:root {
  --bg-dark: #121212;
  --text-dark: #ddd;
  --bg-light: #f5f5f5;
  --text-light: #111;
  --accent: #0078d7;
  --accent-hover: #005ea2;
  --button-primary: var(--accent);
  --button-primary-hover: var(--accent-hover);
  --radius: 4px;
  --font-size-base: 1rem;
}

@media (prefers-color-scheme: light) {
  body:not(.dark):not(.light) {
    background-color: var(--bg-light);
    color: var(--text-light);
  }
}

body {
  margin: 0;
  font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;
  background-color: var(--bg-dark);
  color: var(--text-dark);
  transition: background-color 0.3s, color 0.3s;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

body.light {
  background-color: var(--bg-light);
  color: var(--text-light);
}

/* ヘッダー */
header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 1rem 1.5rem;
  background-color: #424242;
}
body.light header {
  background-color: #cccccc;
}

header h1 {
  margin: 0;
  font-weight: 700;
  font-size: 1.25rem;
}

#modeToggle {
  font-size: 1.5rem;
  background: none;
  border: none;
  cursor: pointer;
  color: inherit;
  user-select: none;
}

/* メイン */
main {
  flex-grow: 1;
  display: flex;
  padding: 1rem 1.5rem;
  gap: 1rem;
  flex-wrap: wrap;
  justify-content: center;
}

/* 入力 */
.input-area {
  max-width: 360px;
  flex: 1 1 360px;
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
  margin-bottom: 1rem;
}

label {
  font-weight: 600;
  margin-bottom: 0.25rem;
}

select,
input[type="text"],
textarea {
  width: 100%;
  padding: 0.4rem 0.5rem;
  border-radius: var(--radius);
  border: 1px solid #444;
  background-color: #1b1b1b;
  color: #fff;
  font-size: var(--font-size-base);
  resize: vertical;
  transition: background-color 0.3s, color 0.3s, border-color 0.3s;
}

select:focus,
input:focus,
textarea:focus {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
  border-color: #66afe9;
  box-shadow: 0 0 4px rgba(102, 175, 233, 0.6);
}

body.light select,
body.light input[type="text"],
body.light textarea {
  background-color: #fff;
  color: #111;
  border-color: #ccc;
}

button {
  padding: 0.5rem 1rem;
  font-weight: 700;
  border-radius: var(--radius);
  font-size: var(--font-size-base);
  cursor: pointer;
  transition: background-color 0.3s;
}

button:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

#generateBtn {
  background-color: var(--button-primary);
  color: white;
  border: none;
}
#generateBtn:hover {
  background-color: var(--button-primary-hover);
}

#downloadBtn {
  background-color: transparent;
  color: inherit;
  border: 1px solid currentColor;
  margin-top: 0.5rem;
}
#downloadBtn:hover {
  background-color: rgba(255, 255, 255, 0.1);
}

/* 出力 */
.output-area {
  max-width: 720px;
  flex: 1 1 720px;
  display: flex;
  justify-content: flex-end;
  margin-top: 2rem;
  padding-left: 1rem;
}

.code-container {
  position: relative;
  width: 100%;
}

pre {
  margin: 0;
  padding: 1rem 1.5rem 1.5rem 1.5rem;
  background-color: #1e1e1e;
  color: #cfcfcf;
  font-size: 0.875rem;
  line-height: 1.4;
  border-radius: 6px;
  overflow-x: auto;
  white-space: pre-wrap;
  word-break: break-word;
  min-height: 320px;
}
body.light pre {
  background-color: #eaeaea;
  color: #222;
}

#copyBtn {
  position: absolute;
  top: 8px;
  right: 8px;
  background-color: transparent;
  border: 1px solid transparent;
  color: #cfcfcf;
  font-size: 0.75rem;
  padding: 4px 10px;
  border-radius: var(--radius);
  cursor: pointer;
  user-select: none;
  z-index: 10;
}
#copyBtn:hover,
#copyBtn:focus {
  background-color: rgba(255 255 255 / 0.15);
  color: #fff;
}
body.light #copyBtn {
  color: #222;
}
body.light #copyBtn:hover,
body.light #copyBtn:focus {
  background-color: rgba(0 0 0 / 0.1);
  color: #000;
}

/* フッター */
footer {
  text-align: center;
  padding: 1rem 1.5rem;
  font-size: 0.9rem;
  background-color: #2a2a2a;
  color: #eee;
}
body.light footer {
  background-color: #afafaf;
  color: #000000;
}
footer .footer-label {
  margin: 0;
  font-weight: 600;
  font-size: 1rem;
}
footer .footer-link {
  margin: 0.25rem 0 0 0;
}
footer a {
  color: #62abff;
  text-decoration: none;
  font-weight: 500;
}
footer a:hover,
footer a:focus {
  text-decoration: underline;
}

/* レスポンシブ */
@media screen and (max-width: 900px) {
  main {
    flex-direction: column;
    gap: 2rem;
  }
  .output-area {
    justify-content: center;
    margin-top: 0;
    padding-left: 0;
  }
}