We need to rewrite CSS with visual identity changes only. Given target style: vertical-flow, but layout pattern says "Aggressive only" but we are conservative mode, cannot change layout. However the "TARGET STYLE: vertical-flow" might guide palette and spacing? But we cannot change grid-template-columns, flex-direction, etc. We can adjust spacing within ±20%? It says padding/margin keep similar values ±20% maximum. Also we cannot change gaps? Actually gap is listed under "keep similar" but allowed? It says "gap, row-gap, column-gap (keep similar)" probably within ±20%? However layout pattern says large vertical gaps 48-72px, but we cannot significantly change gap values. We can only change colors, shadows, radius. Also effect variant flat-solid: box-shadow none everywhere. Currently shadow is already none. We can keep none. Need new palette: warm minimal: off-white #faf8f3, soft black #2d2d2d, one muted accent (sage #87a878 or terracotta #c47b5a). We'll pick sage maybe. Need to replace all colors: --color-primary, --color-primary-dark, --color-accent, --color-surface, --color-text, --rgb-primary, --rgb-accent. Also any background colors etc. There's cta-inner background var(--color-surface). Need set surface to off-white maybe. But body background isn't defined. Could add? We can add body background? It's not in original CSS. But we are allowed to add color properties? The instruction says "All color values" change. We can add background? But must preserve layout. Adding background doesn't affect layout. We can add body background. But careful: original CSS didn't set body background. We can set body background to off-white. But must not change selectors? We can modify rules, not selectors. We can add declarations to existing selectors. That's fine.

Also need update border-radius to minimal radius (0-6px) per flat-solid. Current radius-sm: 8px, md:16px, lg:24px, xl:32px. We should reduce to 0-6px. Need use "minimal radius (0-6px)". So set --radius-sm: 2px, --radius-md: 4px, --radius-lg: 6px, --radius-xl: 6px maybe. But note layout uses border-radius on cards and buttons. Fine.

Transitions: original bouncy cubic-bezier(0.34, 1.56, 0.64, 1). Effect flat-solid maybe should be simpler? We can change transition to shorter and ease? Need "transition timing, easing, duration" can change. We'll use something like 0.2s ease-out? But also need "Transition: bouncy" in original comment? Actually original has "Transition: bouncy" but target effect flat-solid doesn't specify. We can choose a nice transition. Since previous attempt didn't change enough, we need more distinct. We'll change to 0.25s ease-in-out maybe.

Also need ensure spacing variables maybe within ±20%? Original --space-section: 3rem, --space-card: 1.25rem, --space-gap: 1rem. We can adjust but must keep similar. Vertical flow wants large vertical gaps, but section spacing can increase from 3rem to 3.5rem (16.7% increase) within 20%. card padding 1.25rem to 1.5rem (20% increase). gap 1rem to 1.25rem (25% increase) exceeds 20%? Actually gap, row-gap, column-gap keep similar, maybe we shouldn't change much. We'll keep gap same or slight. But target vertical-flow says large vertical gaps 48-72px. However this is "Aggressive only" and we're conservative; we can't change layout. We can adjust --space-section to 4rem? That's 33% increase, maybe too much. Better stick to 3.5rem. Also page-main max-width 1200px could be narrowed to 800px? But that changes layout width. Not allowed. So keep.

Need update CSS variables for palette. Also need change any hardcoded colors? Search file: There are no other hex codes except variables and comments. But we need update --color-primary etc. We'll set:

--color-primary: #2d2d2d (soft black?) But primary is used for links. In warm minimal, primary could be terracotta/sage as accent? Usually primary is accent, text is soft black. Let's design:

--color-primary: #c47b5a (terracotta) or #87a878 (sage). Since "one muted accent (sage #87a878 or terracotta #c47b5a)" we can choose sage as primary? But for links, sage might be low contrast. Terracotta is better for links. Let's set primary to terracotta #c47b5a, primary-dark to #a05f43 (darker terracotta), accent to sage #87a878? Actually accent is hover color. Could set accent to sage. But "one muted accent" maybe one accent only; but we can use both? The palette says "One muted accent (sage #87a878 or terracotta #c47b5a)". Could use sage for surface? Let's define:

--color-primary: #c47b5a (terracotta)
--color-primary-dark: #a35c3d
--color-accent: #87a878 (sage)
--color-surface: #faf8f3 (off-white)
--color-text: #2d2d2d (soft black)

Need --rgb-primary and --rgb-accent for possible rgba usage elsewhere? They are defined but not used in this file. Still update to RGB values of new colors.

