Seltrax
Mobile-first storefronts

Built for the Phone
In Your Customer's Hand

Most of your buyers will never see your store on a desktop. Seltrax storefronts are designed at 360px first, then scaled up — not the other way round. Here is exactly what that means.

Start Free Trial Read the spec sheet
  • 360px-first layouts
  • LCP under 2.5s on 4G
  • 44px tap targets
  • One-thumb COD checkout
A Seltrax storefront on a phone

One storefront,Every Screen Width

The layout is fluid between breakpoints, not just swapped at them. Pick a width to see the same store reflow.

A Seltrax storefront on a phone
360px · Budget Android — the width we design at first

The hard detailsWhat Mobile-first Actually Means

Layout

Designed at 360px, then scaled up

Every template starts as a single-column phone layout. Larger screens add columns; they never squeeze a desktop grid down.

Base breakpoint
360px (single column)
Breakpoints
640 · 1024 · 1280px
Product grid
2 cols on phones, 3–4 from tablet
Type scale
Fluid 14–18px body, clamp() headings
Tap targets
≥ 44 × 44px, ≥ 8px apart
Safe areas
env(safe-area-inset-*) respected
Sticky bar
Add-to-cart pinned to the thumb zone
Menus
Bottom-sheet nav and filters, no hover states

Performance

A load budget, not a hope

Storefronts ship with a fixed budget so a store on a mid-range Android on 4G opens before the customer's thumb leaves the screen.

LCP target
< 2.5s on 4G, mid-range Android
CLS target
< 0.1 — every image has reserved space
INP target
< 200ms
Critical CSS
Inlined; the rest deferred
JavaScript
Deferred, split per page, no theme plugins
Fonts
Subset, preloaded, font-display: swap
Caching
Edge-cached HTML, immutable hashed assets
Third parties
Pixel / Analytics loaded after interaction

Images

Product photos that don't cost the sale

Photos are the heaviest thing on any store page. Each one is resized, converted and lazy-loaded automatically when you upload it.

Formats
AVIF / WebP with JPEG fallback
Sizes
srcset at 320 · 640 · 960 · 1280 · 1920w
Loading
Lazy below the fold, eager for the hero
Placeholders
Blurred preview while the full image loads
Aspect ratios
1:1 or 4:5 enforced, no layout shift
Gallery
Swipe with momentum, pinch-to-zoom
Compression
Quality 75–80, visually lossless

Checkout

One thumb, one screen, cash on delivery

The checkout is a single page built around how Pakistan buys: phone number first, COD selected by default, no account required.

Steps
1 page — contact, address, confirm
Fields
Name · phone · city · address (4 fields)
Keyboards
inputmode=tel / numeric per field
Autofill
autocomplete attributes on every field
Input size
16px min — no iOS zoom on focus
Payment
COD default; other methods optional
Account
Guest checkout, no password
Errors
Inline, next to the field, before submit

Network

Fine on 3G, fast on 4G

Pages are small and resilient, so a flaky connection slows the store down instead of breaking it.

Page weight
< 500KB on first view, typical product page
Requests
< 30 on first view
Compression
Brotli for text, HTTP/2 multiplexing
Forms
Retry-safe; a double tap never double-orders
Fallbacks
Content renders before JS arrives
Offline
Cached shell and last-seen pages

Search & SEO

Found on a phone, too

Google indexes the mobile version of your store. Every page is built so that version is the complete one.

Markup
Semantic HTML, one H1 per page
Structured data
Product, Offer, BreadcrumbList, Organization
Meta
Canonical, Open Graph, Twitter cards per page
Sitemap
Generated automatically, robots.txt included
Mobile-friendly
Passes Google's mobile usability checks
Accessibility
Labels, focus order, contrast ≥ 4.5:1

Spec sheetThe Numbers We Build To

Design baseline360 × 640px viewport, single column
Breakpointssm 640px · md 1024px · lg 1280px
Minimum tap target44 × 44px (48px on primary actions)
Minimum body text14px; inputs 16px
Line length45–75 characters on phones
Largest Contentful Paint< 2.5s (4G, mid-range Android)
Cumulative Layout Shift< 0.1
Interaction to Next Paint< 200ms
First-view page weight< 500KB, < 30 requests
Image formatsAVIF → WebP → JPEG fallback
Image widths served320 / 640 / 960 / 1280 / 1920
Checkout fields4 (name, phone, city, address)
Checkout pages1
Default paymentCash on Delivery
Structured dataProduct · Offer · BreadcrumbList · Organization
Colour contrast≥ 4.5:1 text, ≥ 3:1 UI

Mobile-firstvs a Desktop Site Shrunk Down

What the customer getsSeltraxTypical “responsive” theme
Single-column layout designed first
Thumb-zone add-to-cart
Images sized for the screen, not the desktop
Hover-free navigation
Phone-first, COD-default checkout
Numeric keyboards on numeric fields
Load budget enforced
Mobile version is the complete version

QuestionsAbout Mobile-first

  • No. Larger screens get more columns, wider galleries and side-by-side layouts. Starting from the phone just guarantees nothing important is hidden or squeezed on the screen most customers actually use.

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