/* ==========================================================================
   Mert Yavuz — Portfolyo
   Koyu, terminal/hacker esintili tema — fosfor yeşili vurgular, tarama
   çizgileri, monospace dokunuşlar. Tek amaç: okunabilir, hızlı, kolay bakım.
   ========================================================================== */

:root {
  --bg: #060907;
  --bg-alt: #0a0f0a;
  --card: #0d130e;
  --card-border: rgba(0, 255, 106, 0.16);
  --text: #e7f5ea;
  --text-dim: #93ac97;
  --text-faint: #57685b;
  --accent: #00ff6a;
  --accent-2: #ff3b5c;
  --accent-soft: rgba(0, 255, 106, 0.12);
  --accent-glow: rgba(0, 255, 106, 0.45);
  --radius: 14px;
  --max-width: 1080px;
  --font-body: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-head: 'Sora', 'Inter', -apple-system, sans-serif;
  --font-mono: 'SF Mono', 'Fira Code', Consolas, 'Courier New', monospace;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  position: relative;
}

::selection {
  background: var(--accent);
  color: #04140a;
}

/* ---- CRT tarama çizgileri (scanlines) ------------------------------------------------------------- */

body::after {
  content: "";
  position: fixed;
  inset: 0;
  z-index: 9999;
  pointer-events: none;
  background-image: repeating-linear-gradient(
    to bottom,
    rgba(0, 0, 0, 0.14) 0px,
    rgba(0, 0, 0, 0.14) 1px,
    transparent 1px,
    transparent 3px
  );
  opacity: 0.35;
  mix-blend-mode: overlay;
}

@media (max-width: 720px) {
  body::after { display: none; }
}

.wrap {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 24px;
}

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

/* ---- language toggle ------------------------------------------------- */

.lang-en { display: none; }
body.lang-mode-en .lang-en { display: inline; }
body.lang-mode-en .lang-tr { display: none; }

/* ---- skip link ---------------------------------------------------------- */

.skip-link {
  position: absolute;
  left: -9999px;
  top: 0;
  background: var(--accent);
  color: #06251f;
  padding: 10px 16px;
  border-radius: 0 0 8px 0;
  font-weight: 600;
  z-index: 100;
}
.skip-link:focus { left: 0; }

/* ---- header -------------------------------------------------------------- */

.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  background: rgba(10, 12, 16, 0.72);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--card-border);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  height: 68px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 10px;
  text-decoration: none;
  color: var(--text);
  font-family: var(--font-head);
  font-weight: 700;
}

.brand-mark {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 34px;
  height: 34px;
  border-radius: 9px;
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  color: #06121a;
  font-size: 13px;
  font-weight: 800;
  letter-spacing: 0.02em;
}

.brand-name { font-size: 16px; }

.main-nav {
  display: flex;
  gap: 28px;
}

.main-nav a {
  color: var(--text-dim);
  text-decoration: none;
  font-family: var(--font-mono);
  font-size: 13.5px;
  font-weight: 500;
  transition: color 0.15s ease;
}

.main-nav a::before { content: "./"; opacity: 0.55; }

.main-nav a:hover { color: var(--text); }

.main-nav a.active { color: var(--accent); }

.header-actions {
  display: flex;
  align-items: center;
  gap: 14px;
}

.lang-toggle {
  display: flex;
  align-items: center;
  background: var(--card);
  border: 1px solid var(--card-border);
  border-radius: 999px;
  padding: 3px;
  cursor: pointer;
  font-family: var(--font-body);
}

.lang-opt {
  padding: 5px 12px;
  font-size: 12.5px;
  font-weight: 700;
  letter-spacing: 0.03em;
  border-radius: 999px;
  color: var(--text-faint);
  transition: background 0.15s ease, color 0.15s ease;
}

body:not(.lang-mode-en) .lang-toggle .lang-opt[data-lang="tr"],
body.lang-mode-en .lang-toggle .lang-opt[data-lang="en"] {
  background: var(--accent-soft);
  color: var(--accent);
}

