/* =================================================================
   Demo Page — v3 Neo-Brutalism
   navy + orange + butter | Bricolage + Hanken + Fraunces + JetBrains
   共用 landing.css nav + mobile menu + footer v3
   專注：hero、2 col grid (upload sidebar + chat iframe)、features、CTA
   ================================================================= */

body.demo-page {
    font-family: var(--brand-v3-sans);
    color: var(--brand-v3-ink-soft);
    background: var(--brand-v3-cream);
}

body.demo-page em,
.demo-page .italic {
    font-family: var(--brand-v3-serif);
    font-style: italic;
    font-weight: 500;
    color: var(--brand-v3-orange);
    font-variation-settings: "opsz" 144;
}

/* ========== Hero ========== */
.demo-hero {
    position: relative;
    padding: 64px 24px 44px;
    text-align: center;
    overflow: hidden;
    background: var(--brand-v3-cream);
    border-bottom: 2.5px solid var(--brand-v3-navy);
}

.demo-hero-bg-blob {
    position: absolute;
    border-radius: 50%;
    pointer-events: none;
    opacity: 0.45;
    z-index: 0;
}

.demo-hero-bg-blob.orange {
    width: 400px;
    height: 400px;
    background: radial-gradient(circle, var(--brand-v3-orange-soft) 0%, transparent 65%);
    top: -100px;
    right: -80px;
}

.demo-hero-bg-blob.yellow {
    width: 320px;
    height: 320px;
    background: radial-gradient(circle, var(--brand-v3-butter) 0%, transparent 65%);
    bottom: -60px;
    left: -60px;
}

.demo-hero-inner {
    position: relative;
    z-index: 1;
    max-width: 780px;
    margin: 0 auto;
}

.demo-hero-badge {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 6px 16px;
    font-family: var(--brand-v3-mono);
    font-size: 11.5px;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.14em;
    color: var(--brand-v3-navy);
    background: var(--brand-v3-butter);
    border: 2px solid var(--brand-v3-navy);
    border-radius: 999px;
    box-shadow: var(--brand-v3-shadow-sm);
    margin-bottom: 18px;
}

.demo-hero-title {
    font-family: var(--brand-v3-display);
    font-size: clamp(32px, 5vw, 58px);
    font-weight: 800;
    color: var(--brand-v3-navy);
    margin: 0 0 14px;
    line-height: 1.03;
    letter-spacing: -0.035em;
    font-variation-settings: "opsz" 72, "wdth" 92;
}

.demo-hero-subtitle {
    font-family: var(--brand-v3-sans);
    font-size: clamp(15.5px, 1.8vw, 18px);
    font-weight: 500;
    color: var(--brand-v3-ink-soft);
    margin: 0 auto;
    max-width: 620px;
    line-height: 1.6;
}

/* ========== Demo Main 2-col Grid ========== */
.demo-main {
    padding: 48px 24px 72px;
}

.demo-grid {
    max-width: 1240px;
    margin: 0 auto;
    display: grid;
    grid-template-columns: 380px 1fr;
    gap: 28px;
    align-items: start;
}

.demo-sidebar {
    display: flex;
    flex-direction: column;
    gap: 20px;
    position: sticky;
    top: 105px;
}

/* ========== Context Card ========== */
.demo-context-card {
    background: var(--brand-v3-paper);
    border: 2.5px solid var(--brand-v3-navy);
    border-radius: 18px;
    padding: 20px 22px;
    box-shadow: var(--brand-v3-shadow-md);
}

.demo-context-title {
    font-family: var(--brand-v3-display);
    font-size: 16px;
    font-weight: 800;
    color: var(--brand-v3-navy);
    margin: 0 0 6px;
    letter-spacing: -0.01em;
}

.demo-context-desc {
    font-family: var(--brand-v3-sans);
    font-size: 13.5px;
    color: var(--brand-v3-ink-soft);
    line-height: 1.55;
    margin: 0;
}

