*, *::before, *::after {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: 'HarmonyOS Sans', 'Noto Sans SC', system-ui, -apple-system, 'Segoe UI', sans-serif;
  background: var(--dn-paper);
  color: var(--dn-teal);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

h1, h2, h3, h4, p, ul, ol, figure, blockquote {
  margin: 0;
  padding: 0;
}

ul, ol {
  list-style: none;
}

a {
  color: inherit;
  text-decoration: none;
}

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

input, button, textarea, select {
  font: inherit;
}

:root {
  --dn-teal: #0F4C5C;
  --dn-wine: #7D2E3A;
  --dn-indigo: #4B3B60;
  --dn-paper: #F8F7F4;
  --dn-spring: #7BC96F;
  --dn-summer: #4A90D9;
  --dn-autumn: #E8B34B;
  --dn-winter: #C0C5CE;
  --dn-cream: #F5F0E6;
  --dn-font-display: 'HarmonyOS Sans', 'Noto Sans SC', system-ui, sans-serif;
  --dn-font-body: 'Noto Sans SC', system-ui, sans-serif;
  --dn-ease: cubic-bezier(0.22, 1, 0.36, 1);
  --dn-gutter: clamp(1rem, 4vw, 4rem);
}

:focus-visible {
  outline: 3px solid var(--dn-summer);
  outline-offset: 4px;
  border-radius: 4px;
}

main {
  min-height: 70vh;
}

#main-content:focus {
  outline: none;
}

.container {
  width: min(100% - 2rem, 1280px);
  margin-inline: auto;
  padding-inline: clamp(1rem, 2vw, 2rem);
  position: relative;
}

.btn {
  display: inline-block;
  background: transparent;
  border: 1px solid var(--dn-teal);
  color: var(--dn-teal);
  font-family: var(--dn-font-body);
  font-weight: 700;
  font-size: 0.875rem;
  padding: 0.75rem 1.5rem;
  cursor: pointer;
  transition: background 0.2s var(--dn-ease), color 0.2s var(--dn-ease);
  text-align: center;
  line-height: 1.4;
}

.btn:hover {
  background: var(--dn-teal);
  color: var(--dn-cream);
}

.btn--primary {
  background: var(--dn-wine);
  border-color: var(--dn-wine);
  color: var(--dn-cream);
}

.btn--primary:hover {
  background: var(--dn-teal);
  border-color: var(--dn-teal);
}

.btn--large {
  padding: 1rem 2rem;
  font-size: 1rem;
}

.paper-layer {
  background: var(--dn-cream);
  border: 1px solid var(--dn-winter);
  box-shadow: 4px 4px 0 0 rgba(15, 76, 92, 0.08);
  padding: clamp(1.5rem, 3vw, 3rem);
}

.section-tag {
  display: inline-block;
  background: var(--dn-indigo);
  color: var(--dn-cream);
  padding: 0.25rem 0.75rem;
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.15em;
  text-transform: uppercase;
}

.section-title {
  font-family: var(--dn-font-display);
  font-size: clamp(2rem, 5vw, 3.5rem);
  font-weight: 900;
  letter-spacing: -0.03em;
  line-height: 1.15;
  margin-top: 1rem;
}

.scroll-progress {
  position: fixed;
  top: 0;
  left: 0;
  height: 3px;
  width: 100%;
  z-index: 200;
  background: linear-gradient(90deg, var(--dn-spring), var(--dn-summer), var(--dn-autumn), var(--dn-winter));
  transform: scaleX(0);
  transform-origin: left;
  pointer-events: none;
}

.skip-link {
  position: fixed;
  top: -100%;
  left: 1rem;
  z-index: 1000;
  background: var(--dn-wine);
  color: var(--dn-cream);
  padding: 0.75rem 1.5rem;
  font-weight: 700;
  border-radius: 4px;
  transition: top 0.3s var(--dn-ease);
}

.skip-link:focus {
  top: 1rem;
}

.site-header {
  background: var(--dn-paper);
  border-bottom: 1px solid var(--dn-winter);
  position: relative;
  z-index: 50;
}