/* lang-toggle's own labels must always show (override the global .lang-en rule) */
.lang-toggle .lang-opt { display: inline-block !important; }

.nav-toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 4px;
  width: 34px;
  height: 34px;
  background: none;
  border: none;
  cursor: pointer;
}
.nav-toggle span {
  display: block;
  height: 2px;
  background: var(--text);
  border-radius: 2px;
}

/* ---- buttons ------------------------------------------------------------- */

.btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 12px 22px;
  border-radius: 999px;
  font-family: var(--font-mono);
  font-weight: 600;
  font-size: 13.5px;
  text-decoration: none;
  border: 1px solid transparent;
  transition: transform 0.15s ease, opacity 0.15s ease, border-color 0.15s ease, box-shadow 0.15s ease;
}
.btn:hover { transform: translateY(-1px); }

.btn-primary {
  background: var(--accent);
  color: #04140a;
  box-shadow: 0 0 0 rgba(0, 255, 106, 0);
}
.btn-primary:hover {
  opacity: 0.92;
  box-shadow: 0 0 22px var(--accent-glow);
}

.btn-ghost {
  background: transparent;
  color: var(--text);
  border-color: var(--card-border);
}
.btn-ghost:hover { border-color: var(--accent); color: var(--accent); }

.btn-text {
  color: var(--text-dim);
  padding: 12px 6px;
}
.btn-text:hover { color: var(--accent); }

/* ---- hero ------------------------------------------------------------- */

.hero {
  position: relative;
  padding: 120px 0 96px;
  overflow: hidden;
}

.hero-bg {
  position: absolute;
  inset: 0;
  background-image:
    radial-gradient(circle at 18% 20%, rgba(0, 255, 106, 0.16), transparent 42%),
    radial-gradient(circle at 82% 0%, rgba(255, 59, 92, 0.09), transparent 45%),
    linear-gradient(rgba(0, 255, 106, 0.05) 1px, transparent 1px),
    linear-gradient(90deg, rgba(0, 255, 106, 0.05) 1px, transparent 1px);
  background-size: auto, auto, 42px 42px, 42px 42px;
  mask-image: linear-gradient(to bottom, black, transparent 92%);
  pointer-events: none;
}

.hero-canvas {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  opacity: 0.55;
  pointer-events: none;
}

.hero-inner {
  position: relative;
  display: grid;
  grid-template-columns: 1.15fr 0.85fr;
  gap: 40px;
  align-items: center;
}

/* ---- identity badges ------------------------------------------------- */

.identity-badges {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin: 0 0 26px;
}

.id-badge {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  background: var(--card);
  border: 1px solid var(--card-border);
  color: var(--text-dim);
  font-family: var(--font-mono);
  font-size: 12.5px;
  font-weight: 600;
  padding: 7px 13px 7px 10px;
  border-radius: 999px;
}

.id-badge svg {
  width: 15px;
  height: 15px;
  color: var(--accent);
  flex-shrink: 0;
}

/* ---- hero terminal ------------------------------------------------- */

.hero-terminal {
  background: #050805;
  border: 1px solid var(--card-border);
  border-radius: var(--radius);
  overflow: hidden;
  box-shadow: 0 24px 60px -24px rgba(0, 0, 0, 0.75), 0 0 40px -20px var(--accent-glow);
}

.terminal-titlebar {
  display: flex;
  align-items: center;
  gap: 7px;
  padding: 12px 14px;
  border-bottom: 1px solid var(--card-border);
  background: #070b07;
}

.terminal-status {
  margin-left: auto;
  display: inline-flex;
  align-items: center;
  gap: 6px;
  color: var(--accent);
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 600;
  letter-spacing: 0.04em;
}

.terminal-status-dot {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--accent);
  box-shadow: 0 0 6px var(--accent-glow);
}

@media (prefers-reduced-motion: no-preference) {
  .terminal-status-dot { animation: term-blink 1.6s ease-in-out infinite; }
}

.term-dot {
  width: 10px;
  height: 10px;
  border-radius: 50%;
  display: inline-block;
}
.term-dot-r { background: #ff5f57; }
.term-dot-y { background: #febc2e; }
.term-dot-g { background: #28c840; }