/* ========== Suggested Questions（chip 列表） ========== */
.demo-suggested {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.demo-suggested-title {
    font-family: var(--brand-v3-mono);
    font-size: 10.5px;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.14em;
    color: var(--brand-v3-muted);
    margin: 0 0 4px;
}

.demo-question-chip {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 10px 14px;
    font-family: var(--brand-v3-sans);
    font-size: 13.5px;
    font-weight: 500;
    color: var(--brand-v3-navy);
    background: var(--brand-v3-paper);
    border: 2px solid var(--brand-v3-navy);
    border-radius: 12px;
    cursor: pointer;
    text-align: left;
    box-shadow: var(--brand-v3-shadow-sm);
    transition: transform 0.2s cubic-bezier(.2,.8,.2,1), box-shadow 0.2s ease, background 0.2s ease;
    line-height: 1.4;
}

.demo-question-chip:hover {
    background: var(--brand-v3-butter);
    transform: translate(-2px, -2px);
    box-shadow: var(--brand-v3-shadow-md);
}

.demo-question-chip svg {
    width: 16px;
    height: 16px;
    flex-shrink: 0;
    color: var(--brand-v3-orange);
}

/* ========== Limit Badge（免費訊息次數） ========== */
.demo-limit-badge {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 12px 16px;
    font-family: var(--brand-v3-sans);
    font-size: 13px;
    font-weight: 600;
    color: var(--brand-v3-navy);
    background: var(--brand-v3-orange-soft);
    border: 2.5px solid var(--brand-v3-navy);
    border-radius: 14px;
    box-shadow: var(--brand-v3-shadow-sm);
}

.demo-limit-badge svg {
    width: 18px;
    height: 18px;
    color: var(--brand-v3-orange-deep);
}

/* ========== Features Mini List ========== */
.demo-features-mini {
    display: flex;
    flex-direction: column;
    gap: 8px;
    padding: 4px 0;
}

.demo-feature-mini-item {
    display: flex;
    align-items: center;
    gap: 8px;
    font-family: var(--brand-v3-sans);
    font-size: 13px;
    color: var(--brand-v3-ink-soft);
}

.demo-feature-mini-item svg {
    width: 14px;
    height: 14px;
    color: var(--brand-v3-orange);
    flex-shrink: 0;
}

/* ========== Upload Card（核心，5 state 切換） ========== */
.demo-upload-card {
    background: var(--brand-v3-paper);
    border: 2.5px solid var(--brand-v3-navy);
    border-radius: 20px;
    padding: 24px;
    box-shadow: var(--brand-v3-shadow-md);
    transition: box-shadow 0.3s ease;
}

.demo-upload-card:hover {
    box-shadow: var(--brand-v3-shadow-lg);
}

.demo-upload-state.hidden {
    display: none;
}

.demo-upload-title {
    display: flex;
    align-items: center;
    gap: 10px;
    font-family: var(--brand-v3-display);
    font-size: 17px;
    font-weight: 800;
    color: var(--brand-v3-navy);
    margin: 0 0 8px;
    letter-spacing: -0.01em;
}

.demo-upload-title svg {
    width: 22px;
    height: 22px;
    color: var(--brand-v3-orange);
}

.demo-upload-desc {
    font-family: var(--brand-v3-sans);
    font-size: 13.5px;
    color: var(--brand-v3-ink-soft);
    line-height: 1.55;
    margin: 0 0 16px;
}

/* Dropzone：dashed navy + cream-2 bg */
.demo-dropzone {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 8px;
    padding: 26px 18px;
    background: var(--brand-v3-cream-2);
    border: 2.5px dashed var(--brand-v3-navy);
    border-radius: 16px;
    margin-bottom: 18px;
    transition: background 0.2s ease, transform 0.2s ease;
}

.demo-dropzone:hover,
.demo-dropzone.dragover {
    background: var(--brand-v3-butter);
    transform: translate(-1px, -1px);
}

