/* CSSリセット */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

/* 基本スタイル */
html {
  font-size: 62.5%; /* 10px = 1rem */
  scroll-behavior: smooth;
}

body {
  font-family: 'Helvetica Neue', Arial, sans-serif;
  font-size: 1.6rem;
  line-height: 1.6;
  color: #333;
  background-color: #f9f9f9;
  max-width: 1200px;
  margin: 0 auto;
  padding: 2rem;
}

/* タイポグラフィ */
h1, h2, h3, h4, h5, h6 {
  margin-bottom: 1.5rem;
  font-weight: 700;
  line-height: 1.2;
  color: #222;
}

h1 {
  font-size: 3.6rem;
  margin-top: 2rem;
}

h2 {
  font-size: 2.8rem;
  margin-top: 4rem;
  padding-bottom: 0.5rem;
  border-bottom: 2px solid #ddd;
}

h3 {
  font-size: 2.4rem;
  margin-top: 3rem;
}

h4 {
  font-size: 2rem;
  margin-top: 2.5rem;
}

p {
  margin-bottom: 1.5rem;
}

a {
  color: #0066cc;
  text-decoration: none;
  transition: color 0.3s;
}

a:hover {
  color: #004499;
  text-decoration: underline;
}

/* リスト */
ul, ol {
  margin: 0 0 2rem 2rem;
}

ul ul, ol ol, ul ol, ol ul {
  margin-bottom: 0;
}

ul {
  list-style-type: disc;
}

ol {
  list-style-type: decimal;
}

li {
  margin-bottom: 0.5rem;
}

dl {
  margin-bottom: 2rem;
}

dt {
  font-weight: bold;
  margin-top: 1rem;
}

dd {
  margin-left: 2rem;
  margin-bottom: 1rem;
}

/* ブロック要素 */
blockquote {
  padding: 1rem 2rem;
  margin: 0 0 2rem;
  border-left: 5px solid #eee;
  font-style: italic;
  color: #555;
}

hr {
  margin: 3rem 0;
  border: 0;
  border-top: 1px solid #ddd;
}

pre {
  background-color: #f5f5f5;
  padding: 1.5rem;
  margin: 0 0 2rem;
  border-radius: 4px;
  overflow-x: auto;
}

code {
  font-family: 'Courier New', Courier, monospace;
  background-color: #f5f5f5;
  padding: 0.2rem 0.4rem;
  border-radius: 3px;
  font-size: 1.4rem;
}

pre code {
  padding: 0;
  background-color: transparent;
  border-radius: 0;
  font-size: inherit;
}

mark {
  background-color: #ffffcc;
  padding: 0.2rem 0.4rem;
}

small {
  font-size: 80%;
}

/* インライン要素 */
em {
  font-style: italic;
}

strong {
  font-weight: bold;
}

del, s {
  text-decoration: line-through;
}

ins {
  text-decoration: underline;
  background-color: #dfd;
}

kbd {
  background-color: #f7f7f7;
  border: 1px solid #ccc;
  border-radius: 3px;
  box-shadow: 0 1px 0 rgba(0, 0, 0, 0.2);
  color: #333;
  display: inline-block;
  font-family: 'Courier New', Courier, monospace;
  font-size: 1.3rem;
  line-height: 1;
  padding: 0.2rem 0.4rem;
  vertical-align: middle;
}

samp {
  font-family: 'Courier New', Courier, monospace;
}

var {
  font-style: italic;
  font-weight: bold;
}

/* レイアウト */
header, footer, main, section, article, aside, nav {
  margin-bottom: 2rem;
}

header {
  background-color: #fff;
  padding: 2rem;
  border-radius: 8px;
  box-shadow: 0 2px 5px rgba(0, 0, 0, 0.1);
  margin-bottom: 3rem;
}

main {
  background-color: #fff;
  padding: 3rem;
  border-radius: 8px;
  box-shadow: 0 2px 5px rgba(0, 0, 0, 0.1);
}

section {
  margin-bottom: 4rem;
  padding-bottom: 2rem;
  border-bottom: 1px solid #eee;
}

article {
  margin-bottom: 3rem;
}

aside {
  background-color: #f5f5f5;
  padding: 2rem;
  border-radius: 8px;
  margin-top: 3rem;
}

footer {
  margin-top: 4rem;
  padding-top: 2rem;
  border-top: 1px solid #ddd;
  text-align: center;
  font-size: 1.4rem;
  color: #777;
}

/* ナビゲーション */
nav {
  margin: 2rem 0;
}

nav ul {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  gap: 2rem;
}

nav li {
  margin: 0;
}

nav a {
  display: block;
  padding: 0.8rem 1.5rem;
  background-color: #f5f5f5;
  border-radius: 4px;
  transition: all 0.3s;
}

nav a:hover {
  background-color: #0066cc;
  color: white;
  text-decoration: none;
}

/* 画像とメディア */
img, video, audio, iframe, canvas {
  max-width: 100%;
  height: auto;
  margin-bottom: 2rem;
  border-radius: 4px;
}

figure {
  margin: 0 0 2rem;
}

figcaption {
  margin-top: 0.5rem;
  font-size: 1.4rem;
  color: #666;
  text-align: center;
}

audio, video {
  display: block;
  width: 100%;
}

/* テーブル */
table {
  width: 100%;
  border-collapse: collapse;
  margin-bottom: 2rem;
  overflow-x: auto;
}

caption {
  font-weight: bold;
  padding: 1rem;
  caption-side: top;
  color: #333;
  text-align: left;
  font-size: 1.8rem;
}

