The user wants me to rewrite the CSS with a visual refresh. The target style is "centered-stage" with "sharp-edges" effect variant.

Key requirements:
- Centered content: max-width 720-960px, margin: 0 auto (but I need to keep existing layout as-is, so I can't change layout properties like max-width on .page-main etc. — wait, the instruction says keep layout. The target style is "Aggressive only" so I should be careful. The instructions say don't change width, height, min/max-width, etc. So I should NOT change max-width values. But the target style suggests centered content... The original CSS already has some centered elements. I'll focus on colors, shadows, radius, transitions.)
- Color palette: dark stage #0f0f1a, bright content area, premium gold or deep purple accent
- Sharp edges: hard offset shadows 4px 4px 0px solid color, small or zero border-radius (0-4px), strong borders (2-3px solid), snappy transitions (0.15s)

I need to:
- Replace all colors with fresh palette: dark stage, gold/deep purple accent
- Shadows: hard offset shadows like 4px 4px 0px
- Border-radius: reduce to 0-4px
- Strong borders: add 2-3px solid borders
- Transitions: 0.15s
- Also update custom properties

Let me pick a palette:
- Background dark stage: #0f0f1a
- Content surface: brighter — maybe #1a1a2e or #202034 for cards
- Primary accent: deep purple #7b2ff7 or #6c63ff... or premium gold #d4af37 or #f5c518
- Let's go with deep purple + gold accent

Palette:
- --color-primary: #d4af37 (gold)
- --color-primary-dark: #aa8c2e (darker gold)
- --color-accent: #9d4edd (purple) or keep gold accent... Maybe primary gold, accent purple
- --color-surface: #1e1e30 (dark card surface)
- --color-text: #f5f0e6 (bright warm text)

Actually let me think: "dark stage #0f0f1a, bright content area" — so body background should be #0f0f1a. Cards should be a bit brighter, like #1c1c2e. Text should be light.

Premium gold accent: #d4af37. Purple accent: #7c3aed.

Let me define:
- --color-primary: #d4af37 (gold)
- --color-primary-dark: #a8862b
- --color-accent: #8b5cf6 (purple)
- --color-surface: #1b1b2f (card surface)
- --color-text: #ede8dc (light text)
- --color-border: #d4af37 or rgba gold... But I need to add borders. I can add border properties. Border-width changes are allowed? "border-color and border-style (NOT border-width)" — so I cannot change border-width. But I can add border declarations if none existed? Hmm. The instruction says border-color and border-style can change, NOT border-width. Adding a border where none existed would introduce border-width, which is a layout-affecting property? Actually border-width affects layout. The rule says don't change border-width. But adding new borders could affect layout. However, the effect variant calls for "Strong borders (2-3px solid)". This is tricky.

The instruction list says NEVER CHANGE: border-color and border-style (NOT border-width). So I should not change border-width values. If there's no border in the original, adding one might be risky. But the effect variant explicitly wants strong borders. Hmm.

Let me re-read: "🔒 NEVER CHANGE (would break HTML layout): ... border-color and border-style (NOT border-width)" — this means border-color and border-style are allowed to change, but border-width must stay the same. If no border exists, adding border-width would change layout. But maybe I can use box-shadow for the hard offset borders instead, which doesn't affect layout. The effect variant says "Hard offset shadows: 4px 4px 0px solid color" — that's a box-shadow, not a border. So I'll use box-shadow for the sharp edges.

Actually "4px 4px 0px solid color" is a bit odd — box-shadow syntax is `offset-x offset-y blur spread color`. So `4px 4px 0px color` gives a hard shadow. I'll use that.

I'll avoid adding borders to keep layout intact, or if I do add borders, use border-color and border-style... but border-width would need to be specified. Since original has no border declarations, adding border: 2px solid would change layout. Safer to use box-shadow.

Wait, but the original `.card` has box-shadow: var(--shadow-md) which is none, and border-radius. I can change box-shadow to hard offset. Border-radius can go to 0-4px.

I can also use outline? But outline also affects layout? No, outline doesn't affect layout actually. Outline is drawn outside the box and doesn't affect layout. But the rule says outline styles (color, type) can change. I could add outline where none exists? Hmm. Better stick to box-shadow.