.demo-dropzone svg {
    width: 36px;
    height: 36px;
    color: var(--brand-v3-navy);
    opacity: 0.7;
}

.demo-dropzone-text {
    font-family: var(--brand-v3-display);
    font-size: 14.5px;
    font-weight: 700;
    color: var(--brand-v3-navy);
    letter-spacing: -0.005em;
}

.demo-dropzone-or {
    font-family: var(--brand-v3-mono);
    font-size: 11px;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.14em;
    color: var(--brand-v3-muted);
}

.demo-browse-btn {
    padding: 8px 20px;
    font-family: var(--brand-v3-sans);
    font-size: 13px;
    font-weight: 700;
    color: var(--brand-v3-cream);
    background: var(--brand-v3-navy);
    border: 2px solid var(--brand-v3-navy);
    border-radius: 999px;
    cursor: pointer;
    box-shadow: var(--brand-v3-shadow-primary-md);
    transition: transform 0.2s cubic-bezier(.2,.8,.2,1), box-shadow 0.2s ease;
}

.demo-browse-btn:hover {
    transform: translate(-2px, -2px);
    box-shadow: var(--brand-v3-shadow-primary-lg);
}

.demo-dropzone-formats {
    font-family: var(--brand-v3-mono);
    font-size: 10.5px;
    font-weight: 500;
    color: var(--brand-v3-muted);
    letter-spacing: 0.06em;
    margin-top: 4px;
}

/* Sample 區段 */
.demo-sample-section {
    display: flex;
    flex-direction: column;
    gap: 8px;
    padding: 16px 0 0;
    border-top: 1.5px dashed var(--brand-v3-navy);
}

.demo-sample-title {
    font-family: var(--brand-v3-mono);
    font-size: 10.5px;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.14em;
    color: var(--brand-v3-muted);
}

.demo-sample-btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    padding: 10px 16px;
    font-family: var(--brand-v3-sans);
    font-size: 13.5px;
    font-weight: 700;
    color: var(--brand-v3-navy);
    background: var(--brand-v3-butter);
    border: 2px solid var(--brand-v3-navy);
    border-radius: 10px;
    cursor: pointer;
    box-shadow: var(--brand-v3-shadow-sm);
    transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.demo-sample-btn:hover {
    transform: translate(-2px, -2px);
    box-shadow: var(--brand-v3-shadow-md);
}

.demo-sample-btn svg {
    width: 16px;
    height: 16px;
    color: var(--brand-v3-orange);
}

.demo-sample-desc {
    font-family: var(--brand-v3-sans);
    font-size: 12px;
    color: var(--brand-v3-muted);
    line-height: 1.5;
}

/* ========== Upload Progress（uploading / processing states） ========== */
.demo-upload-progress {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 10px;
    padding: 36px 20px;
    text-align: center;
}

.demo-upload-spinner {
    width: 40px;
    height: 40px;
    border: 3.5px solid var(--brand-v3-butter);
    border-top-color: var(--brand-v3-orange);
    border-radius: 50%;
    animation: demoSpinnerRotate 0.8s linear infinite;
}

@keyframes demoSpinnerRotate {
    to { transform: rotate(360deg); }
}

.demo-upload-progress-text {
    font-family: var(--brand-v3-display);
    font-size: 15px;
    font-weight: 700;
    color: var(--brand-v3-navy);
    letter-spacing: -0.005em;
}

.demo-upload-progress-sub {
    font-family: var(--brand-v3-sans);
    font-size: 12.5px;
    color: var(--brand-v3-muted);
    line-height: 1.5;
}

.demo-progress-bar {
    width: 100%;
    height: 10px;
    background: var(--brand-v3-butter);
    border: 2px solid var(--brand-v3-navy);
    border-radius: 999px;
    overflow: hidden;
    margin-top: 8px;
}

.demo-progress-fill {
    height: 100%;
    background: var(--brand-v3-orange);
    width: 0%;
    transition: width 0.4s cubic-bezier(.2,.8,.2,1);
}

