/* ==========================================================================
   Ertunç Özbay — Personal Workshop, Project Lab & Technical Notebook
   Dark Metallic Engineering / Workshop Aesthetic
   Plain CSS • Accessible • Responsive • Reduced-Motion Ready
   ========================================================================== */

:root {
  /* Core Metallic & Workshop Surfaces */
  --bg-primary: #0d1117;
  --bg-secondary: #131922;
  --bg-card: #171f2b;
  --bg-card-hover: #1c2635;
  --bg-code: #0a0d12;

  /* Brushed Steel Borders & Hairlines */
  --border-subtle: #253041;
  --border-strong: #37465d;
  --border-accent: #e5a93c;

  /* High-Contrast Typography (WCAG AA/AAA compliant on dark surfaces) */
  --text-primary: #e6edf3;
  --text-secondary: #b1bfd0;
  --text-muted: #8494a7;

  /* Workshop Indicator Accents */
  --accent-amber: #e5a93c;
  --accent-amber-soft: rgba(229, 169, 60, 0.14);
  --accent-teal: #4db6ac;
  --accent-teal-soft: rgba(77, 182, 172, 0.14);
  --accent-blue: #6ea8fe;
  --status-progress: #e5a93c;
  --status-experimental: #4db6ac;

  /* Typography & Rhythm */
  --font-sans: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas, "Liberation Mono", monospace;

  --max-width: 1040px;
  --max-reading-width: 72ch;
  --radius-sm: 6px;
  --radius-md: 10px;
  --shadow-panel: 0 8px 24px rgba(0, 0, 0, 0.35);
}

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

html {
  font-size: 100%;
  scroll-behavior: smooth;
  background-color: var(--bg-primary);
  color: var(--text-primary);
}

body {
  margin: 0;
  font-family: var(--font-sans);
  line-height: 1.65;
  background-color: var(--bg-primary);
  background-image:
    radial-gradient(rgba(255, 255, 255, 0.03) 1px, transparent 1px),
    linear-gradient(180deg, #0d1117 0%, #10161f 100%);
  background-size: 28px 28px, 100% 100%;
  color: var(--text-primary);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

/* Accessibility: Skip Link */
.skip-link {
  position: absolute;
  top: -100px;
  left: 1rem;
  z-index: 1000;
  background-color: var(--accent-amber);
  color: #0d1117;
  padding: 0.65rem 1.1rem;
  font-weight: 700;
  border-radius: var(--radius-sm);
  text-decoration: none;
  box-shadow: var(--shadow-panel);
}

.skip-link:focus {
  top: 1rem;
  outline: 3px solid #ffffff;
  outline-offset: 2px;
}

/* Accessibility: Visible Keyboard Focus States */
a:focus-visible,
button:focus-visible,
input:focus-visible,
select:focus-visible,
textarea:focus-visible,
summary:focus-visible,
[tabindex]:focus-visible {
  outline: 2px solid var(--accent-amber);
  outline-offset: 3px;
  border-radius: 3px;
}

/* Typography Hierarchy */
h1, h2, h3, h4 {
  color: var(--text-primary);
  line-height: 1.25;
  margin-top: 0;
  font-weight: 700;
  letter-spacing: -0.015em;
}

h1 {
  font-size: clamp(1.85rem, 3.5vw, 2.55rem);
  margin-bottom: 1rem;
}

h2 {
  font-size: clamp(1.35rem, 2.4vw, 1.75rem);
  margin-bottom: 0.85rem;
}

h3 {
  font-size: 1.18rem;
  margin-bottom: 0.55rem;
}

p {
  margin-top: 0;
  margin-bottom: 1.15rem;
  color: var(--text-secondary);
}

ul, ol {
  margin-top: 0;
  margin-bottom: 1.15rem;
  padding-left: 1.35rem;
  color: var(--text-secondary);
}

