
  box-shadow: 0 0 0 4px var(--correct-glow);
  animation: flash 0.3s var(--ease);
}

@keyframes flash {
  0% {
    background: rgba(52, 211, 153, 0.12);
  }

  100% {
    background: rgba(255, 255, 255, 0.03);
  }
}

input[type="number"]::-webkit-inner-spin-button,
input[type="number"]::-webkit-outer-spin-button {
  -webkit-appearance: none;
  appearance: none;
  margin: 0;
}

/* Feedback */
.feedback {
  position: fixed;
  top: 24px;
  right: 24px;
  padding: 8px 16px;
  border-radius: var(--radius-xs);
  font-family: var(--font-mono);
  font-weight: 600;
  font-size: 0.85rem;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.25s, transform 0.25s var(--spring);
  z-index: 100;
  transform: translateX(12px);
}

.feedback.show-correct {
  background: rgba(52, 211, 153, 0.12);
  color: var(--correct);
  border: 1px solid rgba(52, 211, 153, 0.2);
  opacity: 1;
  transform: translateX(0);
}

/* ═══════════════════════════════════════════════
   RESULTS
   ═══════════════════════════════════════════════ */
.results-container {
  width: 100%;
  max-width: 400px;
  padding: 48px 24px;
}

.results-card {
  text-align: center;
}

.results-label {
  display: block;
  font-size: 0.72rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 2px;
  color: var(--text-muted);
  margin-bottom: 8px;
}

.results-score-big {
  font-family: var(--font-mono);
  font-size: 5rem;
  font-weight: 900;
  background: var(--accent-gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  line-height: 1;
  animation: scoreIn 0.5s var(--spring);
}

@keyframes scoreIn {
  from {
    opacity: 0;
    transform: scale(0.6);
  }

  to {
    opacity: 1;
    transform: scale(1);
  }
}

.new-high {
  display: inline-block;
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--warn);
  margin-top: 8px;
  animation: glow 1.5s ease-in-out infinite;
}

@keyframes glow {

  0%,
  100% {
    opacity: 1;
  }

  50% {
    opacity: 0.6;
  }
}

.results-divider {
  width: 48px;
  height: 1px;
  background: rgba(148, 163, 184, 0.15);
  margin: 24px auto;
}

.results-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 16px;
  margin-bottom: 28px;
}

.result-item {
  display: flex;
  flex-direction: column;
  gap: 2px;
  text-align: center;
}

.result-val {
  font-family: var(--font-mono);
  font-size: 1.3rem;
  font-weight: 700;
  color: var(--text-primary);
}

.result-lbl {
  font-size: 0.68rem;
  text-transform: uppercase;
  letter-spacing: 1.2px;
  color: var(--text-muted);
  font-weight: 500;
}

.results-actions {
  display: flex;
  gap: 10px;
  justify-content: center;
}

.hidden {
  display: none !important;
}

/* ═══════════════════════════════════════════════
   STATISTICS
   ═══════════════════════════════════════════════ */
.stats-container {
  width: 100%;
  max-width: 960px;
  padding: 64px 32px;
  display: flex;
  flex-direction: column;
  gap: 32px;
}

#stats.active {
  align-items: flex-start;
  justify-content: flex-start;
}

.stats-page-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  width: 100%;
  margin-bottom: 8px;
}

.stats-page-title {
  font-size: 2rem;
  font-weight: 800;
  letter-spacing: -0.5px;
  background: var(--accent-gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.stats-summary-row {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.stats-mini-card {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 12px;
  padding: 40px 24px;
  text-align: center;
  position: relative;
  overflow: hidden;
  transition: transform 0.3s var(--ease), box-shadow 0.3s var(--ease);
  animation: statCardIn 0.5s var(--ease) both;
}

