/* ============================================================
   Kai Feng Yi — Japanese / Zen Minimalist Stylesheet
   Palette: warm paper, ink black, terracotta accent
   ============================================================ */

/* --- Fonts ------------------------------------------------ */
@import url('https://fonts.googleapis.com/css2?family=Noto+Serif+SC:wght@400;600;700&family=Noto+Sans+SC:wght@300;400;500&display=swap');

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

/* --- Root Variables --------------------------------------- */
:root {
  --color-bg: #F5F0EB;
  --color-text: #2D2A24;
  --color-accent: #C4724A;
  --color-secondary: #8B7355;
  --color-divider: #DDD5CC;
  --color-light-text: #6B6258;
  --color-input-border: #D6CEC4;
  --color-input-focus: #C4724A;

  --font-serif: 'Noto Serif SC', 'Songti SC', 'SimSun', 'STSong', serif;
  --font-sans: 'Noto Sans SC', 'PingFang SC', 'Microsoft YaHei', 'Hiragino Sans GB', sans-serif;

  --space-xs: 0.5rem;
  --space-sm: 1rem;
  --space-md: 2rem;
  --space-lg: 4rem;
  --space-xl: 6rem;
  --space-2xl: 10rem;

  --max-width: 720px;
  --max-width-wide: 880px;
}

/* --- Base ------------------------------------------------- */
html {
  font-size: 16px;
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  font-family: var(--font-sans);
  font-size: 1rem;
  line-height: 1.8;
  color: var(--color-text);
  background-color: var(--color-bg);
  min-height: 100vh;
}

/* --- Typography ------------------------------------------- */
h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-serif);
  font-weight: 600;
  line-height: 1.3;
  color: var(--color-text);
}

h1 { font-size: clamp(2.2rem, 5vw, 3.6rem); }
h2 { font-size: clamp(1.6rem, 3.5vw, 2.2rem); }
h3 { font-size: 1.25rem; }

p {
  margin-bottom: 1rem;
  font-size: 1rem;
  color: var(--color-text);
}

a {
  color: var(--color-accent);
  text-decoration: none;
  transition: color 0.3s ease;
}

a:hover,
a:focus-visible {
  color: var(--color-secondary);
  text-decoration: underline;
}

::selection {
  background-color: var(--color-accent);
  color: var(--color-bg);
}

/* --- Thin Horizontal Rule --------------------------------- */
hr {
  border: none;
  border-top: 1px solid var(--color-divider);
  margin: var(--space-lg) 0;
}

hr.thin {
  border-top-width: 0.5px;
  margin: var(--space-md) 0;
}

hr.short {
  width: 60px;
  margin-left: 0;
}

/* --- Layout Containers ------------------------------------ */
.container {
  width: 100%;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--space-md);
}

.container-wide {
  max-width: var(--max-width-wide);
}

section {
  padding: var(--space-xl) var(--space-md);
}

@media (max-width: 600px) {
  section {
    padding: var(--space-lg) var(--space-sm);
  }
}

/* --- Header / Navigation ---------------------------------- */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  padding: var(--space-md);
  background: transparent;
  transition: background-color 0.4s ease;
}

.site-header.scrolled {
  background-color: rgba(245, 240, 235, 0.92);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
}

.header-inner {
  display: flex;
  justify-content: space-between;
  align-items: center;
  max-width: var(--max-width-wide);
  margin: 0 auto;
}

.site-brand {
  font-family: var(--font-serif);
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--color-text);
  text-decoration: none;
  letter-spacing: 0.02em;
}

.site-brand:hover {
  text-decoration: none;
  color: var(--color-accent);
}

.nav-links {
  display: flex;
  list-style: none;
  gap: 2rem;
}

.nav-links a {
  font-family: var(--font-sans);
  font-size: 0.875rem;
  font-weight: 400;
  color: var(--color-light-text);
  text-decoration: none;
  letter-spacing: 0.03em;
  text-transform: uppercase;
  transition: color 0.3s ease;
}

.nav-links a:hover,
.nav-links a:focus-visible {
  color: var(--color-accent);
  text-decoration: none;
}

/* Hamburger */
.hamburger {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 4px;
  z-index: 101;
}

.hamburger span {
  display: block;
  width: 22px;
  height: 1.5px;
  background: var(--color-text);
  transition: transform 0.3s ease, opacity 0.3s ease;
}

.hamburger.active span:nth-child(1) {
  transform: translateY(6.5px) rotate(45deg);
}

.hamburger.active span:nth-child(2) {
  opacity: 0;
}

.hamburger.active span:nth-child(3) {
  transform: translateY(-6.5px) rotate(-45deg);
}

@media (max-width: 640px) {
  .hamburger {
    display: flex;
  }

  .nav-links {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    gap: 2.5rem;
    background: var(--color-bg);
    opacity: 0;
    pointer-events: none;
    transition: opacity 0.35s ease;
  }