.terminal-title {
  margin-left: 6px;
  color: var(--text-faint);
  font-size: 12.5px;
  font-family: 'SF Mono', 'Fira Code', Consolas, monospace;
}

.terminal-body {
  margin: 0;
  padding: 20px 18px 24px;
  min-height: 220px;
  color: #6dffa0;
  font-family: var(--font-mono);
  font-size: 13.5px;
  line-height: 1.7;
  white-space: pre-wrap;
  word-break: break-word;
  text-shadow: 0 0 8px rgba(0, 255, 106, 0.25);
}

.term-line { min-height: 1.7em; }
.term-line.term-prompt { color: var(--accent); font-weight: 600; margin-top: 10px; }
.term-line.term-prompt:first-child { margin-top: 0; }
.term-line.term-output { color: #6dffa0; opacity: 0.85; }

.terminal-cursor {
  display: inline-block;
  width: 7px;
  height: 14px;
  background: var(--accent);
  margin-left: 2px;
  vertical-align: middle;
  animation: term-blink 1s step-end infinite;
}

@keyframes term-blink {
  0%, 49% { opacity: 1; }
  50%, 100% { opacity: 0; }
}

/* ==========================================================================
   KOD TERMİNALİ — deneysel bölüm (kolayca geri alınabilir)
   Kaldırmak için: bu blok ile eşleşen "/KOD TERMİNALİ" yorumuna kadar
   olan CSS'i sil. HTML tarafı index.html'de, JS tarafı js/script.js
   içinde aynı şekilde işaretli.
   ========================================================================== */

.code-terminal-section {
  padding: 56px 0 8px;
  display: flex;
  justify-content: center;
}

.code-terminal-wrap {
  width: 100%;
  max-width: 680px;
  margin: 0 auto;
}

.code-terminal {
  margin: 0 auto;
}

.code-terminal-body {
  max-height: 300px;
  overflow: hidden;
  padding: 18px 18px 20px;
  font-size: 12.5px;
  line-height: 1.65;
}

.code-terminal-body .term-line {
  min-height: 1.65em;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.code-terminal-body .term-line.term-file {
  color: var(--accent-2);
  opacity: 0.85;
  margin-top: 10px;
  font-weight: 600;
}
.code-terminal-body .term-line.term-file:first-child { margin-top: 0; }

.code-terminal-body .term-line.term-code {
  color: #6dffa0;
}

.code-terminal .terminal-title {
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

@media (max-width: 640px) {
  .code-terminal-body { max-height: 240px; font-size: 11px; padding: 15px 15px 17px; }
  .code-terminal .terminal-title { max-width: 150px; min-width: 0; }
}

/* ==========================================================================
   /KOD TERMİNALİ
   ========================================================================== */

.eyebrow {
  color: var(--accent);
  font-family: var(--font-mono);
  font-weight: 600;
  font-size: 13.5px;
  margin: 0 0 10px;
  letter-spacing: 0.02em;
}

.eyebrow::before { content: "> "; opacity: 0.7; }

.hero h1 {
  position: relative;
  font-family: var(--font-head);
  font-size: clamp(2.4rem, 6vw, 4rem);
  margin: 0 0 14px;
  line-height: 1.05;
  letter-spacing: -0.02em;
  text-shadow: 0 0 18px var(--accent-glow);
}

@media (prefers-reduced-motion: no-preference) {
  .hero h1[data-text]::before,
  .hero h1[data-text]::after {
    content: attr(data-text);
    position: absolute;
    inset: 0;
    background: var(--bg);
    clip-path: inset(50% 0 50% 0);
  }
  .hero h1[data-text]::before {
    left: 2px;
    color: var(--accent-2);
    animation: glitch-1 7s infinite linear;
  }
  .hero h1[data-text]::after {
    left: -2px;
    color: var(--accent);
    animation: glitch-2 7s infinite linear;
  }

