header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  width: 90%;
  z-index: 999;
  background-color: rgba(255, 255, 255, 0.8);
  backdrop-filter: blur(2px);
  box-shadow: 0 2px 5px rgba(0, 0, 0, 0.1);
  margin: 20px auto;
  padding: 5px;
  height: 50px;
  border-radius: 10px;
}

.header-title-image {
  width: 150px;
  height: auto;
  display: block;
}

.header-inner {
  display: flex;
  justify-content: space-between;
  align-items: center;
  height: 43px;
  padding: 0 20px;
  position: relative;
  z-index: 1000;
}

.hamburger {
  position: relative;
  width: 25px;
  height: 20px;
  cursor: pointer;
  display: flex;
  justify-content: center;
  align-items: center;
}

.hamburger span {
  position: absolute;
  width: 100%;
  height: 3px;
  background-color: #333;
  border-radius: 2px;
  transition: 0.3s ease;
}

/* 通常時の3本線 */
.hamburger span:nth-child(1) {
  top: 0;
}

.hamburger span:nth-child(3) {
  bottom: 0;
}

/* ✖ に変形 */
.hamburger.active span:nth-child(1) {
  transform: rotate(45deg);
  top: 10px;
  background-color: red;
}

.hamburger.active span:nth-child(2) {
  opacity: 0;
}

.hamburger.active span:nth-child(3) {
  transform: rotate(-45deg);
  top: 10px;
  background-color: red;
}


/* メニュー本体 */
.nav {
  position: absolute;
  top: 120%;
  right: 0;
  width: 250px;
  min-width: 200px;
  max-height: 0;
  overflow: hidden;
  background-color: rgba(255, 255, 255, 0.8);
  backdrop-filter: blur(2px);
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
  transition: max-height 0.4s ease;
  z-index: 500;
  border-radius: 10px;
}

/* 展開された状態 */
.nav.active {
  max-height: 500px;
}

/* メニューの中身 */
.nav ul {
  list-style: none;
  padding: 10px 20px;
  margin: 0;
  display: flex;
  flex-direction: column;
  gap: 15px;
  text-align: left;
  margin-left: 10px;
}

.nav ul li {
  padding: 3px 10px;
}

.nav ul li a {
  text-decoration: none;
  color: #333;
  font-weight: bold;
  margin-left: 10px;
  transition: color 0.3s ease;
}

.nav ul li:hover {
  transform: scale(1.1);
  background-color: var(--blue);
  border-radius: 10px;
}

.nav ul li:hover a,
.nav ul li:hover i {
  color: white;
}