/* ========================================
   yugshetty.com — Design System & Styles
   Phase 1 MVP
   ======================================== */

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

button {
  font: inherit;
  color: inherit;
  cursor: pointer;
  border: none;
  background: none;
}

ul,
ol {
  list-style: none;
}

a {
  text-decoration: none;
  color: inherit;
}

img {
  max-width: 100%;
  display: block;
}

/* --- Custom Properties — Light Mode (Default) --- */
:root {
  /* Colors */
  --bg-primary: #fafaf9;
  --bg-secondary: #f0efed;
  --bg-tertiary: #e7e5e4;
  --bg-primary-alpha: rgba(250, 250, 249, 0.85);
  --text-primary: #1c1917;
  --text-secondary: #57534e;
  --text-tertiary: #78716c;
  --accent: #2563eb;
  --accent-hover: #1d4ed8;
  --border: #e7e5e4;
  --border-subtle: #f0efed;

  /* Typography */
  --font-heading: "Manrope", sans-serif;
  --font-body: "Satoshi", sans-serif;
  --font-mono: "SF Mono", "Fira Code", "Roboto Mono", monospace;

  /* Spacing (8px grid) */
  --space-xs: 4px;
  --space-sm: 8px;
  --space-md: 12px;
  --space-base: 16px;
  --space-lg: 24px;
  --space-xl: 32px;
  --space-2xl: 48px;
  --space-3xl: 64px;
  --space-4xl: 96px;
  --space-5xl: 128px;

  /* Layout */
  --content-width: 680px;
  --site-width: 720px;

  /* Transitions */
  --transition-fast: 150ms ease;
  --transition-base: 200ms ease;
  --transition-slow: 300ms ease;

  /* Radius */
  --radius-sm: 4px;
  --radius-md: 6px;
  --radius-lg: 8px;
  --radius-full: 9999px;
}

/* --- Dark Mode --- */
[data-theme="dark"] {
  --bg-primary: #121212;
  --bg-secondary: #1a1a1a;
  --bg-tertiary: #232323;
  --bg-primary-alpha: rgba(18, 18, 18, 0.85);
  --text-primary: #ededed;
  --text-secondary: #a1a1a1;
  --text-tertiary: #6b6b6b;
  --accent: #60a5fa;
  --accent-hover: #93c5fd;
  --border: #2a2a2a;
  --border-subtle: #1f1f1f;
}

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

body {
  font-family: var(--font-body);
  font-weight: 400;
  line-height: 1.7;
  color: var(--text-primary);
  background-color: var(--bg-primary);
  transition: background-color var(--transition-slow),
    color var(--transition-slow);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

main {
  flex: 1;
}

/* --- Typography --- */
h1,
h2,
h3,
h4,
h5,
h6 {
  font-family: var(--font-heading);
  line-height: 1.2;
  color: var(--text-primary);
  letter-spacing: -0.02em;
}

h1 {
  font-size: 2rem;
  font-weight: 700;
}
h2 {
  font-size: 1.5rem;
  font-weight: 600;
}
h3 {
  font-size: 1.25rem;
  font-weight: 600;
}
h4 {
  font-size: 1.125rem;
  font-weight: 500;
}

p {
  margin-bottom: var(--space-base);
}
p:last-child {
  margin-bottom: 0;
}

/* --- Layout --- */
.container {
  width: 100%;
  max-width: var(--site-width);
  margin: 0 auto;
  padding: 0 var(--space-lg);
}

.section {
  padding: var(--space-2xl) 0;
}

/* ========================================
   HEADER & NAVIGATION
   ======================================== */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background-color: var(--bg-primary);
  border-bottom: 1px solid var(--border);
  transition: background-color var(--transition-slow),
    border-color var(--transition-slow);
}

@supports (backdrop-filter: blur(12px)) {
  .site-header {
    background-color: var(--bg-primary-alpha);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
  }
}

.nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
}

.nav-logo {
  font-family: var(--font-heading);
  font-size: 1.125rem;
  font-weight: 600;
  color: var(--text-primary);
  letter-spacing: -0.02em;
  transition: color var(--transition-base);
}
.nav-logo:hover {
  color: var(--text-primary);
}

