:root {
  --bg: #f7f7f7;
  --text: #222;
  --muted: #888;
  --card-bg: #ffffff;
  --shadow: 0 0 8px #bbb;
  --accent: #2196f3;
  --accent-hover: #1769aa;
  --accent-contrast: #ffffff;
  --error: #c62828;
}

body {
  background: var(--bg);
  color: var(--text);
  font-family: 'Montserrat', Arial, sans-serif;
  text-align: center;
  margin: 0;
  padding: 20px;
}

h1 {
  margin-top: 20px;
  color: var(--text);
  font-weight: 700;
}

#game-box {
  background: var(--card-bg);
  width: 350px;
  max-width: 94vw;
  margin: 30px auto;
  padding: 30px 20px;
  border-radius: 12px;
  box-shadow: var(--shadow);
}

.input-row {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 12px;
  flex-wrap: wrap;
  margin-bottom: 10px;
}

input[type="number"] {
  width: 120px;
  font-size: 1.1em;
  padding: 8px 10px;
  margin-bottom: 10px;
  border: 1px solid #ddd;
  border-radius: 8px;
  outline: none;
}

input[type="number"]:focus-visible {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px rgba(33, 150, 243, 0.25);
}

select#difficulty {
  font-size: 1em;
  padding: 6px 10px;
  border-radius: 8px;
  border: 1px solid #ddd;
  margin: 8px 0 14px 0;
}

button {
  font-size: 1em;
  padding: 9px 22px;
  border: none;
  border-radius: 44px;
  background: var(--accent);
  color: var(--accent-contrast);
  cursor: pointer;
  margin-bottom: 10px;
  transition: transform .12s, box-shadow .16s, background .16s;
}

button:hover {
  background: var(--accent-hover);
  transform: translateY(-1px);
  box-shadow: 0 4px 10px rgba(33,150,243,0.3);
}

button:focus-visible {
  outline: none;
  box-shadow: 0 0 0 3px rgba(33,150,243,0.35);
}

button:disabled {
  opacity: 0.6;
  cursor: not-allowed;
  transform: none;
  box-shadow: none;
}

#error {
  color: var(--error);
  font-size: 0.95em;
  min-height: 1.6em;
}

#info {
  font-size: 1.2em;
  margin-top: 14px;
  min-height: 2em;
}

#attempts {
  margin-top: 8px;
  color: var(--muted);
}

#best {
  margin-top: 6px;
  color: var(--muted);
}

#history {
  margin-top: 16px;
  text-align: left;
}

#history h2 {
  font-size: 1.05em;
  margin: 8px 0;
  color: var(--text);
}

#history-list {
  list-style: none;
  padding: 0;
  margin: 0;
  max-height: 160px;
  overflow-y: auto;
  border-top: 1px dashed #ddd;
  padding-top: 8px;
}

#history-list li {
  padding: 6px 0;
  border-bottom: 1px dashed #eee;
  color: var(--text);
}

.hidden {
  display: none;
}

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

@media (max-width: 480px) {
  #game-box {
    padding: 24px 14px;
  }
  .input-row {
    flex-direction: column;
    gap: 8px;
  }
}

@media (min-width: 728px) {
  #game-box { width: 450px; }
  body { font-size: 110%; }
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0f1222;
    --text: #eaeaf0;
    --muted: #a0a3b0;
    --card-bg: #171a2e;
    --shadow: 0 0 0 rgba(0,0,0,0);
    --accent: #3d5afe;
    --accent-hover: #0a2459;
    --accent-contrast: #ffffff;
    --error: #ef5350;
  }
  #game-box {
    box-shadow: 0 6px 24px rgba(61,90,254,0.12);
    border: 1px solid rgba(255,255,255,0.06);
  }
  input[type="number"], select#difficulty {
    background: #20233a;
    color: var(--text);
    border-color: #2c3252;
  }
  #history-list {
    border-top-color: #2c3252;
  }
  #history-list li {
    border-bottom-color: #2c3252;
  }
}