Modern Native CSS Expert (2026 Standard & Primitives)

English | Bahasa Indonesia

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<a name="english"></a>

English

Orchestration & Integration

Integrates tightly with the following domain skills:

• modern-web-guidance: Primary companion tool to look up standardized native CSS best practices (npx -y modern-web-guidance@latest search "<query>").
• design-system-architect: Supplies headless token definitions and surface container hierarchies.
• tailwind-expert: Bridges native CSS primitives with Tailwind v4 @theme and dynamic utility classes.
• visual-ui-auditor: Validates smooth top-layer transitions, focus rings, and layout stability.
• anti-slop: Eliminates unnecessary JS polyfills and div-soup wrappers.
• senior-frontend: Integrates native CSS features into React 19 / Next.js 15 architectures.

Purpose & Overview

Production-grade engineering guide for modern Native CSS features (2026 Edition) that replace cumbersome JavaScript libraries with pure browser-native primitives. Covers the CSS Anchor Positioning API for tooltips/popovers, @starting-style for smooth entry/exit animations on top-layer elements (<dialog>, popover), View Transitions API Level 2, Container Queries (@container), and the :has() relational selector.

Key Capabilities

1. CSS Anchor Positioning: Eliminating Floating UI / Popper.js dependencies. Tether tooltips, menus, and popovers to trigger elements natively with auto-flip fallbacks (position-try-fallbacks).
2. Smooth Top-Layer Transitions: Animating <dialog> and [popover] elements from display: none to visible with @starting-style and transition-behavior: allow-discrete.
3. Container Queries (@container): Component-level responsive design based on parent container dimensions rather than viewport width.
4. Relational :has() Selector: Styling parent containers or sibling trees based on nested child states without React/JS state overhead.
5. Native CSS Nesting & @layer: Structuring clean, zero-build styles with cascade priority layers.

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Production Implementation Recipes

Recipe 1: Pure Native Anchor Positioning for Tooltips & Dropdowns (No JS)

/* Define the anchor trigger button */
.anchor-trigger {
  anchor-name: --my-dropdown-anchor;
}

/* Tether the popover menu to the anchor trigger */
.dropdown-menu {
  position: fixed;
  position-anchor: --my-dropdown-anchor;
  
  /* Place below the anchor by default */
  top: anchor(bottom);
  left: anchor(left);
  margin-top: 8px;

  /* Automatic flip to top if screen boundary is reached */
  position-try-fallbacks: flip-block;
}

Recipe 2: Smooth <dialog> Entry/Exit Animation with @starting-style

/* Dialog element with discrete transition support */
dialog {
  opacity: 0;
  transform: scale(0.95) translateY(10px);
  transition: opacity 0.25s ease-out, transform 0.25s ease-out, display 0.25s allow-discrete;
}

/* Open state */
dialog[open] {
  opacity: 1;
  transform: scale(1) translateY(0);
}

/* Starting style when transitioning from display: none to open */
@starting-style {
  dialog[open] {
    opacity: 0;
    transform: scale(0.95) translateY(10px);
  }
}

/* Backdrop smooth fade */
dialog::backdrop {
  background-color: rgb(0 0 0 / 0%);
  transition: background-color 0.25s ease-out, display 0.25s allow-discrete;
}

dialog[open]::backdrop {
  background-color: rgb(0 0 0 / 50%);
}

@starting-style {
  dialog[open]::backdrop {
    background-color: rgb(0 0 0 / 0%);
  }
}

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Recipe 5: Material Design 3 (M3) Top-Layer Overlays with Emphasized Decelerate Easing

Implement M3 dialogs and modal bottom sheets natively using <dialog> and @starting-style with M3 Emphasized Decelerate Easing (cubic-bezier(0.05, 0.7, 0.1, 1.0)):

/* M3 Modal Dialog using Native CSS Top-Layer with M3 Tokens */
dialog.m3-dialog {
  border: none;
  border-radius: var(--md-sys-shape-corner-extra-large, 28px);
  background-color: var(--md-sys-color-surface-container-high, #ECE6F0);
  color: var(--md-sys-color-on-surface, #1D1B20);
  box-shadow: var(--md-sys-elevation-level3, 0 4px 12px rgba(0, 0, 0, 0.18));
  padding: 24px;
  max-width: 560px;
  opacity: 0;
  transform: scale(0.9) translateY(16px);
  transition: 
    opacity 0.4s cubic-bezier(0.05, 0.7, 0.1, 1.0),
    transform 0.4s cubic-bezier(0.05, 0.7, 0.1, 1.0),
    display 0.4s allow-discrete;
}

dialog.m3-dialog[open] {
  opacity: 1;
  transform: scale(1) translateY(0);
}

@starting-style {
  dialog.m3-dialog[open] {
    opacity: 0;
    transform: scale(0.9) translateY(16px);
  }
}

dialog.m3-dialog::backdrop {
  background-color: rgb(0 0 0 / 0%);
  transition: background-color 0.4s cubic-bezier(0.05, 0.7, 0.1, 1.0), display 0.4s allow-discrete;
}

dialog.m3-dialog[open]::backdrop {
  background-color: rgb(0 0 0 / 32%); /* M3 Scrim */
}

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Implementation Checklist

• Replace JS positioning libraries (Popper, Floating UI) with native anchor-name and position-anchor.
• Use @starting-style and transition-behavior: allow-discrete for animating modals and popovers without JavaScript timers.
• Use @container on modular components to allow seamless reuse across sidebars, grids, and modals.
• Organize design tokens and reset styles into @layer (e.g. @layer base, components, utilities;).

