/* ==========================================================================
   ProcessPlan Design System — style.css
   Global styles, custom properties, typography, and base layout
   ========================================================================== */

/* ---------- Custom Properties (Design Tokens) ---------- */
:root {
  /* Colors */
  --color-primary: #0f172a;
  --color-primary-light: #1e293b;
  --color-accent: #3b82f6;
  --color-accent-hover: #2563eb;
  --color-accent-light: #dbeafe;
  --color-cyan: #06b6d4;
  --color-cyan-light: #cffafe;

  --color-surface: #f8fafc;
  --color-surface-alt: #f1f5f9;
  --color-white: #ffffff;
  --color-border: #e2e8f0;
  --color-border-light: #f1f5f9;

  --color-text: #1e293b;
  --color-text-secondary: #64748b;
  --color-text-muted: #94a3b8;
  --color-text-inverse: #ffffff;

  --color-success: #10b981;
  --color-warning: #f59e0b;
  --color-error: #ef4444;

  /* Typography */
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', 'Consolas', monospace;

  --text-xs: 0.75rem;
  --text-sm: 0.875rem;
  --text-base: 1rem;
  --text-lg: 1.125rem;
  --text-xl: 1.25rem;
  --text-2xl: 1.5rem;
  --text-3xl: 1.875rem;
  --text-4xl: 2.25rem;
  --text-5xl: 3rem;
  --text-6xl: 3.75rem;

  --leading-tight: 1.15;
  --leading-snug: 1.3;
  --leading-normal: 1.6;
  --leading-relaxed: 1.75;

  --weight-normal: 400;
  --weight-medium: 500;
  --weight-semibold: 600;
  --weight-bold: 700;
  --weight-extrabold: 800;

  /* Spacing */
  --space-1: 0.25rem;
  --space-2: 0.5rem;
  --space-3: 0.75rem;
  --space-4: 1rem;
  --space-5: 1.25rem;
  --space-6: 1.5rem;
  --space-8: 2rem;
  --space-10: 2.5rem;
  --space-12: 3rem;
  --space-16: 4rem;
  --space-20: 5rem;
  --space-24: 6rem;
  --space-32: 8rem;

  /* Layout */
  --container-max: 1200px;
  --container-narrow: 800px;
  --container-wide: 1400px;

  /* Borders */
  --radius-sm: 0.375rem;
  --radius-md: 0.5rem;
  --radius-lg: 0.75rem;
  --radius-xl: 1rem;
  --radius-2xl: 1.5rem;
  --radius-full: 9999px;

  /* Shadows */
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.07), 0 2px 4px -2px rgba(0, 0, 0, 0.05);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.08), 0 4px 6px -4px rgba(0, 0, 0, 0.04);
  --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.08), 0 8px 10px -6px rgba(0, 0, 0, 0.04);
  --shadow-glow: 0 0 20px rgba(59, 130, 246, 0.3);

  /* Transitions */
  --transition-fast: 150ms ease;
  --transition-base: 250ms ease;
  --transition-slow: 400ms ease;

  /* Z-index scale */
  --z-dropdown: 100;
  --z-sticky: 200;
  --z-overlay: 300;
  --z-modal: 400;
  --z-toast: 500;
}

/* ---------- Reset & Base ---------- */
*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
  font-size: 16px;
}

body {
  font-family: var(--font-sans);
  font-size: var(--text-base);
  font-weight: var(--weight-normal);
  line-height: var(--leading-normal);
  color: var(--color-text);
  background-color: var(--color-white);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  overflow-x: hidden;
}

/* ---------- Typography ---------- */
h1, h2, h3, h4, h5, h6 {
  font-weight: var(--weight-bold);
  line-height: var(--leading-tight);
  color: var(--color-primary);
  letter-spacing: -0.02em;
  text-wrap: pretty; /* prevents single-word orphans on line breaks */
}

h1 {
  font-size: var(--text-5xl);
  font-weight: var(--weight-extrabold);
}

h2 {
  font-size: var(--text-4xl);
  font-weight: var(--weight-bold);
}

h3 {
  font-size: var(--text-2xl);
  font-weight: var(--weight-semibold);
}

h4 {
  font-size: var(--text-xl);
  font-weight: var(--weight-semibold);
}

h5 {
  font-size: var(--text-lg);
  font-weight: var(--weight-medium);
}

h6 {
  font-size: var(--text-base);
  font-weight: var(--weight-medium);
}

p {
  margin-bottom: var(--space-4);
  color: var(--color-text-secondary);
  line-height: var(--leading-relaxed);
  text-wrap: pretty;
}

p:last-child {
  margin-bottom: 0;
}

a {
  color: var(--color-accent);
  text-decoration: none;
  transition: color var(--transition-fast);
}

a:hover {
  color: var(--color-accent-hover);
}

strong {
  font-weight: var(--weight-semibold);
}

small {
  font-size: var(--text-sm);
}

/* ---------- Images ---------- */
img, svg {
  display: block;
  max-width: 100%;
  height: auto;
}

