:root {
    --white: #fafafa;
    --off-white: #f2f0ed;
    --black: #111;
    --gray-dark: #333;
    --gray-mid: #666;
    --gray-light: #aaa;
    --gray-border: #e0ddd8;
    --accent: #1a1a1a;
    --font-display: 'Cormorant Garamond', serif;
    --font-jp: 'Noto Serif JP', serif;
    --font-mono: 'IBM Plex Mono', monospace;
  }

  * { margin: 0; padding: 0; box-sizing: border-box; }

  html { scroll-behavior: smooth; font-size: 16px; }

  body {
    background: var(--white);
    color: var(--black);
    font-family: var(--font-jp);
    font-weight: 300;
    overflow-x: hidden;
    -webkit-font-smoothing: antialiased;
  }

  /* ====== HERO ====== */
  .hero {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    position: relative;
    padding: 2rem;
  }

  .hero-bg-letter {
    position: absolute;
    font-family: var(--font-display);
    font-size: clamp(300px, 50vw, 600px);
    font-weight: 300;
    color: transparent;
    -webkit-text-stroke: 1px var(--gray-border);
    opacity: 0;
    animation: fadeInSlow 2s ease-out 0.3s forwards;
    user-select: none;
    pointer-events: none;
    line-height: 1;
    bottom: -5%;
    right: 2%;
  }

  .hero-title {
    font-family: var(--font-display);
    font-size: clamp(3rem, 8vw, 7rem);
    font-weight: 300;
    letter-spacing: 0.15em;
    opacity: 0;
    animation: riseIn 1.2s cubic-bezier(0.22, 1, 0.36, 1) 0.6s forwards;
    position: relative;
    z-index: 2;
  }

  .hero-title em { font-style: italic; font-weight: 300; }

  .hero-subtitle {
    font-family: var(--font-jp);
    font-size: clamp(1rem, 2.5vw, 1.5rem);
    font-weight: 200;
    letter-spacing: 0.4em;
    margin-top: 3rem;
    opacity: 0;
    animation: riseIn 1.2s cubic-bezier(0.22, 1, 0.36, 1) 1s forwards;
    position: relative;
    z-index: 2;
  }

  .hero-line {
    width: 1px;
    height: 0;
    background: var(--gray-light);
    margin-top: 3rem;
    animation: lineGrow 1.5s ease-out 1.6s forwards;
    position: relative;
    z-index: 2;
  }

  .hero-scroll {
    position: absolute;
    bottom: 2.5rem;
    font-family: var(--font-mono);
    font-size: 0.65rem;
    letter-spacing: 0.2em;
    text-transform: uppercase;
    color: var(--gray-light);
    opacity: 0;
    animation: fadeInSlow 1.5s ease 2.5s forwards;
  }

  /* ====== INTRO ====== */
  .intro {
    max-width: 720px;
    margin: 0 auto;
    padding: 6rem 2rem 4rem;
  }

  .intro-label {
    font-family: var(--font-mono);
    font-size: 0.7rem;
    letter-spacing: 0.25em;
    text-transform: uppercase;
    color: var(--gray-light);
    margin-bottom: 2.5rem;
    opacity: 0;
    transform: translateY(20px);
    transition: all 0.8s ease;
  }

  .intro-text {
    font-family: var(--font-jp);
    font-size: clamp(0.95rem, 1.8vw, 1.15rem);
    font-weight: 300;
    line-height: 2.4;
    color: var(--gray-dark);
    opacity: 0;
    transform: translateY(30px);
    transition: all 1s ease 0.2s;
  }

  /* ====== QUESTION / PROVOCATION ====== */
  .question-section {
    min-height: auto;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    padding: 3rem 2rem;
    position: relative;
  }

  .question-line-top {
    width: 1px;
    height: 50px;
    background: linear-gradient(to bottom, transparent, var(--gray-border));
    margin-bottom: 2.5rem;
    opacity: 0;
    transition: opacity 1s ease;
  }

