:root {
    --paper: #f4f1e8;
    --ink: #102b27;
    --muted: #5e706b;
    --line: rgba(16, 43, 39, 0.18);
    --accent: #d84832;
    --accent-2: #0f6b5c;
    --panel: rgba(255, 255, 255, 0.66);
    --shadow: 0 18px 60px rgba(16, 43, 39, 0.13);
    --ease: cubic-bezier(0.16, 1, 0.3, 1);
}

* { box-sizing: border-box; }
html, body { width: 100%; height: 100%; margin: 0; }
html { color-scheme: light; }
body {
    overflow: hidden;
    background: var(--paper);
    color: var(--ink);
    font-family: "Noto Sans SC", "Source Han Sans SC", "PingFang SC", "Microsoft YaHei", sans-serif;
    text-rendering: optimizeLegibility;
}
button, a { font: inherit; }
a { color: inherit; }

.deck[data-edition="beginner"] {
    --paper: #fff8e8;
    --ink: #19324a;
    --muted: #647589;
    --line: rgba(25, 50, 74, 0.17);
    --accent: #ef6a3a;
    --accent-2: #2078a3;
    --panel: rgba(255, 255, 255, 0.74);
    --shadow: 0 18px 60px rgba(49, 75, 95, 0.12);
}
.deck[data-edition="referee"] {
    --paper: #eef2f1;
    --ink: #132f38;
    --muted: #5d7076;
    --line: rgba(19, 47, 56, 0.18);
    --accent: #b84b35;
    --accent-2: #1d6574;
    --panel: rgba(255, 255, 255, 0.72);
}

.progress {
    position: fixed;
    inset: 0 auto auto 0;
    width: 0;
    height: clamp(0.18rem, 0.4vh, 0.3rem);
    background: var(--accent);
    transition: width 420ms var(--ease);
    z-index: 50;
}

.deck-nav {
    position: fixed;
    inset: clamp(0.7rem, 1.8vw, 1.3rem) clamp(0.8rem, 2.2vw, 2rem) auto;
    z-index: 40;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: clamp(0.5rem, 1vw, 1rem);
    pointer-events: none;
}
.deck-nav > * { pointer-events: auto; }
.nav-left { display: flex; align-items: center; gap: clamp(0.35rem, 0.7vw, 0.6rem); }
.site-return,
.edition-switch a {
    display: inline-flex;
    align-items: center;
    min-height: clamp(2rem, 5vh, 2.8rem);
    padding: clamp(0.42rem, 0.8vw, 0.66rem) clamp(0.7rem, 1.3vw, 1rem);
    border: 1px solid var(--line);
    background: color-mix(in srgb, var(--paper) 90%, transparent);
    text-decoration: none;
    font-size: clamp(0.72rem, 1vw, 0.92rem);
    font-weight: 700;
    letter-spacing: 0.02em;
    backdrop-filter: blur(12px);
}
.site-return { border-radius: 999px; }
.edition-switch { display: flex; }
.edition-switch a:first-child { border-radius: 999px 0 0 999px; }
.edition-switch a { margin-left: -1px; }
.edition-switch a:last-child { border-radius: 0 999px 999px 0; }
.edition-switch a[aria-current="page"] { background: var(--ink); color: var(--paper); }

.slide {
    position: fixed;
    inset: 0;
    width: 100vw;
    height: 100vh;
    height: 100dvh;
    overflow: hidden;
    opacity: 0;
    pointer-events: none;
    transform: translateX(2.2vw);
    transition: opacity 360ms var(--ease), transform 520ms var(--ease);
}
.slide.active { opacity: 1; pointer-events: auto; transform: translateX(0); }
.slide-inner {
    position: relative;
    width: min(92vw, 92rem);
    height: 100%;
    margin: 0 auto;
    padding: clamp(5.1rem, 11vh, 7.6rem) clamp(0.5rem, 2vw, 2rem) clamp(4.2rem, 9vh, 6.2rem);
    display: flex;
    flex-direction: column;
    justify-content: center;
}
.slide::before {
    content: "";
    position: absolute;
    inset: 0;
    background-image: linear-gradient(var(--line) 1px, transparent 1px), linear-gradient(90deg, var(--line) 1px, transparent 1px);
    background-size: clamp(2.7rem, 6vw, 5.5rem) clamp(2.7rem, 6vw, 5.5rem);
    opacity: 0.24;
    mask-image: linear-gradient(90deg, #000 0, transparent 64%);
}
.slide[data-tone="dark"] { background: var(--ink); color: var(--paper); }
.slide[data-tone="dark"]::before {
    background-image: linear-gradient(rgba(244, 241, 232, 0.12) 1px, transparent 1px), linear-gradient(90deg, rgba(244, 241, 232, 0.12) 1px, transparent 1px);
    opacity: 0.5;
}
.slide[data-tone="dark"] .lead,
.slide[data-tone="dark"] .chapter-rules { color: color-mix(in srgb, var(--paper) 72%, transparent); }
.slide[data-tone="dark"] .rule-ref { color: var(--paper); }
.deck[data-edition="beginner"] .slide::before {
    background-image: radial-gradient(circle, var(--line) 1.1px, transparent 1.1px);
    background-size: clamp(1.6rem, 3vw, 2.4rem) clamp(1.6rem, 3vw, 2.4rem);
    opacity: 0.34;
}

