/* ==========================================================================
   erdemsakin.com — shared design system
   One accent, no gradients, no emoji. Edit tokens here, all pages follow.
   ========================================================================== */

:root {
  --bg:        #0b0b0c;
  --surface:   #101012;
  --raised:    #16161a;
  --line:      rgba(255, 255, 255, 0.08);
  --line-soft: rgba(255, 255, 255, 0.05);
  --line-hard: rgba(255, 255, 255, 0.16);

  --ink:       #ececed;
  --ink-2:     #9b9ba3;
  --ink-3:     #83838d;

  --accent:      #3cbf9a;
  --accent-soft: rgba(60, 191, 154, 0.12);

  --sans:    'Inter', system-ui, -apple-system, sans-serif;
  --display: 'Inter Tight', 'Inter', system-ui, sans-serif;
  --serif:   'Instrument Serif', Georgia, serif;
  --mono:    'JetBrains Mono', ui-monospace, monospace;

  --ease: cubic-bezier(0.22, 1, 0.36, 1);
  --wrap: 1120px;
}

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

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

body {
  background: var(--bg);
  color: var(--ink);
  font-family: var(--sans);
  font-size: 16px;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
  overflow-x: hidden;
}

a { color: inherit; text-decoration: none; }
img { display: block; max-width: 100%; }
::selection { background: var(--accent); color: #05130f; }

:focus-visible { outline: 2px solid var(--accent); outline-offset: 3px; border-radius: 4px; }

.skip {
  position: absolute; left: -9999px; top: 0; z-index: 999;
  background: var(--ink); color: var(--bg);
  padding: 0.6rem 1rem; font-size: 0.85rem; font-weight: 500; border-radius: 0 0 8px 0;
}
.skip:focus { left: 0; }

.wrap { max-width: var(--wrap); margin: 0 auto; padding: 0 1.5rem; }

/* ---------- type ---------- */
h1, h2, h3, h4 { font-family: var(--display); font-weight: 600; letter-spacing: -0.022em; line-height: 1.12; }
.serif { font-family: var(--serif); font-style: italic; font-weight: 400; letter-spacing: 0; }
.mono {
  font-family: var(--mono); font-size: 0.72rem; font-weight: 500;
  letter-spacing: 0.09em; text-transform: uppercase; color: var(--ink-3);
}

/* ---------- header ---------- */
header {
  position: sticky; top: 0; z-index: 50;
  background: rgba(11, 11, 12, 0.72);
  backdrop-filter: blur(14px) saturate(1.4);
  -webkit-backdrop-filter: blur(14px) saturate(1.4);
  border-bottom: 1px solid transparent;
  transition: border-color 0.3s ease, background 0.3s ease;
}
header.stuck { border-bottom-color: var(--line); background: rgba(11, 11, 12, 0.9); }

.nav { display: flex; align-items: center; justify-content: space-between; height: 68px; gap: 1rem; }
.brand { display: flex; align-items: center; gap: 0.7rem; min-width: 0; }
.brand-mark {
  width: 30px; height: 30px; border-radius: 8px; flex-shrink: 0;
  display: flex; align-items: center; justify-content: center;
  border: 1px solid var(--line-hard); background: var(--raised);
  font-family: var(--display); font-size: 0.72rem; font-weight: 600;
  letter-spacing: 0.02em; color: var(--ink);
  transition: border-color 0.25s ease, color 0.25s ease;
}
.brand:hover .brand-mark { border-color: var(--accent); color: var(--accent); }
.brand-name { font-family: var(--display); font-weight: 600; font-size: 0.92rem; letter-spacing: -0.01em; white-space: nowrap; }
.brand-role { font-family: var(--mono); font-size: 0.68rem; color: var(--ink-3); letter-spacing: 0.04em; }

.nav-links { display: flex; align-items: center; gap: 0.15rem; }
.nav-link {
  padding: 0.45rem 0.75rem; font-size: 0.875rem; color: var(--ink-2);
  border-radius: 7px; transition: color 0.2s ease, background 0.2s ease;
}
.nav-link:hover { color: var(--ink); background: rgba(255, 255, 255, 0.045); }
.nav-link[aria-current='page'] { color: var(--ink); }
.nav-cta {
  margin-left: 0.5rem; padding: 0.45rem 0.95rem; font-size: 0.875rem; font-weight: 500;
  color: var(--ink); border: 1px solid var(--line-hard); border-radius: 7px;
  transition: border-color 0.2s ease, color 0.2s ease, background 0.2s ease;
}
.nav-cta:hover { border-color: var(--accent); color: var(--accent); background: var(--accent-soft); }
.ext { display: inline-block; font-size: 0.7em; opacity: 0.55; vertical-align: 0.35em; margin-left: 0.25em; }

.menu-btn {
  display: none; width: 40px; height: 40px; align-items: center; justify-content: center;
  background: none; border: 1px solid var(--line); border-radius: 9px; cursor: pointer;
  transition: border-color 0.2s ease;
}
.menu-btn:hover { border-color: var(--line-hard); }
.menu-btn span { position: relative; width: 16px; height: 1.5px; background: var(--ink); display: block; transition: background 0.2s ease; }
.menu-btn span::before, .menu-btn span::after {
  content: ''; position: absolute; left: 0; width: 16px; height: 1.5px; background: var(--ink);
  transition: transform 0.32s var(--ease);
}
.menu-btn span::before { top: -5px; }
.menu-btn span::after { top: 5px; }
.menu-btn[aria-expanded='true'] span { background: transparent; }
.menu-btn[aria-expanded='true'] span::before { transform: translateY(5px) rotate(45deg); }
.menu-btn[aria-expanded='true'] span::after { transform: translateY(-5px) rotate(-45deg); }

