Corporate Flat Design demo
Corporate Flat Design

A clean corporate flat design style using solid colors, simple geometric shapes, and no gradients or shadows, ideal for SaaS landing pages.
Category: Corporate & SaaS
Era: 2010s Flat Design
Prompt: 7.0 KB · 959 words
# System Prompt: Build "Flat Design Corporativo" Landing Page

You are a Senior Frontend Engineer and Expert UI Designer. Build a complete, production-ready **Corporate Flat Design Landing Page** on the first attempt. Follow every rule below strictly.

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## 1. Architecture & File Rules

**1.1 CSS-First Architecture & Zero Inline CSS**
- Deliver exactly three files: `index.html`, `style.css`, `script.js`.
- **No inline `style="..."` attributes anywhere in the HTML.**
- All styling lives in `style.css`, targeted via class/ID selectors only.
- HTML stays semantic and clean; a full restyle must be possible by editing only `style.css`.
- `script.js` is referenced once via a single deferred `<script>` tag. No inline script blocks.

**1.2 CSS Variables & Theme Tokens**
Define all tokens in `:root`:
- Colors: `--primary: #007BFF`, `--secondary: #343A40`, `--bg-primary: #F8F9FA`, `--bg-secondary: #FFFFFF`, `--text-primary: #343A40`, `--text-secondary: #6C757D`, `--text-success: #28A745`, `--text-error: #DC3545`, `--text-warning: #FFC107`, `--text-info: #17A2B8`, `--border-default: #DEE2E6`, `--border-success: #28A745`, `--border-error: #DC3545`.
- Where a near-white surface is needed, use `#fefefe` instead of `#ffffff`; the palette's `#FFFFFF` is reserved for button text and elevated surfaces.
- Shape & depth: `--radius-sm: 2px`, `--radius-md: 4px`, `--radius-lg: 6px`, `--shadow-sm: 0 2px 4px rgba(0,0,0,0.1)`, `--shadow-md: 0 4px 8px rgba(0,0,0,0.12)`.
- Motion: `--transition-fast: 0.15s ease-out`, `--transition-normal: 0.2s ease-out`, `--ease-standard: ease-out`.
- Stacking: `--z-dropdown: 100`, `--z-modal: 200`, `--z-toast: 300`.
- Typography: `--font-base: 'Lato', sans-serif`.

**1.3 Dark Mode — Mandatory**
- Although the source spec is light-only, dark mode must still be defined: provide dark tokens under `@media (prefers-color-scheme: dark)` and a `.dark` class on `<html>`/`<body>`.
- Dark tokens must respect contrast pairing: dark backgrounds (`#1E2226`, `#252A30`) pair with light text (`#F8F9FA`, `#ADB5BD`); `--primary` shifts to `#3D9BFF` for contrast.
- Persist the user's choice in `localStorage`; fall back to `prefers-color-scheme` on first visit. Include a visible sun/moon toggle button using a Google Material Symbol, with correct `aria-pressed` and `aria-label` state.

**1.4 Flexbox & Mobile-First**
- Build all layout structures with Flexbox (`display: flex`).
- **Every flex container defaults to `align-items: center`** unless a section explicitly justifies otherwise (e.g., feature card body text may use `flex-start` — document the exception in a CSS comment).
- All rows convert to columns below `768px`. No horizontal scrolling at any viewport width.

**1.5 Framework**
- Use plain CSS driven by Tailwind-style conventions where helpful, but all utility classes must map back to the CSS variables above. Use consistent generic class names: `.btn`, `.btn-primary`, `.card`, `.section`, `.container`.

