:root {
    --primary: #6366f1;
    --primary-dark: #4f46e5;
    --secondary: #ec4899;
    --accent: #06b6d4;
    --dark-bg: #0f172a;
    --dark-card: #1e293b;
    --dark-text: #f1f5f9;
    --light-bg: #f8fafc;
    --light-card: #ffffff;
    --light-text: #1e293b;
    --gray: #64748b;
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    --shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
}

* {
    box-sizing: border-box;
}

html,
body {
    margin: 0;
    min-height: 100%;
    font-family: Inter, sans-serif;
    color: var(--dark-text);
    background: radial-gradient(circle at 20% 16%, rgba(99, 102, 241, 0.22) 0%, transparent 36%),
                radial-gradient(circle at 82% 14%, rgba(6, 182, 212, 0.18) 0%, transparent 26%),
                radial-gradient(circle at 18% 82%, rgba(236, 72, 153, 0.14) 0%, transparent 28%),
                var(--dark-bg);
    transition: var(--transition);
}

body.light-mode {
    color: var(--light-text);
    background: radial-gradient(circle at 20% 16%, rgba(99, 102, 241, 0.12) 0%, transparent 36%),
                radial-gradient(circle at 82% 14%, rgba(6, 182, 212, 0.11) 0%, transparent 26%),
                radial-gradient(circle at 18% 82%, rgba(236, 72, 153, 0.09) 0%, transparent 28%),
                var(--light-bg);
}

.intro-shell {
    position: relative;
    min-height: 100vh;
    overflow: hidden;
    isolation: isolate;
    padding: 28px clamp(20px, 4vw, 64px) 34px;
}

.intro-grid-overlay {
    position: absolute;
    inset: 0;
    z-index: -3;
    background-image:
        linear-gradient(rgba(99, 102, 241, 0.12) 1px, transparent 1px),
        linear-gradient(90deg, rgba(99, 102, 241, 0.12) 1px, transparent 1px);
    background-size: 52px 52px;
    mask-image: radial-gradient(circle at 54% 45%, #000 36%, transparent 94%);
    animation: gridShift 26s linear infinite;
}

.intro-blob {
    position: absolute;
    z-index: -2;
    pointer-events: none;
    background: radial-gradient(circle, rgba(6, 182, 212, 0.34), rgba(99, 102, 241, 0.16) 56%, transparent 76%);
    filter: blur(0.3px);
}

body.light-mode .intro-grid-overlay {
    background-image:
        linear-gradient(rgba(99, 102, 241, 0.08) 1px, transparent 1px),
        linear-gradient(90deg, rgba(99, 102, 241, 0.08) 1px, transparent 1px);
}

body.light-mode .intro-blob {
    background: radial-gradient(circle, rgba(99, 102, 241, 0.18), rgba(6, 182, 212, 0.09) 56%, transparent 76%);
}

.intro-blob-top {
    width: clamp(260px, 35vw, 520px);
    height: clamp(260px, 35vw, 520px);
    right: -8%;
    top: -7%;
    border-radius: 42% 58% 61% 39% / 35% 37% 63% 65%;
    animation: blobMorphA 10s ease-in-out infinite;
}

.intro-blob-bottom {
    width: clamp(300px, 52vw, 760px);
    height: clamp(140px, 18vw, 250px);
    left: -10%;
    bottom: -6%;
    border-radius: 52% 48% 44% 56% / 66% 45% 55% 34%;
    animation: blobMorphB 11s ease-in-out infinite;
}

.intro-nav {
    display: flex;
    gap: 26px;
    align-items: center;
    justify-content: flex-start;
    flex-wrap: nowrap;
    width: 100%;
    text-transform: none;
    letter-spacing: 0;
    font-size: 0.96rem;
    margin-top: 8px;
}

.intro-nav a {
    position: relative;
    font-weight: 500;
    color: var(--dark-text);
    text-decoration: none;
    transition: var(--transition);
    flex-shrink: 0;
}

body.light-mode .intro-nav a {
    color: var(--light-text);
}

.intro-nav a::after {
    content: '';
    position: absolute;
    bottom: -5px;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--primary);
    transition: var(--transition);
}