/* Hamburger toggle (mobile) */
.nav-toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  padding: var(--space-sm);
  z-index: 110;
}

.hamburger-line {
  display: block;
  width: 20px;
  height: 2px;
  background-color: var(--text-primary);
  border-radius: 1px;
  transition: transform var(--transition-base), opacity var(--transition-base);
}

.nav-toggle[aria-expanded="true"] .hamburger-line:nth-child(1) {
  transform: translateY(7px) rotate(45deg);
}
.nav-toggle[aria-expanded="true"] .hamburger-line:nth-child(2) {
  opacity: 0;
}
.nav-toggle[aria-expanded="true"] .hamburger-line:nth-child(3) {
  transform: translateY(-7px) rotate(-45deg);
}

/* Nav menu */
.nav-menu {
  display: flex;
  align-items: center;
  gap: var(--space-xl);
}

.nav-link {
  font-family: var(--font-body);
  font-size: 0.875rem;
  font-weight: 400;
  color: var(--text-secondary);
  transition: color var(--transition-base);
  letter-spacing: 0.01em;
}
.nav-link:hover,
.nav-link.active {
  color: var(--text-primary);
}

/* Theme toggle button */
.theme-toggle {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  color: var(--text-secondary);
  transition: color var(--transition-base),
    border-color var(--transition-base),
    background-color var(--transition-base);
}
.theme-toggle:hover {
  color: var(--text-primary);
  border-color: var(--text-tertiary);
  background-color: var(--bg-secondary);
}

/* Sun/Moon icon visibility */
.icon-sun {
  display: none;
}
.icon-moon {
  display: block;
}
[data-theme="dark"] .icon-sun {
  display: block;
}
[data-theme="dark"] .icon-moon {
  display: none;
}

/* ========================================
   HERO SECTION
   ======================================== */
.hero {
  padding: var(--space-4xl) 0 var(--space-3xl);
}

.hero-title {
  font-size: 2.5rem;
  font-weight: 700;
  margin-bottom: var(--space-base);
  letter-spacing: -0.03em;
}

.hero-subtitle {
  font-size: 1.125rem;
  font-weight: 300;
  color: var(--text-secondary);
  max-width: 540px;
  line-height: 1.6;
}

/* ========================================
   SECTION HEADERS
   ======================================== */
.section-header {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  margin-bottom: var(--space-xl);
}

.section-title {
  font-size: 1.25rem;
  font-weight: 600;
}

.section-link {
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--text-tertiary);
  transition: color var(--transition-base);
}
.section-link:hover {
  color: var(--accent);
}

/* ========================================
   FEATURED ARTICLE
   ======================================== */
.featured-article {
  padding: var(--space-xl);
  background-color: var(--bg-secondary);
  border-radius: var(--radius-lg);
  border: 1px solid var(--border);
  transition: background-color var(--transition-slow),
    border-color var(--transition-slow);
}

.featured-label {
  font-family: var(--font-body);
  font-size: 0.75rem;
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--accent);
  margin-bottom: var(--space-md);
  display: block;
}

.featured-article .article-title {
  font-size: 1.5rem;
  font-weight: 600;
  margin-bottom: var(--space-md);
  letter-spacing: -0.02em;
}

.featured-article .article-title a {
  color: var(--text-primary);
  transition: color var(--transition-base);
}
.featured-article .article-title a:hover {
  color: var(--accent);
}

.featured-article .article-excerpt {
  color: var(--text-secondary);
  font-size: 1rem;
  line-height: 1.7;
  margin-bottom: var(--space-base);
}

/* Article meta (date, read time, tag) */
.article-meta {
  display: flex;
  align-items: center;
  gap: var(--space-base);
  font-size: 0.8125rem;
  color: var(--text-tertiary);
  font-weight: 400;
}

.article-meta .separator {
  width: 3px;
  height: 3px;
  border-radius: 50%;
  background-color: var(--text-tertiary);
  display: inline-block;
  flex-shrink: 0;
}

