/* ============================================
   DESIGN TOKENS - FOUNDATION
   ALL values must use tokens, NO hard-coded pixels
   ============================================ */

:root {
  /* TYPOGRAPHY TOKENS */
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --font-serif: ui-serif, Georgia, "Times New Roman", Times, serif;
  --font-mono: ui-monospace, "Courier New", monospace;

  /* FONT SIZES - Modular scale */
  --fs-xs: 0.75rem;     /* 12px */
  --fs-sm: 0.875rem;    /* 14px */
  --fs-base: 1rem;      /* 16px */
  --fs-lg: 1.125rem;    /* 18px */
  --fs-xl: 1.25rem;     /* 20px */
  --fs-2xl: 1.5rem;     /* 24px */
  --fs-3xl: 1.875rem;   /* 30px */
  --fs-4xl: 2.25rem;    /* 36px */
  --fs-5xl: 3rem;       /* 48px */

  /* LINE HEIGHTS - Prioritize readability */
  --lh-tight: 1.2;
  --lh-snug: 1.35;
  --lh-body: 1.65;      /* Body text optimized for long reading */
  --lh-loose: 1.8;

  /* FONT WEIGHTS */
  --fw-regular: 400;
  --fw-medium: 500;
  --fw-semibold: 600;
  --fw-bold: 700;

  /* SPACING SCALE - Base unit = 0.25rem (4px) */
  --space-1: 0.25rem;   /* 4px */
  --space-2: 0.5rem;    /* 8px */
  --space-3: 0.75rem;   /* 12px */
  --space-4: 1rem;      /* 16px */
  --space-5: 1.5rem;    /* 24px */
  --space-6: 2rem;      /* 32px */
  --space-7: 3rem;      /* 48px */
  --space-8: 4rem;      /* 64px */
  --space-9: 6rem;      /* 96px */
  --space-10: 8rem;     /* 128px */

  /* LAYOUT TOKENS */
  --width-max: 1100px;           /* Max content width */
  --width-prose: 680px;          /* Optimal reading width for body text */
  --width-container-pad: 2rem;   /* Horizontal padding for containers */

  /* SECTION SPACING */
  --section-gap-vertical: 3rem;  /* Gap between major sections */
  --section-pad-block: 2.75rem;   /* Top/bottom padding for major sections */

  /* COLOR TOKENS - Neutral-first palette */
  --color-bg-primary: #fafaf8;      /* Off-white, warm neutral */
  --color-bg-secondary: #f5f3f0;    /* Slightly darker off-white */
  --color-bg-tertiary: #efefed;     /* Subtle backgrounds */

  --color-text-primary: #1a1a1a;    /* Near-black, high contrast */
  --color-text-secondary: #5a5a5a;  /* Muted text for secondary info */
  --color-text-tertiary: #8a8a8a;   /* Light gray for metadata */

  --color-border: rgba(0, 0, 0, 0.08);      /* Very subtle borders */
  --color-border-light: rgba(0, 0, 0, 0.04);

  --color-accent: #00a8a8;          /* Bright, obvious teal accent */
  --color-accent-light: #00c9c9;    /* Lighter teal for hover */

  /* DIVIDER TOKENS - Page segmentation system */
  --divider-color: #c8e8e8;         /* Light, calm teal (not saturated) */
  --divider-thickness: 1px;         /* Hairline weight */
  --divider-width: calc(100% - 4rem); /* Nearly full-width with 2rem insets left/right */
  --divider-inset: 2rem;            /* Left and right inset margins */
  --divider-spacing-top: 2rem;      /* Generous vertical spacing */
  --divider-spacing-bottom: 2rem;   /* Editorial rhythm */

  /* INTERACTION TOKENS */
  --transition-base: 200ms ease;
  --transition-slow: 300ms ease;

  /* BORDER RADIUS */
  --radius-sm: 4px;
  --radius-md: 8px;
  --radius-lg: 12px;
  --radius-full: 9999px;

  /* SHADOWS - Extremely subtle if used at all */
  --shadow-none: none;
  --shadow-xs: 0 2px 8px rgba(0, 0, 0, 0.04);
  --shadow-sm: 0 4px 12px rgba(0, 0, 0, 0.06);
}

