:root {
    --navy:       #0b1d31;
    --navy-mid:   #102440;
    --navy-soft:  #1a3353;
    --accent:     #2563eb;
    --accent-dim: rgba(37, 99, 235, 0.15);
    --accent-glow:rgba(37, 99, 235, 0.25);
    --white:      #ffffff;
    --off-white:  #f7f9fc;
    --section-bg: #eef2f7;
    --surface:    #f0f4f9;
    --border:     #dde4ed;
    --border-dark:rgba(255,255,255,0.1);
    --text:       #0f2137;
    --muted:      #5a7191;
    --muted-dark: rgba(255,255,255,0.55);
    --shell:      1200px;
    --radius:     4px;
}

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

html {
    scroll-behavior: smooth;
    scroll-padding-top: 5rem;
    -webkit-font-smoothing: antialiased;
}

body {
    font-family: "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Helvetica Neue", sans-serif;
    color: var(--text);
    background: var(--white);
    line-height: 1.6;
}

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

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

/* ─── Layout ─── */
.shell {
    width: min(calc(100% - 2.5rem), var(--shell));
    margin: 0 auto;
}

/* ─── Nav ─── */
.site-nav {
    position: sticky;
    top: 0;
    z-index: 100;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(16px);
    border-bottom: 1px solid var(--border);
}

.nav-inner {
    display: flex;
    align-items: center;
    gap: 1rem;
    min-height: 4.25rem;
    position: relative;
}

.brand {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    flex-shrink: 0;
}

.brand-icon {
    width: 2.25rem;
    height: 2.25rem;
    background: var(--accent);
    display: flex;
    align-items: center;
    justify-content: center;
    color: #fff;
    font-size: 0.85rem;
    font-weight: 900;
    letter-spacing: -0.03em;
}

.brand-text strong {
    display: block;
    color: var(--text);
    font-size: 0.95rem;
    font-weight: 700;
    letter-spacing: -0.02em;
}

.brand-text span {
    display: block;
    color: var(--muted);
    font-size: 0.6rem;
    font-weight: 600;
    letter-spacing: 0.18em;
    text-transform: uppercase;
    margin-top: 0.15rem;
}

.nav-links {
    display: flex;
    align-items: center;
    gap: 1.75rem;
    margin-left: 2.5rem;
    margin-right: auto;
}

.nav-links a {
    color: var(--muted);
    font-size: 0.9rem;
    font-weight: 600;
    transition: color 150ms;
}

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

.nav-cta {
    display: inline-flex;
    align-items: center;
    height: 2.5rem;
    padding: 0 1.25rem;
    background: var(--accent);
    color: #fff;
    font-size: 0.875rem;
    font-weight: 700;
    border-radius: var(--radius);
    transition: background 150ms, transform 150ms;
    flex-shrink: 0;
}

.nav-cta:hover {
    background: #1d4ed8;
    transform: translateY(-1px);
}

/* ─── Mobile nav toggle ─── */
.nav-toggle {
    display: none;
    width: 2.5rem;
    height: 2.5rem;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    gap: 4px;
    background: transparent;
    border: 1px solid var(--border);
    border-radius: var(--radius);
    cursor: pointer;
    padding: 0;
    flex-shrink: 0;
}

.nav-toggle span {
    display: block;
    width: 18px;
    height: 1.5px;
    background: var(--text);
    transition: transform 200ms, opacity 200ms;
}

.nav-toggle.is-open span:nth-child(1) { transform: translateY(5.5px) rotate(45deg); }
.nav-toggle.is-open span:nth-child(2) { opacity: 0; }
.nav-toggle.is-open span:nth-child(3) { transform: translateY(-5.5px) rotate(-45deg); }

/* ─── Hero ─── */
.hero {
    background: #fff;
    padding: 5.5rem 0 5rem;
    position: relative;
    overflow: hidden;
    border-bottom: 1px solid var(--border);
}

