body {
  margin: 0;
  margin-top: 64px;
  font-family: 'Arial', sans-serif;
  position: relative;
}

/* 左右のサイドバー（ヘッダー・フッターの下に表示）— 幅は左右同じ */
body::before,
body::after {
  content: '';
  position: fixed;
  top: 0;
  width: clamp(3rem, 4vw, 5rem);
  height: 100vh;
  z-index: 0;
}


.main-content {
  margin-left: clamp(3rem, 4vw, 5rem);
  margin-right: clamp(3rem, 4vw, 5rem);
  position: relative;
  z-index: 2;
}

.header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  width: 100%;
  box-sizing: border-box;
  background-color: var(--header-color);
  color: white;
  z-index: 1000;
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
}

.header-container {
  max-width: 90%;
  margin: 0 auto;
  padding: 0 2%;
  display: flex;
  justify-content: space-between;
  align-items: center;
  min-height: 64px;
  height: 64px;
  position: relative;
}

.logo {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.logo-link {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  text-decoration: none;
  color: inherit;
}

.logo-link:hover {
  opacity: 0.9;
}

.logo-image {
  height: 36px;
  width: auto;
  display: block;
}

.logo h1 {
  margin: 0;
  font-size: clamp(1.25rem, 2.5vw, 2rem);
  font-weight: bold;
  color: var(--color-main);
}

.logo span {
  font-size: clamp(0.75rem, 1.5vw, 0.875rem);
  color: #ccc;
}

.navigation {
  display: flex;
}

.nav-list {
  display: flex;
  list-style: none;
  margin: 0;
  padding: 0;
  gap: 1.5rem;
  align-items: center;
}

.nav-link {
  color: var(--color-main);
  text-decoration: none;
  font-size: 15px;
  font-weight: 500;
  padding: 0.4rem 0.75rem;
  border-radius: 0.25rem;
  transition: all 0.3s ease;
}

.nav-link:hover {
  background-color: var(--color-main);
  color: white;
}

.hamburger {
  display: none;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  cursor: pointer;
  gap: 0.25rem;
  border: none;
  background: transparent;
  padding: 0.35rem;
  margin: 0;
  color: inherit;
  font: inherit;
}

.hamburger span {
  width: clamp(1.25rem, 5vw, 1.5rem);
  height: 0.2rem;
  background-color: white;
  transition: 0.3s;
}

@media (max-width: 768px) {
  body {
    margin-top: 56px;
  }

  body::before,
  body::after {
    width: 3px;
  }

  .main-content {
    margin-left: 3px;
    margin-right: 3px;
  }

  .header-container {
    padding: 0 3%;
    min-height: 56px;
    height: 56px;
  }

  .logo-image {
    height: 28px;
  }

  .logo h1 {
    font-size: 1.2rem;
  }

  .logo span {
    font-size: 0.75rem;
  }

  .navigation {
    display: block;
    position: absolute;
    top: 100%;
    left: auto;
    right: 0;
    width: auto;
    min-width: min(12rem, 70vw);
    max-width: 85vw;
    z-index: 1001;
  }

  .hamburger {
    display: flex;
  }

  .nav-list {
    display: none;
    position: relative;
    flex-direction: column;
    align-items: flex-end;
    padding: 0.5rem 0.65rem 0.65rem;
    gap: 0.25rem;
    margin: 0;
    background-color: #192437;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
    border-radius: 0 0 0 10px;
  }

  .nav-list li {
    width: 100%;
    text-align: right;
  }

  .nav-list .nav-link {
    display: inline-block;
    text-align: right;
  }

  .nav-list.active {
    display: flex;
  }
}