/* ============================================================
   DESIGN TOKENS
   ============================================================ */
:root,
[data-theme='light'] {
  /* Type Scale */
  --text-xs: clamp(0.75rem, 0.7rem + 0.25vw, 0.875rem);
  --text-sm: clamp(0.875rem, 0.8rem + 0.35vw, 1rem);
  --text-base: clamp(1rem, 0.95rem + 0.25vw, 1.125rem);
  --text-lg: clamp(1.125rem, 1rem + 0.75vw, 1.5rem);
  --text-xl: clamp(1.5rem, 1.2rem + 1.25vw, 2.25rem);
  --text-2xl: clamp(2rem, 1.2rem + 2.5vw, 3rem);

  /* Spacing (4px system) */
  --space-1: 0.25rem;
  --space-2: 0.5rem;
  --space-3: 0.75rem;
  --space-4: 1rem;
  --space-5: 1.25rem;
  --space-6: 1.5rem;
  --space-8: 2rem;
  --space-10: 2.5rem;
  --space-12: 3rem;
  --space-16: 4rem;
  --space-20: 5rem;

  /* Surfaces */
  --color-bg: #f7f8fa;
  --color-surface: #ffffff;
  --color-surface-offset: #f0f2f5;
  --color-surface-hover: #eef1f6;
  --color-divider: #e8eaef;
  --color-border: #e0e4ea;

  /* Text */
  --color-text: #1a1d23;
  --color-text-muted: #6b7280;
  --color-text-faint: #9ca3af;

  /* Primary Accent (Blue) */
  --color-primary: #2563eb;
  --color-primary-hover: #1d4ed8;
  --color-primary-active: #1e40af;
  --color-primary-light: #dbeafe;
  --color-primary-highlight: #eff6ff;

  /* Semantic — Typing */
  --color-correct: #16a34a;
  --color-correct-bg: #dcfce7;
  --color-incorrect: #dc2626;
  --color-incorrect-bg: #fee2e2;
  --color-pending: #9ca3af;

  /* Chart Colors */
  --chart-line: #2563eb;
  --chart-fill: rgba(37, 99, 235, 0.1);
  --chart-correct: #16a34a;
  --chart-incorrect: #dc2626;
  --chart-axis: #d1d5db;
  --chart-grid: #e8eaef;
  --chart-label: #6b7280;

  /* Radius */
  --radius-sm: 0.375rem;
  --radius-md: 0.625rem;
  --radius-lg: 0.875rem;
  --radius-xl: 1.25rem;
  --radius-full: 9999px;

  /* Transitions */
  --transition-interactive: 180ms cubic-bezier(0.16, 1, 0.3, 1);
  --transition-smooth: 300ms cubic-bezier(0.16, 1, 0.3, 1);

  /* Shadows */
  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.06);
  --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.08);
  --shadow-lg: 0 12px 40px rgba(0, 0, 0, 0.12);
  --shadow-focus: 0 0 0 3px rgba(37, 99, 235, 0.25);

  /* Fonts */
  --font-display: 'Cabinet Grotesk', 'Inter', sans-serif;
  --font-body: 'Satoshi', 'Inter', system-ui, sans-serif;
  --font-mono: 'JetBrains Mono', 'Courier New', monospace;

  /* Content Widths */
  --content-narrow: 720px;
  --content-default: 960px;
  --content-wide: 1200px;
}

/* DARK MODE */
[data-theme='dark'] {
  --color-bg: #0f1115;
  --color-surface: #181b22;
  --color-surface-offset: #1e2128;
  --color-surface-hover: #252934;
  --color-divider: #2a2e37;
  --color-border: #2f343f;

  --color-text: #e4e6eb;
  --color-text-muted: #9ca3af;
  --color-text-faint: #6b7280;

  --color-primary: #3b82f6;
  --color-primary-hover: #60a5fa;
  --color-primary-active: #2563eb;
  --color-primary-light: #1e3a5f;
  --color-primary-highlight: #1a2332;

  --color-correct: #22c55e;
  --color-correct-bg: #14532d;
  --color-incorrect: #ef4444;
  --color-incorrect-bg: #5f1d1d;
  --color-pending: #4b5563;

  --chart-line: #3b82f6;
  --chart-fill: rgba(59, 130, 246, 0.12);
  --chart-correct: #22c55e;
  --chart-incorrect: #ef4444;
  --chart-axis: #374151;
  --chart-grid: #1e2128;
  --chart-label: #9ca3af;

