/**
 * N2O Graphics Standards Manual - CSS Design Tokens
 * NHB 2026.1
 *
 * Based on NASA Graphics Standards Manual (NHB 1430.2, January 1976)
 *
 * Usage:
 *   @import url('design-system/n2o-design-tokens.css');
 */

/* ==========================================================================
   Fonts - Inter (Primary) + JetBrains Mono (Technical)
   ========================================================================== */

@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700&display=swap');
@import url('https://fonts.googleapis.com/css2?family=JetBrains+Mono:wght@400;500;600&display=swap');


/* ==========================================================================
   Root Variables - Design Tokens
   ========================================================================== */

:root {
  /* -------------------------------------------------------------------------
     Colors: Primary Palette
     Per NASA manual specifications
     ------------------------------------------------------------------------- */

  /* N2O Red - The signature color (matches NASA Red) */
  --n2o-red:             #E03C31;
  --n2o-red-dark:        #C4342A;
  --n2o-red-light:       #E85C52;

  /* N2O Warm Gray - Secondary color (matches NASA Warm Gray) */
  --n2o-warm-gray:       #8C857B;
  --n2o-warm-gray-light: #A8A299;
  --n2o-warm-gray-dark:  #6B655D;

  /* -------------------------------------------------------------------------
     Colors: Neutral Palette
     ------------------------------------------------------------------------- */

  /* Black */
  --black:               #000000;
  --black-90:            #1A1A1A;
  --black-80:            #333333;
  --black-70:            #4D4D4D;

  /* Grays */
  --gray-60:             #666666;
  --gray-50:             #808080;
  --gray-40:             #999999;
  --gray-30:             #B3B3B3;
  --gray-20:             #CCCCCC;
  --gray-10:             #E6E6E6;

  /* Whites */
  --white:               #FFFFFF;
  --off-white:           #F5F5F0;
  --warm-white:          #FAF9F7;

  /* -------------------------------------------------------------------------
     Colors: Semantic
     ------------------------------------------------------------------------- */

  /* Status */
  --status-success:      #2E7D32;
  --status-warning:      #ED6C02;
  --status-error:        #D32F2F;
  --status-info:         #0288D1;

  /* -------------------------------------------------------------------------
     Typography: Font Families
     ------------------------------------------------------------------------- */

  /* Inter - Clean, modern humanist sans-serif */
  --font-sans:           'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;

  /* JetBrains Mono - Technical/code content */
  --font-mono:           'JetBrains Mono', 'SF Mono', 'Monaco', monospace;

  /* -------------------------------------------------------------------------
     Typography: Font Sizes
     Based on modular scale, 8px grid alignment
     ------------------------------------------------------------------------- */

  --text-xs:             0.75rem;     /* 12px */
  --text-sm:             0.875rem;    /* 14px */
  --text-base:           1rem;        /* 16px */
  --text-lg:             1.125rem;    /* 18px */
  --text-xl:             1.25rem;     /* 20px */
  --text-2xl:            1.5rem;      /* 24px */
  --text-3xl:            2rem;        /* 32px */
  --text-4xl:            2.5rem;      /* 40px */
  --text-5xl:            3rem;        /* 48px */
  --text-6xl:            4rem;        /* 64px */

  /* -------------------------------------------------------------------------
     Typography: Font Weights
     Per NASA manual: Light and Medium preferred
     ------------------------------------------------------------------------- */

  --font-light:          300;
  --font-regular:        400;
  --font-medium:         500;
  --font-semibold:       600;
  --font-bold:           700;

  /* -------------------------------------------------------------------------
     Typography: Line Heights
     ------------------------------------------------------------------------- */

  --leading-none:        1;
  --leading-tight:       1.2;
  --leading-snug:        1.35;
  --leading-normal:      1.5;
  --leading-relaxed:     1.625;
  --leading-loose:       1.75;

  /* -------------------------------------------------------------------------
     Typography: Letter Spacing
     ------------------------------------------------------------------------- */

  --tracking-tight:      -0.025em;
  --tracking-normal:     0;
  --tracking-wide:       0.025em;
  --tracking-wider:      0.05em;
  --tracking-widest:     0.1em;