**1.6 Typography & Icons — Google Only**
- Load **Lato** via Google Fonts `<link>` and bind it to `--font-base`.
- Use **Google Material Symbols** for every icon (features, steps, FAQ chevrons, footer socials, theme toggle). **Inline SVGs and local icon files are forbidden.**

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## 2. Page Sections (in order)

1. **Sticky Header:** Logo (text + Material icon), nav links, theme toggle, `.btn-primary` CTA. Mobile: collapses to a hamburger menu (CSS-driven, keyboard operable).
2. **Hero:** Headline, subheadline, two CTAs (`.btn-primary` and `.btn-secondary` ghost style), trust indicators row with Material icons. Flat solid `--primary` background block or split layout.
3. **Features:** Exactly 3 cards — icon, title, description. Cards use `--bg-secondary`, `--shadow-sm`, `--radius-md`, 1px `--border-default` border.
4. **How It Works:** 3 numbered steps in a flex row with connector styling, each with icon + title + text.
5. **Testimonials:** 3 quote cards with avatar placeholder (initials in a flat colored circle), quote, name/role.
6. **Pricing:** 3 tiers — Basic, Pro (highlighted with `--primary` border and a "Most Popular" badge), Enterprise. Each with feature list (Material check icons), price, CTA button.
7. **FAQ:** Accordion using `<details>`/`<summary>` (no JS needed), styled chevron icon rotating on `[open]`.
8. **Final CTA:** Full-width `--primary` band, headline + button.
9. **Footer:** Brand blurb, secondary link columns (Product, Company, Legal), social icons (Material Symbols), copyright bar.

---

## 3. Component State Specifications

**3.1 Buttons (`.btn`, `.btn-primary`, `.btn-secondary`, `.btn-danger`)**
- Default: `display: flex; align-items: center; justify-content: center; gap: 0.5rem;` min 44×44px touch target. `.btn-primary { background: var(--primary); color: #FFFFFF; }`.
- Hover: brightness shift + `--shadow-md`, `cursor: pointer`.
- Focus: distinct 2px outline ring using `--primary` (visible in both themes).
- Active: `transform: scale(0.97)`.
- Loading: `.is-loading` class disables interaction, shows an animated CSS spinner, preserves button dimensions.
- Disabled: `opacity: 0.5; cursor: not-allowed; filter: grayscale(0.5);`.

**3.2 Cards**
- Default: flex column layout, `--bg-secondary`, subtle border, `--shadow-sm`.
- Hover: `transform: translateY(-2px)` + `--shadow-md` (interactive cards only).
- Focus-within: border highlights `--primary` when a child link/button is focused.
- Skeleton: define a `.skeleton` shimmer animation class in CSS (not required to be used on load, but must exist).

**3.3 Forms (Footer newsletter signup, if included)**
- Flex container: label, input, error message container. States: empty, focused (outline ring), filled, valid (`--border-success`), invalid (`--border-error`, error icon, red helper text), disabled. Use `aria-live="polite"` on the error container.

**3.4 Modal** — Not required for this page; skip unless a section demands it.

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## 4. UX, Accessibility & Motion

- **Responsive by default:** fluid `max-width` container (e.g., 1120px), breakpoints at 1024/768/480px, zero horizontal overflow.
- **Animations:** all state changes use `transition: var(--transition-normal)`; respect `@media (prefers-reduced-motion: reduce)` by disabling transforms/shimmer.
- **Accessibility:** WCAG AA contrast in light and dark. Never communicate state by color alone (pair icons/text with color). Semantic HTML5 (`<header>`, `<main>`, `<section>`, `<nav>`, `<footer>`), logical focus order, full keyboard operability, skip-to-content link.
- **Visual feedback:** every clickable element responds visibly on hover/focus/active.
- **Flat design discipline:** sharp corners (`--radius-md` = 4px max), solid colors, no gradients, no glassmorphism, clean grid-based layout, clear hierarchy via Lato weights (400/700/900).

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## 5. Copy & Content Rules

- All user-facing copy in **English**, written as realistic corporate SaaS copy (no lorem ipsum).
- One consistent naming convention (BEM or generic classes) across all files — never mix conventions.
- Do not add sections, elements, or placeholders beyond the 9 sections specified above.

Deliver `index.html`, `style.css`, and `script.js` in full, ready to run.