  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.3);
  --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.4);
  --shadow-lg: 0 12px 40px rgba(0, 0, 0, 0.5);
  --shadow-focus: 0 0 0 3px rgba(59, 130, 246, 0.3);
}

/* System preference fallback */
@media (prefers-color-scheme: dark) {
  :root:not([data-theme]) {
    --color-bg: #0f1115;
    --color-surface: #181b22;
    --color-surface-offset: #1e2128;
    --color-surface-hover: #252934;
    --color-divider: #2a2e37;
    --color-border: #2f343f;
    --color-text: #e4e6eb;
    --color-text-muted: #9ca3af;
    --color-text-faint: #6b7280;
    --color-primary: #3b82f6;
    --color-primary-hover: #60a5fa;
    --color-primary-active: #2563eb;
    --color-primary-light: #1e3a5f;
    --color-primary-highlight: #1a2332;
    --color-correct: #22c55e;
    --color-correct-bg: #14532d;
    --color-incorrect: #ef4444;
    --color-incorrect-bg: #5f1d1d;
    --color-pending: #4b5563;
    --chart-line: #3b82f6;
    --chart-fill: rgba(59, 130, 246, 0.12);
    --chart-correct: #22c55e;
    --chart-incorrect: #ef4444;
    --chart-axis: #374151;
    --chart-grid: #1e2128;
    --chart-label: #9ca3af;
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.4);
    --shadow-lg: 0 12px 40px rgba(0, 0, 0, 0.5);
    --shadow-focus: 0 0 0 3px rgba(59, 130, 246, 0.3);
  }
}

/* ============================================================
   BASE STYLESHEET
   ============================================================ */
*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  -moz-text-size-adjust: none;
  -webkit-text-size-adjust: none;
  text-size-adjust: none;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
  scroll-behavior: smooth;
  scroll-padding-top: var(--space-16);
}

body {
  min-height: 100dvh;
  line-height: 1.6;
  font-family: var(--font-body);
  font-size: var(--text-base);
  color: var(--color-text);
  background-color: var(--color-bg);
  transition: background-color var(--transition-smooth), color var(--transition-smooth);
}

img,
picture,
video,
canvas,
svg {
  display: block;
  max-width: 100%;
  height: auto;
}

input,
button,
textarea,
select {
  font: inherit;
  color: inherit;
}

h1,
h2,
h3,
h4,
h5,
h6 {
  text-wrap: balance;
  line-height: 1.15;
  font-family: var(--font-display);
}

p,
li,
figcaption {
  text-wrap: pretty;
  max-width: 72ch;
}

::selection {
  background: var(--color-primary-light);
  color: var(--color-text);
}

:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 3px;
  border-radius: var(--radius-sm);
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
}

button {
  cursor: pointer;
  background: none;
  border: none;
}

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

a,
button,
[role='button'],
input,
textarea,
select {
  transition:
    color var(--transition-interactive),
    background var(--transition-interactive),
    border-color var(--transition-interactive),
    box-shadow var(--transition-interactive),
    transform var(--transition-interactive);
}

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border-width: 0;
}

.skip-link {
  position: absolute;
  top: -100px;
  left: var(--space-4);
  z-index: 1000;
  padding: var(--space-2) var(--space-4);
  background: var(--color-primary);
  color: #fff;
  border-radius: var(--radius-md);
  font-size: var(--text-sm);
  font-weight: 500;
}

.skip-link:focus {
  top: var(--space-4);
}

/* ============================================================
   LAYOUT
   ============================================================ */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: color-mix(in srgb, var(--color-surface) 80%, transparent);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--color-border);
}

.header-inner {
  max-width: var(--content-narrow);
  margin: 0 auto;
  padding: var(--space-4) var(--space-6);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-4);
}

.brand {
  display: flex;
  align-items: center;
  gap: var(--space-3);
}

.brand-logo {
  width: 28px;
  height: 28px;
  color: var(--color-primary);
  flex-shrink: 0;
}

.brand-name {
  font-family: var(--font-display);
  font-weight: 800;
  font-size: var(--text-lg);
  letter-spacing: -0.02em;
  color: var(--color-text);
}

.brand-accent {
  color: var(--color-primary);
}

.header-actions {
  display: flex;
  align-items: center;
  gap: var(--space-2);
}