.site-header::before {
  content: '';
  position: absolute;
  inset: 0;
  pointer-events: none;
  z-index: -1;
  background-image:
    linear-gradient(rgba(15, 76, 92, 0.03) 1px, transparent 1px),
    linear-gradient(90deg, rgba(15, 76, 92, 0.03) 1px, transparent 1px);
  background-size: 24px 24px;
}

.header-meta {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding-block: 0.75rem;
  border-bottom: 1px solid var(--dn-winter);
}

.brand-tagline {
  font-size: 0.875rem;
  font-weight: 700;
  color: var(--dn-indigo);
  letter-spacing: 0.2em;
}

.brand-badge {
  background: linear-gradient(135deg, var(--dn-spring), var(--dn-summer));
  color: var(--dn-teal);
  font-size: 0.75rem;
  font-weight: 900;
  padding: 0.25rem 0.75rem;
  border-radius: 999px;
  letter-spacing: 0.1em;
  box-shadow: 0 2px 8px rgba(15, 76, 92, 0.15);
}

.masthead {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  align-items: center;
  padding-block: clamp(2.5rem, 5vh, 4.5rem);
}

.masthead-annotation {
  writing-mode: vertical-rl;
  justify-self: start;
  font-size: 0.875rem;
  font-weight: 700;
  letter-spacing: 0.3em;
  color: var(--dn-indigo);
  border-left: 2px solid var(--dn-autumn);
  padding-left: 0.5rem;
  min-height: 100px;
}

.site-brand {
  grid-column: 2 / 3;
  justify-self: center;
  display: flex;
  align-items: baseline;
  gap: 0.5rem;
  line-height: 1;
  color: var(--dn-teal);
}

.site-brand-name {
  font-family: var(--dn-font-display);
  font-size: clamp(3.5rem, 14vw, 9rem);
  font-weight: 900;
  letter-spacing: -0.05em;
}

.site-brand-sub {
  font-size: clamp(1rem, 2.5vw, 1.75rem);
  font-weight: 700;
  color: var(--dn-wine);
  letter-spacing: 0.1em;
}

.season-prism {
  grid-column: 3 / 4;
  justify-self: end;
  width: clamp(4rem, 7vw, 7rem);
  aspect-ratio: 1;
  position: relative;
}

.prism-ring {
  position: absolute;
  inset: 12%;
  border: 1px solid var(--dn-winter);
  transform: rotate(45deg);
  animation: prism-spin-reverse 20s linear infinite;
  transition: border-color 0.4s var(--dn-ease);
}

.prism-core {
  position: absolute;
  inset: 22%;
  background: conic-gradient(from 45deg, var(--dn-spring), var(--dn-summer), var(--dn-autumn), var(--dn-winter), var(--dn-spring));
  clip-path: polygon(50% 0%, 100% 50%, 50% 100%, 0% 50%);
  animation: prism-spin 12s linear infinite;
  filter: drop-shadow(0 8px 16px rgba(15, 76, 92, 0.2));
}

.prism-dot {
  position: absolute;
  width: 14%;
  aspect-ratio: 1;
  background: var(--dn-wine);
  border-radius: 50%;
  box-shadow: 0 2px 6px rgba(15, 76, 92, 0.2);
}

.prism-dot--1 {
  top: 0;
  left: 50%;
  transform: translateX(-50%);
  background: var(--dn-spring);
}

.prism-dot--2 {
  top: 50%;
  right: 0;
  transform: translateY(-50%);
  background: var(--dn-summer);
}

.prism-dot--3 {
  bottom: 0;
  left: 50%;
  transform: translateX(-50%);
  background: var(--dn-autumn);
}

.prism-dot--4 {
  top: 50%;
  left: 0;
  transform: translateY(-50%);
  background: var(--dn-winter);
}

@keyframes prism-spin {
  to {
    transform: rotate(360deg);
  }
}

@keyframes prism-spin-reverse {
  to {
    transform: rotate(-360deg);
  }
}

.site-nav {
  position: relative;
}

.nav-rule--top {
  display: block;
  border-top: 3px double var(--dn-teal);
}

.nav-rule--bottom {
  display: block;
  margin-top: 0.5rem;
  border-top: 1px solid var(--dn-winter);
}