  /* -------------------------------------------------------------------------
     Spacing (8px base grid)
     ------------------------------------------------------------------------- */

  --space-0:             0;
  --space-1:             0.25rem;     /* 4px */
  --space-2:             0.5rem;      /* 8px - Base unit */
  --space-3:             0.75rem;     /* 12px */
  --space-4:             1rem;        /* 16px */
  --space-5:             1.5rem;      /* 24px */
  --space-6:             2rem;        /* 32px */
  --space-8:             3rem;        /* 48px */
  --space-10:            4rem;        /* 64px */
  --space-12:            6rem;        /* 96px */
  --space-16:            8rem;        /* 128px */

  /* -------------------------------------------------------------------------
     Layout: Max Widths
     ------------------------------------------------------------------------- */

  --max-w-xs:            320px;
  --max-w-sm:            480px;
  --max-w-md:            640px;
  --max-w-lg:            768px;
  --max-w-xl:            1024px;
  --max-w-2xl:           1280px;
  --max-w-content:       680px;       /* Optimal reading width */
  --max-w-page:          1200px;

  /* -------------------------------------------------------------------------
     Layout: Breakpoints
     ------------------------------------------------------------------------- */

  --breakpoint-sm:       640px;
  --breakpoint-md:       768px;
  --breakpoint-lg:       1024px;
  --breakpoint-xl:       1280px;

  /* -------------------------------------------------------------------------
     Borders
     ------------------------------------------------------------------------- */

  --border-width-1:      1px;
  --border-width-2:      2px;
  --border-width-4:      4px;

  --radius-none:         0;
  --radius-sm:           2px;
  --radius-md:           4px;

  /* -------------------------------------------------------------------------
     Animation
     ------------------------------------------------------------------------- */

  --duration-fast:       150ms;
  --duration-normal:     250ms;
  --duration-slow:       400ms;

  --ease-out:            cubic-bezier(0, 0, 0.2, 1);
  --ease-in-out:         cubic-bezier(0.4, 0, 0.2, 1);

  /* -------------------------------------------------------------------------
     Z-Index Scale
     ------------------------------------------------------------------------- */

  --z-0:                 0;
  --z-10:                10;
  --z-20:                20;
  --z-30:                30;
  --z-40:                40;
  --z-50:                50;
  --z-dropdown:          100;
  --z-sticky:            200;
  --z-modal:             500;
  --z-tooltip:           700;
}


/* ==========================================================================
   Theme: Light Mode (Default - matches NASA print aesthetic)
   ========================================================================== */

:root,
[data-theme="light"] {
  --bg-primary:          var(--white);
  --bg-surface:          var(--off-white);
  --bg-elevated:         var(--warm-white);
  --bg-muted:            var(--gray-10);

  --text-primary:        var(--black);
  --text-secondary:      var(--gray-60);
  --text-tertiary:       var(--gray-40);
  --text-accent:         var(--n2o-red);

  --border-default:      var(--gray-20);
  --border-subtle:       var(--gray-10);
  --border-strong:       var(--black);

  --focus-ring:          var(--n2o-red);
  --scanline-opacity:    0.03;
}


/* ==========================================================================
   Theme: Dark Mode
   ========================================================================== */

[data-theme="dark"] {
  --bg-primary:          var(--black);
  --bg-surface:          var(--black-90);
  --bg-elevated:         var(--black-80);
  --bg-muted:            var(--black-70);

  --text-primary:        var(--white);
  --text-secondary:      var(--gray-30);
  --text-tertiary:       var(--gray-40);
  --text-accent:         var(--n2o-red);

  --border-default:      var(--gray-60);
  --border-subtle:       var(--black-70);
  --border-strong:       var(--white);

  --focus-ring:          var(--n2o-red);
  --scanline-opacity:    0.05;
}


/* ==========================================================================
   Base Styles
   ========================================================================== */

*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
}

body {
  margin: 0;
  font-family: var(--font-sans);
  font-size: var(--text-base);
  font-weight: var(--font-regular);
  line-height: var(--leading-relaxed);
  color: var(--text-primary);
  background-color: var(--bg-primary);
}