  .question-lines {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 1.5rem;
    max-width: 700px;
  }

  .question-text {
    font-family: var(--font-jp);
    font-size: clamp(1.1rem, 2.5vw, 1.6rem);
    font-weight: 300;
    letter-spacing: 0.12em;
    line-height: 2;
    text-align: center;
    color: var(--black);
    opacity: 0;
    transform: translateY(30px);
    transition: all 1s cubic-bezier(0.22, 1, 0.36, 1);
  }

  .question-text.line-2 { transition-delay: 0.4s; }
  .question-text.line-3 {
    transition-delay: 0.8s;
    font-weight: 400;
  }

  .question-em {
    font-style: normal;
  }

  .question-line-bottom {
    width: 1px;
    height: 50px;
    background: linear-gradient(to bottom, var(--gray-border), transparent);
    margin-top: 2.5rem;
    opacity: 0;
    transition: opacity 1s ease 1.2s;
  }

  /* ====== STRUCTURE DIAGRAM ====== */
  .structure-section {
    padding: 3rem 2rem 4rem;
    display: flex;
    flex-direction: column;
    align-items: center;
  }

  .structure-label {
    font-family: var(--font-mono);
    font-size: 0.65rem;
    letter-spacing: 0.3em;
    text-transform: uppercase;
    color: var(--gray-light);
    margin-bottom: 4rem;
    opacity: 0;
    transform: translateY(15px);
    transition: all 0.8s ease;
  }

  .structure-diagram {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0;
    max-width: 880px;
    width: 100%;
    opacity: 0;
    transform: translateY(20px);
    transition: all 1.2s cubic-bezier(0.22, 1, 0.36, 1) 0.2s;
  }

  /* Core node */
  .struct-core {
    display: flex;
    flex-direction: column;
    align-items: center;
    margin-bottom: 0;
    text-decoration: none;
    color: inherit;
    transition: opacity 0.3s ease;
  }

  .struct-core:hover {
    opacity: 0.7;
  }

  .struct-core-circle {
    width: 150px;
    height: 150px;
    border: 1px solid var(--black);
    border-radius: 50%;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    background: var(--white);
    transition: box-shadow 0.4s ease;
  }

  .struct-core-circle:hover {
    box-shadow: 0 0 0 10px rgba(0,0,0,0.025);
  }

  .struct-core-formula {
    font-family: var(--font-display);
    font-size: 1.4rem;
    font-weight: 400;
    font-style: italic;
    letter-spacing: 0.03em;
  }

  .struct-core-name {
    font-family: var(--font-jp);
    font-size: 0.95rem;
    font-weight: 400;
    letter-spacing: 0.08em;
    margin-top: 0.8rem;
  }

  .struct-core-en {
    font-family: var(--font-display);
    font-size: 0.8rem;
    font-style: italic;
    color: var(--gray-mid);
    margin-top: 0.2rem;
  }

  .struct-core-tag {
    font-family: var(--font-mono);
    font-size: 0.55rem;
    letter-spacing: 0.2em;
    text-transform: uppercase;
    color: var(--gray-light);
    margin-top: 0.5rem;
  }

  /* Connector lines */
  .struct-connector {
    display: flex;
    justify-content: center;
    align-items: stretch;
    width: 100%;
    position: relative;
    height: 50px;
  }

  .struct-connector-line {
    width: 1px;
    height: 100%;
    background: var(--gray-border);
  }

  .struct-connector-branch {
    position: relative;
    height: 50px;
    width: 70%;
    max-width: 600px;
  }

  .struct-connector-branch::before {
    content: '';
    position: absolute;
    top: 0;
    left: 50%;
    width: 1px;
    height: 50%;
    background: var(--gray-border);
  }

  .struct-connector-branch::after {
    content: '';
    position: absolute;
    top: 50%;
    left: 0;
    width: 100%;
    height: 1px;
    background: var(--gray-border);
  }

  /* Row of nodes */
  .struct-row {
    display: flex;
    justify-content: space-between;
    width: 70%;
    max-width: 600px;
    position: relative;
  }