  @keyframes glitch-1 {
    0%, 94%, 100% { clip-path: inset(50% 0 50% 0); transform: translate(0); }
    95% { clip-path: inset(20% 0 65% 0); transform: translate(-3px, -1px); }
    96% { clip-path: inset(70% 0 8% 0); transform: translate(3px, 1px); }
    97% { clip-path: inset(40% 0 45% 0); transform: translate(-2px, 0); }
    98% { clip-path: inset(50% 0 50% 0); transform: translate(0); }
  }
  @keyframes glitch-2 {
    0%, 93%, 100% { clip-path: inset(50% 0 50% 0); transform: translate(0); }
    94% { clip-path: inset(10% 0 75% 0); transform: translate(3px, 0); }
    95% { clip-path: inset(60% 0 15% 0); transform: translate(-3px, 1px); }
    96% { clip-path: inset(35% 0 55% 0); transform: translate(2px, -1px); }
    97% { clip-path: inset(50% 0 50% 0); transform: translate(0); }
  }
}

.hero-role {
  font-family: var(--font-head);
  font-size: clamp(1.1rem, 2.4vw, 1.4rem);
  color: var(--text-dim);
  margin: 0 0 22px;
  font-weight: 600;
}

.hero-desc {
  max-width: 640px;
  color: var(--text-dim);
  font-size: 16.5px;
  margin: 0 0 34px;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
}

/* ---- sections ------------------------------------------------------------ */

.section { padding: 88px 0; }
.section-alt { background: var(--bg-alt); }

.section-label {
  font-family: var(--font-mono);
  color: var(--accent);
  font-weight: 700;
  font-size: 13px;
  letter-spacing: 0.06em;
  margin: 0 0 10px;
}

.section-label::before { content: "[ "; opacity: 0.6; }
.section-label::after { content: " ]"; opacity: 0.6; }

.section h2 {
  font-family: var(--font-head);
  font-size: clamp(1.6rem, 3.4vw, 2.1rem);
  margin: 0 0 28px;
  letter-spacing: -0.01em;
}

.section-intro {
  color: var(--text-dim);
  max-width: 640px;
  margin: -14px 0 32px;
}

/* ---- about ------------------------------------------------------------- */

.about-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 32px;
}

.about-text {
  color: var(--text-dim);
  font-size: 16px;
  margin: 0;
}

/* ---- interests marquee ------------------------------------------------------------- */

.interests-section {
  padding: 40px 0 56px;
  border-bottom: 1px solid var(--card-border);
}

.interests-label {
  text-align: center;
  color: var(--text-faint);
  font-size: 12.5px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  margin: 0 0 20px;
}

.marquee {
  overflow: hidden;
  mask-image: linear-gradient(90deg, transparent, black 8%, black 92%, transparent);
  -webkit-mask-image: linear-gradient(90deg, transparent, black 8%, black 92%, transparent);
}

.marquee-track {
  display: flex;
  width: max-content;
  animation: marquee-scroll 34s linear infinite;
}

.marquee:hover .marquee-track { animation-play-state: paused; }

.marquee-copy {
  display: flex;
  gap: 14px;
  padding-right: 14px;
  flex-shrink: 0;
}

.marquee-item {
  display: inline-flex;
  align-items: center;
  white-space: nowrap;
  background: var(--card);
  border: 1px solid var(--card-border);
  color: var(--text-dim);
  font-family: var(--font-mono);
  font-size: 13px;
  font-weight: 600;
  padding: 10px 18px;
  border-radius: 999px;
}

.marquee-item::before { content: "# "; color: var(--accent); opacity: 0.8; }

@keyframes marquee-scroll {
  from { transform: translateX(0); }
  to { transform: translateX(-50%); }
}

/* ---- skills ------------------------------------------------------------- */

.skills-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 18px;
}

.skill-card {
  background: var(--card);
  border: 1px solid var(--card-border);
  border-radius: var(--radius);
  padding: 22px;
}

.skill-card h3 {
  font-family: var(--font-head);
  font-size: 15px;
  margin: 0 0 14px;
  color: var(--text);
  display: flex;
  align-items: center;
  gap: 10px;
}