.intro-nav a:hover::after {
    width: 100%;
}

.intro-nav a:hover {
    color: var(--primary);
}

.intro-nav a.active {
    color: var(--primary);
}

.intro-theme-toggle {
    margin-left: auto;
    flex-shrink: 0;
    flex: 0 0 auto;
    aspect-ratio: 66 / 34;
    min-width: 66px;
    min-height: 34px;
}

.intro-theme-toggle {
    margin-left: auto;
    width: 66px;
    height: 34px;
    border-radius: 999px;
    border: 1px solid rgba(148, 163, 184, 0.32);
    background: rgba(15, 23, 42, 0.8);
    display: inline-flex;
    align-items: center;
    justify-content: space-between;
    padding: 3px;
    cursor: pointer;
    box-shadow: none;
    transition: var(--transition);
    position: relative;
}

body.light-mode .intro-theme-toggle {
    background: rgba(255, 255, 255, 0.92);
}

.intro-theme-toggle:hover {
    transform: translateY(-2px);
    border-color: rgba(6, 182, 212, 0.35);
}

.intro-theme-toggle .toggle-circle {
    position: absolute;
    left: 34px;
    width: 26px;
    height: 26px;
    border-radius: 50%;
    background: linear-gradient(135deg, var(--primary), var(--accent));
    box-shadow: inset 0 0 0 1px rgba(255, 255, 255, 0.16), 0 6px 14px rgba(6, 182, 212, 0.25);
    transition: var(--transition);
    z-index: 2;
}

.intro-theme-toggle .theme-icon {
    width: 28px;
    height: 28px;
    display: grid;
    place-items: center;
    position: relative;
    z-index: 3;
    pointer-events: none;
}

.intro-theme-toggle .theme-icon svg {
    width: 15px;
    height: 15px;
    fill: #e2e8f0;
    opacity: 0.72;
    transition: opacity 0.3s ease, fill 0.3s ease;
}

body.light-mode .intro-theme-toggle .theme-icon svg {
    fill: #475569;
}

body:not(.light-mode) .intro-theme-toggle .theme-icon-sun svg {
    opacity: 1;
    fill: #f8fafc;
}

body.light-mode .intro-theme-toggle .theme-icon-moon svg {
    opacity: 1;
    fill: #1e293b;
}

@media (max-width: 768px) {
    .intro-theme-toggle {
        width: 60px;
        height: 32px;
        min-width: 60px;
        min-height: 32px;
        aspect-ratio: 60 / 32;
    }

    .intro-theme-toggle .theme-icon {
        width: 24px;
        height: 24px;
    }

    .intro-theme-toggle .theme-icon svg {
        width: 13px;
        height: 13px;
    }

    .intro-theme-toggle .toggle-circle {
        width: 22px;
        height: 22px;
        left: 32px;
    }

    body.light-mode .intro-theme-toggle .toggle-circle {
        left: 4px;
    }
}

@media (max-width: 420px) {
    .intro-theme-toggle {
        width: 56px;
        height: 30px;
        min-width: 56px;
        min-height: 30px;
        aspect-ratio: 56 / 30;
    }

    .intro-theme-toggle .theme-icon {
        width: 22px;
        height: 22px;
    }

    .intro-theme-toggle .theme-icon svg {
        width: 12px;
        height: 12px;
    }

    .intro-theme-toggle .toggle-circle {
        width: 20px;
        height: 20px;
        left: 32px;
    }

    body.light-mode .intro-theme-toggle .toggle-circle {
        left: 4px;
    }
}

.intro-nav a {
    color: var(--dark-text);
    text-decoration: none;
    opacity: 0.86;
    transition: opacity 0.3s ease, color 0.3s ease;
}