  .struct-row::before {
    content: '';
    position: absolute;
    top: -25px;
    left: 0;
    right: 0;
    display: flex;
    justify-content: space-between;
  }

  /* Vertical ticks from horizontal line to nodes */
  .struct-node {
    display: flex;
    flex-direction: column;
    align-items: center;
    flex: 1;
    position: relative;
    padding-top: 0;
    text-decoration: none;
    color: inherit;
    transition: opacity 0.3s ease;
  }

  .struct-node:hover {
    opacity: 0.7;
  }

  .struct-node::before {
    content: '';
    width: 1px;
    height: 20px;
    background: var(--gray-border);
    margin-bottom: 0.8rem;
  }

  .struct-node-dot {
    width: 7px;
    height: 7px;
    border-radius: 50%;
    background: var(--black);
    margin-bottom: 0.7rem;
    transition: transform 0.3s ease;
  }

  .struct-node:hover .struct-node-dot {
    transform: scale(1.6);
  }

  .struct-node-jp {
    font-family: var(--font-jp);
    font-size: 0.95rem;
    font-weight: 400;
    letter-spacing: 0.06em;
    text-align: center;
    white-space: nowrap;
  }

  .struct-node-en {
    font-family: var(--font-display);
    font-size: 0.75rem;
    font-style: italic;
    color: var(--gray-mid);
    margin-top: 0.2rem;
    text-align: center;
  }

  .struct-node-tag {
    font-family: var(--font-mono);
    font-size: 0.55rem;
    letter-spacing: 0.15em;
    text-transform: uppercase;
    color: var(--gray-light);
    margin-top: 0.4rem;
  }

  /* Second connector */
  .struct-connector-branch-2 {
    position: relative;
    height: 50px;
    width: 46%;
    max-width: 400px;
  }

  .struct-connector-branch-2::before {
    content: '';
    position: absolute;
    top: 50%;
    left: 0;
    width: 100%;
    height: 1px;
    background: var(--gray-border);
  }

  /* Three vertical lines going down from row 1 to the horizontal line */
  .struct-drop-lines {
    display: flex;
    justify-content: space-between;
    width: 70%;
    max-width: 600px;
    height: 30px;
  }

  .struct-drop-line {
    width: 1px;
    height: 100%;
    background: var(--gray-border);
  }

  .struct-drop-line.hidden {
    background: transparent;
  }

  /* Bottom horizontal merge */
  .struct-merge-line {
    width: 46%;
    max-width: 400px;
    height: 1px;
    background: var(--gray-border);
  }

  .struct-drop-lines-2 {
    display: flex;
    justify-content: space-between;
    width: 46%;
    max-width: 400px;
    height: 20px;
  }

  .struct-row-2 {
    display: flex;
    justify-content: space-between;
    width: 46%;
    max-width: 400px;
  }

  .struct-row-2 .struct-node {
    flex: 1;
  }

  .struct-row-2 .struct-node::before {
    height: 0;
    margin-bottom: 0;
  }

  .structure-note {
    font-family: var(--font-jp);
    font-size: 0.75rem;
    font-weight: 300;
    color: var(--gray-mid);
    letter-spacing: 0.06em;
    margin-top: 3.5rem;
    opacity: 0;
    transition: opacity 1s ease 0.8s;
  }

  .struct-layer-tag {
    font-family: var(--font-mono);
    font-size: 0.6rem;
    letter-spacing: 0.2em;
    text-transform: uppercase;
    color: var(--gray-light);
    margin-top: 1rem;
    margin-bottom: 0.5rem;
  }

  /* ====== FORMULA ====== */
  .formula-section {
    padding: 3rem 2rem;
    text-align: center;
    position: relative;
  }

  .formula-label {
    font-family: var(--font-mono);
    font-size: 0.65rem;
    letter-spacing: 0.3em;
    text-transform: uppercase;
    color: var(--gray-light);
    margin-bottom: 3rem;
    opacity: 0;
    transform: translateY(20px);
    transition: all 0.8s ease;
  }