  .nav-links.active {
    opacity: 1;
    pointer-events: auto;
  }

  .nav-links a {
    font-size: 1.3rem;
    letter-spacing: 0.05em;
  }
}

/* --- Fade-in Animation (Intersection Observer) ------------ */
.fade-in {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.9s ease, transform 0.9s ease;
}

.fade-in.visible {
  opacity: 1;
  transform: translateY(0);
}

.fade-in-delay-1 { transition-delay: 0.15s; }
.fade-in-delay-2 { transition-delay: 0.3s; }
.fade-in-delay-3 { transition-delay: 0.45s; }

/* --- Hero Section ----------------------------------------- */
.hero {
  padding-top: var(--space-2xl);
  padding-bottom: var(--space-xl);
  text-align: center;
  min-height: 80vh;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
}

.hero h1 {
  margin-bottom: var(--space-sm);
  font-weight: 700;
  letter-spacing: 0.01em;
}

.hero .subtitle {
  font-family: var(--font-sans);
  font-size: 0.95rem;
  font-weight: 300;
  color: var(--color-light-text);
  margin-bottom: var(--space-lg);
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.hero hr {
  width: 80px;
  margin: 0 auto;
  border-color: var(--color-divider);
}

/* --- Statement Section ------------------------------------ */
.statement {
  padding: var(--space-xl) var(--space-md);
  text-align: center;
  max-width: var(--max-width);
  margin: 0 auto;
}

.statement p {
  font-family: var(--font-serif);
  font-size: clamp(1.3rem, 3vw, 1.8rem);
  font-style: italic;
  line-height: 1.7;
  color: var(--color-text);
  font-weight: 400;
}

/* --- Services Section ------------------------------------- */
.services {
  padding: var(--space-xl) var(--space-md);
  max-width: var(--max-width);
  margin: 0 auto;
}

.services .section-label {
  font-family: var(--font-sans);
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--color-light-text);
  margin-bottom: var(--space-lg);
}

.service-item {
  padding: var(--space-md) 0;
  border-top: 1px solid var(--color-divider);
}

.service-item:last-child {
  border-bottom: 1px solid var(--color-divider);
}

.service-item h3 {
  font-size: 1.35rem;
  margin-bottom: 0.3rem;
}

.service-item p {
  font-size: 0.95rem;
  color: var(--color-light-text);
  margin-bottom: 0;
}

/* --- Approach Section ------------------------------------- */
.approach {
  padding: var(--space-xl) var(--space-md);
  max-width: var(--max-width-wide);
  margin: 0 auto;
}

.approach .section-label {
  font-family: var(--font-sans);
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--color-light-text);
  margin-bottom: var(--space-lg);
}

.approach-grid {
  display: grid;
  grid-template-columns: 140px 1fr;
  gap: var(--space-lg);
  align-items: start;
}

@media (max-width: 600px) {
  .approach-grid {
    grid-template-columns: 1fr;
    gap: var(--space-sm);
  }
}

.approach-label {
  font-family: var(--font-sans);
  font-size: 0.8rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--color-light-text);
  padding-top: 0.3rem;
}

.approach-text {
  font-family: var(--font-serif);
  font-size: 1.15rem;
  line-height: 1.9;
  color: var(--color-text);
}

/* --- Values Section --------------------------------------- */
.values {
  padding: var(--space-xl) var(--space-md);
  max-width: var(--max-width);
  margin: 0 auto;
}

.values .section-label {
  font-family: var(--font-sans);
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--color-light-text);
  margin-bottom: var(--space-lg);
}

.value-item {
  padding: var(--space-sm) 0 var(--space-sm) var(--space-md);
  border-left: 2px solid var(--color-accent);
  margin-bottom: var(--space-md);
}

.value-item h3 {
  font-size: 1.2rem;
  margin-bottom: 0.25rem;
}

.value-item p {
  font-size: 0.9rem;
  color: var(--color-light-text);
  margin-bottom: 0;
}

/* --- CTA Section ------------------------------------------ */
.cta {
  padding: var(--space-xl) var(--space-md);
  text-align: center;
  max-width: var(--max-width);
  margin: 0 auto;
}

.cta p {
  font-family: var(--font-serif);
  font-size: 1.3rem;
  color: var(--color-text);
}

.cta a {
  color: var(--color-accent);
  text-decoration: none;
  border-bottom: 1px solid var(--color-accent);
  padding-bottom: 2px;
  transition: color 0.3s ease, border-color 0.3s ease;
}

.cta a:hover {
  color: var(--color-secondary);
  border-color: var(--color-secondary);
}

/* --- Contact Form ----------------------------------------- */
.contact {
  padding: var(--space-xl) var(--space-md);
  max-width: 520px;
  margin: 0 auto;
}

.contact .section-label {
  font-family: var(--font-sans);
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--color-light-text);
  margin-bottom: var(--space-lg);
}