.intro-nav a:hover {
    opacity: 1;
    color: var(--accent);
}

.intro-nav a.active {
    color: #dffbff;
    background: rgba(6, 182, 212, 0.18);
    border: 1px solid rgba(6, 182, 212, 0.35);
    border-radius: 10px;
    padding: 4px 10px;
}

body.light-mode .intro-nav a {
    color: var(--light-text);
}

body.light-mode .intro-nav a:hover {
    color: var(--primary);
}

body.light-mode .intro-nav a.active {
    color: var(--primary-dark);
    background: rgba(99, 102, 241, 0.12);
    border-color: rgba(99, 102, 241, 0.24);
}

.intro-stage {
    width: min(1180px, 100%);
    margin: clamp(34px, 5vw, 74px) auto 0;
    display: grid;
    grid-template-columns: 1.08fr minmax(280px, 0.92fr);
    align-items: end;
    gap: clamp(18px, 4vw, 44px);
}

.intro-copy {
    max-width: 720px;
}

.intro-kicker {
    margin: 0 0 4px;
    color: var(--accent);
    letter-spacing: 0.18em;
    text-transform: uppercase;
    font-weight: 700;
    font-size: 0.78rem;
}

.intro-copy h1 {
    margin: 0;
    font-family: "Space Grotesk", sans-serif;
    color: var(--accent);
    line-height: 0.98;
    font-size: clamp(2.5rem, 6.2vw, 6.2rem);
    text-shadow: 0 0 30px rgba(6, 182, 212, 0.32);
}

body.light-mode .intro-copy h1 {
    color: var(--primary);
    text-shadow: none;
}

.intro-points {
    margin: 18px 0 18px;
    padding: 0;
    list-style: none;
    display: grid;
    gap: 9px;
    font-size: clamp(1rem, 1.05vw + 0.64rem, 1.62rem);
    line-height: 1.22;
    max-width: 760px;
}

.intro-points li {
    position: relative;
    padding-left: 22px;
    color: var(--dark-text);
    transform: translateX(-18px);
    opacity: 0;
    animation: pointSlideIn 0.65s ease forwards;
}

.intro-points li::before {
    content: "-";
    position: absolute;
    left: 0;
    top: 0;
    color: var(--secondary);
}

body.light-mode .intro-points li {
    color: var(--light-text);
}

.intro-points li:nth-child(1) { animation-delay: 0.22s; }
.intro-points li:nth-child(2) { animation-delay: 0.34s; }
.intro-points li:nth-child(3) { animation-delay: 0.46s; }
.intro-points li:nth-child(4) { animation-delay: 0.58s; }
.intro-points li:nth-child(5) { animation-delay: 0.7s; }

.intro-quote {
    margin: 10px 0 0;
    color: var(--gray);
    font-size: clamp(1rem, 1.1vw + 0.6rem, 1.35rem);
    font-style: italic;
    min-height: 1.6em;
}

.continue-btn {
    margin-top: 24px;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 13px 24px;
    text-decoration: none;
    color: white;
    font-weight: 700;
    letter-spacing: 0.02em;
    border-radius: 999px;
    border: 1px solid rgba(6, 182, 212, 0.5);
    background: linear-gradient(120deg, var(--primary), var(--primary-dark));
    box-shadow: var(--shadow);
    transition: transform 0.28s ease, box-shadow 0.28s ease, background 0.28s ease;
}

.continue-btn:hover {
    transform: translateY(-4px) scale(1.02);
    box-shadow: 0 20px 25px -5px rgba(99, 102, 241, 0.3);
}

body.light-mode .continue-btn:hover {
    box-shadow: 0 20px 25px -5px rgba(99, 102, 241, 0.24);
}

.intro-visual {
    position: relative;
    min-height: clamp(420px, 55vw, 720px);
    display: grid;
    place-items: end center;
    overflow: visible;
}

.intro-message-box {
    position: absolute;
    z-index: 3;
    width: min(265px, 36vw);
    padding: 14px 16px 15px;
    border-radius: 18px;
    border: 1px solid rgba(148, 163, 184, 0.22);
    background:
        linear-gradient(140deg, rgba(255, 255, 255, 0.14), rgba(255, 255, 255, 0.05) 55%, rgba(255, 255, 255, 0.08)),
        rgba(30, 41, 59, 0.62);
    -webkit-backdrop-filter: blur(16px) saturate(140%);
    backdrop-filter: blur(16px) saturate(140%);
    box-shadow: 0 18px 36px rgba(2, 6, 23, 0.32), inset 0 1px 0 rgba(255, 255, 255, 0.14);
    display: grid;
    gap: 6px;
    animation: messageFloat 6.2s ease-in-out infinite;
}