  .formula-main {
    font-family: var(--font-display);
    font-size: clamp(2.5rem, 7vw, 5rem);
    font-weight: 300;
    letter-spacing: 0.08em;
    color: var(--black);
    opacity: 0;
    transform: translateY(30px);
    transition: all 1s cubic-bezier(0.22, 1, 0.36, 1) 0.2s;
  }

  .formula-main em { font-style: italic; }

  .formula-desc {
    font-family: var(--font-jp);
    font-size: 0.85rem;
    font-weight: 300;
    color: var(--gray-mid);
    margin-top: 2rem;
    letter-spacing: 0.1em;
    opacity: 0;
    transform: translateY(20px);
    transition: all 0.8s ease 0.4s;
  }

  .formula-explanation {
    font-family: var(--font-jp);
    font-size: 0.9rem;
    font-weight: 300;
    line-height: 2.2;
    color: var(--gray-dark);
    margin-top: 2.5rem;
    max-width: 560px;
    margin-left: auto;
    margin-right: auto;
    text-align: left;
    letter-spacing: 0.04em;
    opacity: 0;
    transform: translateY(20px);
    transition: all 0.8s ease 0.6s;
  }

  .formula-explanation-2 {
    margin-top: 0.8rem;
    transition-delay: 0.8s;
  }

  .formula-divider {
    width: 60px;
    height: 1px;
    background: var(--gray-border);
    margin: 3rem auto 0;
    opacity: 0;
    transition: opacity 1s ease 0.6s;
  }

  /* ====== THEORIES ====== */
  .theories {
    max-width: 960px;
    margin: 0 auto;
    padding: 3rem 2rem 6rem;
  }

  .theories-header {
    display: flex;
    justify-content: space-between;
    align-items: baseline;
    margin-bottom: 4rem;
    padding-bottom: 1rem;
    border-bottom: 1px solid var(--gray-border);
  }

  .theories-label {
    font-family: var(--font-mono);
    font-size: 0.65rem;
    letter-spacing: 0.3em;
    text-transform: uppercase;
    color: var(--gray-light);
    opacity: 0;
    transform: translateY(15px);
    transition: all 0.8s ease;
  }

  .theories-count {
    font-family: var(--font-mono);
    font-size: 0.65rem;
    color: var(--gray-light);
    letter-spacing: 0.1em;
    opacity: 0;
    transition: opacity 0.8s ease 0.3s;
  }

  .theory-card {
    display: grid;
    grid-template-columns: 2.5rem 1fr auto;
    align-items: baseline;
    padding: 2rem 0;
    border-bottom: 1px solid var(--gray-border);
    cursor: pointer;
    text-decoration: none;
    color: inherit;
    position: relative;
    opacity: 0;
    transform: translateY(25px);
    transition: all 0.7s cubic-bezier(0.22, 1, 0.36, 1);
  }

  .theory-card::after {
    content: '';
    position: absolute;
    left: 0;
    bottom: 0;
    width: 0;
    height: 1px;
    background: var(--black);
    transition: width 0.5s cubic-bezier(0.22, 1, 0.36, 1);
  }

  .theory-card:hover::after { width: 100%; }

  .theory-card:hover .theory-arrow {
    transform: translateX(6px);
    opacity: 1;
  }

  .theory-card:hover .theory-name-jp-card {
    transform: translateX(4px);
  }

  .theory-index {
    font-family: var(--font-mono);
    font-size: 0.7rem;
    color: var(--gray-light);
    padding-top: 0.15rem;
  }

  .theory-content {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
  }

  .theory-name-jp-card {
    font-family: var(--font-jp);
    font-size: clamp(1.1rem, 2vw, 1.35rem);
    font-weight: 400;
    letter-spacing: 0.08em;
    transition: transform 0.4s cubic-bezier(0.22, 1, 0.36, 1);
  }