.nav-list {
  display: flex;
  justify-content: center;
  flex-wrap: wrap;
  gap: clamp(0.25rem, 1.5vw, 2rem);
  padding-block: 0.5rem;
}

.nav-link {
  display: inline-block;
  padding: 0.5rem 0.5rem;
  font-weight: 700;
  color: var(--dn-teal);
  position: relative;
  transition: color 0.2s var(--dn-ease);
}

.nav-link::after {
  content: '';
  position: absolute;
  left: 0.25rem;
  right: 0.25rem;
  bottom: 0;
  height: 3px;
  background: var(--dn-autumn);
  transform: scaleX(0);
  transform-origin: right;
  transition: transform 0.3s var(--dn-ease);
}

.nav-link:hover {
  color: var(--dn-wine);
}

.nav-link:hover::after,
.nav-link[aria-current="page"]::after {
  transform: scaleX(1);
  transform-origin: left;
}

.nav-link[aria-current="page"] {
  color: var(--dn-wine);
}

.nav-link[aria-current="page"]::before {
  content: '';
  position: absolute;
  top: 0.15rem;
  left: 0;
  width: 0.45rem;
  height: 0.45rem;
  background: var(--dn-spring);
  border-radius: 1px;
}

.nav-toggle {
  display: none;
}

[data-reveal] {
  opacity: 0;
  transform: translateY(20px);
  transition: opacity 0.6s var(--dn-ease), transform 0.6s var(--dn-ease);
}

[data-reveal="visible"] {
  opacity: 1;
  transform: translateY(0);
}

.site-footer {
  background: var(--dn-teal);
  color: var(--dn-cream);
  margin-top: 4rem;
  position: relative;
  overflow: hidden;
}

.site-footer::after {
  content: '四季';
  position: absolute;
  right: 4%;
  bottom: -3rem;
  font-size: 22vw;
  font-weight: 900;
  color: rgba(255, 255, 255, 0.03);
  pointer-events: none;
  line-height: 1;
  z-index: 0;
}

.footer-season-bar {
  display: flex;
  height: 6px;
  position: relative;
  z-index: 1;
}

.season-bar-item {
  flex: 1;
}

.season-bar-item--spring {
  background: var(--dn-spring);
}

.season-bar-item--summer {
  background: var(--dn-summer);
}

.season-bar-item--autumn {
  background: var(--dn-autumn);
}

.season-bar-item--winter {
  background: var(--dn-winter);
}

.footer-container {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr;
  gap: clamp(1rem, 4vw, 4rem);
  padding-block: 3rem 2rem;
  position: relative;
  z-index: 1;
}

.footer-brand {
  max-width: 40ch;
}

.footer-logo {
  font-family: var(--dn-font-display);
  font-size: clamp(2rem, 4vw, 3rem);
  font-weight: 900;
  letter-spacing: -0.02em;
  line-height: 1.1;
}

.footer-logo-sub {
  color: var(--dn-spring);
  font-size: 0.5em;
  font-weight: 700;
  letter-spacing: 0.1em;
  margin-left: 0.25rem;
}

.footer-trust {
  margin-top: 1rem;
  font-size: 0.9rem;
  color: var(--dn-winter);
  line-height: 1.8;
}

.footer-heading {
  font-size: 0.875rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.2em;
  color: var(--dn-autumn);
  margin-bottom: 1rem;
  padding-bottom: 0.5rem;
  border-bottom: 1px solid rgba(255, 255, 255, 0.2);
}

.footer-list li + li {
  margin-top: 0.6rem;
}

.footer-list a {
  color: var(--dn-cream);
  text-decoration: underline dashed;
  text-underline-offset: 4px;
  transition: color 0.2s var(--dn-ease);
}

.footer-list a:hover {
  color: var(--dn-spring);
}

.footer-list--contact li {
  color: var(--dn-cream);
  font-size: 0.9rem;
  line-height: 1.6;
  padding-left: 1rem;
  position: relative;
}

.footer-list--contact li::before {
  content: '';
  position: absolute;
  left: 0;
  top: 0.6em;
  width: 0.4rem;
  height: 0.4rem;
  background: var(--dn-autumn);
  border-radius: 1px;
}