.intro-message-box::after {
    content: '';
    position: absolute;
    width: 14px;
    height: 14px;
    background: inherit;
    border: 1px solid rgba(148, 163, 184, 0.28);
    border-top: 0;
    border-right: 0;
    bottom: -6px;
}

.intro-message-box::before {
    content: '';
    position: absolute;
    inset: 0;
    border-radius: inherit;
    padding: 1px;
    background: linear-gradient(140deg, rgba(6, 182, 212, 0.8), rgba(99, 102, 241, 0.55), rgba(236, 72, 153, 0.45));
    -webkit-mask: linear-gradient(#000 0 0) content-box, linear-gradient(#000 0 0);
    -webkit-mask-composite: xor;
    mask-composite: exclude;
    opacity: 0.72;
    pointer-events: none;
}

.intro-message-meta {
    position: relative;
    z-index: 1;
    font-size: 0.62rem;
    font-weight: 600;
    letter-spacing: 0.07em;
    text-transform: uppercase;
    color: #cbd5e1;
}

.intro-message-text {
    position: relative;
    z-index: 1;
    font-size: 0.76rem;
    line-height: 1.45;
    color: var(--dark-text);
}

.intro-message-text strong {
    color: #dffbff;
    font-weight: 700;
}

.intro-message-left {
    left: 0;
    top: 30%;
    transform: translateX(-16%);
    animation-name: messageFloatLeft;
    animation-delay: -1.8s;
}

.intro-message-right {
    right: 0;
    top: 50%;
    transform: translateX(16%);
    animation-name: messageFloatRight;
    animation-delay: -0.8s;
}

.intro-message-left::after {
    left: 18px;
    transform: rotate(-28deg);
}

.intro-message-right::after {
    right: 18px;
    transform: rotate(150deg);
}

body.light-mode .intro-theme-toggle {
    background: rgba(255, 255, 255, 0.84);
    border-color: rgba(99, 102, 241, 0.24);
}

body.light-mode .intro-theme-toggle .toggle-circle {
    left: 4px;
}

body.light-mode .intro-message-box {
    border-color: rgba(99, 102, 241, 0.18);
    background:
        linear-gradient(140deg, rgba(255, 255, 255, 0.78), rgba(255, 255, 255, 0.42) 55%, rgba(255, 255, 255, 0.54)),
        rgba(255, 255, 255, 0.78);
    box-shadow: 0 16px 30px rgba(15, 23, 42, 0.12), inset 0 1px 0 rgba(255, 255, 255, 0.78);
}

body.light-mode .intro-message-meta {
    color: #475569;
}

body.light-mode .intro-message-text {
    color: var(--light-text);
}

body.light-mode .intro-message-text strong {
    color: var(--primary-dark);
}

.portrait-frame {
    position: absolute;
    right: 0;
    top: 0;
    width: min(100%, 560px);
    height: clamp(420px, 54vw, 720px);
    display: grid;
    align-items: end;
    justify-items: center;
}

.portrait-frame-glow {
    position: absolute;
    inset: 11% 8% 8%;
    background: radial-gradient(circle at 50% 42%, rgba(6, 182, 212, 0.34), rgba(99, 102, 241, 0.12) 40%, transparent 72%);
    filter: blur(10px);
    animation: haloBreath 6.4s ease-in-out infinite;
}

.portrait-frame-rings {
    position: absolute;
    inset: 0;
    pointer-events: none;
}

.portrait-frame-rings span {
    position: absolute;
    border-radius: 50%;
    border: 1px dashed rgba(125, 211, 252, 0.5);
    animation: ringOrbit 18s linear infinite;
}

