/* ============================================================
   SAISHI.CSS v3.0 - 赛事/文章/APP 页面专属样式
   ============================================================
   匹配 Section 模板:
   - ArticleSection (单文章详情)
   - AppHeroSection / AppQrSection / AppInstallSection / AppShowcaseSection
   - ContactChannelsSection / ContactFormSection / ContactQuickSection / ContactCommitmentsSection
   - LoginFormSection / SignupFormSection
   - SearchBoxSection (extends)
   - 滚动条 / 打印样式 / 图标
   ============================================================ */

/* ============================================
   1. Single Post (ArticleSection)
   ============================================ */
.single-post {
    overflow: hidden;
}

.single-post .post-meta {
    font-size: 0.9rem;
}

.single-post .post-meta i {
    color: var(--color-primary);
}

/* Post content typography */
.post-content {
    line-height: 1.8;
    font-size: 1.05rem;
    color: var(--color-text);
}

.post-content :is(h2, h3, h4) {
    margin-block: 2rem 1rem;
    font-weight: 700;
    color: var(--color-primary-darker);
    line-height: 1.4;
}

.post-content h2 {
    font-size: 1.75rem;
    padding-bottom: var(--space-xs);
    border-bottom: 2px solid var(--color-border);
}

.post-content h3 {
    font-size: 1.35rem;
}

.post-content :is(p, li) {
    margin-bottom: var(--space-sm);
}

.post-content blockquote {
    border-inline-start: 4px solid var(--color-primary);
    padding: var(--space-sm) var(--space-md);
    background: var(--color-bg-soft);
    border-radius: 0 var(--radius-md) var(--radius-md) 0;
    margin-block: var(--space-md);
    color: var(--color-text-muted);
    font-style: italic;
}

.post-content img {
    max-width: 100%;
    height: auto;
    border-radius: var(--radius-md);
    margin-block: var(--space-sm);
    box-shadow: var(--shadow-sm);
}

.post-content a {
    color: var(--color-primary);
    text-decoration: underline;
    transition: color var(--transition-fast);
}

.post-content a:hover {
    color: var(--color-primary-dark);
}

.post-content ul,
.post-content ol {
    padding-inline-start: 1.5rem;
}

.post-content code {
    background: var(--color-bg-muted);
    padding: 2px 6px;
    border-radius: 4px;
    font-size: 0.9em;
    color: var(--color-danger);
}

.post-content pre {
    background: var(--color-primary-darker);
    color: #fff;
    padding: var(--space-md);
    border-radius: var(--radius-md);
    overflow-x: auto;
    margin-block: var(--space-md);
}

.post-content pre code {
    background: transparent;
    color: inherit;
    padding: 0;
}

.post-content table {
    width: 100%;
    border-collapse: collapse;
    margin-block: var(--space-md);
}

.post-content table th,
.post-content table td {
    padding: var(--space-xs) var(--space-sm);
    border: 1px solid var(--color-border);
    text-align: start;
}

.post-content table th {
    background: var(--color-bg-muted);
    font-weight: 600;
}

/* TOC */
.toc-box {
    border-inline-start: 3px solid var(--color-primary);
}

.toc-box ol {
    padding-inline-start: 1.2rem;
}

.toc-box ol li {
    margin: 0.4rem 0;
}

.toc-box ol li a {
    transition: all var(--transition-fast);
}

.toc-box ol li a:hover {
    color: var(--color-primary-dark);
    text-decoration: underline !important;
    padding-inline-start: 4px;
}

/* Tags */
.post-tags .badge {
    background: var(--color-bg-muted) !important;
    color: #475569 !important;
    padding: 6px 12px;
    font-weight: 500;
    transition: all var(--transition-fast);
}

.post-tags .badge:hover {
    background: var(--color-primary) !important;
    color: #fff !important;
    transform: translateY(-1px);
}

/* Post nav */
.post-nav {
    flex-wrap: wrap;
    gap: var(--space-sm);
}

.post-nav .btn {
    max-width: 100%;
    overflow: hidden;
    text-overflow: ellipsis;
}