.mobile-nav { display: none; flex-direction: column; padding: 0.5rem 0 1.25rem; border-top: 1px solid var(--line-soft); }
.mobile-nav.open { display: flex; }
.mobile-nav a { padding: 0.85rem 0.25rem; font-size: 1rem; color: var(--ink-2); border-bottom: 1px solid var(--line-soft); }
.mobile-nav a:last-child { border-bottom: 0; color: var(--accent); }

/* ---------- buttons ---------- */
.btn {
  display: inline-flex; align-items: center; gap: 0.5rem;
  padding: 0.72rem 1.25rem; font-family: var(--sans); font-size: 0.9rem; font-weight: 500;
  border-radius: 9px; border: 1px solid transparent; cursor: pointer;
  transition: background 0.22s ease, color 0.22s ease, border-color 0.22s ease, transform 0.22s var(--ease);
}
.btn:hover { transform: translateY(-1px); }
.btn-solid { background: var(--ink); color: #0b0b0c; }
.btn-solid:hover { background: #fff; }
.btn-ghost { border-color: var(--line-hard); color: var(--ink); }
.btn-ghost:hover { border-color: var(--accent); color: var(--accent); background: var(--accent-soft); }
.btn-logo { width: 20px; height: 20px; border-radius: 6px; background: #f7f7f8; padding: 1px; }
.arrow { transition: transform 0.22s var(--ease); }
.btn:hover .arrow { transform: translateX(3px); }

/* ---------- sections ---------- */
section { padding: 4.75rem 0; }
.sec-head {
  display: flex; align-items: baseline; gap: 1.25rem;
  margin-bottom: 2.75rem; padding-bottom: 1.25rem; border-bottom: 1px solid var(--line-soft);
}
.sec-head h2 { font-size: clamp(1.5rem, 2.6vw, 1.95rem); font-weight: 600; }
.sec-head p { margin-left: auto; font-size: 0.9rem; color: var(--ink-3); max-width: 42ch; text-align: right; }

/* page masthead (sub-pages) */
.masthead { padding: 4rem 0 2.5rem; border-bottom: 1px solid var(--line-soft); }
.masthead h1 { font-size: clamp(2.1rem, 4.6vw, 3.15rem); font-weight: 600; letter-spacing: -0.03em; max-width: 18ch; }
.masthead .lede { margin-top: 1.15rem; font-size: 1.03rem; color: var(--ink-2); max-width: 58ch; }
.crumb { display: inline-flex; align-items: center; gap: 0.45rem; margin-bottom: 1.5rem; font-size: 0.84rem; color: var(--ink-3); transition: color 0.2s ease; }
.crumb:hover { color: var(--accent); }

.tally { display: flex; flex-wrap: wrap; gap: 2.25rem; margin-top: 2.25rem; }
.tally div { display: flex; flex-direction: column; gap: 0.1rem; }
.tally dt { font-family: var(--mono); font-size: 0.66rem; letter-spacing: 0.09em; text-transform: uppercase; color: var(--ink-3); }
.tally dd { font-family: var(--display); font-size: 1.5rem; font-weight: 600; letter-spacing: -0.02em; }

/* ---------- filters ---------- */
.filters { display: flex; flex-wrap: wrap; gap: 0.4rem; padding: 1.75rem 0 2.25rem; }
.filter {
  padding: 0.42rem 0.85rem; font-family: var(--mono); font-size: 0.72rem; letter-spacing: 0.05em;
  color: var(--ink-2); background: none; border: 1px solid var(--line); border-radius: 7px; cursor: pointer;
  transition: color 0.2s ease, border-color 0.2s ease, background 0.2s ease;
}
.filter:hover { color: var(--ink); border-color: var(--line-hard); }
.filter[aria-pressed='true'] { color: var(--accent); border-color: var(--accent); background: var(--accent-soft); }

/* ---------- footer ---------- */
footer { padding: 2.5rem 0; border-top: 1px solid var(--line-soft); }
.foot { display: flex; justify-content: space-between; align-items: center; gap: 1.5rem; flex-wrap: wrap; }
.foot small { font-size: 0.82rem; color: var(--ink-3); }
.foot nav { display: flex; flex-wrap: wrap; gap: 1.25rem; }
.foot nav a { font-size: 0.82rem; color: var(--ink-3); transition: color 0.22s ease; }
.foot nav a:hover { color: var(--accent); }

/* ---------- reveal (only when JS is running) ---------- */
.js .reveal { opacity: 0; transform: translateY(14px); transition: opacity 0.6s var(--ease), transform 0.6s var(--ease); }
.js .reveal.in { opacity: 1; transform: none; }

/* ---------- responsive ---------- */
@media (max-width: 780px) {
  .nav-links { display: none; }
  .menu-btn { display: flex; }
  .sec-head { flex-direction: column; gap: 0.6rem; align-items: flex-start; }
  .sec-head p { margin-left: 0; text-align: left; }
}
@media (max-width: 640px) {
  .wrap { padding: 0 1.15rem; }
  section { padding: 3.75rem 0; }
  .masthead { padding: 2.75rem 0 2rem; }
  .brand-role { display: none; }
  .tally { gap: 1.5rem 2rem; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { animation-duration: 0.01ms !important; transition-duration: 0.01ms !important; }
  .js .reveal { opacity: 1; transform: none; }
}