/* ========== Upload Success（ready state） ========== */
.demo-upload-success {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 10px;
    padding: 28px 20px;
    text-align: center;
}

.demo-upload-success > svg {
    width: 44px;
    height: 44px;
    color: var(--brand-v3-orange);
}

.demo-upload-ready-title {
    font-family: var(--brand-v3-display);
    font-size: 17px;
    font-weight: 800;
    color: var(--brand-v3-navy);
    letter-spacing: -0.01em;
}

.demo-upload-ready-desc {
    font-family: var(--brand-v3-sans);
    font-size: 13px;
    color: var(--brand-v3-ink-soft);
    line-height: 1.55;
    max-width: 280px;
}

.demo-start-chat-btn {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 12px 28px;
    margin-top: 10px;
    font-family: var(--brand-v3-sans);
    font-size: 14px;
    font-weight: 700;
    color: var(--brand-v3-cream);
    background: var(--brand-v3-navy);
    border: 2px solid var(--brand-v3-navy);
    border-radius: 999px;
    cursor: pointer;
    box-shadow: var(--brand-v3-shadow-primary-md);
    transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.demo-start-chat-btn:hover {
    transform: translate(-2px, -2px);
    box-shadow: var(--brand-v3-shadow-primary-lg);
}

.demo-upload-another {
    padding: 6px 14px;
    font-family: var(--brand-v3-mono);
    font-size: 11px;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.1em;
    color: var(--brand-v3-muted);
    background: transparent;
    border: none;
    cursor: pointer;
    text-decoration: underline;
    text-underline-offset: 3px;
    transition: color 0.2s ease;
}

.demo-upload-another:hover {
    color: var(--brand-v3-navy);
}

/* ========== Upload Error state ========== */
.demo-upload-error {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 12px;
    padding: 28px 20px;
    text-align: center;
}

.demo-upload-error > svg {
    width: 40px;
    height: 40px;
    color: #B02A2A;
}

.demo-upload-error-text {
    font-family: var(--brand-v3-sans);
    font-size: 13.5px;
    color: var(--brand-v3-navy);
    line-height: 1.55;
    max-width: 280px;
}

.demo-retry-btn {
    padding: 10px 22px;
    font-family: var(--brand-v3-sans);
    font-size: 13px;
    font-weight: 700;
    color: var(--brand-v3-navy);
    background: var(--brand-v3-paper);
    border: 2px solid var(--brand-v3-navy);
    border-radius: 999px;
    cursor: pointer;
    box-shadow: var(--brand-v3-shadow-sm);
    transition: transform 0.2s ease, box-shadow 0.2s ease, background 0.2s ease;
}

.demo-retry-btn:hover {
    background: var(--brand-v3-butter);
    transform: translate(-2px, -2px);
    box-shadow: var(--brand-v3-shadow-md);
}

/* ========== Context Section（上傳後顯示） ========== */
.demo-context-section {
    display: flex;
    flex-direction: column;
    gap: 16px;
}

.demo-context-section.hidden {
    display: none;
}

/* ========== Chat Area（右欄 iframe） ========== */
.demo-chat-area {
    position: relative;
    background: var(--brand-v3-paper);
    border: 2.5px solid var(--brand-v3-navy);
    border-radius: 20px;
    overflow: hidden;
    box-shadow: var(--brand-v3-shadow-lg);
    min-height: 640px;
    height: calc(100vh - 180px);
    max-height: 800px;
}

/* Locked overlay（未上傳前的提示） */
.demo-chat-locked {
    position: absolute;
    inset: 0;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 14px;
    padding: 40px 24px;
    background: var(--brand-v3-cream-2);
    z-index: 2;
    transition: opacity 0.3s ease;
}