.kicker {
    margin: 0 0 clamp(0.7rem, 1.8vh, 1.1rem);
    color: var(--accent);
    font-size: clamp(0.72rem, 1.2vw, 1rem);
    font-weight: 900;
    letter-spacing: 0.16em;
    text-transform: uppercase;
}
h1, h2, h3, p { overflow-wrap: break-word; }
h1, h2, h3 { margin: 0; }
h1 {
    max-width: 12ch;
    font-family: "Noto Serif SC", "Source Han Serif SC", "Songti SC", serif;
    font-size: clamp(3rem, 7vw, 7.2rem);
    font-weight: 800;
    line-height: 1.06;
    letter-spacing: -0.055em;
}
h2 {
    max-width: 18ch;
    font-family: "Noto Serif SC", "Source Han Serif SC", "Songti SC", serif;
    font-size: clamp(2rem, 4.2vw, 4.3rem);
    line-height: 1.12;
    letter-spacing: -0.035em;
}
.wide-title { max-width: none; font-size: clamp(2rem, 3.35vw, 3.4rem); }
h3 { font-size: clamp(1.05rem, 1.8vw, 1.5rem); line-height: 1.35; }
p, li, td, th { font-size: clamp(0.86rem, 1.35vw, 1.16rem); line-height: 1.68; }
.lead {
    max-width: 48rem;
    margin: clamp(1rem, 2.8vh, 1.8rem) 0 0;
    color: var(--muted);
    font-size: clamp(1rem, 1.65vw, 1.38rem);
}
.rule-ref {
    display: inline-flex;
    align-items: center;
    min-height: clamp(1.6rem, 3vh, 2rem);
    padding: clamp(0.18rem, 0.45vw, 0.32rem) clamp(0.45rem, 0.8vw, 0.7rem);
    border: 1px solid currentColor;
    border-radius: 999px;
    color: var(--accent-2);
    font-size: clamp(0.68rem, 0.95vw, 0.84rem);
    font-weight: 800;
    line-height: 1;
    white-space: nowrap;
}
.title-rule { align-self: flex-start; margin-top: clamp(1.2rem, 3vh, 2rem); }

.chapter-number {
    position: absolute;
    right: clamp(0.6rem, 3vw, 2.5rem);
    bottom: clamp(3.8rem, 9vh, 6rem);
    color: color-mix(in srgb, var(--paper) 12%, transparent);
    font-family: "Noto Serif SC", "Source Han Serif SC", serif;
    font-size: clamp(9rem, 28vw, 25rem);
    font-weight: 900;
    line-height: 0.72;
    letter-spacing: -0.08em;
}
.chapter-rules {
    max-width: 54rem;
    margin: clamp(1.1rem, 3vh, 2rem) 0 0;
    font-size: clamp(0.9rem, 1.45vw, 1.2rem);
    line-height: 1.7;
}
.chapter-rules strong { color: var(--paper); }

.chapter-grid {
    display: grid;
    grid-template-columns: repeat(4, minmax(0, 1fr));
    gap: clamp(0.55rem, 1.4vw, 1rem);
    margin-top: clamp(1rem, 2.5vh, 1.8rem);
}
.chapter-card {
    display: block;
    min-height: clamp(6.4rem, 16vh, 9.5rem);
    padding: clamp(0.75rem, 1.5vw, 1.2rem);
    border-top: clamp(0.16rem, 0.32vw, 0.26rem) solid var(--accent);
    background: var(--panel);
    color: var(--ink);
    text-decoration: none;
}
.chapter-card[href] { transition: transform 220ms var(--ease), box-shadow 220ms var(--ease), border-color 220ms var(--ease); }
.chapter-card[href]:hover, .chapter-card[href]:focus-visible { z-index: 2; transform: translateY(-0.2rem); border-top-color: var(--accent-2); box-shadow: var(--shadow); outline: 0.16rem solid color-mix(in srgb, var(--accent) 34%, transparent); }
.chapter-card b { display: block; color: var(--accent); font-size: clamp(0.72rem, 1vw, 0.9rem); }
.chapter-card strong { display: block; margin-top: clamp(0.3rem, 0.7vh, 0.55rem); font-family: "Noto Serif SC", "Source Han Serif SC", serif; font-size: clamp(1rem, 1.7vw, 1.4rem); }
.chapter-card span { display: block; margin-top: clamp(0.25rem, 0.6vh, 0.45rem); color: var(--muted); font-size: clamp(0.7rem, 1vw, 0.88rem); line-height: 1.5; }

.split {
    display: grid;
    grid-template-columns: minmax(0, 1.05fr) minmax(18rem, 0.95fr);
    align-items: center;
    gap: clamp(2rem, 6vw, 6rem);
}
.stack { display: grid; gap: clamp(0.7rem, 1.6vh, 1.15rem); }
.facts {
    display: grid;
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: clamp(0.6rem, 1.6vw, 1.2rem);
    margin-top: clamp(1.2rem, 3vh, 2rem);
}
.fact {
    min-height: clamp(6.2rem, 16vh, 10rem);
    padding: clamp(0.8rem, 1.6vw, 1.35rem);
    border-top: clamp(0.18rem, 0.3vw, 0.28rem) solid var(--accent);
    background: var(--panel);
}
.fact strong {
    display: block;
    font-family: "Noto Serif SC", "Source Han Serif SC", serif;
    font-size: clamp(1.5rem, 3.5vw, 3.3rem);
    line-height: 1;
    white-space: nowrap;
}
.fact span { display: block; margin-top: clamp(0.5rem, 1vh, 0.8rem); color: var(--muted); font-size: clamp(0.76rem, 1.1vw, 0.98rem); line-height: 1.55; }

.rule-list { list-style: none; margin: clamp(1rem, 2.6vh, 1.8rem) 0 0; padding: 0; max-width: 58rem; }
.rule-list li {
    display: grid;
    grid-template-columns: minmax(4.2rem, 6.3rem) minmax(0, 1fr);
    gap: clamp(0.7rem, 1.4vw, 1.2rem);
    align-items: baseline;
    padding: clamp(0.55rem, 1.25vh, 0.9rem) 0;
    border-top: 1px solid var(--line);
}
.rule-list li:last-child { border-bottom: 1px solid var(--line); }
.rule-list strong { color: var(--accent-2); font-size: clamp(0.76rem, 1.1vw, 0.96rem); }
.rule-list span { color: var(--ink); }