/* ============================================
   RESET & BASE STYLES
   ============================================ */

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-sans);
  font-size: var(--fs-base);
  line-height: var(--lh-body);
  color: var(--color-text-primary);
  background-color: var(--color-bg-primary);
}

/* ============================================
   TYPOGRAPHY - Strong hierarchy
   ============================================ */

h1 {
  font-size: var(--fs-5xl);
  line-height: var(--lh-tight);
  font-weight: var(--fw-semibold);
  margin-bottom: var(--space-5);
  letter-spacing: -0.02em;
}

h2 {
  font-size: var(--fs-4xl);
  line-height: var(--lh-snug);
  font-weight: var(--fw-semibold);
  margin-bottom: var(--space-6);
  letter-spacing: -0.01em;
  color: var(--color-text-primary);
}

h3 {
  font-size: var(--fs-2xl);
  line-height: var(--lh-snug);
  font-weight: var(--fw-semibold);
  margin-bottom: var(--space-4);
}

h4 {
  font-size: var(--fs-xl);
  line-height: var(--lh-snug);
  font-weight: var(--fw-semibold);
  margin-bottom: var(--space-4);
}

p {
  margin-bottom: var(--space-4);
  color: var(--color-text-secondary);
  line-height: var(--lh-body);
}

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

/* Lead paragraph - larger intro text */
.lead {
  font-size: var(--fs-lg);
  line-height: var(--lh-loose);
  color: var(--color-text-secondary);
  margin-bottom: var(--space-6);
}

/* Metadata - small, restrained */
.meta {
  font-size: var(--fs-sm);
  line-height: var(--lh-snug);
  color: var(--color-text-tertiary);
  text-transform: uppercase;
  letter-spacing: 0.1em;
  margin-bottom: var(--space-4);
}

/* Captions */
.caption {
  font-size: var(--fs-sm);
  color: var(--color-text-tertiary);
  line-height: var(--lh-snug);
}

a {
  color: var(--color-accent);
  text-decoration: none;
  transition: color var(--transition-base);
  border-bottom: 1px solid var(--color-accent);
}

a:hover,
a:focus {
  color: var(--color-accent-light);
  border-bottom-color: var(--color-accent-light);
}

/* ============================================
   IMAGES
   ============================================ */

img {
  max-width: 100%;
  height: auto;
  display: block;
  border-radius: var(--radius-md);
}

figure {
  margin: var(--space-8) 0;
}

figcaption {
  font-size: var(--fs-sm);
  color: var(--color-text-tertiary);
  margin-top: var(--space-3);
  line-height: var(--lh-snug);
}

/* ============================================
   LAYOUT & CONTAINERS
   ============================================ */

.container {
  width: min(var(--width-max), calc(100% - var(--width-container-pad)));
  margin: 0 auto;
}

.container-prose {
  width: min(var(--width-prose), calc(100% - var(--width-container-pad)));
  margin: 0 auto;
}

main {
  display: grid;
  gap: var(--section-gap-vertical);
  padding: var(--section-pad-block) var(--space-6) var(--space-10);
}

section {
  display: grid;
  gap: var(--space-5);
}

/* ============================================
   PAGE SEGMENTATION - Editorial dividers
   Centered, minimal, consistent rhythm
   ============================================ */

.section-divider {
  width: var(--divider-width);
  height: var(--divider-thickness);
  background-color: var(--divider-color);
  margin: var(--divider-spacing-top) var(--divider-inset) var(--divider-spacing-bottom) var(--divider-inset);
  border-radius: 0;
  opacity: 1;
  /* Semantic only - not a visual element for screen readers */
  aria-hidden: true;
}

/* ============================================
   NAVIGATION - IDEO-inspired editorial design
   ============================================ */

.navigation {
  position: sticky;
  top: 0;
  background: linear-gradient(
    to bottom,
    var(--color-bg-primary),
    rgba(250, 250, 248, 0.98)
  );
  -webkit-backdrop-filter: blur(0.5px);
  backdrop-filter: blur(0.5px);
  border-bottom: 1px solid var(--color-border);
  z-index: 50;
  /* Smooth elevation on scroll - add subtle shadow */
  box-shadow: 0 0 0 rgba(0, 0, 0, 0);
  transition: box-shadow var(--transition-slow);
}