/* ---------- Lists ---------- */
ul, ol {
  list-style: none;
}

/* ---------- Layout Utilities ---------- */
.container {
  width: 100%;
  max-width: var(--container-max);
  margin-left: auto;
  margin-right: auto;
  padding-left: var(--space-6);
  padding-right: var(--space-6);
}

.container--narrow {
  max-width: var(--container-narrow);
}

.container--wide {
  max-width: var(--container-wide);
}

/* ---------- Sections ---------- */
.section {
  padding-top: var(--space-20);
  padding-bottom: var(--space-20);
}

.section--lg {
  padding-top: var(--space-32);
  padding-bottom: var(--space-32);
}

.section--sm {
  padding-top: var(--space-12);
  padding-bottom: var(--space-12);
}

.section--surface {
  background-color: var(--color-surface);
}

.section--dark {
  background-color: var(--color-primary);
  color: var(--color-text-inverse);
}

.section--dark h1,
.section--dark h2,
.section--dark h3,
.section--dark h4,
.section--dark h5,
.section--dark h6 {
  color: var(--color-text-inverse);
}

.section--dark p {
  color: rgba(255, 255, 255, 0.8);
}

/* ---------- Section Headers ---------- */
.section-header {
  text-align: center;
  max-width: 700px;
  margin-left: auto;
  margin-right: auto;
  margin-bottom: var(--space-16);
}

.section-header__label {
  display: inline-block;
  font-size: var(--text-sm);
  font-weight: var(--weight-semibold);
  color: var(--color-accent);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  margin-bottom: var(--space-3);
}

.section-header__title {
  margin-bottom: var(--space-4);
}

.section-header__description {
  font-size: var(--text-lg);
  color: var(--color-text-secondary);
}

/* ---------- Grid System ---------- */
.grid {
  display: grid;
  gap: var(--space-8);
}

.grid--2 {
  grid-template-columns: repeat(2, 1fr);
}

.grid--3 {
  grid-template-columns: repeat(3, 1fr);
}

.grid--4 {
  grid-template-columns: repeat(4, 1fr);
}

/* ---------- Flex Utilities ---------- */
.flex {
  display: flex;
}

.flex--center {
  align-items: center;
  justify-content: center;
}

.flex--between {
  align-items: center;
  justify-content: space-between;
}

.flex--col {
  flex-direction: column;
}

.flex--gap-sm {
  gap: var(--space-2);
}

.flex--gap {
  gap: var(--space-4);
}

.flex--gap-lg {
  gap: var(--space-8);
}

/* ---------- Text Utilities ---------- */
.text-center {
  text-align: center;
}

.text-accent {
  color: var(--color-accent);
}

.text-muted {
  color: var(--color-text-muted);
}

.text-gradient {
  background: linear-gradient(135deg, var(--color-accent) 0%, var(--color-cyan) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

/* ---------- Scroll Reveal Animation ---------- */
.reveal {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

.reveal.revealed {
  opacity: 1;
  transform: translateY(0);
}

/* Stagger children */
.reveal-group > .reveal:nth-child(1) { transition-delay: 0ms; }
.reveal-group > .reveal:nth-child(2) { transition-delay: 100ms; }
.reveal-group > .reveal:nth-child(3) { transition-delay: 200ms; }
.reveal-group > .reveal:nth-child(4) { transition-delay: 300ms; }
.reveal-group > .reveal:nth-child(5) { transition-delay: 400ms; }
.reveal-group > .reveal:nth-child(6) { transition-delay: 500ms; }

/* ---------- Visually Hidden (Accessibility) ---------- */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border-width: 0;
}

/* ---------- Selection ---------- */
::selection {
  background-color: var(--color-accent);
  color: var(--color-white);
}

/* ---------- Scrollbar ---------- */
::-webkit-scrollbar {
  width: 8px;
}

::-webkit-scrollbar-track {
  background: var(--color-surface);
}

::-webkit-scrollbar-thumb {
  background: var(--color-text-muted);
  border-radius: var(--radius-full);
}

::-webkit-scrollbar-thumb:hover {
  background: var(--color-text-secondary);
}