.callout {
    padding: clamp(1rem, 2vw, 1.6rem);
    border-left: clamp(0.22rem, 0.45vw, 0.38rem) solid var(--accent);
    background: var(--panel);
    box-shadow: var(--shadow);
}
.callout b { display: block; margin-bottom: clamp(0.35rem, 0.7vh, 0.55rem); color: var(--accent); font-size: clamp(0.76rem, 1vw, 0.92rem); letter-spacing: 0.08em; }
.callout p { margin: 0; }
.quote {
    margin: 0;
    font-family: "Noto Serif SC", "Source Han Serif SC", serif;
    font-size: clamp(1.7rem, 3.7vw, 3.6rem);
    line-height: 1.35;
}

.court {
    position: relative;
    width: min(40vw, 32rem);
    aspect-ratio: 1.55;
    margin-inline: auto;
    border: clamp(0.18rem, 0.35vw, 0.3rem) solid var(--ink);
    background: #d88452;
    box-shadow: inset 0 0 0 clamp(0.8rem, 2vw, 1.5rem) #4f9a83, var(--shadow);
    transform: perspective(50rem) rotateX(54deg) rotateZ(-4deg);
    transform-origin: center;
    cursor: zoom-in;
    transition: transform 300ms var(--ease), box-shadow 300ms var(--ease), filter 300ms var(--ease);
}
.court:hover,
.court:focus-visible,
.court.court-focused {
    z-index: 12;
    outline: 0.18rem solid color-mix(in srgb, var(--accent) 72%, white);
    outline-offset: 0.35rem;
    box-shadow: inset 0 0 0 clamp(0.8rem, 2vw, 1.5rem) #4f9a83, 0 1.7rem 4rem rgba(16, 43, 39, 0.28);
    filter: saturate(1.08) contrast(1.04);
    transform: perspective(50rem) rotateX(48deg) rotateZ(-2deg) scale(1.14);
}
.court-slide .split {
    grid-template-columns: minmax(0, 0.88fr) minmax(24rem, 1.12fr);
    gap: clamp(1.2rem, 3vw, 3rem);
}
.court-slide .court:hover,
.court-slide .court:focus-visible,
.court-slide .court.court-focused {
    transform: perspective(50rem) rotateX(38deg) rotateZ(-1deg) scale(1.24);
}
.court-slide .court:is(:hover, :focus-visible, .court-focused) .attack-line b {
    padding: 0.16rem 0.38rem;
    font-size: clamp(0.74rem, 1vw, 0.9rem);
    transform: translateX(-50%) rotateZ(1deg) rotateX(-38deg);
}
.court-slide .court:is(:hover, :focus-visible, .court-focused) .front-zone-label {
    padding: 0.2rem 0.42rem;
    font-size: clamp(0.74rem, 1vw, 0.9rem);
    transform: translate(-50%, -50%) rotateZ(1deg) rotateX(-38deg);
}
.court-slide .court:is(:hover, :focus-visible, .court-focused) .service-zone span {
    font-size: clamp(0.68rem, 0.9vw, 0.82rem);
    transform: rotateZ(1deg) rotateX(-38deg) rotate(-90deg);
}
.court-with-service { width: min(34vw, 28rem); }
.court::before { content: ""; position: absolute; inset: 0 50% 0 auto; z-index: 2; width: clamp(0.18rem, 0.35vw, 0.3rem); background: #f9f2df; transform: translateX(50%); }
.court .net { position: absolute; inset: -7% 50% -7% auto; z-index: 3; width: clamp(0.32rem, 0.65vw, 0.55rem); background: var(--ink); transform: translateX(50%); }
.court .attack-line { position: absolute; inset-block: 0; z-index: 2; width: clamp(0.13rem, 0.25vw, 0.22rem); background: #f9f2df; transform: translateX(-50%); }
.court .attack-line-left { left: 33.333%; }
.court .attack-line-right { left: 66.667%; }
.court .attack-line b {
    position: absolute;
    top: 4%;
    left: 50%;
    padding: 0.12rem 0.3rem;
    border-radius: 999px;
    background: rgba(16, 43, 39, 0.86);
    color: #fffaf0;
    font-size: clamp(0.58rem, 0.9vw, 0.78rem);
    line-height: 1;
    white-space: nowrap;
    transform: translateX(-50%) rotateZ(4deg) rotateX(-54deg);
    transform-origin: center;
}
.court .front-zone-label {
    position: absolute;
    top: 50%;
    z-index: 4;
    padding: 0.16rem 0.34rem;
    border: 1px solid rgba(255, 250, 240, 0.82);
    border-radius: 999px;
    background: rgba(216, 72, 50, 0.9);
    color: #fffaf0;
    font-size: clamp(0.58rem, 0.92vw, 0.8rem);
    font-weight: 900;
    line-height: 1;
    white-space: nowrap;
    transform: translate(-50%, -50%) rotateZ(4deg) rotateX(-54deg);
}
.court .front-zone-left { left: 41.667%; }
.court .front-zone-right { left: 58.333%; }
.court-with-service .service-zone {
    position: absolute;
    inset-block: 0;
    z-index: 1;
    display: grid;
    width: 12%;
    place-items: center;
    border-block: clamp(0.1rem, 0.2vw, 0.15rem) dashed rgba(255, 250, 240, 0.9);
    background: rgba(216, 72, 50, 0.34);
}
.court-with-service .service-zone-left { right: 100%; border-left: clamp(0.1rem, 0.2vw, 0.15rem) dashed rgba(255, 250, 240, 0.9); }
.court-with-service .service-zone-right { left: 100%; border-right: clamp(0.1rem, 0.2vw, 0.15rem) dashed rgba(255, 250, 240, 0.9); }
.court-with-service .service-zone::before,
.court-with-service .service-zone::after { content: ""; position: absolute; width: 34%; height: clamp(0.13rem, 0.24vw, 0.2rem); background: #fffaf0; box-shadow: 0 1px 0 rgba(16, 43, 39, 0.32); }
.court-with-service .service-zone::before { top: 0; }
.court-with-service .service-zone::after { bottom: 0; }
.court-with-service .service-zone-left::before,
.court-with-service .service-zone-left::after { right: 14%; }
.court-with-service .service-zone-right::before,
.court-with-service .service-zone-right::after { left: 14%; }
.court-with-service .service-zone span {
    color: #fffaf0;
    font-size: clamp(0.52rem, 0.82vw, 0.7rem);
    font-weight: 900;
    line-height: 1.15;
    text-align: center;
    text-shadow: 0 1px 0 rgba(16, 43, 39, 0.5);
    white-space: nowrap;
    transform: rotateZ(4deg) rotateX(-54deg) rotate(-90deg);
}
.court .zone {
    position: absolute;
    z-index: 7;
    display: grid;
    place-items: center;
    width: clamp(2.25rem, 12%, 3.5rem);
    aspect-ratio: 1;
    border: clamp(0.13rem, 0.25vw, 0.2rem) solid #fffaf0;
    border-radius: 50%;
    background: var(--ink);
    color: #fffaf0;
    box-shadow: 0 0.38rem 0.9rem rgba(16, 43, 39, 0.32);
    font-weight: 950;
    font-size: clamp(1.1rem, 2.4vw, 1.65rem);
    line-height: 1;
    transform: rotateZ(4deg) rotateX(-54deg);
    will-change: left, top;
}
.court .zone > b { display: block; color: inherit; font: inherit; line-height: 1; pointer-events: none; }
.court .z4 { left: 35%; top: 18%; }.court .z3 { left: 35%; top: 43%; }.court .z2 { left: 35%; top: 68%; }
.court .z5 { left: 10%; top: 18%; }.court .z6 { left: 10%; top: 43%; }.court .z1 { left: 10%; top: 68%; }
.court.is-rotating .z4 { animation: court-z4 1.25s var(--ease) both; }
.court.is-rotating .z3 { animation: court-z3 1.25s var(--ease) both; }
.court.is-rotating .z2 { animation: court-z2 1.25s var(--ease) both; }
.court.is-rotating .z1 { animation: court-z1 1.25s var(--ease) both; }
.court.is-rotating .z6 { animation: court-z6 1.25s var(--ease) both; }
.court.is-rotating .z5 { animation: court-z5 1.25s var(--ease) both; }
@keyframes court-z4 { 0%, 12% { left: 35%; top: 18%; } 82%, 100% { left: 35%; top: 43%; } }
@keyframes court-z3 { 0%, 12% { left: 35%; top: 43%; } 82%, 100% { left: 35%; top: 68%; } }
@keyframes court-z2 { 0%, 12% { left: 35%; top: 68%; } 82%, 100% { left: 10%; top: 68%; } }
@keyframes court-z1 { 0%, 12% { left: 10%; top: 68%; } 82%, 100% { left: 10%; top: 43%; } }
@keyframes court-z6 { 0%, 12% { left: 10%; top: 43%; } 82%, 100% { left: 10%; top: 18%; } }
@keyframes court-z5 { 0%, 12% { left: 10%; top: 18%; } 82%, 100% { left: 35%; top: 18%; } }