/* ========================================
   ARTICLE LIST (homepage latest)
   ======================================== */
.article-list {
  display: flex;
  flex-direction: column;
}

.article-item {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  padding: var(--space-base) 0;
  border-bottom: 1px solid var(--border);
  gap: var(--space-base);
  transition: border-color var(--transition-slow);
}
.article-item:last-child {
  border-bottom: none;
}

.article-item-content {
  flex: 1;
  min-width: 0;
}

.article-item .article-title {
  font-family: var(--font-heading);
  font-size: 1rem;
  font-weight: 500;
  margin-bottom: var(--space-xs);
}

.article-item .article-title a {
  color: var(--text-primary);
  transition: color var(--transition-base);
}
.article-item .article-title a:hover {
  color: var(--accent);
}

.article-date {
  font-size: 0.8125rem;
  color: var(--text-tertiary);
  white-space: nowrap;
  font-variant-numeric: tabular-nums;
}

/* ========================================
   TAGS / PILLS
   ======================================== */
.tag {
  display: inline-block;
  font-size: 0.75rem;
  font-weight: 500;
  padding: 2px 10px;
  border-radius: var(--radius-full);
  background-color: var(--bg-tertiary);
  color: var(--text-secondary);
  transition: background-color var(--transition-slow),
    color var(--transition-slow);
}
.tag.active {
  background-color: var(--text-primary);
  color: var(--bg-primary);
}

/* ========================================
   FOCUS AREAS
   ======================================== */
.focus-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: var(--space-base);
}

.focus-card {
  padding: var(--space-lg);
  background-color: var(--bg-secondary);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  transition: background-color var(--transition-slow),
    border-color var(--transition-slow),
    transform var(--transition-base);
}
.focus-card:hover {
  transform: translateY(-2px);
  border-color: var(--text-tertiary);
}

.focus-card-title {
  font-family: var(--font-heading);
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: var(--space-sm);
  color: var(--text-primary);
}

.focus-card-desc {
  font-size: 0.875rem;
  color: var(--text-secondary);
  line-height: 1.5;
}

/* ========================================
   PROJECT CARDS
   ======================================== */
.project-list {
  display: flex;
  flex-direction: column;
  gap: var(--space-base);
}

.project-card {
  display: block;
  padding: var(--space-lg);
  background-color: var(--bg-secondary);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  transition: background-color var(--transition-slow),
    border-color var(--transition-base),
    transform var(--transition-base);
}
.project-card:hover {
  border-color: var(--text-tertiary);
  transform: translateY(-2px);
}

.project-card-title {
  font-family: var(--font-heading);
  font-size: 1.0625rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: var(--space-sm);
}

.project-card-desc {
  font-size: 0.9375rem;
  color: var(--text-secondary);
  line-height: 1.6;
  margin-bottom: var(--space-md);
}

.project-tags {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-sm);
}

.project-tag {
  font-size: 0.75rem;
  font-weight: 400;
  padding: 2px 8px;
  border-radius: var(--radius-sm);
  background-color: var(--bg-tertiary);
  color: var(--text-tertiary);
  font-family: var(--font-mono);
  transition: background-color var(--transition-slow),
    color var(--transition-slow);
}

/* ========================================
   FOOTER
   ======================================== */
.site-footer {
  padding: var(--space-3xl) 0 var(--space-xl);
  border-top: 1px solid var(--border);
  transition: border-color var(--transition-slow);
}

.footer-content {
  text-align: center;
}

.footer-tagline {
  font-size: 0.9375rem;
  color: var(--text-secondary);
  margin-bottom: var(--space-lg);
  font-weight: 300;
}

.footer-links {
  display: flex;
  justify-content: center;
  gap: var(--space-lg);
  margin-bottom: var(--space-lg);
}

.footer-link {
  font-size: 0.875rem;
  font-weight: 400;
  color: var(--text-tertiary);
  transition: color var(--transition-base);
}
.footer-link:hover {
  color: var(--text-primary);
}

.footer-copyright {
  font-size: 0.8125rem;
  color: var(--text-tertiary);
}

/* ========================================
   PAGE HEADER (inner pages)
   ======================================== */
.page-header {
  padding: var(--space-3xl) 0 var(--space-xl);
}