.portrait-frame-rings span:nth-child(1) {
    inset: 8% 12% 10% 10%;
}

.portrait-frame-rings span:nth-child(2) {
    inset: 18% 22% 18% 18%;
    animation-direction: reverse;
    opacity: 0.7;
}

.portrait-frame-rings span:nth-child(3) {
    inset: 28% 30% 28% 30%;
    opacity: 0.45;
}

.portrait-card {
    position: relative;
    width: min(100%, 455px);
    height: clamp(380px, 48vw, 630px);
    border-radius: 32px;
    overflow: hidden;
    border: 1px solid rgba(148, 163, 184, 0.28);
    background:
        linear-gradient(160deg, rgba(255, 255, 255, 0.12), rgba(255, 255, 255, 0.03) 52%, rgba(255, 255, 255, 0.08)),
        rgba(30, 41, 59, 0.7);
    -webkit-backdrop-filter: blur(16px) saturate(138%);
    backdrop-filter: blur(16px) saturate(138%);
    box-shadow:
        0 30px 65px rgba(0, 7, 28, 0.52),
        inset 0 0 0 1px rgba(255, 255, 255, 0.08),
        inset 0 0 60px rgba(6, 182, 212, 0.14);
    transform: perspective(1400px) rotateY(-6deg) rotateX(1.5deg);
    animation: portraitFloat 6.5s ease-in-out infinite;
}

.portrait-card::before {
    content: '';
    position: absolute;
    inset: 0;
    background: linear-gradient(145deg, rgba(255, 255, 255, 0.14), transparent 36%, transparent 60%, rgba(255, 255, 255, 0.06));
    pointer-events: none;
}

.portrait-scanline {
    position: absolute;
    inset: 0;
    background: linear-gradient(180deg, transparent 0%, rgba(255, 255, 255, 0.08) 50%, transparent 100%);
    background-size: 100% 120px;
    mix-blend-mode: screen;
    opacity: 0.35;
    animation: scanMove 5.2s linear infinite;
}

.portrait-corner {
    position: absolute;
    width: 22px;
    height: 22px;
    border-color: rgba(6, 182, 212, 0.9);
    pointer-events: none;
}

.corner-tl { top: 14px; left: 14px; border-top: 2px solid; border-left: 2px solid; }
.corner-tr { top: 14px; right: 14px; border-top: 2px solid; border-right: 2px solid; }
.corner-bl { bottom: 14px; left: 14px; border-bottom: 2px solid; border-left: 2px solid; }
.corner-br { bottom: 14px; right: 14px; border-bottom: 2px solid; border-right: 2px solid; }

.intro-portrait {
    position: absolute;
    left: 50%;
    bottom: -2px;
    width: 100%;
    height: 100%;
    object-fit: cover;
    object-position: center 18%;
    transform: translateX(-50%);
    filter: drop-shadow(0 24px 42px rgba(0, 4, 20, 0.78));
    opacity: 0;
    transition: opacity 1.15s ease, transform 1.15s ease, filter 1.15s ease;
    will-change: opacity, transform;
}

.intro-portrait-active {
    opacity: 0.96;
    transform: translateX(-50%) scale(1.02);
}

.intro-portrait:not(.intro-portrait-active) {
    transform: translateX(-50%) scale(0.992);
}

.portrait-caption {
    position: absolute;
    left: 50%;
    bottom: 8px;
    transform: translateX(-50%);
    margin: 0;
    padding: 6px 12px;
    max-width: calc(100% - 22px);
    text-align: center;
    font-size: 0.74rem;
    letter-spacing: 0.16em;
    text-transform: uppercase;
    color: var(--dark-text);
    border: 1px solid rgba(148, 163, 184, 0.24);
    border-radius: 999px;
    background: rgba(15, 23, 42, 0.52);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
}

body.light-mode .portrait-card {
    background:
        linear-gradient(160deg, rgba(255, 255, 255, 0.72), rgba(255, 255, 255, 0.36) 52%, rgba(255, 255, 255, 0.55)),
        rgba(255, 255, 255, 0.72);
    border-color: rgba(99, 102, 241, 0.2);
    box-shadow:
        0 24px 52px rgba(15, 23, 42, 0.14),
        inset 0 0 0 1px rgba(255, 255, 255, 0.7),
        inset 0 0 60px rgba(99, 102, 241, 0.08);
}