.skill-icon {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 30px;
  height: 30px;
  flex-shrink: 0;
  border-radius: 8px;
  background: var(--accent-soft);
  color: var(--accent);
}

.skill-icon svg { width: 16px; height: 16px; }

.tags {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.tag {
  background: var(--bg-alt);
  border: 1px solid var(--card-border);
  color: var(--text-dim);
  font-family: var(--font-mono);
  font-size: 12px;
  padding: 5px 11px;
  border-radius: 999px;
}

.skill-card .tag { background: var(--bg); }

/* ---- timeline ------------------------------------------------------------- */

.timeline {
  position: relative;
  padding-left: 28px;
  border-left: 1px solid var(--card-border);
}

.timeline-item { position: relative; padding-bottom: 40px; }
.timeline-item:last-child { padding-bottom: 0; }

.timeline-dot {
  position: absolute;
  left: -33px;
  top: 4px;
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: var(--accent);
  box-shadow: 0 0 0 4px var(--accent-soft);
}

.timeline-head {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 8px 16px;
}

.timeline-head h3 {
  font-family: var(--font-head);
  font-size: 17px;
  margin: 0;
}

.timeline-date {
  color: var(--text-faint);
  font-size: 13px;
  font-weight: 600;
  white-space: nowrap;
}

.timeline-org {
  color: var(--accent);
  font-size: 14px;
  font-weight: 600;
  margin: 4px 0 12px;
}

.timeline-content ul {
  margin: 0;
  padding-left: 18px;
  color: var(--text-dim);
  font-size: 14.5px;
}

.timeline-content li { margin-bottom: 6px; }
.timeline-content li:last-child { margin-bottom: 0; }

/* ---- education ------------------------------------------------------------- */

.edu-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 18px;
}

.edu-card {
  background: var(--card);
  border: 1px solid var(--card-border);
  border-radius: var(--radius);
  padding: 22px;
}

.edu-card h3 {
  font-family: var(--font-head);
  font-size: 15.5px;
  margin: 0 0 8px;
}

.edu-card p {
  color: var(--text-dim);
  font-size: 14px;
  margin: 0 0 10px;
}

/* ---- projects ------------------------------------------------------------- */

.projects-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 20px;
}

.project-card {
  background: var(--card);
  border: 1px solid var(--card-border);
  border-radius: var(--radius);
  overflow: hidden;
  display: flex;
  flex-direction: column;
  transition: border-color 0.15s ease, transform 0.15s ease;
}

.project-card:hover {
  border-color: var(--accent);
  transform: translateY(-2px);
}

.project-card-media {
  aspect-ratio: 16 / 9;
  background: var(--bg-alt);
  overflow: hidden;
}
.project-card-media img { width: 100%; height: 100%; object-fit: cover; }

.project-card-body {
  padding: 20px;
  display: flex;
  flex-direction: column;
  gap: 10px;
  flex: 1;
}

.project-card-head {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 10px;
}

.project-card h3 {
  font-family: var(--font-head);
  font-size: 16.5px;
  margin: 0;
}

.project-card-date {
  color: var(--text-faint);
  font-size: 12.5px;
  white-space: nowrap;
}

.project-card p.project-desc {
  color: var(--text-dim);
  font-size: 14px;
  margin: 0;
  flex: 1;
}

.project-card-links {
  display: flex;
  gap: 14px;
  margin-top: 4px;
}

.project-card-links a {
  color: var(--accent);
  font-size: 13.5px;
  font-weight: 600;
  text-decoration: none;
}
.project-card-links a:hover { text-decoration: underline; }

.projects-empty {
  text-align: center;
  color: var(--text-faint);
  border: 1px dashed var(--card-border);
  border-radius: var(--radius);
  padding: 48px 24px;
  font-size: 14.5px;
}
.projects-empty code {
  background: var(--card);
  border: 1px solid var(--card-border);
  padding: 2px 7px;
  border-radius: 6px;
  font-size: 13px;
  color: var(--accent);
}
.projects-empty a {
  color: var(--accent);
  font-family: var(--font-mono);
  font-weight: 600;
  text-decoration: none;
  border-bottom: 1px dashed var(--accent);
}
.projects-empty a:hover { border-bottom-style: solid; }