.footer-bottom {
  grid-column: 1 / -1;
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 0.5rem;
  border-top: 1px solid rgba(255, 255, 255, 0.2);
  margin-top: 2rem;
  padding-top: 1.5rem;
  font-size: 0.875rem;
  color: var(--dn-winter);
}

.footer-copy,
.footer-icp {
  margin: 0;
}

@media (max-width: 960px) {
  .masthead {
    grid-template-columns: 1fr auto;
  }

  .masthead-annotation {
    display: none;
  }

  .season-prism {
    grid-column: 2 / 3;
  }

  .site-brand {
    grid-column: 1 / 2;
    justify-self: start;
  }

  .footer-container {
    grid-template-columns: 1fr;
    gap: 2rem;
  }

  .footer-bottom {
    margin-top: 1rem;
  }
}

@media (max-width: 820px) {
  .header-meta {
    padding-right: 3rem;
  }

  .nav-toggle {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    position: absolute;
    top: 0.75rem;
    right: 1rem;
    z-index: 60;
    background: var(--dn-paper);
    border: 1px solid var(--dn-teal);
    padding: 0.5rem 0.75rem;
    font-size: 0.875rem;
    font-weight: 700;
    color: var(--dn-teal);
    cursor: pointer;
    border-radius: 4px;
  }

  .nav-toggle-box {
    width: 1.25rem;
    height: 1rem;
    position: relative;
  }

  .nav-toggle-inner,
  .nav-toggle-inner::before,
  .nav-toggle-inner::after {
    content: '';
    position: absolute;
    left: 0;
    width: 100%;
    height: 2px;
    background: currentColor;
    border-radius: 1px;
    transition: transform 0.3s var(--dn-ease), background 0.3s var(--dn-ease);
  }

  .nav-toggle-inner {
    top: 50%;
    transform: translateY(-50%);
  }

  .nav-toggle-inner::before {
    top: -0.4rem;
  }

  .nav-toggle-inner::after {
    top: 0.4rem;
  }

  .nav-toggle[aria-expanded="true"] .nav-toggle-inner {
    background: transparent;
  }

  .nav-toggle[aria-expanded="true"] .nav-toggle-inner::before {
    transform: translateY(0.4rem) rotate(45deg);
  }

  .nav-toggle[aria-expanded="true"] .nav-toggle-inner::after {
    transform: translateY(-0.4rem) rotate(-45deg);
  }

  .site-nav {
    position: fixed;
    top: 0;
    right: 0;
    bottom: 0;
    z-index: 55;
    min-width: 75vw;
    max-width: 400px;
    background: var(--dn-paper);
    border-left: 1px solid var(--dn-winter);
    transform: translateX(100%);
    padding: 4.5rem 2rem 2rem;
    transition: transform 0.4s var(--dn-ease);
    box-shadow: -10px 0 30px rgba(15, 76, 92, 0.15);
  }

  .site-nav[data-open] {
    transform: translateX(0);
  }

  .nav-list {
    flex-direction: column;
    gap: 0.25rem;
  }

  .nav-link {
    display: block;
    padding: 0.75rem 1rem;
    font-size: 1.125rem;
    border-left: 3px solid transparent;
    border-radius: 4px;
  }

  .nav-link::after {
    display: none;
  }

  .nav-link[aria-current="page"] {
    border-left-color: var(--dn-wine);
    background: rgba(125, 46, 58, 0.05);
  }

  .nav-link[aria-current="page"]::before {
    top: 50%;
    left: 0.25rem;
    transform: translateY(-50%);
  }

  .footer-bottom {
    flex-direction: column;
    align-items: flex-start;
  }
}

@media (max-width: 480px) {
  .brand-tagline {
    font-size: 0.75rem;
    letter-spacing: 0.1em;
  }

  .brand-badge {
    font-size: 0.65rem;
    padding: 0.2rem 0.5rem;
  }

  .site-brand-name {
    font-size: clamp(3rem, 16vw, 4.5rem);
  }

  .site-brand-sub {
    font-size: 0.9rem;
  }

  .footer-logo {
    font-size: 1.75rem;
  }
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }

  .prism-core,
  .prism-ring {
    animation: none;
  }

  .scroll-progress {
    display: none;
  }

  [data-reveal] {
    opacity: 1;
    transform: none;
    transition: none;
  }
}