.demo-chat-locked-icon {
    width: 72px;
    height: 72px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--brand-v3-butter);
    border: 2.5px solid var(--brand-v3-navy);
    border-radius: 50%;
    box-shadow: var(--brand-v3-shadow-md);
    transform: rotate(-4deg);
}

.demo-chat-locked-icon svg {
    width: 30px;
    height: 30px;
    color: var(--brand-v3-navy);
}

.demo-chat-locked-title {
    font-family: var(--brand-v3-display);
    font-size: 20px;
    font-weight: 800;
    color: var(--brand-v3-navy);
    letter-spacing: -0.015em;
}

.demo-chat-locked-hint {
    font-family: var(--brand-v3-sans);
    font-size: 14px;
    color: var(--brand-v3-ink-soft);
    text-align: center;
    max-width: 320px;
    line-height: 1.55;
}

.demo-chat-locked.unlocked {
    opacity: 0;
    pointer-events: none;
}

.demo-chat-area iframe {
    width: 100%;
    height: 100%;
    border: none;
    display: block;
    background: var(--brand-v3-paper);
}

.demo-placeholder {
    position: absolute;
    inset: 0;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 14px;
    background: var(--brand-v3-cream-2);
}

.demo-placeholder svg {
    width: 48px;
    height: 48px;
    color: var(--brand-v3-navy);
    opacity: 0.4;
}

.demo-placeholder p {
    font-family: var(--brand-v3-display);
    font-size: 16px;
    font-weight: 700;
    color: var(--brand-v3-navy);
    margin: 0;
}

/* ========== Features Section（3 feature cards） ========== */
.demo-features {
    padding: 72px 24px;
    background: var(--brand-v3-cream-2);
    border-top: 2.5px solid var(--brand-v3-navy);
    border-bottom: 2.5px solid var(--brand-v3-navy);
}

.demo-features-inner {
    max-width: 1160px;
    margin: 0 auto;
}

.demo-features-title {
    font-family: var(--brand-v3-display);
    font-size: clamp(26px, 3.6vw, 38px);
    font-weight: 800;
    color: var(--brand-v3-navy);
    text-align: center;
    margin: 0 0 44px;
    letter-spacing: -0.025em;
    line-height: 1.1;
    font-variation-settings: "opsz" 72, "wdth" 92;
}

.demo-features-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 28px;
    padding: 6px 2px 10px;
}

/* Feature cards（3 張交錯微 rotate） */
.demo-feature-card {
    background: var(--brand-v3-paper);
    border: 2.5px solid var(--brand-v3-navy);
    border-radius: 20px;
    padding: 28px 26px;
    box-shadow: var(--brand-v3-shadow-md);
    transition: transform 0.3s cubic-bezier(.2,.8,.2,1), box-shadow 0.3s ease;
    will-change: transform;
}

.demo-feature-card:nth-child(1) { transform: rotate(-0.8deg); }
.demo-feature-card:nth-child(2) { transform: rotate(0); }
.demo-feature-card:nth-child(3) { transform: rotate(0.8deg); }

.demo-feature-card:hover {
    transform: rotate(0) translate(-3px, -3px);
    box-shadow: var(--brand-v3-shadow-lg);
}

.demo-feature-icon {
    width: 56px;
    height: 56px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--brand-v3-butter);
    border: 2.5px solid var(--brand-v3-navy);
    border-radius: 14px;
    margin-bottom: 18px;
}

.demo-feature-icon svg {
    width: 26px;
    height: 26px;
    color: var(--brand-v3-navy);
}

.demo-feature-card h3 {
    font-family: var(--brand-v3-display);
    font-size: 19px;
    font-weight: 800;
    color: var(--brand-v3-navy);
    margin: 0 0 10px;
    line-height: 1.2;
    letter-spacing: -0.015em;
}

.demo-feature-card p {
    font-family: var(--brand-v3-sans);
    font-size: 14.5px;
    color: var(--brand-v3-ink-soft);
    line-height: 1.62;
    margin: 0;
}