.flow {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: clamp(0.5rem, 1.3vw, 1rem);
    margin-top: clamp(1.2rem, 3vh, 2.2rem);
}
.flow-step { position: relative; padding: clamp(0.8rem, 1.7vw, 1.4rem); border-top: 1px solid var(--ink); }
.flow-step::after { content: ""; position: absolute; top: -0.28rem; right: -0.24rem; width: clamp(0.45rem, 0.8vw, 0.7rem); aspect-ratio: 1; border-top: 1px solid var(--ink); border-right: 1px solid var(--ink); transform: rotate(45deg); }
.flow-step:last-child::after { display: none; }
.flow-step b { color: var(--accent); font-size: clamp(0.72rem, 0.95vw, 0.86rem); }
.flow-step p { margin: clamp(0.45rem, 1vh, 0.7rem) 0 0; font-size: clamp(0.8rem, 1.15vw, 1rem); }

.cards { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: clamp(0.65rem, 1.5vw, 1.2rem); margin-top: clamp(1rem, 2.2vh, 1.6rem); }
.card { padding: clamp(0.8rem, 1.7vw, 1.35rem); border: 1px solid var(--line); background: var(--panel); }
.card h3 { color: var(--accent-2); }
.card p { margin: clamp(0.35rem, 0.8vh, 0.6rem) 0 0; color: var(--muted); font-size: clamp(0.8rem, 1.1vw, 0.98rem); }

.compare {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: clamp(0.8rem, 2vw, 1.5rem);
    margin-top: clamp(1rem, 2.3vh, 1.7rem);
}
.compare-column { padding: clamp(0.9rem, 1.8vw, 1.45rem); border-top: clamp(0.18rem, 0.35vw, 0.3rem) solid var(--accent-2); background: var(--panel); }
.compare-column.is-fault { border-top-color: var(--accent); }
.compare-column > b { color: var(--accent-2); font-size: clamp(0.75rem, 1vw, 0.9rem); letter-spacing: 0.08em; }
.compare-column.is-fault > b { color: var(--accent); }
.compare-column h3 { margin-top: clamp(0.35rem, 0.8vh, 0.6rem); }
.compare-column p { margin: clamp(0.35rem, 0.8vh, 0.6rem) 0 0; color: var(--muted); font-size: clamp(0.8rem, 1.15vw, 1rem); }