.hero::before {
    content: "";
    position: absolute;
    inset: 0;
    background:
        radial-gradient(ellipse 55% 60% at 100% 0%, rgba(37,99,235,0.07) 0%, transparent 65%),
        radial-gradient(ellipse 40% 40% at 0% 100%, rgba(37,99,235,0.04) 0%, transparent 60%);
    pointer-events: none;
}

.hero-inner {
    position: relative;
    z-index: 1;
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 3rem;
    align-items: center;
}

.hero-copy,
.hero-arch {
    min-width: 0;
}

.hero h1 {
    color: var(--text);
    font-size: clamp(2.4rem, 4vw, 3.75rem);
    font-weight: 800;
    line-height: 1.08;
    letter-spacing: -0.04em;
    max-width: 8.2em;
}

.hero h1 em {
    font-style: normal;
    color: var(--accent);
}

.hero-desc {
    margin-top: 1.5rem;
    color: var(--muted);
    font-size: 1rem;
    line-height: 1.85;
    max-width: 36rem;
}

.hero-actions {
    display: flex;
    flex-wrap: wrap;
    gap: 0.75rem;
    margin-top: 2rem;
}

.btn {
    display: inline-flex;
    align-items: center;
    height: 3rem;
    padding: 0 1.5rem;
    font-size: 0.9rem;
    font-weight: 700;
    border-radius: var(--radius);
    transition: transform 150ms, box-shadow 150ms, background 150ms, border-color 150ms;
    border: 1px solid transparent;
    cursor: pointer;
}

.btn:hover { transform: translateY(-1px); }

.btn-primary {
    background: var(--accent);
    color: #fff;
    box-shadow: 0 8px 24px rgba(37,99,235,0.25);
}

.btn-primary:hover { background: #1d4ed8; }

.btn-ghost {
    background: transparent;
    color: var(--text);
    border-color: var(--border);
}

.btn-ghost:hover {
    border-color: var(--accent);
    color: var(--accent);
}

/* ─── Hero Architecture Diagram ─── */
.hero-arch {
    background: var(--off-white);
    border: 1px solid var(--border);
    border-radius: 6px;
    padding: 1.5rem 1.25rem 1rem;
    display: flex;
    flex-direction: column;
    overflow: hidden;
}

.arch-cap {
    font-size: 0.7rem;
    font-weight: 800;
    letter-spacing: 0.18em;
    text-transform: uppercase;
    color: var(--muted);
    margin: 0 0 0.75rem 0.25rem;
}

.arch-svg {
    width: 100%;
    height: auto;
    display: block;
}

.arch-svg text {
    font-family: "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Helvetica Neue", sans-serif;
}

.arch-legend {
    display: flex;
    gap: 1.5rem;
    padding: 0.85rem 0.25rem 0.1rem;
    border-top: 1px solid var(--border);
    margin-top: 0.5rem;
}

.arch-legend span {
    display: inline-flex;
    align-items: center;
    gap: 0.45rem;
    font-size: 0.78rem;
    color: var(--muted);
    font-weight: 600;
}

.dot {
    display: inline-block;
    width: 18px;
    height: 2px;
    border-radius: 1px;
}

.dot-on  { background: var(--accent); }
.dot-off { background: transparent; border-top: 1.4px dashed #c8d2e0; height: 0; }

/* ─── Problem Strip ─── */
.problems {
    background: var(--white);
    border-bottom: 1px solid var(--border);
}

.problems-inner {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
}

.problem-item {
    padding: 2.5rem 2rem;
    border-right: 1px solid var(--border);
}

.problem-item:last-child { border-right: 0; }

.problem-num {
    font-size: 0.7rem;
    font-weight: 800;
    color: var(--accent);
    letter-spacing: 0.18em;
    text-transform: uppercase;
}

.problem-item h3 {
    margin-top: 0.6rem;
    font-size: 1.05rem;
    font-weight: 700;
    letter-spacing: -0.02em;
    line-height: 1.4;
}