li {
  margin-bottom: 0.4rem;
}

strong {
  color: var(--text-primary);
  font-weight: 600;
}

code, pre {
  font-family: var(--font-mono);
  font-size: 0.9em;
}

code {
  background-color: var(--bg-code);
  color: var(--accent-amber);
  padding: 0.15rem 0.4rem;
  border-radius: 4px;
  border: 1px solid var(--border-subtle);
}

pre {
  background-color: var(--bg-code);
  color: var(--text-primary);
  padding: 1rem 1.2rem;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border-subtle);
  overflow-x: auto;
  line-height: 1.5;
}

pre code {
  background: none;
  border: none;
  padding: 0;
  color: inherit;
}

a {
  color: var(--accent-amber);
  text-decoration: underline;
  text-underline-offset: 0.22em;
  transition: color 0.15s ease;
}

a:hover {
  color: #f3c66f;
}

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

/* Layout Containers */
.container {
  width: 100%;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 1.25rem;
}

.reading-width {
  max-width: var(--max-reading-width);
}

main {
  flex: 1;
  padding: 2.5rem 0 4rem;
}

/* Header & Navigation */
.site-header {
  background-color: rgba(19, 25, 34, 0.94);
  border-bottom: 1px solid var(--border-subtle);
  position: sticky;
  top: 0;
  z-index: 100;
  backdrop-filter: blur(8px);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  min-height: 4.25rem;
  gap: 1rem;
}

.site-brand {
  display: inline-flex;
  align-items: center;
  gap: 0.65rem;
  text-decoration: none;
  color: var(--text-primary);
  font-weight: 700;
  font-size: 1.05rem;
}

.site-brand:hover {
  color: var(--accent-amber);
}

.brand-mark {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 2rem;
  height: 2rem;
  background-color: var(--bg-card);
  border: 1px solid var(--border-strong);
  border-radius: var(--radius-sm);
  font-family: var(--font-mono);
  font-size: 0.85rem;
  color: var(--accent-amber);
}

.brand-subtitle {
  display: block;
  font-family: var(--font-mono);
  font-size: 0.72rem;
  font-weight: 400;
  color: var(--text-muted);
}

/* Mobile Navigation Button */
.nav-toggle {
  display: none;
  align-items: center;
  gap: 0.45rem;
  background-color: var(--bg-card);
  color: var(--text-primary);
  border: 1px solid var(--border-strong);
  border-radius: var(--radius-sm);
  padding: 0.5rem 0.8rem;
  font-family: var(--font-mono);
  font-size: 0.85rem;
  cursor: pointer;
}

.nav-toggle:hover {
  border-color: var(--accent-amber);
  color: var(--accent-amber);
}

.nav-list {
  display: flex;
  align-items: center;
  gap: 0.35rem;
  list-style: none;
  margin: 0;
  padding: 0;
}

.nav-list li {
  margin: 0;
}

.nav-link {
  display: inline-block;
  padding: 0.45rem 0.8rem;
  color: var(--text-secondary);
  text-decoration: none;
  font-size: 0.95rem;
  font-weight: 500;
  border-radius: var(--radius-sm);
  border: 1px solid transparent;
  transition: background-color 0.15s ease, color 0.15s ease, border-color 0.15s ease;
}

.nav-link:hover {
  color: var(--text-primary);
  background-color: var(--bg-card);
  border-color: var(--border-subtle);
}

.nav-link[aria-current="page"] {
  color: var(--accent-amber);
  background-color: var(--accent-amber-soft);
  border-color: rgba(229, 169, 60, 0.4);
  font-weight: 600;
}

/* Workshop Hero / Intro Panel */
.workshop-hero {
  background: linear-gradient(180deg, var(--bg-secondary) 0%, var(--bg-card) 100%);
  border: 1px solid var(--border-strong);
  border-left: 4px solid var(--accent-amber);
  border-radius: var(--radius-md);
  padding: clamp(1.5rem, 3.5vw, 2.5rem);
  margin-bottom: 2.5rem;
  box-shadow: var(--shadow-panel);
}