.decision-grid {
    display: grid;
    grid-template-columns: repeat(4, minmax(0, 1fr));
    gap: clamp(0.5rem, 1.2vw, 0.9rem);
    margin-top: clamp(1rem, 2.4vh, 1.7rem);
}
.decision {
    position: relative;
    padding: clamp(0.75rem, 1.5vw, 1.2rem);
    border: 1px solid var(--line);
    background: var(--panel);
}
.decision b { color: var(--accent); font-size: clamp(1.35rem, 2.8vw, 2.4rem); line-height: 1; }
.decision h3 { margin-top: clamp(0.35rem, 0.8vh, 0.6rem); }
.decision p { margin: clamp(0.3rem, 0.7vh, 0.5rem) 0 0; color: var(--muted); font-size: clamp(0.76rem, 1.05vw, 0.94rem); }

.coverage-note { display: flex; align-items: center; gap: clamp(0.6rem, 1.2vw, 1rem); margin-top: clamp(0.8rem, 2vh, 1.3rem); color: var(--muted); font-size: clamp(0.72rem, 1vw, 0.9rem); }
.coverage-note::before { content: ""; width: clamp(2.5rem, 7vw, 6rem); height: 0.22rem; background: var(--accent-2); }
.facts + .callout, .cards + .callout, .flow + .callout, .decision-grid + .callout { margin-top: clamp(1.8rem, 4vh, 3.2rem); }
.rule-list > li, .flow-step, .fact, .card, .chapter-card, .decision, .compare-column, .signal-card { transition: outline-color 220ms var(--ease), box-shadow 220ms var(--ease), background-color 220ms var(--ease), transform 220ms var(--ease); }
:is(.rule-list > li, .flow-step, .fact, .card, .chapter-card, .decision, .compare-column, .signal-card):is(:hover, :focus-visible, :focus-within) {
    z-index: 2;
    outline: 0.18rem solid color-mix(in srgb, var(--accent) 52%, transparent);
    outline-offset: 0.16rem;
    background-color: color-mix(in srgb, var(--panel) 87%, var(--accent) 13%);
    box-shadow: 0 0.75rem 1.8rem color-mix(in srgb, var(--ink) 13%, transparent);
    transform: translateY(-0.12rem);
}

.position-fault-slide .compare { gap: clamp(1.8rem, 4vw, 3.4rem); }
.position-fault-slide h2 { max-width: none; }
.position-fault-slide .compare + .callout { margin-top: clamp(2.3rem, 5vh, 3.8rem); }

.court-facts { grid-template-columns: minmax(0, 1.08fr) minmax(0, 0.82fr) minmax(0, 1.24fr); }
.court-facts .fact { min-width: 0; padding-inline: clamp(0.55rem, 1.25vw, 1rem); }
.court-facts .court-size { font-size: clamp(1.25rem, 3vw, 2.8rem); }
.court-facts .net-heights { font-size: clamp(1rem, 2.45vw, 2.25rem); }

/* Beginner page 3: the measurement diagram becomes a large, near-flat teaching view. */
.court-detail-slide .split {
    grid-template-columns: minmax(0, 0.82fr) minmax(26rem, 1.18fr);
    gap: clamp(1rem, 2vw, 2rem);
}
.court-detail-slide .court:hover,
.court-detail-slide .court:focus-visible,
.court-detail-slide .court.court-focused {
    transform: perspective(50rem) rotateX(30deg) rotateZ(-1deg) scale(1.34);
}
.court-detail-slide .court:is(:hover, :focus-visible, .court-focused) .attack-line b {
    padding: 0.18rem 0.42rem;
    font-size: clamp(0.82rem, 1.15vw, 1rem);
    transform: translateX(-50%) rotateZ(1deg) rotateX(-30deg);
}
.court-detail-slide .court:is(:hover, :focus-visible, .court-focused) .front-zone-label {
    padding: 0.22rem 0.46rem;
    font-size: clamp(0.82rem, 1.15vw, 1rem);
    transform: translate(-50%, -50%) rotateZ(1deg) rotateX(-30deg);
}
.court-detail-slide .court:is(:hover, :focus-visible, .court-focused) .service-zone span {
    font-size: clamp(0.74rem, 1vw, 0.9rem);
    transform: rotateZ(1deg) rotateX(-30deg) rotate(-90deg);
}

.scoreboard { display: flex; align-items: stretch; gap: clamp(0.55rem, 1.2vw, 1rem); }
.score-cell { min-width: clamp(6.5rem, 11vw, 10rem); padding: clamp(0.8rem, 1.8vw, 1.4rem); background: var(--ink); color: var(--paper); }
.score-cell strong { display: block; font-size: clamp(2.2rem, 5vw, 4.8rem); line-height: 1; }
.score-cell span { font-size: clamp(0.7rem, 1vw, 0.9rem); }
.score-cell.accent { background: var(--accent); }