/* Optional: Add shadow when scrolled */
.navigation.scrolled {
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.04);
}

.nav-container {
  width: min(var(--width-max), calc(100% - var(--width-container-pad)));
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-7);
  padding: var(--space-5) var(--space-6);
  /* Slightly increased padding for breathing room */
}

.logo {
  font-size: var(--fs-lg);
  font-weight: var(--fw-semibold);
  letter-spacing: -0.01em;
  color: var(--color-text-primary);
  text-decoration: none;
  white-space: nowrap;
  flex-shrink: 0;
  /* Refined transition */
  transition: color var(--transition-base), letter-spacing var(--transition-slow);
  position: relative;
}

.logo::after {
  content: '';
  position: absolute;
  bottom: -2px;
  left: 0;
  width: 0;
  height: 1px;
  background-color: var(--color-accent);
  transition: width var(--transition-base);
}

.logo:hover::after,
.logo:focus::after {
  width: 100%;
}

.logo:hover,
.logo:focus {
  color: var(--color-text-primary);
  outline: none;
}

.nav-links {
  display: flex;
  list-style: none;
  gap: var(--space-6);
  align-items: center;
  flex-wrap: nowrap;
  margin: 0;
  padding: 0;
}

.nav-links li {
  white-space: nowrap;
  margin: 0;
  padding: 0;
}

.nav-links a {
  font-size: var(--fs-base);
  font-weight: var(--fw-regular);
  color: var(--color-text-secondary);
  text-decoration: none;
  border: none;
  position: relative;
  padding-bottom: var(--space-2);
  transition: color var(--transition-base);
  /* Underline animation */
  background: linear-gradient(
    to right,
    var(--color-accent) 0%,
    var(--color-accent) 0%
  ) no-repeat bottom;
  background-size: 0% 1px;
  transition: color var(--transition-base), background-size var(--transition-base);
}

.nav-links a:hover,
.nav-links a:focus {
  color: var(--color-text-primary);
  outline: none;
  background-size: 100% 1px;
}

/* Active page indicators - persistent underline */
.nav-links a[href="resume.html"],
.resume-page .nav-links a[href="resume.html"] {
  color: var(--color-text-primary);
  background-size: 100% 1px;
}

.home-page .nav-links a[href="../index.html"],
.home-page .nav-links a[href="index.html"] {
  color: var(--color-text-primary);
  background-size: 100% 1px;
}

.work-page .nav-links a[href="work.html"] {
  color: var(--color-text-primary);
  background-size: 100% 1px;
}

.resume-page .nav-links a[href="resume.html"] {
  color: var(--color-text-primary);
  background-size: 100% 1px;
}

/* Keyboard focus indicator - accessible */
.nav-links a:focus-visible {
  outline: 2px solid var(--color-accent);
  outline-offset: 2px;
}

/* Skip to main content link (accessibility best practice) */
.skip-link {
  position: absolute;
  top: -40px;
  left: 0;
  background-color: var(--color-accent);
  color: #fff;
  padding: var(--space-3) var(--space-4);
  text-decoration: none;
  border-radius: var(--radius-sm);
  font-size: var(--fs-sm);
  font-weight: var(--fw-semibold);
  z-index: 100;
}

.skip-link:focus {
  top: var(--space-2);
  left: var(--space-2);
}

/* ============================================
   PREFERS REDUCED MOTION - Respect user preferences
   ============================================ */

@media (prefers-reduced-motion: reduce) {
  * {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
}

/* ============================================
   HERO / PAGE HEADER
   ============================================ */

.hero {
  padding-top: var(--space-2);
  display: grid;
  gap: var(--space-6);
}

.hero-content {
  max-width: var(--width-prose);
}

/* ============================================
   SECTIONS
   ============================================ */

.intro-section {
  background-color: var(--color-bg-secondary);
  padding: var(--section-pad-block) var(--space-6);
}