/* ========== CTA Section（深 navy 底） ========== */
.demo-cta {
    padding: 88px 24px;
    background: var(--brand-v3-navy);
    text-align: center;
    position: relative;
    overflow: hidden;
}

.demo-cta::before {
    content: "";
    position: absolute;
    top: 50%;
    left: 50%;
    width: 620px;
    height: 620px;
    background: radial-gradient(circle, var(--brand-v3-orange-deep) 0%, transparent 55%);
    opacity: 0.22;
    transform: translate(-50%, -50%);
    pointer-events: none;
}

.demo-cta-inner {
    position: relative;
    z-index: 1;
    max-width: 620px;
    margin: 0 auto;
}

.demo-cta-title {
    font-family: var(--brand-v3-display);
    font-size: clamp(26px, 3.8vw, 38px);
    font-weight: 800;
    color: var(--brand-v3-cream);
    margin: 0 0 14px;
    letter-spacing: -0.025em;
    line-height: 1.1;
}

.demo-cta-subtitle {
    font-family: var(--brand-v3-sans);
    font-size: 15.5px;
    font-weight: 500;
    color: var(--brand-v3-cream);
    opacity: 0.82;
    margin: 0 0 30px;
    line-height: 1.6;
}

.demo-cta-buttons {
    display: inline-flex;
    gap: 14px;
    flex-wrap: wrap;
    justify-content: center;
}

.demo-cta-btn {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 14px 30px;
    border-radius: 999px;
    font-family: var(--brand-v3-sans);
    font-size: 15px;
    font-weight: 700;
    text-decoration: none;
    border: 2.5px solid var(--brand-v3-paper);
    box-sizing: border-box;
    transition: transform 0.25s cubic-bezier(.2,.8,.2,1), box-shadow 0.25s ease, background 0.2s ease, color 0.2s ease, border-color 0.2s ease;
    letter-spacing: -0.005em;
}

.demo-cta-btn.primary {
    background: var(--brand-v3-orange);
    color: var(--brand-v3-paper);
    box-shadow: 5px 5px 0 var(--brand-v3-orange-deep);
}

.demo-cta-btn.primary:hover {
    background: var(--brand-v3-paper);
    color: var(--brand-v3-navy);
    border-color: var(--brand-v3-navy);
    transform: translate(-2px, -2px);
    box-shadow: 7px 7px 0 var(--brand-v3-cream);
}

.demo-cta-btn.secondary {
    background: transparent;
    color: var(--brand-v3-cream);
    box-shadow: 3px 3px 0 var(--brand-v3-orange-deep);
}

.demo-cta-btn.secondary:hover {
    background: var(--brand-v3-cream);
    color: var(--brand-v3-navy);
    border-color: var(--brand-v3-navy);
    transform: translate(-2px, -2px);
    box-shadow: 5px 5px 0 var(--brand-v3-orange-deep);
}

/* =================================================================
   RWD 斷點系統（對齊 v3 skill §17）
   ≤1080: grid 2 cols → 1 col（sidebar 放最上，chat 在下）
   ≤820:  hero padding 縮、features 單欄、CTA 縮
   ≤640:  各元件字縮、padding 緊湊
   ================================================================= */

@media (max-width: 1080px) {
    .demo-grid {
        grid-template-columns: 1fr;
        gap: 24px;
        max-width: 680px;
    }

    .demo-sidebar {
        position: static;
    }

    .demo-chat-area {
        height: 640px;
        max-height: 70vh;
    }

    .demo-features-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: 24px;
    }

    .demo-feature-card:nth-child(3) {
        grid-column: 1 / -1;
        max-width: 420px;
        margin: 0 auto;
    }
}

@media (max-width: 820px) {
    .demo-hero {
        padding: 48px 20px 36px;
    }