th, td {
  padding: 1rem;
  text-align: left;
  border: 1px solid #ddd;
}

th {
  background-color: #f5f5f5;
  font-weight: bold;
}

tbody tr:nth-child(even) {
  background-color: #f9f9f9;
}

tbody tr:hover {
  background-color: #f1f1f1;
}

/* フォーム */
form {
  margin-bottom: 2rem;
}

fieldset {
  border: 1px solid #ddd;
  border-radius: 4px;
  padding: 2rem;
  margin-bottom: 2rem;
}

legend {
  padding: 0 1rem;
  font-weight: bold;
  font-size: 1.8rem;
}

label {
  display: block;
  margin-bottom: 0.5rem;
  font-weight: bold;
}

input, select, textarea, button {
  width: 100%;
  padding: 0.8rem;
  margin-bottom: 1.5rem;
  border: 1px solid #ddd;
  border-radius: 4px;
  font-family: inherit;
  font-size: inherit;
}

input:focus, select:focus, textarea:focus {
  outline: none;
  border-color: #0066cc;
  box-shadow: 0 0 5px rgba(0, 102, 204, 0.5);
}

button {
  background-color: #0066cc;
  color: white;
  border: none;
  cursor: pointer;
  transition: background-color 0.3s;
}

button:hover {
  background-color: #004499;
}

button:active {
  transform: translateY(1px);
}

button[type="reset"] {
  background-color: #777;
}

button[type="reset"]:hover {
  background-color: #555;
}

input[type="checkbox"], input[type="radio"] {
  width: auto;
  margin-right: 0.5rem;
}

.checkbox-group, .radio-group {
  display: flex;
  align-items: center;
  margin-bottom: 1rem;
}

.checkbox-group label, .radio-group label {
  margin: 0;
  font-weight: normal;
}

.form-group {
  margin-bottom: 2rem;
}

.form-actions {
  display: flex;
  gap: 1rem;
  justify-content: flex-end;
}

.form-actions button {
  width: auto;
  padding: 0.8rem 2rem;
}

/* インタラクティブ要素 */
details {
  margin-bottom: 2rem;
  border: 1px solid #ddd;
  border-radius: 4px;
  overflow: hidden;
}

summary {
  padding: 1rem;
  background-color: #f5f5f5;
  cursor: pointer;
  font-weight: bold;
}

details[open] summary {
  border-bottom: 1px solid #ddd;
}

details > *:not(summary) {
  padding: 1rem;
}

dialog {
  padding: 2rem;
  border: 1px solid #ddd;
  border-radius: 8px;
  box-shadow: 0 4px 8px rgba(0, 0, 0, 0.2);
  max-width: 500px;
}

dialog::backdrop {
  background-color: rgba(0, 0, 0, 0.5);
}

/* カスタム要素 */
custom-card {
  display: block;
  margin: 2rem 0;
}

/* レスポンシブデザイン */
@media (max-width: 768px) {
  body {
      padding: 1rem;
  }
  
  main, header, footer, aside {
      padding: 1.5rem;
  }
  
  h1 {
      font-size: 2.8rem;
  }
  
  h2 {
      font-size: 2.4rem;
  }
  
  h3 {
      font-size: 2rem;
  }
  
  nav ul {
      flex-direction: column;
      gap: 0.5rem;
  }
  
  fieldset {
      padding: 1rem;
  }
  
  .form-actions {
      flex-direction: column;
  }
}

@media (max-width: 480px) {
  body {
      font-size: 1.4rem;
  }
  
  h1 {
      font-size: 2.4rem;
  }
  
  h2 {
      font-size: 2rem;
  }
  
  h3 {
      font-size: 1.8rem;
  }
  
  pre, table {
      font-size: 1.2rem;
  }
}

/* アニメーション */
@keyframes fadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

.fade-in {
  animation: fadeIn 0.5s ease-in;
}

/* CSS変数 (カスタムプロパティ) */
:root {
  --primary-color: #0066cc;
  --secondary-color: #004499;
  --background-color: #f9f9f9;
  --text-color: #333;
  --border-color: #ddd;
  --shadow: 0 2px 5px rgba(0, 0, 0, 0.1);
  --border-radius: 4px;
  --spacing-unit: 1rem;
}

/* フレックスボックス */
.flex-container {
  display: flex;
  flex-wrap: wrap;
  gap: var(--spacing-unit);
}

.flex-item {
  flex: 1 1 200px;
  padding: var(--spacing-unit);
  background-color: white;
  border-radius: var(--border-radius);
  box-shadow: var(--shadow);
}

/* グリッド */
.grid-container {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
  gap: var(--spacing-unit);
}

.grid-item {
  padding: var(--spacing-unit);
  background-color: white;
  border-radius: var(--border-radius);
  box-shadow: var(--shadow);
}

/* トランジションとトランスフォーム */
.card {
  transition: transform 0.3s, box-shadow 0.3s;
}

.card:hover {
  transform: translateY(-5px);
  box-shadow: 0 5px 15px rgba(0, 0, 0, 0.1);
}

/* アクセシビリティ関連 */
.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

.skip-link {
  position: absolute;
  top: -40px;
  left: 0;
  padding: 8px;
  background-color: #000;
  color: #fff;
  z-index: 100;
}

.skip-link:focus {
  top: 0;
}

/* 印刷スタイル */
@media print {
  body {
      color: #000;
      background-color: #fff;
      font-size: 12pt;
  }
  
  a {
      color: #000;
      text-decoration: underline;
  }
  
  a[href^="http"]:after {
      content: " (" attr(href) ")";
  }
  
  nav, button, audio, video, iframe, .no-print {
      display: none !important;
  }
  
  img {
      max-width: 100% !important;
      page-break-inside: avoid;
  }
  
  h1, h2, h3, h4, h5, h6 {
      page-break-after: avoid;
  }
  
  table, figure {
      page-break-inside: avoid;
  }
}