* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  background: linear-gradient(145deg, #e8eaf0 0%, #d4d8e2 100%);
  padding: 1rem;
}

.window {
  background: #fff;
  border-radius: 12px;
  box-shadow: 0 8px 32px rgba(0, 0, 0, 0.08), 0 2px 8px rgba(0, 0, 0, 0.04);
  padding: 2rem;
  text-align: center;
  max-width: 520px;
  width: 100%;
}

.header {
  margin-bottom: 1.25rem;
  padding-bottom: 1rem;
  border-bottom: 1px solid #eaecef;
}

.title {
  margin: 0 0 0.5rem;
  font-size: 1.35rem;
  font-weight: 700;
  color: #1a1d24;
  letter-spacing: -0.02em;
}

.instruction {
  margin: 0;
  font-size: 0.9rem;
  color: #5c6170;
  line-height: 1.45;
}

.settings {
  margin-bottom: 1.5rem;
  padding: 1rem 1.1rem;
  background: #f6f7f9;
  border-radius: 10px;
  text-align: left;
}

.settings-title {
  margin: 0 0 0.25rem;
  font-size: 0.85rem;
  font-weight: 600;
  color: #3d4250;
}

.settings-hint {
  margin: 0 0 0.6rem;
  font-size: 0.75rem;
  color: #7a7f8c;
}

.settings-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem 1.25rem;
  align-items: center;
}

.settings-row label {
  font-size: 0.85rem;
  color: #4a4e5a;
}

.settings-row input[type="number"] {
  width: 6rem;
  padding: 0.4rem 0.6rem;
  font-size: 0.9rem;
  border: 1px solid #c8ccd4;
  border-radius: 6px;
  background: #fff;
}

.settings-row input[type="number"]:focus {
  outline: 2px solid #0066cc;
  outline-offset: 1px;
}

.stimulus-wrapper {
  min-height: 130px;
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 1.25rem;
  padding: 1rem;
  border-radius: 10px;
  transition: background 0.2s;
}

.stimulus-wrapper.feedback-correct {
  background: rgba(0, 128, 0, 0.12);
}

.stimulus-wrapper.feedback-wrong {
  background: rgba(200, 0, 0, 0.12);
}

.hidden {
  display: none !important;
}

.summary {
  margin-bottom: 1.5rem;
  padding: 1.5rem 1.5rem 1.25rem;
  background: #f6f7f9;
  border-radius: 10px;
  border: 1px solid #e4e6eb;
  text-align: left;
}

.summary-title {
  margin: 0 0 1rem;
  font-size: 1.1rem;
  font-weight: 700;
  color: #1a1d24;
  text-align: center;
}

.summary-stats {
  margin: 0;
  display: grid;
  gap: 0.5rem 1.5rem;
  grid-template-columns: auto 1fr;
  align-items: baseline;
  max-width: 18rem;
  margin-left: auto;
  margin-right: auto;
}

.summary-row {
  display: contents;
}

.summary-row dt {
  margin: 0;
  font-size: 0.9rem;
  font-weight: 500;
  color: #5c6170;
}

.summary-row dd {
  margin: 0;
  font-size: 1rem;
  font-weight: 700;
  color: #1a1d24;
  text-align: right;
}

#stimulus {
  font-size: 5rem;
  font-weight: 700;
  color: #1a1d24;
  line-height: 1;
}

.stats {
  display: flex;
  gap: 1rem 1.5rem;
  justify-content: center;
  flex-wrap: wrap;
  margin-bottom: 1rem;
  padding: 0.85rem 1rem;
  background: #fafbfc;
  border-radius: 8px;
  font-size: 0.9rem;
  color: #4a4e5a;
}

.stats strong {
  color: #1a1d24;
}

.progress-wrap {
  height: 6px;
  margin-bottom: 1.25rem;
  background: #e4e6eb;
  border-radius: 3px;
  overflow: hidden;
}

.progress-bar {
  height: 100%;
  width: 0;
  max-width: 100%;
  background: linear-gradient(90deg, #2d7aff, #5b9cff);
  border-radius: 3px;
  transition: width 0.25s ease;
}

.buttons {
  display: flex;
  gap: 0.6rem;
  justify-content: center;
  flex-wrap: wrap;
}

.buttons button {
  padding: 0.65rem 1.1rem;
  font-size: 0.9rem;
  font-weight: 500;
  border: 1px solid #c8ccd4;
  border-radius: 8px;
  background: #fff;
  color: #3d4250;
  cursor: pointer;
  transition: background 0.15s, border-color 0.15s, color 0.15s;
}

.buttons button:hover {
  background: #f0f2f5;
  border-color: #a8adb8;
  color: #1a1d24;
}

.buttons button:focus {
  outline: 2px solid #0066cc;
  outline-offset: 2px;
}

.buttons #btn-letter {
  order: 1;
}

.buttons #btn-reset {
  order: 2;
}

.buttons #btn-number {
  order: 3;
}

@media (max-width: 420px) {
  .window {
    padding: 1.25rem;
  }

  .settings-row {
    flex-direction: column;
    align-items: flex-start;
  }

  .settings-row input[type="number"] {
    width: 100%;
    max-width: 8rem;
  }

  #stimulus {
    font-size: 4rem;
  }

  .stats {
    flex-direction: column;
    gap: 0.5rem;
    align-items: center;
  }

  .buttons {
    flex-direction: column;
  }

  .buttons button {
    width: 100%;
  }
}