    .demo-hero-title {
        font-size: clamp(26px, 7vw, 40px);
    }

    .demo-hero-subtitle {
        font-size: 15px;
    }

    .demo-hero-badge {
        font-size: 10.5px;
        padding: 5px 14px;
    }

    .demo-main {
        padding: 36px 20px 56px;
    }

    .demo-upload-card {
        padding: 20px;
    }

    .demo-dropzone {
        padding: 22px 16px;
    }

    .demo-features {
        padding: 56px 20px;
    }

    .demo-features-title {
        margin-bottom: 32px;
    }

    .demo-features-grid {
        grid-template-columns: 1fr;
        gap: 22px;
        max-width: 420px;
        margin: 0 auto;
    }

    .demo-feature-card:nth-child(3) {
        grid-column: auto;
        max-width: none;
    }

    .demo-cta {
        padding: 64px 20px;
    }

    .demo-hero-bg-blob.orange {
        width: 300px;
        height: 300px;
        opacity: 0.32;
    }

    .demo-hero-bg-blob.yellow {
        width: 240px;
        height: 240px;
        opacity: 0.32;
    }
}

@media (max-width: 640px) {
    .demo-hero {
        padding: 40px 18px 32px;
    }

    .demo-hero-title {
        font-size: clamp(22px, 8vw, 32px);
        letter-spacing: -0.025em;
    }

    .demo-main {
        padding: 28px 18px 48px;
    }

    .demo-upload-title {
        font-size: 16px;
    }

    .demo-question-chip {
        font-size: 13px;
        padding: 9px 12px;
    }

    .demo-chat-area {
        height: 560px;
        border-radius: 16px;
    }

    .demo-chat-locked-title {
        font-size: 18px;
    }

    .demo-features {
        padding: 48px 18px;
    }

    .demo-feature-card {
        padding: 24px 22px;
    }

    .demo-feature-card h3 {
        font-size: 17px;
    }

    .demo-cta {
        padding: 52px 18px;
    }

    .demo-cta-buttons {
        flex-direction: column;
        gap: 12px;
        width: 100%;
    }

    .demo-cta-btn {
        width: 100%;
        padding: 13px 24px;
        font-size: 14px;
        justify-content: center;
    }
}

/* =================================================================
   覆蓋 landing.css 的 global .animate-on-scroll
   JS 會給 .demo-feature-card + .demo-cta-inner 加 .animate-on-scroll
   用 CSS 3 translate 保留卡片 rotate，並確保 observer 沒觸發時也可見
   ================================================================= */
.demo-feature-card.animate-on-scroll,
.demo-cta-inner.animate-on-scroll {
    opacity: 0;
    transform: none;          /* 覆蓋 landing 的 translateY(40px) */
    translate: 0 20px;        /* CSS 3 translate，不影響卡片 rotate */
    transition: opacity 0.6s cubic-bezier(.2,.8,.2,1),
                translate 0.6s cubic-bezier(.2,.8,.2,1);
}

.demo-feature-card.animate-on-scroll.visible,
.demo-feature-card.animate-on-scroll.in-view,
.demo-cta-inner.animate-on-scroll.visible,
.demo-cta-inner.animate-on-scroll.in-view {
    opacity: 1;
    translate: 0 0;
}

/* ========== Reduced Motion ========== */
@media (prefers-reduced-motion: reduce) {
    .demo-feature-card,
    .demo-question-chip,
    .demo-browse-btn,
    .demo-sample-btn,
    .demo-start-chat-btn,
    .demo-retry-btn,
    .demo-upload-card,
    .demo-chat-area,
    .demo-cta-btn {
        transition: none !important;
    }

    /* 不清 feature-card 的 transform（保留 nth-child rotate），但禁用 animate 位移 */
    .demo-feature-card.animate-on-scroll,
    .demo-cta-inner.animate-on-scroll {
        opacity: 1 !important;
        translate: 0 0 !important;
        transition: none !important;
    }

    .demo-upload-spinner {
        animation: none !important;
        border-top-color: var(--brand-v3-orange);
    }

    .demo-chat-locked-icon {
        transform: none !important;
    }
}