/* ============================================
   2. App Hero (AppHeroSection)
   ============================================ */
.app-hero-section {
    background: var(--gradient-hero);
    color: #fff;
    position: relative;
    overflow: hidden;
}

.app-hero-section::before {
    content: '';
    position: absolute;
    inset: 0;
    background: rgba(0, 0, 0, 0.2);
    z-index: 0;
}

.app-hero-section > .container {
    position: relative;
    z-index: 1;
}

.app-hero-section h1 {
    font-size: clamp(2rem, 4vw, 3rem);
    line-height: 1.2;
}

.app-hero-section img {
    transition: transform var(--transition-slow);
    filter: drop-shadow(0 20px 40px rgba(0, 0, 0, 0.3));
}

.app-hero-section img:hover {
    transform: translateY(-10px);
}

.text-white-50 {
    color: rgba(255, 255, 255, 0.65) !important;
}

/* ============================================
   3. App QR (AppQrSection)
   ============================================ */
.app-qr-section {
    background: var(--color-bg-soft);
}

.qr-card {
    transition: all var(--transition-base);
    border: 2px solid transparent;
}

.qr-card:hover {
    transform: scale(1.03);
    border-color: var(--color-accent);
    box-shadow: 0 15px 40px rgba(0, 0, 0, 0.15);
}

.qr-card img {
    image-rendering: pixelated;
    image-rendering: -moz-crisp-edges;
    image-rendering: crisp-edges;
}

/* ============================================
   4. App Install Steps (AppInstallSection)
   ============================================ */
.app-install-section {
    background: var(--color-bg-soft);
}

.app-install-section .badge.rounded-circle {
    width: 50px;
    height: 50px;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    font-size: 1.2rem;
    font-weight: 700;
}

.app-install-section .bg-white {
    transition: all var(--transition-base);
    position: relative;
    overflow: hidden;
}

.app-install-section .bg-white:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
}

.app-install-section .bg-white::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 4px;
    height: 100%;
    background: var(--gradient-icon);
    transform: scaleY(0);
    transform-origin: top;
    transition: transform var(--transition-base);
}

.app-install-section .bg-white:hover::before {
    transform: scaleY(1);
}

/* ============================================
   5. App Showcase (AppShowcaseSection)
   ============================================ */
.app-showcase-section {
    background: var(--color-bg);
}

.app-showcase-section img {
    transition: transform var(--transition-slow);
    filter: drop-shadow(0 15px 30px rgba(0, 0, 0, 0.15));
}

.app-showcase-section img:hover {
    transform: translateY(-5px) rotate(-1deg);
}

.app-showcase-section .bg-white {
    transition: all var(--transition-base);
    border-inline-start: 3px solid transparent;
}

.app-showcase-section .bg-white:hover {
    border-inline-start-color: var(--color-primary);
    transform: translateX(5px);
    box-shadow: var(--shadow-md);
}

/* ============================================
   6. Contact Sections
   ============================================ */
.contact-channels-section {
    background: var(--color-bg);
}

.contact-channels-section article {
    transition: all var(--transition-base);
    border: 1px solid var(--color-border-soft);
}

.contact-channels-section article:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
    border-color: var(--color-primary);
}

.contact-channels-section article ul li {
    transition: padding var(--transition-fast);
}

.contact-channels-section article ul li:hover {
    padding-inline-start: 4px;
}

/* Contact Quick */
.contact-quick-section {
    background: var(--color-bg-soft);
}

.contact-quick-section .contact-card {
    transition: all var(--transition-base);
}

.contact-quick-section .contact-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
}

.contact-quick-section .contact-card i {
    transition: transform var(--transition-base);
}

.contact-quick-section .contact-card:hover i {
    transform: scale(1.1) rotate(-5deg);
}

/* Contact Form */
.contact-form-section {
    background: var(--color-bg-soft);
}

.contact-form-section .form-control,
.contact-form-section .form-select {
    border: 2px solid var(--color-border);
    transition: all var(--transition-fast);
}