--rgb-primary: 196,123,90
--rgb-accent: 135,168,120

Also --color-surface used for cta background; okay.

Need update shadows: none everywhere, so variables remain none. But maybe we need "box-shadow: none" already. We can keep.

Need update border-radius values to minimal. Also maybe change --radius-sm: 2px, --radius-md: 4px, --radius-lg: 6px, --radius-xl: 6px. But note .cta-inner uses --radius-xl, so 6px.

Need update transition: --transition: 0.25s ease-in-out; or maybe 0.2s cubic-bezier(0.4, 0, 0.2, 1). We'll change.

Need change body line-height? Can't change line-height? Actually typography includes line-height, so keep same. Heading weight can't change? font-weight is fixed. Keep.

Need maybe add border-color? Not present. We could add borders with solid color for flat-solid. Since flat-solid uses borders instead of shadows. We can add border to .card, .btn? That's allowed? It says border-color and border-style can change, not border-width. We cannot change border-width, but there are no existing borders. Could add border? Adding border-width would change layout if not account box-sizing? Since box-sizing is border-box likely, but adding border could change size. To maintain layout, avoid adding borders with non-zero width unless compensate with padding? But we are not allowed to change padding much? We can change padding within ±20%. Adding border would increase element size, potentially layout shift. Better not add borders unless already present. Original CSS has none. So flat-solid relies on contrast.

Need update "a:not([class]) { color: var(--color-primary); }" okay.

Need update body color and perhaps background. We can set body { color: var(--color-text); background-color: var(--color-surface); line-height: var(--body-line-height); }

Original body rule lacked background. Adding background is a color change, no layout.

Need ensure "Section layouts" comments can stay? They are comments not CSS. We can leave or update? The instruction says output only CSS. Comments are okay. But we can update comments? Better leave as is or adjust? Not necessary.

Need ensure all selectors preserved exactly. The file has weird indentation. We need preserve selectors and structure. We can reformat? It says output rewritten CSS preserving all selectors. We can output clean CSS. Should be okay as long as selectors same.

Need also handle @media max-width 640px :root variables. We can update those values? They are custom property assignments, allowed. We can adjust within constraints. In media, --space-section: 2rem, --space-card: 1rem, --space-gap: 0.75rem. We can maybe change to 2.25rem, 1rem, 0.75rem? But to keep similar, maybe keep. Since visual refresh, maybe change radius? Already handled.

Need make sure no layout properties changed: display, grid-template-columns etc preserved exactly. Yes.

Potential issue: The "vertical-flow" target style suggests single column layout, but we cannot change layout. However maybe we can adjust --space-section to larger to feel vertical. Need stay within 20%. We'll set --space-section: 3.5rem (from 3rem, +16.7%). --space-card: 1.5rem (from 1.25rem, +20%). --space-gap: 1.25rem (from 1rem, +25%) which is too much? But gap is layout-related? It says gap, row-gap, column-gap keep similar. Maybe 25% not okay. We'll set 1.1rem? That's +10%. But vertical flow wants bigger gaps; however not for cards maybe. We'll set --space-gap: 1.25rem? Actually "keep similar" not as strict as padding/margin? It says "keep similar" not ±20%, but to be safe we can keep 1rem or 1.125rem. Use 1.125rem (+12.5%). Good.

Need update --space-section in media? Could also adjust small breakpoint --space-section: 2.25rem (12.5% increase from 2). But original 2rem, okay.

Need maybe add visual flat-solid by ensuring no gradients. There are none.

Need update "transition: var(--transition)" on .card, .btn, a. That's fine.

Need maybe add focus styles? No.

Let's craft final CSS.

We must preserve comments? Comments are not required but can be included. We'll keep the original section comments maybe updated? Since output should include all CSS, comments okay. But we should not add extra comments like AI. We'll keep minimal comments or original. We'll maintain original section comments to be safe.

Need also "no markdown fences". We'll output pure CSS.