  .theory-name-en-card {
    font-family: var(--font-display);
    font-size: 0.85rem;
    font-weight: 400;
    font-style: italic;
    color: var(--gray-mid);
    letter-spacing: 0.04em;
  }

  .theory-desc {
    font-family: var(--font-jp);
    font-size: 0.8rem;
    font-weight: 300;
    color: var(--gray-mid);
    letter-spacing: 0.06em;
    margin-top: 0.25rem;
  }

  .theory-arrow {
    font-family: var(--font-mono);
    font-size: 0.8rem;
    color: var(--gray-light);
    opacity: 0;
    transform: translateX(0);
    transition: all 0.4s cubic-bezier(0.22, 1, 0.36, 1);
    align-self: center;
  }

  /* ====== PROJECTS ====== */
  .projects {
    max-width: 960px;
    margin: 0 auto;
    padding: 4rem 2rem 3rem;
  }

  .projects-label {
    font-family: var(--font-mono);
    font-size: 0.65rem;
    letter-spacing: 0.3em;
    text-transform: uppercase;
    color: var(--gray-light);
    margin-bottom: 2rem;
    padding-bottom: 1rem;
    border-bottom: 1px solid var(--gray-border);
    opacity: 0;
    transform: translateY(15px);
    transition: all 0.8s ease;
  }

  .projects-grid {
    display: flex;
    gap: 1.5rem;
    opacity: 0;
    transform: translateY(20px);
    transition: all 0.8s ease 0.2s;
  }

  .project-card {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.8rem 1.2rem;
    border: 1px solid var(--gray-border);
    text-decoration: none;
    color: inherit;
    transition: border-color 0.3s ease;
  }

  .project-card:hover {
    border-color: var(--gray-mid);
  }

  .project-card:hover .project-arrow {
    transform: translate(2px, -2px);
    opacity: 1;
  }

  .project-name {
    font-family: var(--font-display);
    font-size: 1rem;
    font-weight: 400;
    font-style: italic;
    letter-spacing: 0.06em;
  }

  .project-arrow {
    font-family: var(--font-mono);
    font-size: 0.7rem;
    color: var(--gray-light);
    opacity: 0.5;
    transition: all 0.3s cubic-bezier(0.22, 1, 0.36, 1);
  }

  /* ====== ABOUT ====== */
  .about {
    max-width: 960px;
    margin: 0 auto;
    padding: 3rem 2rem 4rem;
  }

  .about-label {
    font-family: var(--font-mono);
    font-size: 0.65rem;
    letter-spacing: 0.3em;
    text-transform: uppercase;
    color: var(--gray-light);
    margin-bottom: 2rem;
    padding-bottom: 1rem;
    border-bottom: 1px solid var(--gray-border);
    opacity: 0;
    transform: translateY(15px);
    transition: all 0.8s ease;
  }

  .about-content {
    opacity: 0;
    transform: translateY(20px);
    transition: all 0.8s ease 0.2s;
  }

  .about-name {
    font-family: var(--font-display);
    font-size: 1.5rem;
    font-weight: 400;
    letter-spacing: 0.1em;
    margin-bottom: 1.2rem;
  }

  .about-text {
    font-family: var(--font-jp);
    font-size: 0.95rem;
    font-weight: 300;
    line-height: 2.2;
    color: var(--gray-dark);
    max-width: 600px;
  }

  /* ====== FOOTER ====== */
  .footer {
    padding: 4rem 2rem;
    text-align: center;
    border-top: 1px solid var(--gray-border);
  }

  .footer-logo {
    font-family: var(--font-display);
    font-size: 1.2rem;
    font-weight: 300;
    font-style: italic;
    letter-spacing: 0.15em;
    color: var(--gray-light);
    margin-bottom: 1rem;
  }

  .footer-credit {
    font-family: var(--font-mono);
    font-size: 0.6rem;
    letter-spacing: 0.2em;
    text-transform: uppercase;
    color: var(--gray-light);
  }