/* ==========================================================================
   Typography Classes
   Inter for all text, with weight hierarchy for emphasis
   ========================================================================== */

/* Display - Large headlines */
.display {
  font-family: var(--font-sans);
  font-size: var(--text-6xl);
  font-weight: var(--font-bold);
  line-height: var(--leading-none);
  letter-spacing: -0.03em;
}

/* Headings */
.h1, h1 {
  font-family: var(--font-sans);
  font-size: var(--text-5xl);
  font-weight: var(--font-bold);
  line-height: var(--leading-tight);
  letter-spacing: -0.02em;
  margin: 0 0 var(--space-6) 0;
}

.h2, h2 {
  font-family: var(--font-sans);
  font-size: var(--text-4xl);
  font-weight: var(--font-semibold);
  line-height: var(--leading-tight);
  letter-spacing: -0.01em;
  margin: 0 0 var(--space-5) 0;
}

.h3, h3 {
  font-family: var(--font-sans);
  font-size: var(--text-3xl);
  font-weight: var(--font-semibold);
  line-height: var(--leading-snug);
  letter-spacing: -0.01em;
  margin: 0 0 var(--space-4) 0;
}

.h4, h4 {
  font-family: var(--font-sans);
  font-size: var(--text-2xl);
  font-weight: var(--font-semibold);
  line-height: var(--leading-snug);
  margin: 0 0 var(--space-4) 0;
}

.h5, h5 {
  font-family: var(--font-sans);
  font-size: var(--text-xl);
  font-weight: var(--font-semibold);
  line-height: var(--leading-snug);
  margin: 0 0 var(--space-3) 0;
}

.h6, h6 {
  font-family: var(--font-sans);
  font-size: var(--text-lg);
  font-weight: var(--font-semibold);
  line-height: var(--leading-snug);
  margin: 0 0 var(--space-3) 0;
}

/* Body Text */
.body, p {
  font-family: var(--font-sans);
  font-size: var(--text-base);
  font-weight: var(--font-regular);
  line-height: var(--leading-relaxed);
  margin: 0 0 var(--space-4) 0;
}

.body-lg {
  font-size: var(--text-lg);
}

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

/* Labels & Captions */
.label {
  font-family: var(--font-sans);
  font-size: var(--text-xs);
  font-weight: var(--font-medium);
  line-height: var(--leading-normal);
  letter-spacing: var(--tracking-wider);
  text-transform: uppercase;
  color: var(--text-secondary);
}

.caption {
  font-family: var(--font-sans);
  font-size: var(--text-sm);
  font-weight: var(--font-light);
  line-height: var(--leading-normal);
  color: var(--text-secondary);
}

/* Section Numbers - like NASA manual (1.1, 2.3, etc.) */
.section-number {
  font-family: var(--font-sans);
  font-size: var(--text-4xl);
  font-weight: var(--font-light);
  color: var(--n2o-red);
  margin-right: var(--space-4);
}

/* Monospace - Technical content */
.mono, code {
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  font-weight: var(--font-regular);
  line-height: var(--leading-normal);
}

code {
  background-color: var(--bg-muted);
  padding: var(--space-1) var(--space-2);
  border-radius: var(--radius-sm);
}

/* Text Emphasis - Best practices for subtle but noticeable emphasis */
strong, b {
  font-weight: var(--font-semibold);  /* 600 - noticeable but not jarring */
}

em, i {
  font-style: italic;
}

u {
  text-decoration: underline;
  text-decoration-skip-ink: auto;  /* Better legibility */
  text-underline-offset: 2px;      /* Slight offset from text */
}

mark {
  background-color: rgba(224, 60, 49, 0.15);
  padding: 0.1em 0.2em;
}

/* Links */
a {
  color: var(--text-accent);
  text-decoration: none;
  transition: color var(--duration-fast) var(--ease-out);
}

a:hover {
  text-decoration: underline;
  text-underline-offset: 2px;
}


/* ==========================================================================
   Layout Utilities
   ========================================================================== */