Let me design the new CSS:

Variables:
```css
:root {
    --color-primary: #d4af37;
    --color-primary-dark: #a8862b;
    --color-accent: #8b5cf6;
    --color-surface: #1c1c2e;
    --color-text: #f0ead8;
    --rgb-primary: 212,175,55;
    --rgb-accent: 139,92,246;
    --radius-sm: 2px;
    --radius-md: 3px;
    --radius-lg: 4px;
    --radius-xl: 4px;
    --shadow-sm: 2px 2px 0px #000000;
    --shadow-md: 4px 4px 0px #000000;
    --shadow-lg: 6px 6px 0px #000000;
    --space-section: 4rem;
    --space-card: 1.5rem;
    --space-gap: 1.25rem;
    --transition: 0.15s cubic-bezier(0.4, 0, 1, 1);
    --heading-weight: 600;
    --body-line-height: 1.65;
}
```

Wait, should I add background color to body? Original body only has color. I need dark stage background. I can add `background-color: #0f0f1a;` to body. That's a visual change, not layout.

Also sections could have backgrounds? Maybe keep sections transparent with body dark.

Cards: background var(--color-surface), hard shadow.

Links: color gold, hover accent purple.

Buttons: background primary gold? The original `.btn` doesn't have background in this file. But I can add color/background for visual identity. Buttons might inherit from elsewhere. I'll add a background to `.btn` — wait, that might conflict. But it's just visual. Adding background-color is allowed. Let me be careful not to break layout — background doesn't affect layout. So adding background is fine.

Let me craft the new CSS:

```css
:root {
    --color-primary: #d4af37;
    --color-primary-dark: #a8862b;
    --color-accent: #8b5cf6;
    --color-surface: #1c1c2e;
    --color-text: #f0ead8;
    --rgb-primary: 212, 175, 55;
    --rgb-accent: 139, 92, 246;
    --radius-sm: 0px;
    --radius-md: 2px;
    --radius-lg: 4px;
    --radius-xl: 4px;
    --shadow-sm: 2px 2px 0px #000000;
    --shadow-md: 4px 4px 0px #000000;
    --shadow-lg: 6px 6px 0px #000000;
    --space-section: 4rem;
    --space-card: 1.5rem;
    --space-gap: 1.25rem;
    --transition: 0.15s cubic-bezier(0.4, 0, 1, 1);
    --heading-weight: 600;
    --body-line-height: 1.65;
}

body { color: var(--color-text); line-height: var(--body-line-height); background-color: #0f0f1a; }
h1, h2, h3, h4 { font-weight: var(--heading-weight); color: #fdf6e3; }
section, .section { padding-top: var(--space-section); padding-bottom: var(--space-section); }
.card, [class*="card"] { border-radius: var(--radius-lg); box-shadow: var(--shadow-md); padding: var(--space-card); transition: var(--transition); background-color: var(--color-surface); }
.btn, button[class*="btn"], a[class*="btn"] { border-radius: var(--radius-md); transition: var(--transition); background-color: var(--color-primary); color: #0f0f1a; box-shadow: 3px 3px 0px #000000; }
a:not([class]) { color: var(--color-primary); transition: var(--transition); }
```

Hmm wait, the `.btn` background might be overridden elsewhere in a different file but that's fine.

But careful: the "sharp-edges" effect wants small or zero radius. I set radius-lg to 4px, radius-md 2px, radius-sm 0px. Good.

Shadows: hard offset 4px 4px 0px. I chose #000000 but maybe use a dark purple/blue shadow like #05050a for a more stage feel. Actually 4px 4px 0px #000 is classic "sharp edges". Let me use #000.

Now sections within: The centered-stage target says max-width 720-960px centered. But layout rules say don't change max-width. The original already has some max-width values: .feature-list max-width 720px, .faq-list max-width 800px, .cta-inner max-width 700px, .page-main max-width 1200px. Those are already set. I shouldn't change them since that's layout. The target style is "Aggressive only", meaning it's a suggestion but the conservative mode restricts.

Actually, the prompt says "TARGET STYLE: centered-stage" and "Layout pattern (Aggressive only)" — the "Aggressive only" means these layout patterns would be for aggressive mode. In conservative mode, we only apply visual changes. So I keep layout as-is.

For testimonial-list, it's a grid but at 640px media query it uses column-count which is odd, but that's existing.

Now, for hover states: original `a:not([class]):hover { color: var(--color-accent); }` — I can keep selector, change color. Maybe make accent purple.

Also `header, .header, .navbar { background: transparent; }` — I can keep as transparent, but maybe change to a dark translucent? That would be a visual change. But transparent is fine. Maybe keep transparent but add backdrop-filter? Hmm, backdrop-filter could be added. Original has background: transparent. I could add `background-color: rgba(15,15,26,0.8); backdrop-filter: blur(8px);` — but that changes the background from transparent. Is that allowed? Yes, colors can change. But it might affect readability. Let me keep it simple: keep transparent, or give it a subtle dark tint. I'll make it `rgba(15, 15, 26, 0.6)` with backdrop-filter.

