* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  font-family:
  "Yu Gothic","游ゴシック","Hiragino Kaku Gothic ProN","Hiragino Sans","Noto Sans JP",
  system-ui,
  -apple-system,
  BlinkMacSystemFont,"Segoe UI",
  sans-serif;
  line-height: 1.7;
  color: #222;
}


.layout {
  display: flex;
  max-width: 900px;   /* 中央カラム幅 */
  margin: 0 auto;
  min-height: 100vh;
}

#flex {
  display: flex;
  min-height: 100vh;
  width: 90%;
  margin: 0 auto;   
}

main {
  flex: 1;
  padding: 2rem;
  text-align: left;
}


/* スキル一覧表示*/
.skillseat {
  display: flex;
  flex-wrap: wrap;
  gap: 1.5rem;   
  list-style: none;
  padding: 0;
}
.skillseat li {
  width: calc(50% - 0.75rem);
}

/* 購入本リスト */
#flex table { 
  border-collapse: collapse;
  padding: 1em 0;
}
#flex table th, td {
  border: 1px solid #222;
  padding: 8px 10px;
}


/* 右の目次表示 */
.side-nav {
  position: fixed;
  top: 0;
  right: 0;   
  width: 250px;
  height: 100%;
  background: white;
  z-index: 1000;       /* ハンバーガーより上 */
  overflow-y: auto;    /* 中身スクロール可能に */
  transition: right 0.3s;
}
.side-nav ul {
  padding: 1.5rem;
  list-style: none;
}
.side-nav.open {
  right: 0;
}
.side-nav ul li a{
  text-decoration: none;/*アンダーラインを消す*/
}

/* お問い合わせフォーム */
#flex label:has(input[type="checkbox"]),
#flex label:has(input[type="radio"]) {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
}
#flex textarea {
  vertical-align: middle;
}


/* ヘッダー（About,Projects,Contact） */
.header-nav {
  width: 100%;
  border-bottom: 1px solid #ddd;
}
.header-nav ul {
  display: flex;
  justify-content: center;
  background-color: white;
  list-style: none; /*ヘッダーリストの点を消す*/
}
.header-nav ul li {
  margin: 0 40px;
}
.header-nav ul li a {
  text-decoration: none;/*アンダーラインを消す*/
}
.menu-btn {
  display: none;
  font-size: 24px;
  background: none;
  border: none;
  color: #222;
  cursor: pointer;
}

/* フッター */
.footer-nav {
  width: 100%;
  background-color: #ddd;
  color: white;
  text-align: center;
  padding: 15px 10px 20px;
}
.footer-nav a {
  color: #222;
}

/* ===== スマホ用 ===== */
/* スマホ: 初期は右外、openでスライド表示 */
@media (max-width: 768px) {
 .header-nav ul {
    font-size: 14px;
    gap: 10px;
  }

  .toggle_btn { display: block; }

  .side-nav {
    position: fixed;
    top: 0;
    right: -250px;  /* 初期は画面外 */
    width: 250px;
    height: 100%;
    background: #fff;
    z-index: 1000;
    overflow-y: auto;
    transition: right 0.3s;
  }

  .side-nav.open { right: 0; }

  #mask { display: none; }
  #mask.open { display: block; }
}
/* ===== PC用 ===== */
@media (min-width: 769px) {
  #flex { width: 100%; }
  #mask { display: none; }
  main {
    margin-right: 250px; /* asideの幅分余白 */
  }
  .toggle_btn { display: none; }
  .side-nav {
    right: 0;
    transition: none;
    z-index: 1;
  }

}

/*============
nav https://125naroom.com/web/2958
=============*/
#navArea nav {
  display: block;
  position: fixed;
  top: 0;
  left: -300px;
  bottom: 0;
  width: 300px;
  background: #ffffff;
  overflow-x: hidden;
  overflow-y: auto;
  -webkit-overflow-scrolling: touch;
  transition: all .5s;
  z-index: 3;
  opacity: 0;
}
#navArea.open nav {
  left: 0;
  opacity: 1;
}
#navArea .inner {
  padding: 25px;
}

#navArea .inner ul {
  list-style: none;
  margin: 0;
  padding: 0;
}
#navArea .inner ul li {
  position: relative;
  margin: 0;
  border-bottom: 1px solid #333;
}
#navArea .inner ul li a {
  display: block;
  color: #333;
  font-size: 14px;
  padding: 1em;
  text-decoration: none;
  transition-duration: 0.2s;
}
#navArea .inner ul li a:hover {
  background: #e4e4e4;
}
@media screen and (max-width: 767px) {
  #navArea nav {
    left: -220px;
    width: 220px;
  }
}
/*============
.toggle_btn
=============*/
/* 🍔ボタン */
.toggle_btn {
  display: none;
  position: fixed;
  top: 20px;
  right: 20px;
  width: 30px;
  height: 30px;
  z-index: 1001;
  cursor: pointer;
}
.toggle_btn span {
  display: block;
  width: 30px;
  height: 2px;
  background-color: #333;
  margin: 6px 0;
}




/*============
#mask
=============*/
#mask {
  display: none;
  position: fixed;
  top: 0; left: 0;
  width: 100%; height: 100%;
  background: rgba(0,0,0,0.6);
  z-index: 999;
}
#mask.open {
  display: block;
}