/* Variables */
:root {
  --color-text: #4a4a4a;
  --color-text-light: #888888;
  --color-primary: #8eadc3;
  /* Soft Blue */
  --color-primary-dark: #6c8a9e;
  --color-secondary: #f4f1ea;
  /* Soft Beige */
  --color-accent: #d8cca5;
  --color-bg: #fcfcfb;
  --color-white: #ffffff;
  --font-base: "Noto Sans JP", "Helvetica Neue", Arial, sans-serif;
  --width-container: 1080px;
  --radius-sm: 8px;
  --radius-md: 20px;
  --radius-lg: 40px;
  --radius-full: 9999px;
  --shadow-sm: 0 4px 12px rgba(0, 0, 0, 0.05);
  --shadow-md: 0 8px 24px rgba(0, 0, 0, 0.08);

  --transition: all 0.3s ease;
}

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

html {
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-base);
  color: var(--color-text);
  background-color: var(--color-bg);
  line-height: 1.8;
  margin: 0;
  overflow-x: hidden;
}

a {
  text-decoration: none;
  color: inherit;
  transition: var(--transition);
}

img {
  max-width: 100%;
  height: auto;
  vertical-align: bottom;
}

/* Layout Utilities */
.container {
  max-width: var(--width-container);
  margin: 0 auto;
  padding: 0 24px;
}

.container--sm {
  max-width: 900px;
}

.hidden-sp {
  display: block;
}

.hidden-pc {
  display: none;
}

@media (max-width: 768px) {
  .hidden-sp {
    display: none;
  }

  .hidden-pc {
    display: block;
  }
}

/* Buttons (Common) */
.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 12px 32px;
  border-radius: var(--radius-full);
  font-weight: 700;
  letter-spacing: 0.05em;
  cursor: pointer;
  transition: var(--transition);
}

.button--primary {
  background-color: var(--color-primary);
  color: var(--color-white);
}

.button--primary:hover {
  background-color: var(--color-primary-dark);
  transform: translateY(-2px);
  box-shadow: var(--shadow-sm);
}

.button--outline {
  border: 1px solid var(--color-primary);
  color: var(--color-primary);
  background: transparent;
}

.button--outline:hover {
  background-color: var(--color-primary);
  color: var(--color-white);
}

.button__icon {
  width: 18px;
  height: 18px;
}

/* Back Link (Common for subpages) */
.back-link {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  color: #888;
  font-size: 14px;
  font-weight: 500;
  text-decoration: none;
  transition: color 0.3s;
}

.back-link:hover {
  color: var(--color-primary);
}

.back-link__icon {
  width: 18px;
  height: 18px;
}

/* Header */
.header {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  z-index: 100;
  padding: 20px 0;
  transition: var(--transition);
}

.header.is-scrolled {
  background-color: rgba(255, 255, 255, 0.9);
  backdrop-filter: blur(10px);
  padding: 12px 0;
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.03);
}

.header__inner {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.header__logo {
  font-size: 24px;
  font-weight: 700;
  letter-spacing: 0.1em;
  color: var(--color-text);
}

.header__nav-list {
  display: flex;
  gap: 32px;
  list-style: none;
  margin: 0;
  padding: 0;
}

.header__nav-link {
  font-size: 14px;
  font-weight: 500;
  letter-spacing: 0.05em;
  position: relative;
}

.header__nav-link::after {
  content: '';
  position: absolute;
  bottom: -4px;
  left: 0;
  width: 0;
  height: 1px;
  background-color: var(--color-primary);
  transition: var(--transition);
}

.header__nav-link:hover {
  color: var(--color-primary);
}

.header__nav-link:hover::after {
  width: 100%;
}

.header__hamburger {
  background: none;
  border: none;
  cursor: pointer;
  padding: 8px;
}

/* Mobile Menu */
.header__mobile-menu {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100vh;
  background-color: var(--color-white);
  z-index: 99;
  display: flex;
  align-items: center;
  justify-content: center;
  opacity: 0;
  visibility: hidden;
  transition: var(--transition);
}

.header.is-open .header__mobile-menu {
  opacity: 1;
  visibility: visible;
}

.header__mobile-nav {
  display: flex;
  flex-direction: column;
  gap: 24px;
  text-align: center;
}

.header__mobile-link {
  font-size: 20px;
  font-weight: 700;
}

.header__close-btn {
  background: none;
  border: none;
  margin-top: 24px;
  color: var(--color-text-light);
  cursor: pointer;
  text-decoration: underline;
}

/* Footer */
.footer {
  background-color: #333;
  color: var(--color-white);
  padding: 60px 0 30px;
  text-align: center;
}

.footer__title {
  font-size: 24px;
  margin: 0 0 24px;
}

.footer__social {
  display: flex;
  justify-content: center;
  gap: 24px;
  margin-bottom: 32px;
}

.footer__social-link {
  width: 40px;
  height: 40px;
  background-color: rgba(255, 255, 255, 0.1);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: var(--transition);
}

.footer__social-link:hover {
  background-color: var(--color-primary);
}

.footer__copyright {
  font-size: 12px;
  color: #888;
}

/* Scroll Animation Utilities */
.js-fade-up {
  opacity: 0;
  transform: translateY(30px);
  transition: opacity 0.8s ease-out, transform 0.8s cubic-bezier(0.215, 0.610, 0.355, 1.000);
  will-change: opacity, transform;
}

.js-fade-up.is-show {
  opacity: 1;
  transform: translateY(0);
}