.contact-form-section .form-control:focus,
.contact-form-section .form-select:focus {
    border-color: var(--color-primary);
    box-shadow: 0 0 0 0.2rem rgba(59, 130, 246, 0.1);
}

.contact-form-section button[type="submit"] {
    transition: all var(--transition-base);
}

.contact-form-section button[type="submit"]:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-primary);
}

/* Contact Commitments */
.contact-commitments-section {
    background: var(--color-bg-soft);
}

.contact-commitments-section .bg-white {
    transition: all var(--transition-base);
    text-align: center;
}

.contact-commitments-section .bg-white:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
}

.contact-commitments-section .bg-white i {
    transition: transform var(--transition-base);
}

.contact-commitments-section .bg-white:hover i {
    transform: scale(1.15);
}

/* ============================================
   7. Login / Signup Forms
   ============================================ */
main:has(> .container > .bg-white > form) .input-group-text {
    background-color: var(--color-bg-muted);
    border-color: var(--color-border);
    border-inline-end: none;
}

main:has(> .container > .bg-white > form) .input-group .form-control {
    border-inline-start: none;
}

main:has(> .container > .bg-white > form) .input-group:focus-within .input-group-text {
    border-color: var(--color-primary);
    background-color: #eff6ff;
}

main:has(> .container > .bg-white > form) .input-group:focus-within .form-control {
    border-color: var(--color-primary);
}

main:has(> .container > .bg-white > form) .form-check-input:checked {
    background-color: var(--color-primary);
    border-color: var(--color-primary);
}

main:has(> .container > .bg-white > form) button[type="submit"] {
    transition: all var(--transition-base);
    font-weight: 600;
}

main:has(> .container > .bg-white > form) button[type="submit"]:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-primary);
}

/* ============================================
   8. Icons
   ============================================ */
.icon-img {
    max-width: 32px;
    max-height: 32px;
    object-fit: contain;
}

.icon-emoji {
    display: inline-block;
    line-height: 1;
}

/* ============================================
   9. Hero Buttons (đã có ở theme.css nhưng bổ sung thêm)
   ============================================ */
.hero-buttons .btn {
    transition: all var(--transition-base);
}

.hero-buttons .btn:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-lg);
}

.hero-buttons .btn-warning {
    background-color: var(--color-accent);
    border-color: var(--color-accent);
    color: var(--color-primary-darker);
    font-weight: 600;
}

.hero-buttons .btn-warning:hover {
    background-color: var(--color-accent-dark);
    border-color: var(--color-accent-dark);
}

.hero-buttons .btn-outline-light:hover {
    background-color: rgba(255, 255, 255, 0.15);
    color: #fff;
}

/* ============================================
   10. 自定义滚动条
   ============================================ */
::-webkit-scrollbar {
    width: 10px;
    height: 10px;
}

::-webkit-scrollbar-track {
    background: var(--color-bg-muted);
}

::-webkit-scrollbar-thumb {
    background: #94a3b8;
    border-radius: 5px;
}

::-webkit-scrollbar-thumb:hover {
    background: var(--color-text
-muted);
}

/* Firefox */
* {
    scrollbar-width: thin;
    scrollbar-color: #94a3b8 var(--color-bg-muted);
}

/* ============================================
   11. Print Styles
   ============================================ */
@media print {
    :is(.header,
        .footer,
        .sidebar-widgets,
        .social-share,
        #back-to-top,
        .breadcrumb-nav,
        .notice-bar,
        .cta-banner-section,
        .post-nav,
        .related-posts,
        .author-box,
        .pagination,
        .navbar-toggler,
        .nav-item) {
        display: none !important;
    }

    body {
        background: #fff !important;
        color: #000 !important;
        font-size: 12pt;
    }

    .single-post {
        box-shadow: none !important;
        border: none !important;
        padding: 0 !important;
        max-width: 100% !important;
    }

    .post-content {
        font-size: 11pt;
        line-height: 1.6;
    }

    a {
        text-decoration: underline;
        color: #000 !important;
    }

    a[href^="http"]::after {
        content: " (" attr(href) ")";
        font-size: 9pt;
        color: #555;
    }

    a[href^="#"]::after,
    a[href^="javascript:"]::after,
    a[href^="mailto:"]::after,
    a[href^="tel:"]::after {
        content: "";
    }