Actually careful: header background transparent means the dark body shows through. If I change to a translucent dark, it's still visually similar but with a slight contrast. I'll do that.

Also the `.news-grid`, `.feature-list`, etc. — these are layout classes but don't have color properties. I should leave them as-is or add decorative properties? They said all colors can change. I can add box-shadow or background to cards. For grids, nothing to change.

Let me also update media query at 640px: `:root { --space-section: 2rem; --space-card: 1rem; --space-gap: 0.75rem; }` — these are spacing vars, should keep as-is since spacing is layout-ish. They said keep padding/margin within ±20%. These are custom properties for spacing. I shouldn't change them. I'll leave them.

Now let me write complete CSS:

```css
:root {
    --color-primary: #d4af37;
    --color-primary-dark: #a8862b;
    --color-accent: #8b5cf6;
    --color-surface: #1b1b2f;
    --color-text: #f0ead8;
    --rgb-primary: 212, 175, 55;
    --rgb-accent: 139, 92, 246;
    --radius-sm: 0px;
    --radius-md: 2px;
    --radius-lg: 4px;
    --radius-xl: 4px;
    --shadow-sm: 2px 2px 0px #0a0a14;
    --shadow-md: 4px 4px 0px #0a0a14;
    --shadow-lg: 6px 6px 0px #0a0a14;
    --space-section: 4rem;
    --space-card: 1.5rem;
    --space-gap: 1.25rem;
    --transition: 0.15s cubic-bezier(0.4, 0, 1, 1);
    --heading-weight: 600;
    --body-line-height: 1.65;
}

body { color: var(--color-text); line-height: var(--body-line-height); background-color: #0f0f1a; }
h1, h2, h3, h4 { font-weight: var(--heading-weight); color: #fdf4d4; }
section, .section { padding-top: var(--space-section); padding-bottom: var(--space-section); }
.card, [class*="card"] { border-radius: var(--radius-lg); box-shadow: var(--shadow-md); padding: var(--space-card); transition: var(--transition); background-color: var(--color-surface); color: var(--color-text); }
.btn, button[class*="btn"], a[class*="btn"] { border-radius: var(--radius-md); transition: var(--transition); background-color: var(--color-primary); color: #0f0f1a; box-shadow: 3px 3px 0px #0a0a14; }
a:not([class]) { color: var(--color-primary); transition: var(--transition); }

/* ========== Section Layout Variants ========== */

.news-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: calc(var(--space-gap) * 0.8); }

.feature-list { display: flex; flex-direction: column; align-items: center; gap: calc(var(--space-gap) * 2); max-width: 720px; margin: 0 auto; }

.hero-inner { display: grid; grid-template-columns: 1fr 1fr; gap: 2rem; align-items: center; }

.testimonial-list { display: grid; grid-template-columns: repeat(3, 1fr); gap: var(--space-gap); }

.partner-grid { display: grid; grid-template-columns: repeat(6, 1fr); gap: var(--space-gap); align-items: center; }

.faq-list { max-width: 800px; margin: 0 auto; }

.stats-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: var(--space-gap); text-align: center; }

.cta-inner { text-align: center; max-width: 700px; margin: 0 auto; }

.page-main { max-width: 1200px; margin: 0 auto; }

a:not([class]):hover { color: var(--color-accent); }
header, .header, .navbar { background: rgba(15, 15, 26, 0.72); backdrop-filter: blur(6px); }

@media (max-width: 1024px) {
    .news-grid { grid-template-columns: repeat(2, 1fr) !important; }
    .feature-list { grid-template-columns: repeat(2, 1fr) !important; }
    .partner-grid { grid-template-columns: repeat(3, 1fr) !important; }
    .stats-grid { grid-template-columns: repeat(2, 1fr) !important; }
    .hero-inner { grid-template-columns: 1fr !important; }
}
@media (max-width: 640px) {
    :root { --space-section: 2rem; --space-card: 1rem; --space-gap: 0.75rem; }
    .news-grid { grid-template-columns: 1fr !important; }
    .feature-list { grid-template-columns: 1fr !important; }
    .faq-list { grid-template-columns: 1fr !important; }
    .testimonial-list { column-count: 1 !important; }
    .partner-grid { grid-template-columns: repeat(2, 1fr) !important; }
    .stats-grid { grid-template-columns: repeat(2, 1fr) !important; }
    .cta-inner { grid-template-columns: 1fr !important; }
}
```

Wait — there's an issue with the media query at 640px: `.feature-list { grid-template-columns: 1fr !important; }` but .feature-list is `display: flex; flex-direction: column