.theme-toggle {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  border-radius: var(--radius-md);
  color: var(--color-text-muted);
  border: 1px solid var(--color-border);
  background: var(--color-surface);
}

.theme-toggle:hover {
  color: var(--color-primary);
  border-color: var(--color-primary);
  background: var(--color-primary-highlight);
}

.theme-toggle:active {
  transform: scale(0.96);
}

/* ============================================================
   MAIN CONTENT
   ============================================================ */
.main-content {
  max-width: var(--content-narrow);
  margin: 0 auto;
  padding: var(--space-8) var(--space-6) var(--space-16);
  display: flex;
  flex-direction: column;
  gap: var(--space-6);
}

/* Intro */
.intro {
  text-align: center;
  padding: var(--space-4) 0 var(--space-2);
}

.intro-title {
  font-size: var(--text-xl);
  font-weight: 700;
  letter-spacing: -0.03em;
  color: var(--color-text);
}

.intro-subtitle {
  margin-top: var(--space-2);
  font-size: var(--text-sm);
  color: var(--color-text-muted);
  max-width: 48ch;
  margin-inline: auto;
}

/* ============================================================
   SETTINGS BAR
   ============================================================ */
.settings-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-4);
  padding: var(--space-3) var(--space-5);
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-sm);
  flex-wrap: wrap;
}

.duration-group {
  display: flex;
  align-items: center;
  gap: var(--space-3);
}

.duration-label {
  font-size: var(--text-sm);
  font-weight: 500;
  color: var(--color-text-muted);
}

.duration-options {
  display: flex;
  gap: var(--space-1);
  background: var(--color-surface-offset);
  padding: var(--space-1);
  border-radius: var(--radius-md);
}

.duration-btn {
  padding: var(--space-2) var(--space-4);
  font-size: var(--text-sm);
  font-weight: 500;
  color: var(--color-text-muted);
  border-radius: var(--radius-sm);
  min-width: 48px;
  text-align: center;
}

.duration-btn:hover {
  color: var(--color-text);
}

.duration-btn.active {
  background: var(--color-surface);
  color: var(--color-primary);
  font-weight: 700;
  box-shadow: var(--shadow-sm);
}

.restart-btn {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  padding: var(--space-2) var(--space-4);
  font-size: var(--text-sm);
  font-weight: 500;
  color: var(--color-text);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  background: var(--color-surface);
}

.restart-btn:hover {
  border-color: var(--color-primary);
  color: var(--color-primary);
  background: var(--color-primary-highlight);
}

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

/* ============================================================
   HUD
   ============================================================ */
.hud {
  display: flex;
  justify-content: center;
  gap: var(--space-12);
  padding: var(--space-5) var(--space-6);
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-sm);
}

.hud-item {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--space-1);
  min-width: 80px;
}

.hud-label {
  font-size: var(--text-xs);
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--color-text-muted);
}

.hud-value {
  font-family: var(--font-mono);
  font-size: var(--text-2xl);
  font-weight: 700;
  line-height: 1;
  color: var(--color-text);
  font-variant-numeric: tabular-nums;
}

.hud-item:first-child .hud-value {
  color: var(--color-primary);
}

.hud-unit {
  font-size: var(--text-sm);
  color: var(--color-text-muted);
  font-weight: 500;
  line-height: 1;
  margin-top: var(--space-1);
}

/* ============================================================
   TYPING AREA
   ============================================================ */
.typing-area {
  position: relative;
  background: var(--color-surface);
  border: 2px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: var(--space-8) var(--space-8);
  box-shadow: var(--shadow-md);
  min-height: 200px;
  cursor: text;
  overflow: hidden;
  transition: border-color var(--transition-interactive), box-shadow var(--transition-interactive);
}

.typing-area:focus {
  outline: none;
  border-color: var(--color-primary);
  box-shadow: var(--shadow-md), var(--shadow-focus);
}

.typing-area.active {
  border-color: var(--color-primary);
}

.text-display {
  font-family: var(--font-mono);
  font-size: var(--text-lg);
  line-height: 2;
  letter-spacing: 0.02em;
  word-break: break-word;
  user-select: none;
}

.char {
  position: relative;
  color: var(--color-pending);
  transition: color 100ms ease;
}