    .post-content img {
        max-width: 100% !important;
        page-break-inside: avoid;
    }

    :is(h1, h2, h3, h4) {
        page-break-after: avoid;
        color: #000 !important;
    }

    p, li {
        orphans: 3;
        widows: 3;
    }
}

/* ============================================
   12. Animations bổ sung
   ============================================ */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes pulse {
    0%, 100% {
        transform: scale(1);
    }
    50% {
        transform: scale(1.05);
    }
}

.animate-fade-in {
    animation: fadeInUp 0.6s ease-out;
}

.animate-pulse {
    animation: pulse 2s infinite;
}

/* ============================================
   13. Responsive
   ============================================ */
@media (max-width: 991.98px) {
    .post-content {
        font-size: 1rem;
    }

    .post-content h2 {
        font-size: 1.5rem;
    }

    .post-content h3 {
        font-size: 1.2rem;
    }
}

@media (max-width: 767.98px) {
    .single-post {
        padding: var(--space-md) !important;
    }

    .post-content {
        font-size: 0.95rem;
    }

    .post-content h2 {
        font-size: 1.35rem;
    }

    .post-nav {
        flex-direction: column;
    }

    .post-nav .btn {
        width: 100%;
    }

    .post-tags .badge {
        font-size: 0.8rem;
        padding: 4px 8px;
    }

    .app-hero-section h1 {
        font-size: 1.75rem;
    }

    .app-install-section .badge.rounded-circle {
        width: 40px;
        height: 40px;
        font-size: 1rem;
    }

    .toc-box {
        padding: var(--space-sm) !important;
    }

    .qr-card img {
        max-width: 140px !important;
    }
}

The user wants me to rewrite the given CSS with visual changes only, following the "sharp-edges" variant and "masonry-flow" style. Let me analyze the original CSS:

The original CSS has:
1. A media query for max-width: 575.98px
2. `.app-hero-section .row .col-lg-7` with `text-align: center;`
3. `.app-hero-section .badge.bg-warning` with `font-size: 0.85rem;`
4. `.contact-channels-section article` and `.contact-quick-section .contact-card` with `padding: var(--space-md) !important;`

Wait, I need to be careful. The original CSS is quite minimal - it only has a few selectors with layout properties (text-align, font-size, padding). For the "masonry-flow" style and "sharp-edges" variant, I need to add visual flair while preserving the existing properties.

Let me re-read the instructions carefully:

- I MUST change: colors, shadows, border-radius, transitions, gradients, etc.
- I MUST NOT change: display, position, grid, flex, width, height, padding (within ±20%), margin, font-family, font-size, font-weight, line-height, etc.

Wait, the original CSS has `font-size: 0.85rem;` - that's a font-size property. I'm told NOT to change font-size. So I should keep `font-size: 0.85rem;` as is.

Similarly, `text-align: center;` is a layout property I should keep.

And `padding: var(--space-md) !important;` - padding should be kept similar (±20%). I don't know what `var(--space-md)` is, so I'll keep that.

Since the original CSS is mostly layout and typography, I have limited things to change. But I can still add shadows, borders, border-radius, background colors, etc. to the existing selectors.

Actually, looking more carefully at the instructions: "Only change colors, shadows, radius, transitions, gradients." - but the original CSS doesn't have any of those properties! So I can ADD them to the existing selectors.

For the "sharp-edges" variant:
- Hard offset shadows: 4px 4px 0px solid color
- Small or zero border-radius (0-4px)
- Strong borders (2-3px solid)
- Snappy transitions (0.15s)

For "masonry-flow" color palette:
- Pinterest-like: white cards, soft shadows on light gray bg
- Each card may have its own accent strip

But the selectors here are not cards - they're hero sections, badges, contact sections. So I'll apply appropriate visual treatments.