.problem-item p {
    margin-top: 0.5rem;
    font-size: 0.9rem;
    color: var(--muted);
    line-height: 1.75;
}

/* ─── Section commons ─── */
.section {
    padding: 5rem 0;
}

.section-alt { background: var(--section-bg); }

.section-head {
    margin-bottom: 3rem;
}

.section-head h2 {
    font-size: clamp(1.75rem, 2.8vw, 2.5rem);
    font-weight: 800;
    letter-spacing: -0.04em;
    line-height: 1.15;
    max-width: 18em;
}

.section-head p {
    margin-top: 0.9rem;
    font-size: 0.97rem;
    color: var(--muted);
    max-width: 44rem;
    line-height: 1.8;
}

.section-head p strong {
    color: var(--accent);
    font-weight: 700;
}

/* ─── Capability Cards ─── */
.cap-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 1px;
    background: var(--border);
    border: 1px solid var(--border);
}

.cap-card {
    background: var(--white);
    padding: 2rem 1.75rem;
}

.section-alt .cap-card { background: var(--off-white); }

.cap-num {
    font-size: 0.7rem;
    font-weight: 800;
    color: var(--accent);
    letter-spacing: 0.16em;
    text-transform: uppercase;
}

.cap-card h3 {
    margin-top: 0.65rem;
    font-size: 1.1rem;
    font-weight: 700;
    letter-spacing: -0.02em;
}

.cap-card p {
    margin-top: 0.6rem;
    font-size: 0.9rem;
    color: var(--muted);
    line-height: 1.75;
}

.cap-examples {
    list-style: none;
    margin: 1rem 0 0;
    padding: 0.9rem 0 0;
    border-top: 1px dashed var(--border);
}

.cap-examples li {
    position: relative;
    padding-left: 1.1rem;
    font-size: 0.83rem;
    color: var(--text);
    line-height: 1.6;
    margin-top: 0.5rem;
}

.cap-examples li:first-child { margin-top: 0; }

.cap-examples li::before {
    content: "→";
    position: absolute;
    left: 0;
    top: 0;
    color: var(--accent);
    font-weight: 700;
}

/* ─── Traits (horizontal band) ─── */
.traits {
    margin-top: 4rem;
}

.trait-list {
    display: flex;
    flex-direction: column;
    gap: 1px;
    background: var(--border);
    border: 1px solid var(--border);
}

.trait-item {
    display: grid;
    grid-template-columns: 14rem 1fr;
    background: var(--white);
}

.section-alt .trait-item { background: var(--off-white); }

.trait-head {
    padding: 1.5rem 1.75rem;
    border-right: 1px solid var(--border);
}

.trait-head h4 {
    font-size: 1rem;
    font-weight: 700;
    letter-spacing: -0.02em;
}

.trait-head span {
    display: block;
    margin-top: 0.25rem;
    font-size: 0.75rem;
    color: var(--accent);
    font-weight: 700;
    letter-spacing: 0.12em;
    text-transform: uppercase;
}

.trait-body {
    padding: 1.5rem 1.75rem;
    font-size: 0.93rem;
    color: var(--muted);
    line-height: 1.75;
    display: flex;
    align-items: center;
}

/* ─── Scenes ─── */
.scene-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 1.5rem;
}

.scene-card {
    padding: 2rem 1.75rem;
    border: 1px solid var(--border);
    background: var(--white);
    position: relative;
}

.scene-card::before {
    content: "";
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 3px;
    background: var(--accent);
    opacity: 0;
    transition: opacity 200ms;
}

.scene-card:hover::before { opacity: 1; }

.scene-card h3 {
    margin-top: 0.65rem;
    font-size: 1.05rem;
    font-weight: 700;
    letter-spacing: -0.02em;
    line-height: 1.4;
}

.scene-card p {
    margin-top: 0.55rem;
    font-size: 0.9rem;
    color: var(--muted);
    line-height: 1.75;
}