Orchestration & Integration

• Integrates with: design-system-architect, design-system-architect, senior-frontend, tailwind-expert, senior-frontend.

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<a name="bahasa-indonesia"></a>

Bahasa Indonesia

Tujuan & Gambaran Umum

Panduan rekayasa tingkat produksi untuk memanfaatkan Fitur CSS Native Modern (Standar 2026) yang menggantikan pustaka JavaScript berukuran besar dengan fitur asli browser. Mencakup CSS Anchor Positioning API untuk tooltip dan popover, @starting-style untuk animasi masuk dan keluar yang mulus pada elemen top-layer (<dialog>, popover), View Transitions API Level 2, Container Queries (@container), dan selektor relasional :has().

Kemampuan Utama

1. CSS Anchor Positioning: Menghapus ketergantungan pada pustaka seperti Floating UI atau Popper.js. Mengikat tooltip, menu, dan popover ke tombol pemicu secara native dengan pembalikan posisi otomatis (position-try-fallbacks).
2. Animasi Mulus Top-Layer: Menganimasikan dialog dari status display: none ke tampil menggunakan @starting-style dan transition-behavior: allow-discrete.
3. Container Queries (@container): Desain responsif berbasis ukuran kontainer induk, bukan lebar layar viewport.
4. Selektor Relasional :has(): Menata gaya elemen induk berdasarkan status elemen anak di dalamnya tanpa membutuhkan state JavaScript.
5. Nesting Native & @layer: Mengatur hierarki gaya CSS tanpa alat build dan mengontrol urutan spesifisitas secara terstruktur.

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Resep Implementasi Produksi

Resep 1: Anchor Positioning Murni untuk Menu Dropdown (Tanpa JavaScript)

/* Definisikan tombol pemicu sebagai jangkar (anchor) */
.tombol-pemicu {
  anchor-name: --jangkar-menu;
}

/* Hubungkan menu popover ke tombol pemicu */
.menu-dropdown {
  position: fixed;
  position-anchor: --jangkar-menu;
  
  /* Posisikan di bawah tombol pemicu */
  top: anchor(bottom);
  left: anchor(left);
  margin-top: 8px;

  /* Balik posisi ke atas jika terpotong batas layar */
  position-try-fallbacks: flip-block;
}

Resep 2: Animasi Modal <dialog> dengan @starting-style

dialog {
  opacity: 0;
  transform: scale(0.95) translateY(10px);
  transition: opacity 0.25s ease-out, transform 0.25s ease-out, display 0.25s allow-discrete;
}

dialog[open] {
  opacity: 1;
  transform: scale(1) translateY(0);
}

@starting-style {
  dialog[open] {
    opacity: 0;
    transform: scale(0.95) translateY(10px);
  }
}

dialog::backdrop {
  background-color: rgb(0 0 0 / 0%);
  transition: background-color 0.25s ease-out, display 0.25s allow-discrete;
}

dialog[open]::backdrop {
  background-color: rgb(0 0 0 / 50%);
}

@starting-style {
  dialog[open]::backdrop {
    background-color: rgb(0 0 0 / 0%);
  }
}

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Checklist Implementasi

• Ganti library positioning pihak ketiga dengan CSS anchor-name dan position-anchor.
• Gunakan @starting-style dan transition-behavior: allow-discrete untuk animasi modal tanpa jeda JavaScript.
• Gunakan @container pada komponen reusable agar adaptif di semua layout.
• Tata arsitektur CSS menggunakan @layer base, components, utilities;.

Resep 5: Overlay Top-Layer Material Design 3 (M3) dengan Easing Emphasized

Implementasikan dialog M3 dan modal bottom sheet secara native menggunakan <dialog> dan @starting-style dengan kurva Emphasized Decelerate M3 (cubic-bezier(0.05, 0.7, 0.1, 1.0)):

• Hubungkan token bentuk M3 (--md-sys-shape-corner-extra-large: 28px) dan surface container (--md-sys-color-surface-container-high).
• Backdrop scrim M3 transparan bertransisi halus ke opasitas 32% hitam (rgb(0 0 0 / 32%)).

Integrasi Orkestrasi

Terintegrasi erat dengan skill berikut:

• modern-web-guidance: Tool pendamping utama untuk menelusuri standar terbaik CSS native modern (npx -y modern-web-guidance@latest search "<query>").
• design-system-architect: Menyuplai definisi token headless dan hierarki kontainer permukaan.
• tailwind-expert: Menjembatani primitif CSS native dengan direktif @theme dan utilitas dinamis Tailwind v4.
• visual-ui-auditor: Memvalidasi transisi top-layer yang halus, indikator fokus, dan stabilitas tata letak.
• anti-slop: Menghilangkan polyfill JavaScript yang tidak diperlukan dan pembungkus div-soup.
• senior-frontend: Mengintegrasikan fitur CSS native ke dalam arsitektur React 19 / Next.js 15.