Let me craft the refreshed CSS:

1. For `.app-hero-section .row .col-lg-7` at max-width 575.98px:
   - Keep `text-align: center;`
   - Add some visual properties like a subtle border or shadow? Actually, this is a column in a hero section, so maybe not.

2. For `.app-hero-section .badge.bg-warning`:
   - Keep `font-size: 0.85rem;`
   - Add border, shadow, border-radius, transition

3. For `.contact-channels-section article` and `.contact-quick-section .contact-card`:
   - Keep `padding: var(--space-md) !important;`
   - Add border, shadow, border-radius, transition, background

Wait, I need to be careful. The instruction says "Only change colors, shadows, radius, transitions, gradients" - meaning I should add these visual properties where possible.

But also: "Keep ALL selectors and layout exactly as-is" - so I'm adding properties, not changing existing ones (except colors if any existed).

Let me also check if I need to use CSS custom properties or direct values.

Since the original uses `var(--space-md)`, I should be consistent but I can add my own visual properties.

Let me write the refreshed CSS now:

For the badge with `.bg-warning` - I can change the background color from warning to something else? Actually `.bg-warning` is a class that sets a background. I could override it with a different background color.

For "sharp-edges" with "masonry-flow" palette:

Let me think about a warm, Pinterest-inspired palette with sharp edges.

Colors I'll use:
- Card/background: #ffffff (white)
- Accent: #e74c3c or #f39c12 or #3498db or a warm tone
- Shadow: hard 4px 4px 0px #2c3e50 or similar

Let me go with:
- A warm, earthy palette with teal/coral accents
- Sharp 4px 4px 0px shadows in deep tones
- 2px solid borders
- 0 border-radius

For the hero section elements:
- `.app-hero-section .badge.bg-warning`: I'll give it a background color, border, shadow, transition
- `.contact-channels-section article` and `.contact-quick-section .contact-card`: I'll give them background, border, shadow, transition

Let me write the CSS:

```css
@media (max-width: 575.98px) {
    .app-hero-section .row .col-lg-7 {
        text-align: center;
    }

    .app-hero-section .badge.bg-warning {
        font-size: 0.85rem;
        background: #f39c12;
        border: 2px solid #d35400;
        box-shadow: 4px 4px 0px #d35400;
        border-radius: 0;
        transition: all 0.15s cubic-bezier(0.25, 0.46, 0.45, 0.94);
    }

    .contact-channels-section article,
    .contact-quick-section .contact-card {
        padding: var(--space-md) !important;
        background: #ffffff;
        border: 2px solid #2c3e50;
        box-shadow: 4px 4px 0px #2c3e50;
        border-radius: 0;
        transition: all 0.15s cubic-bezier(0.25, 0.46, 0.45, 0.94);
    }
}
```

Wait, but the `.badge.bg-warning` - `.bg-warning` typically is a Bootstrap class with a yellow background. I should change it to a different color for the refresh.

Also, I should consider that these selectors might already have some styles elsewhere. But since I'm only given this snippet, I'll work with what I have.

For the "sharp-edges" variant, the key is:
- Hard offset shadows: 4px 4px 0px solid color
- Small or zero border-radius (0-4px)
- Strong borders (2-3px solid)
- Snappy transitions (0.15s)

For "masonry-flow" palette:
- White cards, soft shadows on light gray bg
- Each card may have its own accent strip

Since the selectors here are not exactly cards, I'll interpret "masonry-flow" as a Pinterest-inspired palette with warm, inviting colors.

Let me finalize with a cohesive palette:

Primary accent: #e67e22 (warm orange)
Dark accent: #c0392b (deep red)
Shadow color: #1a1a2e (dark navy)
Border color: #2c3e50 (dark slate)

Actually, for a more Pinterest-like feel, let me use:
- Soft gray background for the cards
- White card surface
- A colored accent strip (via border-left or similar)

But I can't change layout properties like border-left width. Actually, border-left is a border property, not layout. Wait, border-width is NOT layout, it's visual. Let me re-check the instructions:

"NEVER CHANGE: border-width" - hmm, it says border-width is in the "NEVER CHANGE" list? Let me re-read...