.workshop-eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  font-family: var(--font-mono);
  font-size: 0.82rem;
  color: var(--accent-teal);
  background-color: var(--accent-teal-soft);
  border: 1px solid rgba(77, 182, 172, 0.35);
  padding: 0.25rem 0.65rem;
  border-radius: 999px;
  margin-bottom: 1rem;
}

.hero-lead {
  font-size: clamp(1.1rem, 2vw, 1.28rem);
  color: var(--text-primary);
  max-width: 65ch;
  margin-bottom: 1rem;
}

.hero-supporting-line {
  font-family: var(--font-mono);
  font-size: 0.9rem;
  color: var(--accent-amber);
  margin-top: 1.1rem;
  margin-bottom: 1.5rem;
}

.button-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  margin-top: 1.25rem;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.45rem;
  padding: 0.6rem 1.1rem;
  font-size: 0.95rem;
  font-weight: 600;
  border-radius: var(--radius-sm);
  text-decoration: none;
  cursor: pointer;
  border: 1px solid transparent;
  transition: background-color 0.15s ease, border-color 0.15s ease, color 0.15s ease;
}

.btn-primary {
  background-color: var(--accent-amber);
  color: #0d1117;
  border-color: var(--accent-amber);
}

.btn-primary:hover {
  background-color: #f0b954;
  color: #0d1117;
}

.btn-secondary {
  background-color: var(--bg-primary);
  color: var(--text-primary);
  border-color: var(--border-strong);
}

.btn-secondary:hover {
  background-color: var(--bg-card-hover);
  border-color: var(--accent-amber);
  color: var(--accent-amber);
}

/* Section Headers & Grid Layouts */
.section-block {
  margin-bottom: 3rem;
}

.section-header {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  justify-content: space-between;
  gap: 0.75rem;
  border-bottom: 1px solid var(--border-subtle);
  padding-bottom: 0.6rem;
  margin-bottom: 1.35rem;
}

.section-label {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--accent-teal);
  display: block;
  margin-bottom: 0.25rem;
}

.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(290px, 1fr));
  gap: 1.25rem;
}

.card-grid-2 {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: 1.25rem;
}

/* Metallic Workshop Cards */
.card {
  background-color: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  padding: 1.4rem;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  box-shadow: 0 4px 14px rgba(0, 0, 0, 0.22);
  transition: border-color 0.15s ease, background-color 0.15s ease;
}

.card:hover {
  border-color: var(--border-strong);
  background-color: var(--bg-card-hover);
}

.card-top {
  margin-bottom: 1rem;
}

.card-meta {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.5rem;
  margin-bottom: 0.75rem;
  font-family: var(--font-mono);
  font-size: 0.78rem;
  color: var(--text-muted);
}

/* Badges & Tags */
.badge {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  font-weight: 600;
  padding: 0.2rem 0.55rem;
  border-radius: 4px;
  border: 1px solid transparent;
}

.badge-progress {
  background-color: var(--accent-amber-soft);
  color: var(--accent-amber);
  border-color: rgba(229, 169, 60, 0.4);
}

.badge-experimental {
  background-color: var(--accent-teal-soft);
  color: var(--accent-teal);
  border-color: rgba(77, 182, 172, 0.4);
}

.badge-draft {
  background-color: rgba(110, 168, 254, 0.14);
  color: var(--accent-blue);
  border-color: rgba(110, 168, 254, 0.4);
}

.tag-list {
  display: flex;
  flex-wrap: wrap;
  gap: 0.45rem;
  list-style: none;
  padding: 0;
  margin: 0.75rem 0 1rem;
}

.tag-list li {
  margin: 0;
}

.tag {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 0.76rem;
  color: var(--text-secondary);
  background-color: var(--bg-primary);
  border: 1px solid var(--border-subtle);
  padding: 0.18rem 0.55rem;
  border-radius: 4px;
}

/* Project Card Learning / Next Step Callouts */
.project-notes {
  background-color: var(--bg-secondary);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-sm);
  padding: 0.85rem 1rem;
  margin: 0.85rem 0 1.1rem;
  font-size: 0.92rem;
}