Double-check selectors:

:root
body
h1,h2,h3,h4
section, .section
.card, [class*="card"]
.btn, button[class*="btn"], a[class*="btn"]
a:not([class])
.news-grid etc all preserved.

Need preserve .news-grid > *:first-child etc.

Need preserve media queries.

Let's write.

Potential nuance: "grid-template-columns" in .cta-inner media max-width 640: ".cta-inner { grid-template-columns: 1fr !important; }" But .cta-inner is not a grid? It's a background container. We must keep this declaration even if weird. Yes.

Let's craft new CSS:

:root {
    --color-primary: #c47b5a;
    --color-primary-dark: #a35c3d;
    --color-accent: #87a878;
    --color-surface: #faf8f3;
    --color-text: #2d2d2d;
    --rgb-primary: 196,123,90;
    --rgb-accent: 135,168,120;
    --radius-sm: 2px;
    --radius-md: 4px;
    --radius-lg: 6px;
    --radius-xl: 6px;
    --shadow-sm: none;
    --shadow-md: none;
    --shadow-lg: none;
    --space-section: 3.5rem;
    --space-card: 1.5rem;
    --space-gap: 1.125rem;
    --transition: 0.25s ease-in-out;
    --heading-weight: 800;
    --body-line-height: 1.75;
}

body { color: var(--color-text); background-color: var(--color-surface); line-height: var(--body-line-height); }

h1, h2, h3, h4 { font-weight: var(--heading-weight); }

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); }

.btn, button[class*="btn"], a[class*="btn"] { border-radius: var(--radius-md); transition: var(--transition); }

a:not([class]) { color: var(--color-primary); transition: var(--transition); }

/* Section layouts... */

.news-grid { display: grid; grid-template-columns: 2fr 1fr; grid-template-rows: auto auto; gap: var(--space-gap); }
.news-grid > *:first-child { grid-row: span 2; }

.feature-list { display: grid; grid-template-columns: repeat(4, 1fr); gap: var(--space-gap); }

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

.testimonial-list { column-count: 2; column-gap: var(--space-gap); }
.testimonial-list > * { break-inside: avoid; margin-bottom: var(--space-gap); }

.partner-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: calc(var(--space-gap) * 1.5); align-items: center; }

.faq-list { display: grid; grid-template-columns: 1fr 1fr; gap: var(--space-gap); }

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

.cta-inner { background: var(--color-surface); border-radius: var(--radius-xl); padding: 3rem; text-align: center; }

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

a:not([class]):hover { color: var(--color-accent); }

@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: 2.25rem; --space-card: 1.25rem; --space-gap: 0.875rem; }
    .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; }
}

Need check media variables: Original 640: --space-section: 2rem, --space-card: 1rem, --space-gap: 0.75rem. We changed to 2.25rem (+12.5% from 2), 1.25rem (+25% from 1? Actually 1 to 1.25 = +25%, too much? Should keep within? It says padding/margin ±20% max. --space-card is used as padding. +25% may violate. Let's set 1.125rem (+12.5%) maybe. And gap 0.875rem (+16.7%). Let's adjust:

@media (max-width: 640px) :root { --space-section: 2.25rem; --space-card: 1.125rem; --space-gap: 0.875rem; }

Main root --space-card: 1.5rem from 1.25 = +20% exactly okay. --space-gap 1.125 from 1 = +12.5%. Good.

Need check "grid-template-columns: 1fr !important" for .cta-inner in media. But .cta-inner is not grid. We preserve.

Need maybe update gap in .hero-inner: gap: 2rem. Original 2rem. We could change to 2.5rem? But gap is layout? Maybe keep as 2rem. Wait hero-inner gap not using variable; we could change? It's a gap property. To keep similar, maybe 2.25rem? But not necessary. For visual refresh maybe larger gap? But layout is horizontal split. Keep.

Could also add border to .cta-inner? Let's not.

Need ensure all colors changed. Yes.

Potential issue: body background color not in original but okay. Since surface off-white #faf8f3, but .cta-inner also same background, might blend. Could set .cta-inner background to slightly different? But original uses --color-surface. We can change cta-inner to use a different color? Since palette only one surface. Could set --color-surface to off-white and cta background maybe #f1ede4? But .cta-inner uses var(--color-surface). We can change its background to a different custom property