body.light-mode .portrait-frame-glow {
    background: radial-gradient(circle at 50% 42%, rgba(99, 102, 241, 0.24), rgba(6, 182, 212, 0.12) 40%, transparent 72%);
}

body.light-mode .portrait-frame-rings span {
    border-color: rgba(99, 102, 241, 0.24);
}

body.light-mode .portrait-corner {
    border-color: rgba(99, 102, 241, 0.9);
}

body.light-mode .portrait-caption {
    color: #334155;
    background: rgba(255, 255, 255, 0.72);
    border-color: rgba(99, 102, 241, 0.2);
}

body.light-mode .intro-portrait {
    filter: drop-shadow(0 20px 34px rgba(15, 23, 42, 0.28));
}

body.light-mode .intro-theme-toggle .toggle-circle {
    background: linear-gradient(135deg, var(--primary), var(--accent));
}

@keyframes pointSlideIn {
    to {
        opacity: 1;
        transform: translateX(0);
    }
}

@keyframes portraitFloat {
    0%, 100% { transform: translateY(0); }
    50% { transform: translateY(-9px); }
}

@keyframes haloBreath {
    0%, 100% { transform: translateY(0) scale(1); }
    50% { transform: translateY(-6px) scale(1.02); }
}

@keyframes ringOrbit {
    from { transform: rotate(0deg); }
    to { transform: rotate(360deg); }
}

@keyframes scanMove {
    from { background-position: 0 -120px; }
    to { background-position: 0 120px; }
}

@keyframes messageFloatLeft {
    0%, 100% { transform: translateX(-16%) translateY(0); }
    50% { transform: translateX(-16%) translateY(-10px); }
}

@keyframes messageFloatRight {
    0%, 100% { transform: translateX(16%) translateY(0); }
    50% { transform: translateX(16%) translateY(-10px); }
}

@keyframes messageFloatLeftMobile {
    0%, 100% { transform: translateY(0) scale(0.9); }
    50% { transform: translateY(-6px) scale(0.9); }
}

@keyframes messageFloatRightMobile {
    0%, 100% { transform: translateY(0) scale(0.9); }
    50% { transform: translateY(-6px) scale(0.9); }
}

@keyframes blobMorphA {
    0%, 100% { border-radius: 42% 58% 61% 39% / 35% 37% 63% 65%; transform: translateY(0); }
    50% { border-radius: 58% 42% 47% 53% / 52% 35% 65% 48%; transform: translateY(8px); }
}

@keyframes blobMorphB {
    0%, 100% { border-radius: 52% 48% 44% 56% / 66% 45% 55% 34%; transform: translateY(0); }
    50% { border-radius: 38% 62% 53% 47% / 52% 56% 44% 48%; transform: translateY(-7px); }
}

@keyframes gridShift {
    from { background-position: 0 0, 0 0; }
    to { background-position: 52px 52px, 52px 52px; }
}

@media (max-width: 980px) {
    .intro-stage {
        grid-template-columns: 1fr;
        align-items: start;
    }

    .intro-copy {
        max-width: 100%;
    }

    .intro-visual {
        min-height: 360px;
    }

    .portrait-frame {
        right: 50%;
        transform: translateX(50%);
        width: min(100%, 460px);
        height: 560px;
    }

    .portrait-card {
        width: min(100%, 372px);
        height: 520px;
        transform: perspective(1200px) rotateY(-5deg) rotateX(2deg);
    }

    .intro-portrait {
        object-position: center 14%;
    }

    .intro-message-box {
        width: clamp(204px, 37vw, 248px);
    }

    .intro-message-left {
        top: 12%;
        left: 2%;
        transform: translateX(0);
    }

    .intro-message-right {
        top: auto;
        bottom: 8%;
        right: 2%;
        transform: translateX(0);
    }
}