.project-notes p {
  margin-bottom: 0.45rem;
}

.project-notes p:last-child {
  margin-bottom: 0;
}

.card-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.65rem;
  padding-top: 0.85rem;
  border-top: 1px solid var(--border-subtle);
}

/* Callout / Philosophy Panels */
.callout-box {
  background-color: var(--bg-secondary);
  border: 1px solid var(--border-strong);
  border-left: 4px solid var(--accent-teal);
  border-radius: var(--radius-md);
  padding: 1.35rem 1.5rem;
  margin: 1.5rem 0;
}

.callout-box.amber {
  border-left-color: var(--accent-amber);
}

.callout-title {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--accent-teal);
  margin-bottom: 0.5rem;
  display: block;
}

.callout-box.amber .callout-title {
  color: var(--accent-amber);
}

/* Figure & Schematic Frames */
.schematic-frame {
  background-color: var(--bg-secondary);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  padding: 1rem;
  margin: 1.5rem 0;
}

.schematic-caption {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--text-muted);
  margin-top: 0.65rem;
  text-align: center;
}

/* Breadcrumb / Back Navigation */
.breadcrumb {
  margin-bottom: 1.25rem;
  font-family: var(--font-mono);
  font-size: 0.85rem;
}

.breadcrumb a {
  color: var(--text-secondary);
  text-decoration: none;
}

.breadcrumb a:hover {
  color: var(--accent-amber);
  text-decoration: underline;
}

/* Filter Toolbar for Blog */
.filter-bar {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-bottom: 1.5rem;
}

.filter-btn {
  background-color: var(--bg-secondary);
  color: var(--text-secondary);
  border: 1px solid var(--border-subtle);
  padding: 0.4rem 0.85rem;
  border-radius: var(--radius-sm);
  font-family: var(--font-mono);
  font-size: 0.82rem;
  cursor: pointer;
}

.filter-btn:hover {
  border-color: var(--border-strong);
  color: var(--text-primary);
}

.filter-btn[aria-pressed="true"] {
  background-color: var(--accent-amber-soft);
  color: var(--accent-amber);
  border-color: var(--accent-amber);
  font-weight: 600;
}

/* Spec / Component Table */
.spec-table {
  width: 100%;
  border-collapse: collapse;
  margin: 1rem 0 1.5rem;
  font-size: 0.95rem;
  background-color: var(--bg-secondary);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-sm);
  overflow: hidden;
}

.spec-table th,
.spec-table td {
  text-align: left;
  padding: 0.75rem 1rem;
  border-bottom: 1px solid var(--border-subtle);
}

.spec-table th {
  background-color: var(--bg-card);
  color: var(--text-primary);
  font-family: var(--font-mono);
  font-size: 0.82rem;
  text-transform: uppercase;
}

.spec-table td {
  color: var(--text-secondary);
}

/* Footer */
.site-footer {
  background-color: var(--bg-secondary);
  border-top: 1px solid var(--border-subtle);
  padding: 2rem 0;
  margin-top: auto;
  font-size: 0.9rem;
}

.footer-inner {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  align-items: center;
  gap: 1rem;
}

.footer-links {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
  list-style: none;
  margin: 0;
  padding: 0;
}

.footer-links li {
  margin: 0;
}

/* Responsive Mobile Navigation */
@media (max-width: 760px) {
  .nav-toggle {
    display: inline-flex;
  }

  .site-nav {
    width: 100%;
    display: none;
  }

  .site-nav.is-open {
    display: block;
    padding: 0.75rem 0 1rem;
    border-top: 1px solid var(--border-subtle);
  }

  .header-inner {
    flex-wrap: wrap;
    padding-top: 0.6rem;
    padding-bottom: 0.6rem;
  }

  .nav-list {
    flex-direction: column;
    align-items: stretch;
    gap: 0.25rem;
  }

  .nav-link {
    display: block;
    padding: 0.65rem 0.85rem;
  }
}

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