body {
  font-family: "Arial", sans-serif;
  background-color: #2c3e50;
  display: flex;
  flex-direction: column;
  justify-content: flex-start;
  height: auto;
  width: 100%;
  margin: 0;
  padding: 0;
}
header{
  width: 100%;
}
body {
  background-color: #2c3e50;
  color: white;
}

h3 {
  text-align: center;
  margin-bottom: 3%;
}
.header-container.cover {
  position: relative;
  background-image: url(../images/construction.jpeg);
  background-size: cover;
  background-position: center;
  background-repeat: no-repeat;
}

.header-container.cover::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%; /* 高さを100%に変更して要素全体を覆う */
  background-color: rgba(0, 0, 0, 0.3); /* 黒の半透明色 */
  z-index: 1; /* 背景画像より前面に表示 */
}

/* 子要素は背景オーバーレイよりも前面に表示 */
.header-container * {
  position: relative;
  z-index: 2;
}
.header-container h1{
  width: 50%;
  padding-top: 25%;
  border-bottom: #fff 3px solid;
  padding-left: 15%;
}
.toptxt{
  padding-top: 10px;
  padding-bottom: 150px;
  padding-left: 15%;
}
main{
  margin-left: 15%;
  margin-right: 15%;
}
.year-navigation {
  display: flex;
  justify-content: center;
  justify-content: space-between;
  gap: 20px;
  margin-top: 7%;
  margin-bottom: 3%;
}
.year-navigation2{
  display: flex;
  justify-content: center;
  justify-content: space-evenly;
  gap: 20px;
  margin-top: 7%;
  margin-bottom: 3%;
}
.year-navigation button,
.year-navigation2 button{
  background-color: #34495e;
  color: #ecf0f1;
  border: 1px solid white;
  padding: 10px 20px;
  cursor: pointer;
  border-radius: 5px;
  font-size: 16px;
  width: 100%;
}
.border {
  border-bottom: 1px solid white; 
}
.border td {
  padding-top: 20px;
  padding-bottom: 20px; 
}
.year-navigation button:hover {
  background-color: #1abc9c;
}
table {
  margin: 0 auto;
  margin-bottom: 10%;
  width: 100%;
  border-collapse: separate;
}
table thead {
  background-color: blue;
  padding: 5px;
}

table {
  border-collapse: collapse;
}
tbody p{
  text-align: center;
}
.mobile{
  display: none;
}
/* 共通のボタンスタイル */
.year-navigation a,
.year-navigation2 a {
  display: block;
  padding: 16px 0;
  margin: 5px auto;
  color: white;
  text-decoration: none;
  border-radius: 8px;
  text-align: center;
  font-weight: bold;
  transition: background-color 0.3s ease;
  max-width: 400px;
  width: 100%;
  box-sizing: border-box;
  border: 2px solid white; /* ← 白枠追加 */
}

/* ホバー効果 */
.year-navigation a:hover,
.year-navigation2 a:hover {
  background-color: #0056b3;
}

/* PC版（横に5等分） */
.year-navigation.pc {
  display: flex;
  justify-content: space-between;
  flex-wrap: nowrap;
  max-width: 100%;
  gap: 10px;
}

.year-navigation.pc a {
  flex: 1;
  max-width: 400px;
}
.back-to-top {
  position: fixed;
  bottom: 30px;
  right: 20px;
  width: 40px;
  height: 40px;
  background-color: #007BFF;
  color: white;
  text-align: center;
  line-height: 40px;
  font-size: 20px;
  border-radius: 50%;
  text-decoration: none;
  box-shadow: 0 4px 8px rgba(0,0,0,0.2);
  transition: background-color 0.3s ease;
  z-index: 1000;
}

.back-to-top:hover {
  background-color: #0056b3;
}


/* モバイル用非表示（PC時） */
@media screen and (min-width: 768px) {
  .mobile {
    display: none;
  }
}

/* モバイル表示 */
@media screen and (max-width: 767px) {
  .year-navigation.pc {
    display: none;
  }

  .mobile .year-navigation,
  .mobile .year-navigation2 {
    display: flex;
    justify-content: space-around;
    gap: 10px;
    margin-bottom: 10px;
  }

  .mobile .year-navigation a,
  .mobile .year-navigation2 a {
    flex: 1;
    max-width: 400px;
  }
}

/* スムーズスクロール */
html {
  scroll-behavior: smooth;
}


@media screen and (max-width: 765px) {
  main{
    margin: 0;
  }
  .header-container h1{
    width: 100%;
    padding: 0;
    padding-top: 150px;
    text-align: center;
    border: 0px solid white;
}
  .toptxt{
    padding: 0;
    padding-top: 10px;
    padding-bottom: 100px;
    text-align: center;
  }
  .year-navigation {
    display: flex;
    justify-content: center;
    justify-content: space-between;
    gap: 20px;
    margin-top: 7%;
    margin-bottom: 3%;
  }
  .year-navigation2{
    display: flex;
    justify-content: center;
    gap: 20px;
    margin-top: 7%;
    margin-bottom: 3%;
  }
  .year-navigation2 button{
    background-color: #34495e;
    color: #ecf0f1;
    border: 1px solid white;
    padding: 10px 20px;
    cursor: pointer;
    border-radius: 5px;
    font-size: 16px;
    width: 34%;
  }
  .pc{
    display: none;
  }
  .mobile{
    display: block;
}
tbody p{
  text-align: center;
}
.one{
  width: 23%;
}
.two{
  width: 14%;
}
.three{
  width: 15%;
}
.four{
  width: 30%;
}
}