.quiz { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: clamp(0.7rem, 1.6vw, 1.2rem); margin-top: clamp(1rem, 2vh, 1.5rem); }
.quiz button { min-height: clamp(4.4rem, 12vh, 7.2rem); padding: clamp(0.8rem, 1.8vw, 1.4rem); border: 1px solid var(--line); background: var(--panel); color: var(--ink); text-align: left; cursor: pointer; transition: transform 220ms var(--ease), background 220ms var(--ease); }
.quiz button:hover, .quiz button:focus-visible { transform: translateY(-0.18rem); outline: 0.18rem solid color-mix(in srgb, var(--accent) 34%, transparent); }
.quiz button.correct { background: #d9efdf; border-color: #348450; }
.quiz button.wrong { background: #f8ded5; border-color: #bd5336; }
.quiz-feedback { min-height: 1.8em; margin: clamp(0.7rem, 1.2vh, 1rem) 0 0; color: var(--accent-2); font-weight: 800; }
.quiz-bank { margin-top: clamp(0.8rem, 2vh, 1.3rem); }
.quiz-tabs { display: flex; flex-wrap: wrap; gap: clamp(0.45rem, 1vw, 0.75rem); }
.quiz-tabs button { min-width: 3.2rem; padding: 0.5rem 0.8rem; border: 1px solid var(--line); border-radius: 999px; background: var(--panel); color: var(--ink); cursor: pointer; font-weight: 900; }
.quiz-tabs button[aria-selected="true"] { border-color: var(--accent); background: var(--accent); color: #fffaf0; }
.quiz-question { display: none; margin-top: clamp(0.8rem, 2vh, 1.3rem); }
.quiz-question.active { display: block; }
.quiz-question h3 { max-width: 36ch; font-size: clamp(1.35rem, 3.2vw, 2.5rem); }
.quiz-question .quiz { max-width: 52rem; }
.quiz-question .quiz button { min-height: clamp(3.4rem, 9vh, 5.2rem); }
.quiz-question .rule-note { margin-top: clamp(0.35rem, 0.8vh, 0.55rem); color: var(--muted); font-size: clamp(0.72rem, 1vw, 0.9rem); }

.heading-actions { display: flex; align-items: flex-end; justify-content: space-between; gap: clamp(0.7rem, 2vw, 1.4rem); }
.diagram-open, .dialog-close {
    min-height: 2.5rem;
    padding: 0.55rem 0.9rem;
    border: 1px solid var(--line);
    border-radius: 999px;
    background: var(--panel);
    color: var(--ink);
    cursor: pointer;
    font-size: clamp(0.72rem, 1vw, 0.9rem);
    font-weight: 900;
    white-space: nowrap;
}
.diagram-open:hover, .diagram-open:focus-visible, .dialog-close:hover, .dialog-close:focus-visible { border-color: var(--accent); outline: 0.16rem solid color-mix(in srgb, var(--accent) 28%, transparent); }
.net-diagram-dialog { width: min(94vw, 66rem); max-height: 92dvh; padding: 0; border: 0; border-radius: clamp(0.7rem, 1.8vw, 1.2rem); background: var(--paper); color: var(--ink); box-shadow: 0 2rem 5rem rgba(16, 43, 39, 0.34); }
.net-diagram-dialog::backdrop { background: rgba(8, 24, 27, 0.72); backdrop-filter: blur(5px); }
.net-diagram-shell { max-height: 92dvh; padding: clamp(1rem, 2.8vw, 2rem); overflow: auto; }
.net-diagram-head { display: flex; align-items: flex-start; justify-content: space-between; gap: 1rem; }
.net-diagram-head h2 { font-size: clamp(1.7rem, 4vw, 3.1rem); }
.net-diagram-head p { margin: 0.35rem 0 0; color: var(--muted); }
.net-diagram-svg { display: block; width: 100%; height: auto; margin-top: clamp(0.8rem, 2vh, 1.4rem); border: 1px solid var(--line); background: #f8f4e9; }
.net-diagram-notes { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: clamp(0.5rem, 1vw, 0.8rem); margin-top: clamp(0.7rem, 1.5vh, 1rem); }
.net-diagram-notes article { padding: clamp(0.65rem, 1.4vw, 0.95rem); border-top: 0.18rem solid var(--accent); background: var(--panel); }
.net-diagram-notes b { display: block; color: var(--accent-2); }
.net-diagram-notes p { margin: 0.35rem 0 0; color: var(--muted); font-size: clamp(0.7rem, 0.95vw, 0.86rem); }
.signal-grid { display: grid; grid-template-columns: repeat(5, minmax(0, 1fr)); gap: clamp(0.5rem, 1vw, 0.8rem); margin-top: clamp(0.8rem, 2vh, 1.3rem); }
.signal-grid[data-columns="3"] { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.signal-card { display: grid; grid-template-rows: minmax(5.2rem, 1fr) auto; min-height: clamp(12rem, 27vh, 16rem); padding: clamp(0.55rem, 1.1vw, 0.85rem); border: 1px solid var(--line); background: var(--panel); }
.signal-art {
    width: min(100%, clamp(7rem, 13vw, 11.5rem));
    height: auto;
    aspect-ratio: var(--signal-ratio);
    justify-self: center;
    border-radius: 0.45rem;
    background-color: #06191f;
    background-position: var(--signal-x) var(--signal-y);
    background-repeat: no-repeat;
    background-size: var(--signal-size-x) auto;
    box-shadow: inset 0 0 0 1px rgba(255, 255, 255, 0.14);
}
.signal-art--r1-r5 { background-image: url("../assets/signals/referee-r1-r5.png"); }
.signal-art--r6-r10 { background-image: url("../assets/signals/referee-r6-r10.png"); }
.signal-art--r11-r20 { background-image: url("../assets/signals/referee-r11-r20.png"); }
.signal-art--r11-eight { background-image: url("../assets/signals/referee-r11-eight-fingers.png"); }
.signal-art--r21-l5 { background-image: url("../assets/signals/official-r21-l5.png"); }
.signal-pose { width: 100%; height: clamp(5.2rem, 13vh, 8rem); }
.signal-pose g { fill: none; stroke: var(--ink); stroke-width: 5; stroke-linecap: round; stroke-linejoin: round; }
.signal-pose text { fill: var(--ink); stroke: none; font-size: 15px; font-weight: 900; }
.signal-pose .motion { stroke: var(--accent); stroke-width: 4; }
.signal-pose .net-mark { stroke: var(--accent-2); stroke-width: 4; }
.signal-pose .flag { fill: var(--accent); stroke: var(--ink); stroke-width: 3; }
.signal-pose .accent-fill { fill: #e4c244; stroke: var(--ink); stroke-width: 2; }
.signal-pose .dark-fill { fill: #d84832; stroke: var(--ink); stroke-width: 2; }
.signal-pose .badge { fill: var(--paper); stroke: var(--accent); stroke-width: 3; }
.signal-card b { display: block; color: var(--accent-2); font-size: clamp(0.72rem, 0.95vw, 0.86rem); }
.signal-card em { display: block; margin-top: 0.18rem; color: var(--accent); font-size: clamp(0.58rem, 0.75vw, 0.68rem); font-style: normal; font-weight: 900; letter-spacing: 0.04em; }
.signal-card p { margin: 0.3rem 0 0; color: var(--ink); font-size: clamp(0.67rem, 0.9vw, 0.8rem); line-height: 1.42; }
.signal-card small { display: block; margin-top: 0.3rem; color: var(--muted); font-size: clamp(0.58rem, 0.75vw, 0.7rem); }