.page-title {
  font-size: 2rem;
  font-weight: 700;
  margin-bottom: var(--space-md);
  letter-spacing: -0.03em;
}

.page-subtitle {
  font-size: 1.0625rem;
  color: var(--text-secondary);
  font-weight: 300;
  line-height: 1.6;
}

/* ========================================
   FILTER TAGS (Articles page)
   ======================================== */
.filter-tags {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-sm);
  margin-bottom: var(--space-xl);
}

.filter-tag {
  font-family: var(--font-body);
  font-size: 0.8125rem;
  font-weight: 500;
  padding: 6px 16px;
  border-radius: var(--radius-full);
  background-color: var(--bg-secondary);
  color: var(--text-secondary);
  border: 1px solid var(--border);
  transition: all var(--transition-base);
}
.filter-tag:hover {
  border-color: var(--text-tertiary);
  color: var(--text-primary);
}
.filter-tag.active {
  background-color: var(--text-primary);
  color: var(--bg-primary);
  border-color: var(--text-primary);
}

/* ========================================
   ARTICLES PAGE — full listing
   ======================================== */
.articles-list {
  display: flex;
  flex-direction: column;
}

.articles-list .article-item {
  flex-direction: column;
  align-items: flex-start;
  padding: var(--space-lg) 0;
  gap: var(--space-sm);
}

.articles-list .article-title {
  font-family: var(--font-heading);
  font-size: 1.125rem;
  font-weight: 500;
  margin-bottom: var(--space-xs);
}

.articles-list .article-excerpt {
  font-size: 0.9375rem;
  color: var(--text-secondary);
  line-height: 1.6;
  margin-bottom: var(--space-sm);
}

/* ========================================
   READS PAGE
   ======================================== */
.reads-list {
  display: flex;
  flex-direction: column;
}

.read-item {
  padding: var(--space-lg) 0;
  border-bottom: 1px solid var(--border);
  transition: border-color var(--transition-slow);
}
.read-item:last-child {
  border-bottom: none;
}

.read-title {
  font-family: var(--font-heading);
  font-size: 1.0625rem;
  font-weight: 500;
  color: var(--text-primary);
  margin-bottom: var(--space-xs);
}

.read-author {
  font-size: 0.875rem;
  color: var(--text-tertiary);
  margin-bottom: var(--space-sm);
}

.read-note {
  font-size: 0.9375rem;
  color: var(--text-secondary);
  line-height: 1.6;
  font-style: italic;
}

.read-tags {
  display: flex;
  gap: var(--space-sm);
  margin-top: var(--space-md);
}

/* ========================================
   ABOUT PAGE
   ======================================== */
.about-content {
  max-width: var(--content-width);
}

.about-content p {
  font-size: 1.0625rem;
  line-height: 1.8;
  color: var(--text-secondary);
  margin-bottom: var(--space-lg);
}

.about-content p:first-of-type {
  color: var(--text-primary);
  font-size: 1.125rem;
}

.about-section {
  margin-bottom: var(--space-2xl);
}

.about-section-title {
  font-family: var(--font-heading);
  font-size: 1.125rem;
  font-weight: 600;
  margin-bottom: var(--space-base);
  color: var(--text-primary);
}

.connect-links {
  display: flex;
  flex-direction: column;
  gap: var(--space-md);
}

.connect-link {
  display: inline-flex;
  align-items: center;
  gap: var(--space-sm);
  font-size: 0.9375rem;
  color: var(--text-secondary);
  transition: color var(--transition-base);
}
.connect-link:hover {
  color: var(--accent);
}

.connect-link-label {
  color: var(--text-tertiary);
  font-size: 0.8125rem;
  min-width: 80px;
}

/* ========================================
   PROJECTS PAGE
   ======================================== */
.projects-grid {
  display: flex;
  flex-direction: column;
  gap: var(--space-base);
}

/* ========================================
   RESPONSIVE — Tablet (≥ 640px)
   ======================================== */
@media (min-width: 640px) {
  .section {
    padding: var(--space-3xl) 0;
  }