.contact-form {
  display: flex;
  flex-direction: column;
  gap: var(--space-md);
}

.form-group {
  position: relative;
}

.form-group label {
  display: block;
  font-family: var(--font-sans);
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--color-light-text);
  margin-bottom: 0.4rem;
}

.form-group input,
.form-group textarea {
  width: 100%;
  border: none;
  border-bottom: 1px solid var(--color-input-border);
  background: transparent;
  padding: 0.6rem 0;
  font-family: var(--font-sans);
  font-size: 1rem;
  color: var(--color-text);
  outline: none;
  transition: border-color 0.3s ease;
}

.form-group input:focus,
.form-group textarea:focus {
  border-bottom-color: var(--color-input-focus);
}

.form-group textarea {
  resize: vertical;
  min-height: 100px;
}

.form-group input::placeholder,
.form-group textarea::placeholder {
  color: var(--color-divider);
}

.btn-submit {
  align-self: flex-start;
  background: none;
  border: none;
  font-family: var(--font-sans);
  font-size: 0.85rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--color-accent);
  cursor: pointer;
  padding: 0.5rem 0;
  border-bottom: 1px solid var(--color-accent);
  transition: color 0.3s ease, border-color 0.3s ease;
}

.btn-submit:hover {
  color: var(--color-secondary);
  border-color: var(--color-secondary);
}

.btn-submit:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

.form-feedback {
  font-size: 0.85rem;
  margin-top: 0.5rem;
}

.form-feedback.success {
  color: #5B7B4A;
}

.form-feedback.error {
  color: var(--color-accent);
}

/* --- Footer ----------------------------------------------- */
.site-footer {
  padding: var(--space-lg) var(--space-md);
  border-top: 1px solid var(--color-divider);
  text-align: center;
}

.site-footer .footer-inner {
  max-width: var(--max-width);
  margin: 0 auto;
}

.site-footer .company-name {
  font-family: var(--font-serif);
  font-size: 0.95rem;
  color: var(--color-text);
  margin-bottom: 0.5rem;
}

.site-footer .footer-links {
  display: flex;
  justify-content: center;
  gap: 2rem;
  list-style: none;
  margin-bottom: 0.5rem;
}

.site-footer .footer-links a {
  font-size: 0.8rem;
  color: var(--color-light-text);
  text-decoration: none;
  letter-spacing: 0.03em;
}

.site-footer .footer-links a:hover {
  color: var(--color-accent);
}

.site-footer .copyright {
  font-size: 0.75rem;
  color: var(--color-light-text);
}

/* --- Legal Pages (Privacy / Terms) ------------------------ */
.legal-page {
  padding-top: var(--space-2xl);
  padding-bottom: var(--space-xl);
  max-width: var(--max-width);
  margin: 0 auto;
}

.legal-page h1 {
  margin-bottom: var(--space-sm);
  font-size: clamp(1.8rem, 4vw, 2.4rem);
}

.legal-page .last-updated {
  font-size: 0.8rem;
  color: var(--color-light-text);
  margin-bottom: var(--space-lg);
  letter-spacing: 0.03em;
}

.legal-page h2 {
  font-size: 1.3rem;
  margin-top: var(--space-lg);
  margin-bottom: var(--space-sm);
  padding-top: var(--space-md);
  border-top: 1px solid var(--color-divider);
}

.legal-page h2:first-of-type {
  border-top: none;
  padding-top: 0;
}

.legal-page p {
  line-height: 1.9;
  color: var(--color-text);
}

.legal-page ul,
.legal-page ol {
  margin: 0 0 var(--space-md) var(--space-md);
}

.legal-page li {
  margin-bottom: 0.4rem;
  line-height: 1.7;
  color: var(--color-text);
}

.legal-page address {
  font-style: normal;
  line-height: 1.8;
  color: var(--color-text);
  margin-bottom: var(--space-md);
}

.legal-back {
  display: inline-block;
  margin-top: var(--space-lg);
  font-size: 0.85rem;
  color: var(--color-light-text);
  text-decoration: none;
  border-bottom: 1px solid var(--color-divider);
  padding-bottom: 2px;
  transition: color 0.3s ease, border-color 0.3s ease;
}

.legal-back:hover {
  color: var(--color-accent);
  border-color: var(--color-accent);
}

/* --- Utility ---------------------------------------------- */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

/* --- 404 / Error ------------------------------------------ */
.error-page {
  padding-top: var(--space-2xl);
  padding-bottom: var(--space-xl);
  text-align: center;
  min-height: 70vh;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
}

.error-page h1 {
  font-size: 5rem;
  font-weight: 300;
  color: var(--color-accent);
  line-height: 1;
  margin-bottom: var(--space-sm);
}

.error-page p {
  color: var(--color-light-text);
  margin-bottom: var(--space-lg);
}