.controls {
    position: fixed;
    inset: auto clamp(0.8rem, 2.2vw, 2rem) clamp(0.7rem, 1.8vw, 1.3rem);
    z-index: 45;
    display: flex;
    align-items: center;
    gap: clamp(0.45rem, 0.9vw, 0.75rem);
}
.controls button {
    display: grid;
    place-items: center;
    width: clamp(2.2rem, 4vw, 3rem);
    aspect-ratio: 1;
    border: 1px solid var(--line);
    border-radius: 50%;
    background: color-mix(in srgb, var(--paper) 90%, transparent);
    color: var(--ink);
    cursor: pointer;
    backdrop-filter: blur(12px);
}
.controls button:disabled { opacity: 0.3; cursor: default; }
.page-counter { min-width: clamp(3.6rem, 6vw, 5rem); color: var(--muted); font-size: clamp(0.72rem, 1vw, 0.9rem); font-variant-numeric: tabular-nums; text-align: center; }
.hint { margin-left: auto; color: var(--muted); font-size: clamp(0.68rem, 0.95vw, 0.84rem); }

.reveal { opacity: 0; transform: translateY(clamp(0.8rem, 2.2vh, 1.6rem)); }
.active .reveal { animation: reveal 650ms var(--ease) forwards; }
.active .reveal:nth-child(2) { animation-delay: 90ms; }
.active .reveal:nth-child(3) { animation-delay: 170ms; }
.active .reveal:nth-child(4) { animation-delay: 250ms; }
.active .reveal:nth-child(5) { animation-delay: 330ms; }
@keyframes reveal { to { opacity: 1; transform: translateY(0); } }

@media (max-width: 760px) {
    .deck-nav { align-items: flex-start; }
    .site-return { max-width: 9.2rem; line-height: 1.2; }
    .slide-inner { width: 94vw; padding-top: clamp(5.3rem, 13vh, 6.6rem); padding-bottom: clamp(4.4rem, 10vh, 5.4rem); }
    .split { grid-template-columns: 1fr; gap: clamp(0.7rem, 2vh, 1.2rem); }
    .split .visual { order: -1; }
    .court { width: min(68vw, 22rem); }
    .court-with-service { width: min(60vw, 19rem); }
    .court:hover, .court:focus-visible, .court.court-focused { transform: perspective(50rem) rotateX(48deg) rotateZ(-2deg) scale(1.08); }
    .court-slide .split { grid-template-columns: 1fr; gap: clamp(0.7rem, 2vh, 1.2rem); }
    .court-slide .court:hover,
    .court-slide .court:focus-visible,
    .court-slide .court.court-focused { transform: perspective(50rem) rotateX(34deg) rotateZ(-1deg) scale(1.16); }
    .court-slide .court-with-service:hover,
    .court-slide .court-with-service:focus-visible,
    .court-slide .court-with-service.court-focused { transform: translateX(-1.5%) perspective(50rem) rotateX(34deg) rotateZ(-1deg) scale(1.16); }
    .court-slide .court:is(:hover, :focus-visible, .court-focused) .attack-line b,
    .court-slide .court:is(:hover, :focus-visible, .court-focused) .front-zone-label { font-size: 0.68rem; }
    .facts { grid-template-columns: repeat(3, minmax(0, 1fr)); }
    .fact { min-height: 0; }
    .fact strong { font-size: clamp(0.88rem, 4vw, 1.25rem); letter-spacing: -0.035em; }
    .court-facts { grid-template-columns: minmax(0, 1.06fr) minmax(0, 0.72fr) minmax(0, 1.28fr); gap: 0.35rem; }
    .court-facts .fact { padding: 0.62rem 0.38rem; }
    .court-facts .court-size { font-size: clamp(0.88rem, 3.85vw, 1.08rem); }
    .court-facts .net-heights { font-size: clamp(0.72rem, 3.15vw, 0.92rem); }
    .court-detail-slide .court:hover,
    .court-detail-slide .court:focus-visible,
    .court-detail-slide .court.court-focused {
        transform: translateX(-9%) perspective(50rem) rotateX(22deg) rotateZ(-1deg) scale(1.25);
    }
    .court-detail-slide .court:is(:hover, :focus-visible, .court-focused) .attack-line b,
    .court-detail-slide .court:is(:hover, :focus-visible, .court-focused) .front-zone-label { font-size: 0.72rem; }
    .court-detail-slide .court:is(:hover, :focus-visible, .court-focused) .service-zone span { font-size: 0.72rem; }
    .flow { grid-template-columns: repeat(2, 1fr); }
    .flow-step:nth-child(2)::after { display: none; }
    .cards { grid-template-columns: repeat(2, minmax(0, 1fr)); }
    .chapter-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
    .chapter-card { min-height: clamp(5.1rem, 12vh, 6.8rem); }
    .decision-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
    .compare { gap: clamp(0.45rem, 1.2vw, 0.7rem); }
    .position-fault-slide .compare { gap: clamp(0.9rem, 3vw, 1.25rem); }
    .position-fault-slide .compare + .callout { margin-top: clamp(1.7rem, 4vh, 2.4rem); }
    .compare-column { padding: clamp(0.65rem, 1.4vw, 0.9rem); }
    .chapter-number { right: -0.2rem; bottom: clamp(4rem, 9vh, 5rem); }
    .heading-actions { align-items: flex-start; }
    .diagram-open { min-height: 2.2rem; padding: 0.45rem 0.65rem; }
    .net-diagram-notes { grid-template-columns: repeat(2, minmax(0, 1fr)); }
    .signal-grid, .signal-grid[data-columns="3"] { grid-template-columns: repeat(2, minmax(0, 1fr)); }
    .signal-card { min-height: clamp(8.6rem, 19vh, 10.5rem); grid-template-columns: 4.2rem minmax(0, 1fr); grid-template-rows: 1fr; align-items: center; }
    .signal-pose { height: 4.8rem; }
    .signal-art { width: 4.2rem; height: auto; }
    .hint { display: none; }
}