  .hero {
    padding: var(--space-5xl) 0 var(--space-3xl);
  }
  .hero-title {
    font-size: 3rem;
  }
  .hero-subtitle {
    font-size: 1.1875rem;
  }

  h1 {
    font-size: 2.25rem;
  }

  .page-header {
    padding: var(--space-4xl) 0 var(--space-xl);
  }

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

/* ========================================
   RESPONSIVE — Desktop (≥ 1024px)
   ======================================== */
@media (min-width: 1024px) {
  .section {
    padding: var(--space-4xl) 0;
  }

  .hero {
    padding: var(--space-5xl) 0 var(--space-4xl);
  }
  .hero-title {
    font-size: 3.25rem;
  }

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

/* ========================================
   RESPONSIVE — Mobile (< 640px)
   ======================================== */
@media (max-width: 639px) {
  .container {
    padding: 0 var(--space-base);
  }

  /* Mobile hamburger nav */
  .nav-toggle {
    display: flex;
  }

  .nav-menu {
    display: none;
    position: absolute;
    top: 64px;
    left: 0;
    right: 0;
    flex-direction: column;
    background-color: var(--bg-primary);
    border-bottom: 1px solid var(--border);
    padding: var(--space-base) var(--space-base) var(--space-lg);
    gap: var(--space-xs);
    transition: background-color var(--transition-slow),
      border-color var(--transition-slow);
  }

  .nav-menu.is-open {
    display: flex;
  }

  .nav-link {
    padding: var(--space-sm) 0;
    font-size: 1rem;
  }

  .theme-toggle {
    align-self: flex-start;
    margin-top: var(--space-sm);
  }

  /* Mobile hero */
  .hero {
    padding: var(--space-2xl) 0;
  }
  .hero-title {
    font-size: 2rem;
  }
  .hero-subtitle {
    font-size: 1rem;
  }

  /* Mobile section headers */
  .section-header {
    flex-direction: column;
    gap: var(--space-sm);
  }

  /* Mobile featured article */
  .featured-article {
    padding: var(--space-base);
  }
  .featured-article .article-title {
    font-size: 1.25rem;
  }

  /* Mobile article items */
  .article-item {
    flex-direction: column;
    align-items: flex-start;
    gap: var(--space-xs);
  }

  /* Mobile focus grid */
  .focus-grid {
    grid-template-columns: repeat(2, 1fr);
    gap: var(--space-sm);
  }
  .focus-card {
    padding: var(--space-base);
  }

  /* Mobile page headers */
  .page-header {
    padding: var(--space-2xl) 0 var(--space-base);
  }
  .page-title {
    font-size: 1.75rem;
  }
}

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

:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

/* 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;
}

/* ========================================
   ARTICLE PAGE
   ======================================== */

.article-container {
  max-width: var(--content-width);
  margin: 0 auto;
}

.back-link {
  display: inline-block;
  margin-bottom: var(--space-xl);
  color: var(--text-secondary);
  transition: color var(--transition-base);
}

.back-link:hover {
  color: var(--accent);
}

.subtitle {
  font-size: 1.125rem;
  line-height: 1.8;
  color: var(--text-secondary);
  margin-bottom: var(--space-2xl);
}

.article-content {
  font-size: 1.0625rem;
  line-height: 1.9;
}

.article-content h1 {
  margin-bottom: var(--space-lg);
  letter-spacing: -0.03em;
}

.article-content h2 {
  margin-top: var(--space-3xl);
  margin-bottom: var(--space-base);
}

.article-content p {
  color: var(--text-secondary);
  margin-bottom: var(--space-lg);
}

.article-content p:first-of-type {
  color: var(--text-primary);
}

.article-content ul {
  margin: var(--space-lg) 0;
  padding-left: 1.5rem;
}

.article-content li {
  margin-bottom: var(--space-sm);
  color: var(--text-secondary);
}

.article-content hr {
  border: none;
  height: 1px;
  background-color: var(--border);
  margin: var(--space-3xl) 0;
}