.char.correct {
  color: var(--color-correct);
}

.char.incorrect {
  color: var(--color-incorrect);
  background: var(--color-incorrect-bg);
  border-radius: 2px;
}

.char.current {
  background: var(--color-primary-light);
  border-radius: 2px;
}

.char.current::after {
  content: '';
  position: absolute;
  left: -1px;
  top: 0;
  bottom: 0;
  width: 2px;
  background: var(--color-primary);
  animation: cursorBlink 1s steps(2, end) infinite;
  border-radius: 1px;
}

@keyframes cursorBlink {
  0%, 50% { opacity: 1; }
  51%, 100% { opacity: 0; }
}

.loading-state {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: var(--space-4);
  min-height: 100px;
  color: var(--color-text-muted);
  font-size: var(--text-sm);
}

.loading-spinner {
  width: 32px;
  height: 32px;
  border: 3px solid var(--color-border);
  border-top-color: var(--color-primary);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
}

@keyframes spin {
  to { transform: rotate(360deg); }
}

.typing-hint {
  text-align: center;
  font-size: var(--text-sm);
  color: var(--color-text-faint);
  font-weight: 400;
  transition: opacity var(--transition-interactive);
}

.typing-hint.hidden {
  opacity: 0;
  pointer-events: none;
}

/* ============================================================
   RESULTS
   ============================================================ */
.results[hidden] {
  display: none !important;
}

.results {
  display: flex;
  flex-direction: column;
  gap: var(--space-8);
  animation: resultsAppear 500ms cubic-bezier(0.16, 1, 0.3, 1);
}

@keyframes resultsAppear {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.results-title {
  font-size: var(--text-xl);
  font-weight: 700;
  text-align: center;
  color: var(--color-text);
}

.results-summary {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: var(--space-3);
}

.summary-card {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--space-1);
  padding: var(--space-4) var(--space-3);
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-sm);
}

.summary-label {
  font-size: var(--text-xs);
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--color-text-muted);
}

.summary-value {
  font-family: var(--font-mono);
  font-size: var(--text-xl);
  font-weight: 700;
  color: var(--color-text);
  font-variant-numeric: tabular-nums;
}

.correct-color {
  color: var(--color-correct);
}

.error-color {
  color: var(--color-incorrect);
}

/* ============================================================
   CHARTS
   ============================================================ */
.chart-container {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: var(--space-6);
  box-shadow: var(--shadow-sm);
}

.chart-title {
  font-size: var(--text-base);
  font-weight: 600;
  margin-bottom: var(--space-4);
  color: var(--color-text);
}

.chart-wrapper {
  width: 100%;
  overflow-x: auto;
}

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

/* ============================================================
   TRY AGAIN BUTTON
   ============================================================ */
.try-again-btn {
  align-self: center;
  padding: var(--space-3) var(--space-8);
  font-size: var(--text-base);
  font-weight: 600;
  color: #fff;
  background: var(--color-primary);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-sm);
  transition: background var(--transition-interactive), transform var(--transition-interactive), box-shadow var(--transition-interactive);
}

.try-again-btn:hover {
  background: var(--color-primary-hover);
  box-shadow: var(--shadow-md);
  transform: translateY(-1px);
}

.try-again-btn:active {
  transform: translateY(0) scale(0.98);
}

/* ============================================================
   FOOTER
   ============================================================ */
.site-footer {
  text-align: center;
  padding: var(--space-8) var(--space-6);
  font-size: var(--text-xs);
  color: var(--color-text-faint);
  border-top: 1px solid var(--color-border);
}

/* ============================================================
   RESPONSIVE
   ============================================================ */
@media (max-width: 640px) {
  .header-inner {
    padding: var(--space-3) var(--space-4);
  }

  .main-content {
    padding: var(--space-6) var(--space-4) var(--space-12);
  }

  .settings-bar {
    flex-direction: column;
    align-items: stretch;
    gap: var(--space-3);
  }

  .duration-group {
    justify-content: space-between;
  }

  .restart-btn {
    justify-content: center;
  }

  .hud {
    gap: var(--space-6);
    padding: var(--space-4);
  }

  .hud-value {
    font-size: var(--text-xl);
  }

  .typing-area {
    padding: var(--space-5) var(--space-4);
  }

  .text-display {
    font-size: var(--text-base);
    line-height: 1.8;
  }

  .results-summary {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 380px) {
  .results-summary {
    grid-template-columns: 1fr;
  }
}