.container {
  width: 100%;
  max-width: var(--max-w-page);
  margin-left: auto;
  margin-right: auto;
  padding-left: var(--space-6);
  padding-right: var(--space-6);
}

.container-content {
  max-width: var(--max-w-content);
  margin-left: auto;
  margin-right: auto;
  padding-left: var(--space-6);
  padding-right: var(--space-6);
}

/* Two-column grid - per NASA manual layout */
.grid-two-col {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-8);
}

/* Flush left alignment - per NASA specifications */
.text-left {
  text-align: left;
}

@media (max-width: 768px) {
  .container,
  .container-content {
    padding-left: var(--space-4);
    padding-right: var(--space-4);
  }

  .grid-two-col {
    grid-template-columns: 1fr;
  }
}


/* ==========================================================================
   Component: Buttons
   ========================================================================== */

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
  padding: var(--space-3) var(--space-6);

  font-family: var(--font-sans);
  font-size: var(--text-sm);
  font-weight: var(--font-medium);
  line-height: var(--leading-none);
  letter-spacing: var(--tracking-wide);
  text-transform: uppercase;
  text-decoration: none;
  white-space: nowrap;

  border: var(--border-width-2) solid transparent;
  border-radius: var(--radius-none);
  cursor: pointer;

  transition:
    background-color var(--duration-fast) var(--ease-out),
    border-color var(--duration-fast) var(--ease-out),
    color var(--duration-fast) var(--ease-out);
}

.btn:focus {
  outline: none;
  box-shadow: 0 0 0 2px var(--bg-primary), 0 0 0 4px var(--focus-ring);
}

.btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

/* Primary Button - Red background */
.btn-primary {
  color: var(--white);
  background-color: var(--n2o-red);
  border-color: var(--n2o-red);
}

.btn-primary:hover:not(:disabled) {
  background-color: var(--n2o-red-dark);
  border-color: var(--n2o-red-dark);
}

/* Secondary Button - Outlined */
.btn-secondary {
  color: var(--text-primary);
  background-color: transparent;
  border-color: var(--border-strong);
}

.btn-secondary:hover:not(:disabled) {
  color: var(--n2o-red);
  border-color: var(--n2o-red);
}

/* Ghost Button - Text only */
.btn-ghost {
  padding: var(--space-2) 0;
  color: var(--n2o-red);
  background-color: transparent;
  border-color: transparent;
  text-transform: none;
  letter-spacing: var(--tracking-normal);
}

.btn-ghost:hover:not(:disabled) {
  text-decoration: underline;
}

/* Button Sizes */
.btn-sm {
  padding: var(--space-2) var(--space-4);
  font-size: var(--text-xs);
}

.btn-lg {
  padding: var(--space-4) var(--space-8);
  font-size: var(--text-base);
}


/* ==========================================================================
   Component: Cards
   ========================================================================== */

.card {
  background-color: var(--bg-surface);
  border: var(--border-width-1) solid var(--border-default);
  padding: var(--space-6);
}

.card-highlight {
  background-color: var(--bg-primary);
  border: none;
  border-left: var(--border-width-4) solid var(--n2o-red);
  padding-left: var(--space-5);
}


/* ==========================================================================
   Component: Inputs
   ========================================================================== */

.input {
  width: 100%;
  padding: var(--space-3) var(--space-4);

  font-family: var(--font-sans);
  font-size: var(--text-base);
  font-weight: var(--font-light);
  line-height: var(--leading-normal);

  color: var(--text-primary);
  background-color: var(--bg-primary);
  border: var(--border-width-1) solid var(--border-default);
  border-radius: var(--radius-none);

  transition: border-color var(--duration-fast) var(--ease-out);
}

.input:focus {
  outline: none;
  border-color: var(--n2o-red);
}

.input::placeholder {
  color: var(--text-tertiary);
}

.input:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

.input-label {
  display: block;
  margin-bottom: var(--space-2);
  font-family: var(--font-sans);
  font-size: var(--text-xs);
  font-weight: var(--font-medium);
  letter-spacing: var(--tracking-wider);
  text-transform: uppercase;
  color: var(--text-secondary);
}


/* ==========================================================================
   Component: Dividers
   ========================================================================== */