/* ─── Pilot Timeline ─── */
.pilot-timeline {
    list-style: none;
    margin: 0;
    padding: 0;
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 0;
    position: relative;
}

.pilot-timeline::before {
    content: "";
    position: absolute;
    top: 19px;
    left: 12.5%;
    right: 12.5%;
    height: 2px;
    background: var(--border);
    z-index: 0;
}

.timeline-step {
    position: relative;
    padding: 0 1.25rem;
    text-align: center;
}

.timeline-dot {
    width: 40px;
    height: 40px;
    border-radius: 50%;
    margin: 0 auto;
    background: var(--white);
    border: 2px solid var(--accent);
    display: flex;
    align-items: center;
    justify-content: center;
    position: relative;
    z-index: 1;
    color: var(--accent);
    font-weight: 800;
    font-size: 0.82rem;
    letter-spacing: 0.04em;
}

.section-alt .timeline-dot { background: var(--off-white); }

.timeline-content { margin-top: 1.25rem; }

.timeline-content h3 {
    font-size: 1rem;
    font-weight: 700;
    letter-spacing: -0.02em;
    line-height: 1.4;
}

.timeline-content p {
    margin-top: 0.55rem;
    font-size: 0.88rem;
    color: var(--muted);
    line-height: 1.75;
}

/* ─── FAQ ─── */
.faq-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1px;
    background: var(--border);
    border: 1px solid var(--border);
}

.faq-item {
    background: var(--white);
    padding: 2rem 1.75rem;
}

.faq-item h3 {
    font-size: 1rem;
    font-weight: 700;
    letter-spacing: -0.02em;
    line-height: 1.5;
}

.faq-item p {
    margin-top: 0.65rem;
    font-size: 0.9rem;
    color: var(--muted);
    line-height: 1.8;
}

/* ─── Footer ─── */
.site-footer {
    background: var(--section-bg);
    border-top: 1px solid var(--border);
}

.footer-top {
    display: grid;
    grid-template-columns: 2fr 1fr 1.2fr 1.2fr;
    gap: 2rem;
    padding: 3rem 0 1rem;
}

.footer-brand-head {
    display: flex;
    align-items: center;
    gap: 0.65rem;
    margin-bottom: 0.85rem;
}

.footer-brand-head .brand-icon {
    width: 2rem;
    height: 2rem;
    font-size: 0.8rem;
}

.footer-brand strong {
    color: var(--text);
    font-size: 0.95rem;
    font-weight: 700;
    letter-spacing: -0.02em;
}

.footer-brand p {
    color: var(--muted);
    font-size: 0.82rem;
    line-height: 1.7;
    max-width: 22rem;
}

.footer-col h4 {
    color: var(--text);
    font-size: 0.82rem;
    font-weight: 700;
    letter-spacing: 0.06em;
    margin-bottom: 1rem;
}

.footer-col a,
.footer-col span {
    display: block;
    color: var(--muted);
    font-size: 0.82rem;
    line-height: 1.5;
    padding: 0.3rem 0;
    transition: color 150ms;
}

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

.footer-bottom {
    display: flex;
    justify-content: flex-start;
    align-items: center;
    gap: 1.5rem;
    padding: 0 0 1rem;
    flex-wrap: wrap;
}

.footer-bottom span,
.footer-bottom a {
    color: rgba(15,33,55,0.42);
    font-size: 0.78rem;
    font-weight: 500;
    transition: color 150ms;
}

.footer-bottom a:hover { color: rgba(15,33,55,0.66); }

.footer-record {
    font-size: 0.68rem;
    color: rgba(15,33,55,0.32);
}

.footer-record:hover {
    color: rgba(15,33,55,0.5);
}

/* ─── Scroll reveal ─── */
.reveal {
    opacity: 1;
    transform: none;
}

.js .reveal {
    opacity: 0;
    transform: translateY(18px);
    transition: opacity 500ms ease, transform 500ms ease;
}