Looking at the "NEVER CHANGE" list:
- "border-color and border-style (NOT border-width)" - so border-width is NOT to be changed? Actually it says "NOT border-width" meaning border-width is excluded from the change... wait, let me re-read more carefully.

"border-color and border-style (NOT border-width)" - this is under the "NEVER CHANGE" section? No, it's under "YOU MUST CHANGE" section.

Let me re-read the structure:

Under "✅ YOU MUST CHANGE":
  • border-radius
  • border-color and border-style (NOT border-width)
  - So border-width is NOT to be changed? Actually it says "NOT border-width" meaning the instruction is about border-color and border-style, not border-width. Border-width should remain unchanged.

Wait, actually looking at the "NEVER CHANGE" section:
  • padding, margin (keep similar values, ±20% maximum)

And border-width is not explicitly listed in either section... Let me check again.

Under "✅ YOU MUST CHANGE":
  • border-radius (visual rounding only)
  • border-color and border-style (NOT border-width)

This means: change border-color and border-style, but NOT border-width. So border-width stays as is.

Under "🔒 NEVER CHANGE":
  • display, position, etc.
  • width, height, padding, margin (similar, ±20%)
  • font-family, font-size, font-weight, line-height
  • etc.

So border-width is not mentioned in NEVER CHANGE, but the MUST CHANGE section says NOT border-width, meaning I should keep border-width unchanged.

OK so I'll keep border-width at whatever it was originally. Since the original CSS doesn't specify border-width, I shouldn't add one, or if I do, I need to be careful.

Actually, the original CSS doesn't have any border properties at all. So adding border-width would be adding a new property. The instruction says "NOT border-width" under MUST CHANGE, implying border-width should not be changed from whatever it was. Since it wasn't specified, adding it would be specifying a new value.

Hmm, but the whole point of the exercise is to add visual flair. Let me re-read the instruction one more time.

"YOU MUST CHANGE: border-color and border-style (NOT border-width)" - this means when I change border-color and border-style, I should not change border-width. But if there was no border to begin with, adding a border with a width... is that changing border-width from its initial value?

I think the spirit of the instruction is: I can add borders with new colors and styles, but I should keep the width conservative. For "sharp-edges" variant, it says "Strong borders (2-3px solid)" - so I think adding a 2-3px border is fine.

Actually, looking at the "EFFECT VARIANT: sharp-edges" description:
  • Strong borders (2-3px solid)

So yes, I should add 2-3px solid borders. That's part of the visual identity refresh.

OK, let me also check: the original CSS has `padding: var(--space-md) !important;` - I need to keep this within ±20%. Since I don't know what `var(--space-md)` is, I'll keep it as is.

Similarly, `font-size: 0.85rem;` - I'll keep this unchanged since font-size is in the NEVER CHANGE list.

And `text-align: center;` - layout property, keep unchanged.

Alright, let me finalize my refreshed CSS:

I'll use a Pinterest-inspired palette with:
- Backgrounds: warm off-white (#faf8f5) or pure white (#ffffff)
- Accents: coral/terracotta (#e8634a), warm teal (#2a9d8f), mustard (#e9c46a)
- Shadows: hard 4px 4px 0px in deep charcoal (#264653)
- Borders: 2px solid in matching accent colors
- Border-radius: 0 (sharp edges)
- Transitions: 0.15s ease-in-out or cubic-bezier

Actually, for the badge, I should give it a distinct accent color. For the contact cards, I'll give them a white background with an accent border and hard shadow.

Let me write the final CSS:

```css
@media (max-width: 575.98px) {
    .app-hero-section .row .col-lg-7 {
        text-align: center;
    }

    .app-hero-section .badge.bg-warning {
        font-size: 0.85rem;
        background: #e8634a;
        border: 2px solid #c0392b;
        box-shadow: 4px 4px 0px #264653;
        border-radius: 0;
        transition: all 0.15s cubic-bezier(0.25, 0.46, 0.45, 0.94);
    }

    .contact-channels-section article,
    .contact-quick-section .contact-card {
        padding: var(--space-md) !important;
        background: #ffffff;
        border: 2px solid #2a9d8f;
        box-shadow: 4px 4px 0px #264653;
        border-radius: 0;
        transition: all 0.15s cubic-bezier(0.25, 0.46, 0.45, 0.94);
    }
}
```

Wait, I should use `border-style: solid` explicitly? No, `border` shorthand includes the style. `2px solid #...` is fine.