/* ---- contact ------------------------------------------------------------- */

.contact-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 16px;
}

.contact-card {
  display: flex;
  flex-direction: column;
  gap: 6px;
  background: var(--card);
  border: 1px solid var(--card-border);
  border-radius: var(--radius);
  padding: 20px 22px;
  text-decoration: none;
  color: var(--text);
  transition: border-color 0.15s ease, transform 0.15s ease;
}
a.contact-card:hover { border-color: var(--accent); transform: translateY(-2px); }

.contact-label {
  color: var(--text-faint);
  font-size: 12.5px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
}

.contact-value {
  font-size: 15.5px;
  font-weight: 600;
}

/* ---- footer ------------------------------------------------------------- */

.site-footer {
  border-top: 1px solid var(--card-border);
  padding: 28px 0;
}

.footer-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  color: var(--text-faint);
  font-size: 13.5px;
}

.footer-inner p { margin: 0; }

.back-to-top {
  color: var(--text-faint);
  text-decoration: none;
}
.back-to-top:hover { color: var(--accent); }

/* ---- reveal-on-scroll ------------------------------------------------------------- */

@media (prefers-reduced-motion: no-preference) {
  .reveal {
    opacity: 0;
    transform: translateY(18px);
    transition: opacity 0.6s ease, transform 0.6s ease;
  }
  .reveal.in-view { opacity: 1; transform: translateY(0); }

  .skills-grid .reveal:nth-child(2) { transition-delay: 0.06s; }
  .skills-grid .reveal:nth-child(3) { transition-delay: 0.12s; }
  .skills-grid .reveal:nth-child(4) { transition-delay: 0.18s; }
  .skills-grid .reveal:nth-child(5) { transition-delay: 0.24s; }
  .skills-grid .reveal:nth-child(6) { transition-delay: 0.3s; }

  .edu-grid .reveal:nth-child(2),
  .contact-grid .reveal:nth-child(2) { transition-delay: 0.08s; }
  .contact-grid .reveal:nth-child(3) { transition-delay: 0.16s; }

  .projects-grid .reveal:nth-child(2) { transition-delay: 0.06s; }
  .projects-grid .reveal:nth-child(3) { transition-delay: 0.12s; }
}

/* ---- scroll-to-top button ------------------------------------------------------------- */

.scroll-top-btn {
  position: fixed;
  right: 22px;
  bottom: 22px;
  width: 44px;
  height: 44px;
  border-radius: 50%;
  background: var(--card);
  border: 1px solid var(--card-border);
  color: var(--text);
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  opacity: 0;
  transform: translateY(10px);
  pointer-events: none;
  transition: opacity 0.2s ease, transform 0.2s ease, border-color 0.15s ease;
  z-index: 40;
}

.scroll-top-btn svg { width: 18px; height: 18px; }

.scroll-top-btn.visible {
  opacity: 1;
  transform: translateY(0);
  pointer-events: auto;
}

.scroll-top-btn:hover { border-color: var(--accent); color: var(--accent); }

/* ---- responsive ------------------------------------------------------------- */

@media (max-width: 980px) {
  .hero-inner { grid-template-columns: 1fr; }
  .hero-terminal { max-width: 560px; }
}

@media (max-width: 860px) {
  .about-grid { grid-template-columns: 1fr; }
}

@media (max-width: 720px) {
  .main-nav {
    position: absolute;
    top: 68px;
    left: 0;
    right: 0;
    background: var(--bg);
    border-bottom: 1px solid var(--card-border);
    flex-direction: column;
    padding: 12px 24px 20px;
    gap: 4px;
    display: none;
  }
  .main-nav.open { display: flex; }
  .main-nav a { padding: 10px 0; }
  .nav-toggle { display: flex; }
  .hero { padding: 96px 0 64px; }
  .section { padding: 64px 0; }
  .terminal-body { min-height: 180px; font-size: 12.5px; }
  .scroll-top-btn { right: 16px; bottom: 16px; }
}