  /* ====== ANIMATIONS ====== */
  @keyframes fadeInSlow {
    from { opacity: 0; }
    to { opacity: 1; }
  }

  @keyframes riseIn {
    from { opacity: 0; transform: translateY(40px); }
    to { opacity: 1; transform: translateY(0); }
  }

  @keyframes lineGrow {
    from { height: 0; }
    to { height: 80px; }
  }

  .visible .intro-label,
  .visible .intro-text,
  .visible .question-line-top,
  .visible .question-text,
  .visible .question-line-bottom,
  .visible .structure-label,
  .visible .structure-diagram,
  .visible .structure-note,
  .visible .formula-label,
  .visible .formula-main,
  .visible .formula-desc,
  .visible .formula-explanation,
  .visible .formula-divider,
  .visible .theories-label,
  .visible .theories-count,
  .visible .projects-label,
  .visible .projects-grid,
  .visible .about-label,
  .visible .about-content,
  .visible.theory-card {
    opacity: 1;
    transform: translateY(0) scale(1);
  }

  /* ====== RESPONSIVE ====== */
  @media (max-width: 768px) {
    .struct-core-circle {
      width: 120px;
      height: 120px;
    }

    .struct-core-formula { font-size: 1.1rem; }
    .struct-core-name { font-size: 0.9rem; }
    .struct-core-en { font-size: 0.75rem; }
    .struct-core-tag { font-size: 0.6rem; }
    .struct-node-jp { font-size: 0.9rem; }
    .struct-node-en { font-size: 0.7rem; }
    .struct-node-tag { font-size: 0.6rem; }
    .struct-layer-tag { font-size: 0.65rem; }
    .struct-row, .struct-connector-branch, .struct-drop-lines { width: 85%; }
    .struct-row-2, .struct-merge-line, .struct-drop-lines-2 { width: 56%; }

    .structure-note { font-size: 0.85rem; }

    /* Intro */
    .intro-label { font-size: 0.8rem; }
    .intro-text { font-size: 1.05rem; }

    /* Question */
    .question-text { font-size: clamp(1.1rem, 4.5vw, 1.5rem); }

    /* Formula */
    .formula-label { font-size: 0.75rem; }
    .formula-desc { font-size: 0.9rem; }
    .formula-explanation { font-size: 0.9rem; }

    /* Structure label */
    .structure-label { font-size: 0.75rem; }

    /* Theories */
    .theories-label { font-size: 0.75rem; }
    .theories-count { font-size: 0.75rem; }
    .theory-index { font-size: 0.8rem; }
    .theory-name-jp-card { font-size: 1.15rem; }
    .theory-name-en-card { font-size: 0.9rem; }
    .theory-desc { font-size: 0.85rem; }

    /* Footer */
    .footer-logo { font-size: 1.3rem; }
    .footer-credit { font-size: 0.7rem; }

    /* Hero scroll */
    .hero-scroll { font-size: 0.7rem; }

    /* Projects */
    .projects-label { font-size: 0.75rem; }
    .project-name { font-size: 1rem; }
    .project-arrow { opacity: 0.5; }

    /* About */
    .about-label { font-size: 0.75rem; }
    .about-name { font-size: 1.4rem; }
    .about-text { font-size: 0.95rem; }
  }

  @media (max-width: 640px) {
    .theory-card {
      grid-template-columns: 2rem 1fr auto;
      padding: 1.5rem 0;
    }

    .theories-header {
      flex-direction: column;
      gap: 0.5rem;
    }

    .intro { padding: 4rem 1.5rem 3rem; }
    .theories { padding: 2rem 1.5rem 4rem; }

    .struct-core-circle { width: 110px; height: 110px; }
    .struct-core-formula { font-size: 1rem; }
    .struct-node-jp { font-size: 0.85rem; white-space: normal; }
    .struct-node-en { font-size: 0.65rem; }
    .struct-row, .struct-connector-branch, .struct-drop-lines { width: 95%; }
    .struct-row-2, .struct-merge-line, .struct-drop-lines-2 { width: 65%; }
  }