@media (max-height: 700px) {
    .slide-inner { padding-top: clamp(4.5rem, 12vh, 5.6rem); padding-bottom: clamp(3.6rem, 9vh, 4.5rem); }
    p, li, td, th { line-height: 1.48; }
    .rule-list li { padding-block: clamp(0.35rem, 1vh, 0.6rem); }
}
@media (max-height: 600px) {
    .lead { margin-top: clamp(0.5rem, 1.5vh, 0.8rem); }
    .facts, .cards, .flow, .rule-list { margin-top: clamp(0.5rem, 1.5vh, 0.8rem); }
    .fact { min-height: clamp(4.5rem, 14vh, 6rem); }
    .callout { padding: clamp(0.6rem, 1.5vw, 0.9rem); }
}
@media (max-height: 500px) {
    .deck-nav { top: clamp(0.3rem, 1vh, 0.5rem); }
    .slide-inner { padding-top: clamp(3.2rem, 10vh, 3.8rem); padding-bottom: clamp(2.8rem, 9vh, 3.4rem); }
    .kicker { margin-bottom: clamp(0.3rem, 1vh, 0.5rem); }
    .controls { bottom: clamp(0.3rem, 1vh, 0.5rem); }
}

@media (prefers-reduced-motion: reduce) {
    *, *::before, *::after { scroll-behavior: auto !important; animation-duration: 1ms !important; transition-duration: 1ms !important; }
    .court.is-rotating .zone { background: var(--accent); }
}

/* Shared selector page: one local entry for all presentation editions. */
.selector-page { min-height: 100%; overflow: auto; background: #f4f1e8; color: #102b27; }
.selector-shell { width: min(92vw, 78rem); margin: 0 auto; padding: clamp(2rem, 5vw, 4.5rem) clamp(0.5rem, 2vw, 1.5rem) clamp(3rem, 7vw, 6rem); }
.selector-top { display: flex; justify-content: space-between; align-items: center; gap: clamp(0.8rem, 2vw, 1.5rem); }
.selector-top a { text-decoration: none; font-size: clamp(0.78rem, 1.1vw, 0.95rem); font-weight: 800; }
.selector-hero { margin-top: clamp(3rem, 10vh, 7rem); }
.selector-hero h1 { max-width: 14ch; }
.selector-grid { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: clamp(0.8rem, 2vw, 1.5rem); margin-top: clamp(2rem, 5vh, 3.5rem); }
.selector-card { position: relative; display: flex; min-height: clamp(20rem, 48vh, 29rem); padding: clamp(1.2rem, 2.5vw, 2rem); flex-direction: column; border: 1px solid rgba(16,43,39,.2); background: rgba(255,255,255,.68); text-decoration: none; overflow: hidden; transition: transform 300ms var(--ease), box-shadow 300ms var(--ease); }
.selector-card::before { content: attr(data-code); position: absolute; right: -0.08em; bottom: -0.2em; color: rgba(16,43,39,.06); font-family: "Noto Serif SC", serif; font-size: clamp(8rem, 18vw, 15rem); font-weight: 900; line-height: .8; }
.selector-card:hover, .selector-card:focus-visible { transform: translateY(-0.35rem); box-shadow: var(--shadow); outline: 0.18rem solid rgba(216,72,50,.35); }
.selector-card .selector-kicker { color: var(--accent); font-size: clamp(0.7rem, 1vw, 0.86rem); font-weight: 900; letter-spacing: .12em; }
.selector-card h2 { position: relative; margin-top: clamp(1.2rem, 3vh, 2rem); font-size: clamp(2rem, 4vw, 3.5rem); }
.selector-card p { position: relative; color: var(--muted); }
.selector-card ul { position: relative; margin: clamp(1rem, 2.5vh, 1.6rem) 0 0; padding-left: 1.2em; color: var(--muted); }
.selector-card li { font-size: clamp(0.78rem, 1.05vw, 0.92rem); }
.selector-card strong { position: relative; margin-top: auto; color: var(--accent-2); font-size: clamp(0.82rem, 1.1vw, 0.96rem); }
@media (max-width: 760px) {
    .selector-grid { grid-template-columns: 1fr; }
    .selector-card { min-height: 18rem; }
}