.stats-mini-card:nth-child(1) {
  animation-delay: 0.05s;
}

.stats-mini-card:nth-child(2) {
  animation-delay: 0.12s;
}

.stats-mini-card:nth-child(3) {
  animation-delay: 0.19s;
}

@keyframes statCardIn {
  from {
    opacity: 0;
    transform: translateY(18px) scale(0.96);
  }

  to {
    opacity: 1;
    transform: translateY(0) scale(1);
  }
}

.stats-mini-card::before {
  content: '';
  position: absolute;
  inset: 0;
  border-radius: inherit;
  background: radial-gradient(ellipse at 50% 0%, rgba(129, 140, 248, 0.08) 0%, transparent 70%);
  pointer-events: none;
}

.stats-mini-card:hover {
  transform: translateY(-3px);
  box-shadow: 0 8px 32px rgba(129, 140, 248, 0.12);
}

.smc-icon {
  font-size: 1.8rem;
  line-height: 1;
  opacity: 0.85;
}

.smc-value {
  font-family: var(--font-mono);
  font-size: 3.5rem;
  font-weight: 800;
  color: var(--text-primary);
  line-height: 1;
  letter-spacing: -1.5px;
}

.smc-accent {
  background: var(--accent-gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.smc-label {
  font-size: 0.85rem;
  text-transform: uppercase;
  letter-spacing: 2px;
  color: var(--text-secondary);
  font-weight: 600;
}

.chart-card {
  padding: 32px;
  animation: statCardIn 0.5s var(--ease) 0.25s both;
}

.chart-wrapper {
  position: relative;
  width: 100%;
  overflow: hidden;
  border-radius: var(--radius-sm);
}

.chart-wrapper canvas {
  width: 100%;
  height: auto;
  display: block;
}

.chart-empty {
  color: var(--text-muted);
  text-align: center;
  font-style: italic;
  padding: 24px 0;
  font-size: 0.88rem;
}

.history-table-wrap {
  max-height: 320px;
  overflow-y: auto;
  padding-right: 4px;
}

.history-table-wrap::-webkit-scrollbar {
  width: 3px;
}

.history-table-wrap::-webkit-scrollbar-track {
  background: transparent;
}

.history-table-wrap::-webkit-scrollbar-thumb {
  background: rgba(148, 163, 184, 0.15);
  border-radius: 4px;
}

.ht-table {
  width: 100%;
  border-collapse: collapse;
}

.ht-table th {
  position: sticky;
  top: 0;
  background: var(--bg-secondary);
  font-size: 0.7rem;
  text-transform: uppercase;
  letter-spacing: 1.4px;
  color: var(--text-muted);
  padding: 12px 14px;
  text-align: left;
  border-bottom: 1px solid rgba(148, 163, 184, 0.1);
  font-weight: 600;
  z-index: 2;
}

.ht-table td {
  padding: 11px 14px;
  font-size: 0.88rem;
  color: var(--text-secondary);
  border-bottom: 1px solid rgba(148, 163, 184, 0.05);
  white-space: nowrap;
  transition: background 0.2s;
}

.ht-table tr:hover td {
  background: rgba(129, 140, 248, 0.04);
}

.ht-table .ht-score {
  font-family: var(--font-mono);
  font-weight: 700;
  color: var(--accent-bright);
  font-size: 1rem;
}

.ht-table .ht-best td {
  background: rgba(129, 140, 248, 0.06);
}

/* ═══════════════════════════════════════════════
   RESPONSIVE
   ═══════════════════════════════════════════════ */
@media (max-width: 500px) {
  .logo {
    font-size: 2.2rem;
  }

  .equation {
    font-size: 2.4rem;
    gap: 10px;
  }

  .answer-input {
    width: 150px;
    font-size: 1.6rem;
    padding: 12px 16px;
  }

  .hud-timer-ring {
    width: 76px;
    height: 76px;
  }

  .hud-timer-text {
    font-size: 1.1rem;
  }

  .hud-value {
    font-size: 1.5rem;
  }

  .results-score-big {
    font-size: 3.8rem;
  }

  .smc-value {
    font-size: 1.8rem;
  }

  .stats-mini-card {
    padding: 20px 10px;
  }

  .stats-page-title {
    font-size: 1.3rem;
  }

  .stats-container {
    padding: 36px 18px;
  }

  .stats-summary-row {
    gap: 10px;
  }

  .landing-container {
    padding: 36px 18px;
  }
}