/* --- Reset & Base --- */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

body {
  font-family: "Noto Sans JP", sans-serif;
  color: #0F172A; /* Brand Dark */
  background-color: #FFFFFF; /* Surface */
  line-height: 1.7;
}

h1, h2, h3, h4, h5, h6 {
  font-family: "Montserrat", sans-serif;
  color: #0F172A; /* Brand Dark */
  line-height: 1.3;
}

a {
  color: #1B57F0; /* Brand Primary */
  text-decoration: none;
}

a:hover {
  text-decoration: underline;
}

img {
  max-width: 100%;
  height: auto;
  display: block;
}

/* --- Variables --- */
:root {
  --brand-primary: #1B57F0;
  --brand-dark: #0F172A;
  --surface: #FFFFFF;
  --neutral-100: #F8FAFC;
}

/* --- Layout --- */
.container {
  max-width: 800px;
  margin-left: auto;
  margin-right: auto;
  padding-left: 1.5rem;
  padding-right: 1.5rem;
}

.container-wide {
  max-width: 1200px;
  margin-left: auto;
  margin-right: auto;
  padding-left: 1.5rem;
  padding-right: 1.5rem;
}

.section {
  padding: 4rem 0;
}

.section-bg {
  background-color: var(--neutral-100);
}

/* --- Header --- */
.header {
  background-color: var(--surface);
  border-bottom: 1px solid #E2E8F0;
  padding: 1rem 1.5rem;
  position: sticky;
  top: 0;
  z-index: 100;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.header .logo {
  font-family: "Montserrat", sans-serif;
  font-weight: 700;
  font-size: 1.5rem;
  color: var(--brand-dark);
}

.header .nav ul {
  list-style: none;
  display: flex;
  gap: 1.5rem;
}

.header .nav a {
  font-weight: 500;
  color: var(--brand-dark);
}

/* --- Footer --- */
.footer {
  background-color: var(--brand-dark);
  color: var(--surface);
  padding: 4rem 1.5rem;
}

.footer a {
  color: var(--surface);
}

.footer .footer-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 2rem;
  max-width: 1200px;
  margin: 0 auto;
}

.footer .logo {
    font-family: "Montserrat", sans-serif;
    font-weight: 700;
    font-size: 1.5rem;
}

/* --- Components --- */
.btn {
  display: inline-block;
  padding: 0.75rem 1.5rem;
  border-radius: 9999px; /* pill shape */
  font-weight: 700;
  text-align: center;
  border: 2px solid transparent;
  transition: background-color 0.3s, color 0.3s, border-color 0.3s;
}

.btn-primary {
  background-color: var(--brand-primary);
  color: var(--surface);
}

.btn-primary:hover {
  background-color: #1a4acc;
  text-decoration: none;
}

.btn-secondary {
  background-color: var(--surface);
  color: var(--brand-primary);
  border-color: var(--brand-primary);
}

.btn-secondary:hover {
  background-color: var(--neutral-100);
  text-decoration: none;
}

.card {
  background-color: var(--surface);
  border: 1px solid #E2E8F0;
  border-radius: 8px;
  overflow: hidden;
  box-shadow: 0 4px 6px rgba(0,0,0,0.05);
}

.card-content {
  padding: 1.5rem;
}

/* --- Mobile Navigation --- */
.hamburger-menu {
  display: none; /* Hidden by default */
  z-index: 101;
  background: none;
  border: none;
  cursor: pointer;
}

.hamburger-menu span {
  display: block;
  width: 28px;
  height: 3px;
  background-color: var(--brand-dark);
  margin: 5px 0;
  transition: transform 0.3s, opacity 0.3s;
}

/* --- Responsive --- */
@media (max-width: 768px) {
  .header .nav {
    display: flex;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    flex-direction: column;
    justify-content: center;
    align-items: center;
    transform: translateX(100%);
    transition: transform 0.3s ease-in-out;
    z-index: 100;
  }

  .header .nav.is-active {
    transform: translateX(0);
  }

  .header .nav ul {
    flex-direction: column;
    text-align: center;
    gap: 2rem;
  }

  .header .nav a {
    font-size: 1.5rem;
  }

  .hamburger-menu {
    display: block;
  }

  .hamburger-menu.is-active span:nth-child(1) {
    transform: translateY(8px) rotate(45deg);
  }
  .hamburger-menu.is-active span:nth-child(2) {
    opacity: 0;
  }
  .hamburger-menu.is-active span:nth-child(3) {
    transform: translateY(-8px) rotate(-45deg);
  }
}