:root {
  --font-main: "Noto Sans JP", sans-serif;
  --font-size-md: 1.2rem;
  --font-size-sm: 1rem;
  --font-size-xs: 0.875rem;
  --color-white: #fff;
  --color-primary: #0051c2;
  --color-mail-gradient: linear-gradient(to right, #0051c2, #00265c);
  --color-line-gradient: linear-gradient(to right, #02ad33, #0bff50);
  --radius-md: 0.5rem;
  --shadow: 0 0.25rem 0.5rem rgba(0, 0, 0, 0.1);
}

/* Base header */
.header {
  width: 100%;
  background-color: var(--color-white);
  z-index: 100;
  box-shadow: 0 2px 2px rgba(0, 0, 0, 0.1);
}

/* Container */
.header_container {
  width: 100%;
  /* max-width: 120rem; */
  margin: 0 auto;
  padding: 0.625rem 19.375rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  box-shadow: 0 4px 4px rgba(0, 0, 0, 0.9);
  z-index: 9999;
}

/* Logo */
.logo {
  height: auto;
  max-height: 3.75rem;
  width: auto;
}

/* Contact buttons */
.header_btn {
  display: flex;
  gap: 2.5rem;
}

.mail_btn,
.line_btn {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.75rem 1.5rem;
  border-radius: var(--radius-md);
  color: white;
  cursor: pointer;
}

.mail_btn {
  background-image: var(--color-mail-gradient);
}

.mail_btn:hover {
  background-image: linear-gradient(to right, #00265c, #0051c2);
}

.line_btn {
  background-image: var(--color-line-gradient);
}

.line_btn:hover {
  background-image: linear-gradient(to right, #0bff50, #02ad33);
}

.mail_btn img,
.line_btn img {
  width: 2rem;
  height: 2rem;
}

.btn_mail_text,
.btn_line_text {
  font-family: var(--font-main);
  font-size: 1.125rem;
  font-weight: bold;
}

/* Hamburger */
.hamburger-menu {
  display: none;
  cursor: pointer;
  z-index: 1000;
}

.hamburger-icon {
  width: 2rem;
  height: 1.25rem;
  position: relative;
}

.hamburger-icon span {
  display: block;
  position: absolute;
  width: 100%;
  height: 0.1875rem;
  background: var(--color-primary);
  border-radius: 0.5rem;
  transition: 0.3s;
}

.hamburger-icon span:nth-child(1) { top: 0; }
.hamburger-icon span:nth-child(2) { top: 0.5rem; }
.hamburger-icon span:nth-child(3) { top: 1rem; }

.hamburger-icon.active span:nth-child(1) {
  transform: rotate(45deg);
  top: 0.5rem;
}
.hamburger-icon.active span:nth-child(2) {
  opacity: 0;
}
.hamburger-icon.active span:nth-child(3) {
  transform: rotate(-45deg);
  top: 0.5rem;
}

/* Mobile nav */
.mobile-nav {
  display: none;
  flex-direction: column;
  padding: 1rem;
  background: white;
  position: fixed;
  top: 4.375rem;
  width: 100%;
  box-shadow: var(--shadow);
  z-index: 999;
  gap: 1rem;
}

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

/* Navigation menu styles */
.mobile-nav ul {
  list-style: none;
  padding: 0;
  margin: 0;
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.mobile-nav ul li {
  border-bottom: 1px solid #f0f0f0;
}

.mobile-nav ul li:last-child {
  border-bottom: none;
}

.mobile-nav ul li a {
  display: block;
  padding: 0.75rem 0;
  color: #333;
  text-decoration: none;
  font-family: var(--font-main);
  font-size: 1rem;
  font-weight: 500;
  transition: color 0.3s ease;
}

.mobile-nav ul li a:hover {
  color: var(--color-primary);
}

/* Mobile nav buttons container */
.mobile-nav-buttons {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
  margin-top: 1rem;
  padding-top: 1rem;
  border-top: 1px solid #f0f0f0;
}

.mobile-nav-item {
  display: flex;
  align-items: center;
  gap: 0.625rem;
  font-weight: bold;
  padding: 0.75rem;
  border-radius: var(--radius-md);
  cursor: pointer;
}

.mail-nav-item {
  background: var(--color-mail-gradient);
  color: white;
}

.line-nav-item {
  background: var(--color-line-gradient);
  color: white;
}

.mobile-nav-item img {
  width: 1.5rem;
  height: 1.5rem;
}

/* Media Queries */
@media (max-width: 1440px) {
  .header_container {
    padding: 0.625rem 9.375rem;
  }

  .header_btn {
    gap: 2rem;
  }
  .mail_btn img,
  .line_btn img {
  width: 1.5rem;
  height: 1.5rem;
}
  .btn_mail_text,
  .btn_line_text {
    font-size: 1rem;
  }

}

@media (max-width: 1024px) {
  .header_container {
    padding: 0.625rem 5rem;
  }
  
  .header_btn {
    gap: 1.25rem;
  }
  .mail_btn,
  .line_btn {
    padding: 0.625rem 1rem;
  }
  .mail_btn img,
  .line_btn img{
    display: none;
  }
  .btn_mail_text,
  .btn_line_text {
    font-size: 1rem;
  }
}

@media (max-width: 768px) {
  .hamburger-menu {
    display: block;
  }

  .header_btn {
    display: none;
  }

  .header_container {
    padding: 0.625rem 2rem;
  }

  .logo {
    max-height: 2.5rem;
  }
}

@media (max-width: 480px) {
  .header_container {
    padding: 0.5rem 1rem;
  }

  .logo {
    max-height: 2.25rem;
  }

  .mobile-nav {
    top: 3.75rem;
  }
}