.js .reveal.visible {
    opacity: 1;
    transform: none;
}

/* ─── Responsive ─── */
@media (max-width: 1024px) {
    .hero-inner { grid-template-columns: 1fr; }

    .cap-grid,
    .scene-grid { grid-template-columns: repeat(2, 1fr); }

    .hero h1 { max-width: none; }
}

@media (max-width: 768px) {
    .nav-toggle { display: inline-flex; }
    .nav-cta { display: none; }

    .nav-links {
        display: none;
        position: absolute;
        top: 100%;
        left: 0;
        right: 0;
        flex-direction: column;
        align-items: stretch;
        gap: 0;
        margin: 0;
        padding: 0.5rem 0;
        background: rgba(255,255,255,0.98);
        backdrop-filter: blur(16px);
        border-bottom: 1px solid var(--border);
        box-shadow: 0 12px 24px -16px rgba(15,33,55,0.18);
    }

    .nav-links.is-open { display: flex; }

    .nav-links a {
        padding: 0.85rem 1.25rem;
        font-size: 0.95rem;
        color: var(--text);
        border-bottom: 1px solid var(--border);
    }

    .nav-links a:last-child { border-bottom: 0; }

    .shell {
        width: min(calc(100% - 2rem), var(--shell));
    }

    .hero-inner {
        gap: 2.75rem;
    }

    .hero h1 {
        max-width: 8em;
    }

    .hero-arch {
        padding: 1.25rem 1rem 0.9rem;
    }

    .problems-inner {
        grid-template-columns: 1fr;
    }

    .problem-item {
        border-right: 0;
        border-bottom: 1px solid var(--border);
    }

    .problem-item:last-child { border-bottom: 0; }

    .cap-grid,
    .faq-grid,
    .scene-grid { grid-template-columns: 1fr; }

    .trait-item { grid-template-columns: 1fr; }
    .trait-head { border-right: 0; border-bottom: 1px solid var(--border); }

    .section { padding: 3.5rem 0; }
    .hero { padding: 3.5rem 0 3rem; }

    .pilot-timeline { grid-template-columns: 1fr; gap: 1.5rem; }
    .pilot-timeline::before {
        top: 0;
        bottom: 0;
        left: 19px;
        right: auto;
        width: 2px;
        height: auto;
    }
    .timeline-step {
        display: grid;
        grid-template-columns: 40px 1fr;
        gap: 1rem;
        padding: 0;
        text-align: left;
        align-items: start;
    }
    .timeline-dot { margin: 0; }
    .timeline-content { margin-top: 0.25rem; }

    .footer-top { grid-template-columns: 1fr 1fr; gap: 1.5rem; padding-top: 2.5rem; }
    .footer-brand { grid-column: 1 / -1; }
    .footer-bottom { flex-direction: column; align-items: flex-start; gap: 0.5rem; }
}

@media (prefers-reduced-motion: reduce) {
    html { scroll-behavior: auto; }
    .js .reveal { opacity: 1; transform: none; transition: none; }
    .btn, .nav-cta { transition: none; }
}

/* ─── Integrations ─── */
.integrations {
    margin-top: 3rem;
    padding: 2rem 1.75rem;
    background: var(--white);
    border: 1px solid var(--border);
    display: grid;
    grid-template-columns: 1fr 1.4fr;
    gap: 2rem;
    align-items: center;
}

.section-alt .integrations { background: var(--white); }

.int-eyebrow {
    display: block;
    font-size: 0.7rem;
    font-weight: 800;
    color: var(--accent);
    letter-spacing: 0.18em;
    text-transform: uppercase;
    margin-bottom: 0.6rem;
}

.int-head h3 {
    font-size: 1.1rem;
    font-weight: 700;
    letter-spacing: -0.02em;
    line-height: 1.5;
    color: var(--text);
}