.divider {
  height: var(--border-width-1);
  background-color: var(--border-default);
  border: none;
  margin: var(--space-8) 0;
}

.divider-strong {
  height: var(--border-width-2);
  background-color: var(--border-strong);
}


/* ==========================================================================
   Component: Color Swatches (for documentation)
   ========================================================================== */

.swatch {
  width: 100%;
  height: 80px;
  display: flex;
  align-items: flex-end;
  padding: var(--space-3);
}

.swatch-red { background-color: var(--n2o-red); color: var(--white); }
.swatch-warm-gray { background-color: var(--n2o-warm-gray); color: var(--white); }
.swatch-black { background-color: var(--black); color: var(--white); }
.swatch-white { background-color: var(--white); color: var(--black); border: 1px solid var(--gray-20); }


/* ==========================================================================
   Utility: Colors
   ========================================================================== */

.text-primary { color: var(--text-primary); }
.text-secondary { color: var(--text-secondary); }
.text-tertiary { color: var(--text-tertiary); }
.text-accent { color: var(--text-accent); }
.text-red { color: var(--n2o-red); }
.text-warm-gray { color: var(--n2o-warm-gray); }

.bg-primary { background-color: var(--bg-primary); }
.bg-surface { background-color: var(--bg-surface); }
.bg-red { background-color: var(--n2o-red); }
.bg-warm-gray { background-color: var(--n2o-warm-gray); }


/* ==========================================================================
   Utility: Spacing
   ========================================================================== */

.m-0 { margin: var(--space-0); }
.m-2 { margin: var(--space-2); }
.m-4 { margin: var(--space-4); }
.m-6 { margin: var(--space-6); }
.m-8 { margin: var(--space-8); }

.mt-0 { margin-top: var(--space-0); }
.mt-2 { margin-top: var(--space-2); }
.mt-4 { margin-top: var(--space-4); }
.mt-6 { margin-top: var(--space-6); }
.mt-8 { margin-top: var(--space-8); }

.mb-0 { margin-bottom: var(--space-0); }
.mb-2 { margin-bottom: var(--space-2); }
.mb-4 { margin-bottom: var(--space-4); }
.mb-6 { margin-bottom: var(--space-6); }
.mb-8 { margin-bottom: var(--space-8); }

.p-0 { padding: var(--space-0); }
.p-2 { padding: var(--space-2); }
.p-4 { padding: var(--space-4); }
.p-6 { padding: var(--space-6); }
.p-8 { padding: var(--space-8); }


/* ==========================================================================
   Utility: Flexbox
   ========================================================================== */

.flex { display: flex; }
.inline-flex { display: inline-flex; }
.flex-col { flex-direction: column; }
.flex-row { flex-direction: row; }
.flex-wrap { flex-wrap: wrap; }
.items-start { align-items: flex-start; }
.items-center { align-items: center; }
.items-end { align-items: flex-end; }
.justify-start { justify-content: flex-start; }
.justify-center { justify-content: center; }
.justify-end { justify-content: flex-end; }
.justify-between { justify-content: space-between; }
.gap-2 { gap: var(--space-2); }
.gap-4 { gap: var(--space-4); }
.gap-6 { gap: var(--space-6); }
.gap-8 { gap: var(--space-8); }


/* ==========================================================================
   Utility: Grid
   ========================================================================== */

.grid { display: grid; }
.grid-cols-1 { grid-template-columns: repeat(1, 1fr); }
.grid-cols-2 { grid-template-columns: repeat(2, 1fr); }
.grid-cols-3 { grid-template-columns: repeat(3, 1fr); }
.grid-cols-4 { grid-template-columns: repeat(4, 1fr); }


/* ==========================================================================
   Animation Classes
   ========================================================================== */

@keyframes fadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

.animate-fade-in {
  animation: fadeIn var(--duration-normal) var(--ease-out) forwards;
}


/* ==========================================================================
   Accessibility
   ========================================================================== */

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

/* Focus visible */
.focus-visible:focus {
  outline: 2px solid var(--focus-ring);
  outline-offset: 2px;
}

/* Reduced motion */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}