.intro-section .container {
  max-width: var(--width-prose);
}

.intro-section p {
  font-size: var(--fs-lg);
  line-height: var(--lh-loose);
}

/* ============================================
   WORK GRID / CARDS
   ============================================ */

.work-section {
  padding: 0;
}

.work-header {
  max-width: var(--width-max);
}

.work-header h2 {
  margin-bottom: var(--space-8);
}

.work-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: var(--space-6);
}

.work-card {
  background-color: #ffffff;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: var(--space-6);
  transition: border-color var(--transition-base), background-color var(--transition-base);
}

.work-card:hover {
  border-color: var(--color-text-secondary);
  background-color: var(--color-bg-secondary);
}

.work-card h3 {
  margin-bottom: var(--space-3);
}

.work-card p {
  margin-bottom: var(--space-5);
  font-size: var(--fs-base);
}

.work-card a {
  font-weight: var(--fw-semibold);
  font-size: var(--fs-base);
}

/* ============================================
   CTA SECTION
   ============================================ */

.cta-section {
  background-color: var(--color-bg-secondary);
  border-top: 1px solid var(--color-border);
  padding: var(--section-pad-block) var(--space-6);
  display: grid;
  gap: var(--space-6);
}

.cta-content {
  max-width: var(--width-prose);
}

.cta-section h2 {
  margin-bottom: var(--space-3);
}

.cta-section p {
  margin-bottom: var(--space-6);
}

/* ============================================
   BUTTONS
   ============================================ */

.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: var(--space-3) var(--space-5);
  font-size: var(--fs-base);
  font-weight: var(--fw-semibold);
  border-radius: var(--radius-sm);
  background-color: var(--color-accent);
  color: #ffffff;
  text-decoration: none;
  border: none;
  cursor: pointer;
  transition: all var(--transition-base);
  border-bottom: none;
}

.button:hover,
.button:focus {
  background-color: var(--color-accent-light);
  transform: translateY(-1px);
  border-bottom: none;
}

.button-secondary {
  background-color: transparent;
  border: 1px solid var(--color-text-primary);
  color: var(--color-text-primary);
}

.button-secondary:hover {
  background-color: var(--color-text-primary);
  color: #ffffff;
}

/* ============================================
   FOOTER
   ============================================ */

.footer {
  background-color: var(--color-bg-secondary);
  border-top: 1px solid var(--color-border);
  padding: var(--space-8) var(--space-6) var(--space-6);
  text-align: center;
}

.footer p {
  font-size: var(--fs-sm);
  margin-bottom: var(--space-2);
  color: var(--color-text-tertiary);
}

.footer a {
  color: var(--color-text-secondary);
  border-bottom-color: var(--color-text-secondary);
}

.footer a:hover {
  color: var(--color-accent);
}
/* ============================================
   RESPONSIVE
   ============================================ */

@media (max-width: 768px) {
  :root {
    --section-pad-block: 3.5rem;
    --section-gap-vertical: 4rem;
    --width-container-pad: 1.5rem;
  }

  h1 {
    font-size: var(--fs-3xl);
  }

  h2 {
    font-size: var(--fs-3xl);
  }

  h3 {
    font-size: var(--fs-xl);
  }

  .nav-container {
    flex-wrap: wrap;
    gap: var(--space-5);
    padding: var(--space-4) var(--space-6);
  }

  .logo {
    font-size: var(--fs-base);
    order: -1;
    width: 100%;
  }

  .nav-links {
    gap: var(--space-5);
    width: 100%;
    justify-content: center;
  }

  .nav-links a {
    font-size: var(--fs-sm);
  }

  .work-grid {
    grid-template-columns: 1fr;
  }

  main {
    padding: var(--section-pad-block) var(--space-4) var(--space-8);
  }
}

@media (max-width: 480px) {
  :root {
    --section-pad-block: 2.5rem;
    --section-gap-vertical: 2.5rem;
    --width-container-pad: 1rem;
  }

  h1 {
    font-size: var(--fs-2xl);
  }

  h2 {
    font-size: var(--fs-2xl);
  }

  .nav-container {
    padding: var(--space-3) var(--space-4);
  }

  .logo {
    font-size: var(--fs-base);
  }

  .nav-links a {
    font-size: var(--fs-sm);
  }
}