.int-chips {
    display: flex;
    flex-wrap: wrap;
    gap: 0.6rem;
}

.int-chip {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.55rem 0.9rem;
    background: var(--off-white);
    border: 1px solid var(--border);
    font-size: 0.86rem;
    font-weight: 600;
    color: var(--text);
    border-radius: 3px;
    transition: border-color 150ms, transform 150ms;
}

.int-chip:hover {
    border-color: rgba(37,99,235,0.4);
    transform: translateY(-1px);
}

.int-dot {
    width: 7px;
    height: 7px;
    border-radius: 50%;
    flex-shrink: 0;
}

.int-chip-custom {
    background: rgba(37,99,235,0.04);
    border: 1px dashed rgba(37,99,235,0.4);
    color: var(--accent);
}

@media (max-width: 768px) {
    .integrations { grid-template-columns: 1fr; gap: 1.5rem; padding: 1.5rem 1.25rem; }
}

/* ─── Trust section (身份源 + 产品承诺) ─── */
.trust .integrations { margin-top: 0; }
.trust .traits { margin-top: 2.5rem; }

/* ─── Card Icon ─── */
.card-icon {
    width: 30px;
    height: 30px;
    color: var(--accent);
    margin-bottom: 1.1rem;
    display: block;
}

.problem-item .card-icon,
.cap-card .card-icon,
.scene-card .card-icon { margin-bottom: 1rem; }

/* ─── Compare Section ─── */
.compare-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: 1.5rem;
}

.compare-pane {
    background: var(--white);
    border: 1px solid var(--border);
    border-radius: 6px;
    padding: 1.75rem 1.75rem 1.5rem;
    display: grid;
    grid-template-columns: 1fr 1fr;
    grid-template-areas:
        "tag   tag"
        "title title"
        "svg   list";
    column-gap: 2rem;
    row-gap: 0.5rem;
    align-items: center;
    width: 100%;
}

.compare-pane > .compare-tag { grid-area: tag; }
.compare-pane > h3 { grid-area: title; }
.compare-pane > .compare-svg { grid-area: svg; }
.compare-pane > .compare-list { grid-area: list; border-top: 0; padding-top: 0; margin-top: 0; }

.compare-pane.compare-good {
    border-color: rgba(37,99,235,0.35);
    box-shadow: 0 12px 32px -16px rgba(37,99,235,0.25);
}

.compare-tag {
    display: inline-flex;
    align-self: flex-start;
    align-items: center;
    height: 1.7rem;
    padding: 0 0.7rem;
    background: rgba(220,38,38,0.08);
    color: #dc2626;
    font-size: 0.72rem;
    font-weight: 800;
    letter-spacing: 0.14em;
    text-transform: uppercase;
    border-radius: 2px;
}

.compare-tag-on {
    background: rgba(37,99,235,0.1);
    color: var(--accent);
}

.compare-pane h3 {
    margin-top: 0.85rem;
    font-size: 1.05rem;
    font-weight: 700;
    letter-spacing: -0.02em;
    line-height: 1.5;
    color: var(--text);
}

.compare-svg {
    width: 100%;
    height: auto;
    display: block;
    margin: 1.25rem 0 0.5rem;
}

.compare-svg text {
    font-family: "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Helvetica Neue", sans-serif;
}

.compare-list {
    list-style: none;
    margin: 1rem 0 0;
    padding: 1rem 0 0;
    border-top: 1px solid var(--border);
    display: flex;
    flex-direction: column;
    gap: 0.85rem;
}

.compare-list li {
    position: relative;
    padding-left: 1.25rem;
    font-size: 1rem;
    color: var(--text);
    line-height: 1.7;
}

.compare-list li::before {
    content: "";
    position: absolute;
    left: 0;
    top: 0.7rem;
    width: 8px;
    height: 1.5px;
    background: #dc2626;
}