Actually, the "YOU MUST CHANGE" section says I should change border-style. So I'm using `solid` which is... well, I'm adding it. That's fine.

Let me also consider if I should add `border-style: solid` explicitly or just use the shorthand. The shorthand `border: 2px solid #...` includes the style, so it's fine.

I think this is good. Let me also consider if there are any other visual properties I should add.

For the `.app-hero-section .row .col-lg-7` selector, I could add some visual flair too, but since it's a layout column in a hero section, adding borders or shadows might be odd. I'll leave it with just text-align: center.

Wait, I could add a `background` or `border` to make it fit the "sharp-edges" theme better. But for a hero section column, that might look weird.

Actually, let me keep it minimal for the column and focus on the badge and contact cards.

Let me also consider using `outline` or `outline-color` since those are in the MUST CHANGE list.

For the badge, I could add an outline:
```css
outline: 2px solid #e9c46a;
outline-offset: 2px;
```

But that might be too much. Let me keep it simple.

One more thing: the instruction says "Each card may have its own accent strip" under the "masonry-flow" palette. For the contact cards, I could add a `border-left` or `border-top` with a different color to simulate an accent strip. But I need to be careful about border-width.

Actually, I could use `border-left: 3px solid #e8634a;` but then the other borders would be different. Let me use a consistent border all around with a different color for one side.

Hmm, but for "sharp-edges", the description says "Strong borders (2-3px solid)" - so a uniform border is fine.

Let me finalize the CSS. I'll keep it clean and cohesive.

Actually, I realize I should also consider that `.bg-warning` is a Bootstrap class that typically sets `background-color: #ffc107;`. By overriding it with `background: #e8634a;` I'm changing the color, which is what I'm supposed to do.

But wait, should I use `background` or `background-color`? Either is fine.

Let me also double-check the "sharp-edges" variant description:
  • Hard offset shadows: 4px 4px 0px solid color
  • Small or zero border-radius (0-4px)
  • Strong borders (2-3px solid)
  • Snappy transitions (0.15s)

And "masonry-flow" palette:
  • Pinterest-like: white cards, soft shadows on light gray bg
  • Each card may have its own accent strip

For "masonry-flow", the description says "soft shadows" but "sharp-edges" says "Hard offset shadows: 4px 4px 0px solid color". These are somewhat contradictory, but the variant takes precedence. So I'll use hard offset shadows.

OK, I think my CSS is ready. Let me write it out.

Hmm, one more thought: should I use CSS custom properties for the colors? The instruction says "CSS custom properties (--color-*, --shadow-*) values" are in the MUST CHANGE list. So I could define custom properties and use them, but since the original CSS doesn't use custom properties, I'll just use direct values.

Wait, actually the instruction says I MUST CHANGE custom property values if they exist. They don't exist in this snippet, so I'll just use direct values.

OK, final CSS:

```css
@media (max-width: 575.98px) {
    .app-hero-section .row .col-lg-7 {
        text-align: center;
    }

    .app-hero-section .badge.bg-warning {
        font-size: 0.85rem;
        background: #e8634a;
        border: 2px solid #c0392b;
        box-shadow: 4px 4px 0px #264653;
        border-radius: 0;
        transition: all 0.15s cubic-bezier(0.25, 0.46, 0.45, 0.94);
    }

    .contact-channels-section article,
    .contact-quick-section .contact-card {
        padding: var(--space-md) !important;
        background: #ffffff;
        border: 2px solid #2a9d8f;
        box-shadow: 4px 4px 0px #264653;
        border-radius: 0;
        transition: all 0.15s cubic-bezier(0.25, 0.46, 0.45, 0.94);
    }
}
```

This looks good. I've