@import url('https://fonts.googleapis.com/css2?family=Press+Start+2P&display=swap');

:root {
  --bg-color-dark: #1a1a1a;
  --text-color-dark: #e0e0e0;
  --accent-color: #55ffff;
  --button-bg: #333;
  --button-hover-bg: #55ffff;
  --button-text: #eee;
  --input-bg: #222;
  --input-text: #eee;
  --border-color: #55ffff;
}

body {
  font-family: 'Press Start 2P', monospace;
  background-color: var(--bg-color-dark);
  color: var(--text-color-dark);
  margin: 0;
  min-height: 100vh;
  padding: 40px 20px;
  user-select: none;
  display: block;
  text-align: center; /* オプション */
}

.container {
  background-color: #111;
  border: 4px solid var(--border-color);
  border-radius: 8px;
  padding: 24px 32px;
  width: 320px;
  box-shadow: 0 0 20px var(--accent-color);
  margin: 0 auto;
}

h1, h2 {
  color: var(--accent-color);
  text-align: center;
  margin-bottom: 16px;
  text-shadow: 2px 2px #000000aa;
  user-select: text;
}

label {
  display: block;
  margin-top: 16px;
  margin-bottom: 6px;
  font-size: 10px;
  color: var(--accent-color);
  text-shadow: 1px 1px #000000aa;
  user-select: text;
}

input[type="number"] {
  width: 100%;
  font-family: 'Press Start 2P', monospace;
  font-size: 14px;
  padding: 6px 8px;
  background-color: var(--input-bg);
  color: var(--input-text);
  border: 2px solid var(--border-color);
  border-radius: 4px;
  outline: none;
  box-sizing: border-box;
  transition: border-color 0.3s ease;
  user-select: text;
}

input[type="number"]:focus {
  border-color: var(--accent-color);
  box-shadow: 0 0 8px var(--accent-color);
}

button {
  margin-top: 20px;
  width: 100%;
  background-color: var(--button-bg);
  color: var(--button-text);
  font-family: 'Press Start 2P', monospace;
  font-size: 12px;
  padding: 10px 0;
  border: none;
  border-radius: 6px;
  cursor: pointer;
  text-shadow: 1px 1px #000000aa;
  transition: background-color 0.3s ease, color 0.3s ease;
  user-select: none;
}

button:hover {
  background-color: var(--button-hover-bg);
  color: #000;
  text-shadow: none;
}

.clear-btn {
  margin-top: 8px;
  background-color: #550000;
}

.clear-btn:hover {
  background-color: #ff4444;
  color: #000;
}

.result {
  margin-top: 20px;
  padding: 12px;
  background-color: #222;
  border: 2px solid var(--border-color);
  border-radius: 6px;
  font-size: 11px;
  line-height: 1.4;
  user-select: text;
  min-height: 42px;
  white-space: pre-wrap;
}

.history-list {
  margin-top: 12px;
  list-style-type: none;
  padding-left: 8px;
  max-height: 220px;
  overflow-y: auto;
  font-size: 9px;
  user-select: text;
}

.history-list li {
  padding: 4px 2px;
  border-bottom: 1px dotted var(--accent-color);
  color: var(--accent-color);
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.history-list li:last-child {
  border-bottom: none;
}

.copy-btn {
  background-color: #3399ff;
  border: none;
  color: white;
  font-family: 'Press Start 2P', monospace;
  font-size: 8px;
  padding: 2px 6px;
  border-radius: 3px;
  cursor: pointer;
  user-select: none;
  vertical-align: middle;
  transition: background-color 0.3s ease;
  margin-left: 8px;
}

.copy-btn:hover {
  background-color: #66bbff;
  color: #000;
  }
.footer {
  width: 100%;
  text-align: center;
  height: 20px;
  padding: 0px 12px;
  background-color: #111;
  border-top: 2px solid var(--border-color);
  font-size: 15px;
  color: #00ffff;
  box-shadow: 0 -2px 10px #00000088;
  margin-top: 20px;
}

.footer a,
.footer a:visited {
  color: #00ffff !important;
  text-decoration: none;
}

.footer a:hover {
  text-decoration: underline;
}