.compare-list-on li::before { background: var(--accent); }

@media (max-width: 1024px) {
    .compare-grid { grid-template-columns: 1fr; }
    .compare-pane {
        grid-template-columns: 1fr;
        grid-template-areas:
            "tag"
            "title"
            "svg"
            "list";
    }
    .compare-pane > .compare-list {
        border-top: 1px solid var(--border);
        padding-top: 1rem;
        margin-top: 1rem;
    }
}

/* ─── Tabs (capabilities & scenes) ─── */
.cap-tabs,
.scene-tabs {
    background: var(--white);
    border: 1px solid var(--border);
    border-radius: 6px;
    overflow: hidden;
}

.section-alt .cap-tabs,
.section-alt .scene-tabs { background: var(--white); }

.tabs-rail {
    display: flex;
    border-bottom: 1px solid var(--border);
    background: var(--off-white);
}

.tabs-rail-scroll {
    overflow-x: auto;
    scrollbar-width: thin;
}

.tabs-rail-scroll::-webkit-scrollbar { height: 3px; }
.tabs-rail-scroll::-webkit-scrollbar-thumb { background: var(--border); border-radius: 2px; }

.tab-btn {
    flex: 1 1 0;
    min-width: 9.5rem;
    display: inline-flex;
    align-items: center;
    gap: 0.6rem;
    padding: 1rem 1.25rem;
    background: transparent;
    border: 0;
    border-right: 1px solid var(--border);
    border-bottom: 2px solid transparent;
    cursor: pointer;
    color: var(--muted);
    font-family: inherit;
    text-align: left;
    transition: color 150ms, background 150ms, border-color 150ms;
    white-space: nowrap;
}

.tab-btn:last-child { border-right: 0; }

.tab-btn:hover {
    color: var(--text);
    background: rgba(37,99,235,0.04);
}

.tab-btn.is-active {
    color: var(--accent);
    background: var(--white);
    border-bottom-color: var(--accent);
}

.tab-num {
    font-size: 0.7rem;
    font-weight: 800;
    letter-spacing: 0.16em;
    color: inherit;
    opacity: 0.7;
}

.tab-btn.is-active .tab-num { opacity: 1; }

.tab-label {
    font-size: 0.92rem;
    font-weight: 700;
    letter-spacing: -0.01em;
}

.tab-panel {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 2.5rem;
    padding: 2.25rem 2rem;
    align-items: center;
}

.tab-panel[hidden] { display: none; }

.tab-copy h3 {
    margin-top: 0.6rem;
    font-size: 1.25rem;
    font-weight: 700;
    letter-spacing: -0.02em;
    line-height: 1.45;
    color: var(--text);
}

.tab-desc {
    margin-top: 0.75rem;
    font-size: 0.94rem;
    color: var(--muted);
    line-height: 1.8;
}

.tab-copy .cap-examples { margin-top: 1.1rem; }

.tab-visual {
    background: var(--off-white);
    border: 1px solid var(--border);
    border-radius: 4px;
    padding: 1.25rem;
    min-height: 240px;
    display: flex;
    align-items: center;
    justify-content: center;
}

.tab-visual:empty::after {
    content: "示意图筹备中";
    color: var(--muted);
    font-size: 0.8rem;
    letter-spacing: 0.1em;
}

.tab-visual svg {
    width: 100%;
    height: auto;
    display: block;
}

.tab-visual svg text {
    font-family: "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Helvetica Neue", sans-serif;
}

@media (max-width: 1024px) {
    .tab-panel {
        grid-template-columns: 1fr;
        gap: 1.5rem;
        padding: 1.75rem 1.5rem;
    }
    .tab-visual { min-height: 200px; }
}

@media (max-width: 768px) {
    .tabs-rail {
        overflow-x: auto;
        scrollbar-width: thin;
    }
    .tab-btn {
        flex: 0 0 auto;
        min-width: 11rem;
        padding: 0.85rem 1rem;
    }
    .tab-panel {
        padding: 1.5rem 1.25rem;
    }
    .tab-copy h3 { font-size: 1.1rem; }
}