@media (max-width: 640px) {
    .intro-shell {
        padding: 14px 12px 18px;
    }

    .intro-nav {
        gap: 8px;
        font-size: 0.72rem;
        justify-content: flex-start;
        flex-wrap: nowrap;
        overflow-x: auto;
        overflow-y: hidden;
        -ms-overflow-style: none;
        scrollbar-width: none;
    }

    .intro-nav::-webkit-scrollbar {
        display: none;
    }

    .intro-nav a.active {
        padding: 3px 8px;
    }

    .intro-theme-toggle {
        margin-left: 0;
    }

    .intro-stage {
        display: flex;
        flex-direction: column;
        align-items: stretch;
        margin-top: 22px;
        gap: 10px;
    }

    .intro-copy {
        max-width: 100%;
        order: 2;
    }

    .intro-points {
        margin: 12px 0 10px;
    }

    .intro-points {
        font-size: 1.03rem;
        gap: 8px;
    }

    .intro-quote {
        font-size: 1.02rem;
    }

    .continue-btn {
        width: 100%;
    }

    .intro-visual {
        order: 1;
        min-height: 290px;
        display: block;
        overflow: visible;
    }

    .portrait-frame {
        position: absolute;
        right: 50%;
        top: -8px;
        transform: translateX(50%);
        width: min(100%, 280px);
        height: 305px;
    }

    .portrait-card {
        width: min(100%, 242px);
        height: 272px;
        border-radius: 22px;
        transform: perspective(1000px) rotateY(-4deg) rotateX(2deg);
    }

    .intro-portrait {
        object-position: center 13%;
    }

    .portrait-caption {
        display: none;
    }

    .intro-message-box {
        position: absolute;
        width: clamp(124px, 34vw, 160px);
        padding: 9px 10px 10px;
        animation-duration: 6.8s;
    }

    .intro-message-left {
        top: 13%;
        left: 3%;
        margin: 0;
        animation-name: messageFloatLeftMobile;
    }

    .intro-message-right {
        top: 55%;
        right: 3%;
        margin: 0;
        animation-name: messageFloatRightMobile;
    }

    .intro-message-meta {
        font-size: 0.54rem;
        letter-spacing: 0.05em;
    }

    .intro-message-text {
        font-size: 0.64rem;
        line-height: 1.3;
    }
}

@media (max-width: 480px) {
    .intro-shell {
        padding: 12px 10px 16px;
    }

    .intro-copy h1 {
        font-size: clamp(2.08rem, 11vw, 2.8rem);
    }

    .intro-points {
        font-size: 0.96rem;
        line-height: 1.28;
    }

    .intro-theme-toggle {
        width: 56px;
        height: 30px;
    }

    .intro-theme-toggle .theme-icon {
        width: 22px;
        height: 22px;
    }

    .intro-theme-toggle .theme-icon svg {
        width: 12px;
        height: 12px;
    }

    .intro-theme-toggle .toggle-circle {
        left: 32px;
        width: 20px;
        height: 20px;
    }

    body.light-mode .intro-theme-toggle .toggle-circle {
        left: 4px;
    }

    .intro-visual {
        min-height: 250px;
    }

    .portrait-frame {
        top: -6px;
        width: min(100%, 236px);
        height: 250px;
    }

    .portrait-card {
        width: min(100%, 208px);
        height: 228px;
        border-radius: 18px;
    }

    .intro-message-box {
        width: clamp(108px, 38vw, 138px);
        padding: 7px 8px 8px;
        border-radius: 14px;
    }

    .intro-message-meta {
        font-size: 0.5rem;
    }

    .intro-message-text {
        font-size: 0.6rem;
        line-height: 1.24;
    }

    .intro-message-left {
        top: 12%;
        left: 4%;
        animation-name: messageFloatLeftMobile;
    }

    .intro-message-right {
        top: 57%;
        right: 4%;
        animation-name: messageFloatRightMobile;
    }
}

@media (prefers-reduced-motion: reduce) {
    *,
    *::before,
    *::after {
        animation: none !important;
        transition: none !important;
    }
}