/* ============================================================
   0xKxbyte — Design System
   ============================================================ */

:root {
  /* Type */
  --font-display: 'Manrope', 'Segoe UI Variable', 'Segoe UI', -apple-system, sans-serif;
  --font-body: 'Inter', 'Segoe UI Variable', 'Segoe UI', -apple-system, sans-serif;

  /* Scale */
  --fs-hero: clamp(2.6rem, 6vw, 5rem);
  --fs-h2: clamp(2rem, 4vw, 3.2rem);
  --fs-h3: 1.375rem;
  --fs-body: 1.0625rem;
  --fs-small: 0.9rem;
  --fs-micro: 0.78rem;

  /* Layout */
  --container: 1160px;
  --gutter: clamp(1.25rem, 5vw, 3rem);
  --radius-sm: 8px;
  --radius-md: 14px;
  --radius-lg: 22px;
  --section-pad: clamp(4.5rem, 10vw, 8rem);

  /* Motion */
  --ease: cubic-bezier(0.22, 1, 0.36, 1);
  --dur-fast: 0.18s;
  --dur-base: 0.42s;
  --dur-slow: 0.9s;

  /* Accent (brand blue, from mark) */
  --accent-h: 213;
  --accent: hsl(213, 100%, 55%);
  --accent-strong: hsl(213, 100%, 62%);
  --accent-soft: hsl(213, 100%, 55%);
}

/* ---------- Theme: Dark (default) ---------- */
:root,
[data-theme="dark"] {
  --bg: #08090c;
  --bg-elevated: #101217;
  --surface: #14161d;
  --surface-hover: #1a1d26;
  --surface-2: #191b22;
  --border: rgba(255, 255, 255, 0.09);
  --border-strong: rgba(255, 255, 255, 0.16);
  --text-primary: #f2f3f5;
  --text-secondary: #a6acb8;
  --text-tertiary: #6b7180;
  --header-bg: rgba(8, 9, 12, 0.72);
  --scrim: rgba(0, 0, 0, 0.4);
  --shadow-color: rgba(0, 0, 0, 0.5);
  color-scheme: dark;
}

/* ---------- Theme: Light ---------- */
[data-theme="light"] {
  --bg: #fafafb;
  --bg-elevated: #ffffff;
  --surface: #ffffff;
  --surface-hover: #f2f3f5;
  --surface-2: #f3f4f7;
  --border: rgba(15, 17, 22, 0.09);
  --border-strong: rgba(15, 17, 22, 0.16);
  --text-primary: #14161c;
  --text-secondary: #52586a;
  --text-tertiary: #83899a;
  --header-bg: rgba(250, 250, 251, 0.78);
  --scrim: rgba(20, 22, 28, 0.06);
  --shadow-color: rgba(20, 22, 28, 0.12);
  color-scheme: light;
}

/* ============================================================
   Reset
   ============================================================ */
*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--text-primary);
  font-family: var(--font-body);
  font-size: var(--fs-body);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  transition: background-color var(--dur-base) var(--ease), color var(--dur-base) var(--ease);
}
img { max-width: 100%; display: block; }
a { color: inherit; text-decoration: none; }
ul { margin: 0; padding: 0; list-style: none; }
h1, h2, h3, p { margin: 0; }
button { font: inherit; color: inherit; background: none; border: none; cursor: pointer; }

.skip-link {
  position: absolute; left: -999px; top: 0; z-index: 999;
  background: var(--accent); color: #fff; padding: 0.75rem 1.25rem; border-radius: var(--radius-sm);
}
.skip-link:focus { left: 1rem; top: 1rem; }

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

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.001ms !important;
    scroll-behavior: auto !important;
  }
}

/* ============================================================
   Layout helpers
   ============================================================ */
.section-inner, .header-inner, .footer-inner {
  max-width: var(--container);
  margin: 0 auto;
  padding-left: var(--gutter);
  padding-right: var(--gutter);
}
.section { padding: var(--section-pad) 0; }
.section-alt { background: var(--bg-elevated); }
.section-head { margin-bottom: clamp(2rem, 5vw, 3.25rem); max-width: 640px; }

.eyebrow {
  font-family: var(--font-display);
  font-size: var(--fs-micro);
  font-weight: 700;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 0.9rem;
}
.section-title {
  font-family: var(--font-display);
  font-size: var(--fs-h2);
  font-weight: 700;
  letter-spacing: -0.01em;
  line-height: 1.12;
  color: var(--text-primary);
}

/* Scroll reveal */
.reveal {
  opacity: 0;
  transform: translateY(18px);
  transition: opacity var(--dur-slow) var(--ease), transform var(--dur-slow) var(--ease);
}
.reveal.is-visible { opacity: 1; transform: translateY(0); }

/* ============================================================
   Buttons
   ============================================================ */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  padding: 0.85rem 1.6rem;
  border-radius: 999px;
  font-weight: 600;
  font-size: 0.95rem;
  white-space: nowrap;
  transition: background-color var(--dur-fast) var(--ease), color var(--dur-fast) var(--ease),
    border-color var(--dur-fast) var(--ease), transform var(--dur-fast) var(--ease);
}
.btn-primary {
  background: var(--accent);
  color: #ffffff;
}
.btn-primary:hover { background: var(--accent-strong); transform: translateY(-1px); }
.btn-ghost {
  background: transparent;
  color: var(--text-primary);
  border: 1px solid var(--border-strong);
}
.btn-ghost:hover { background: var(--surface-hover); border-color: var(--text-tertiary); }
.btn-small { padding: 0.55rem 1.15rem; font-size: 0.85rem; }

/* ============================================================
   Header
   ============================================================ */
.site-header {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 100;
  background: transparent;
  border-bottom: 1px solid transparent;
  transition: background-color var(--dur-base) var(--ease), border-color var(--dur-base) var(--ease),
    backdrop-filter var(--dur-base) var(--ease);
}
.site-header.is-scrolled {
  background: var(--header-bg);
  border-bottom-color: var(--border);
  backdrop-filter: blur(16px) saturate(140%);
  -webkit-backdrop-filter: blur(16px) saturate(140%);
}
.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 72px;
}
.brand { display: flex; align-items: center; gap: 0.6rem; }
.brand-mark { border-radius: 6px; }
.brand-name {
  font-family: var(--font-display);
  font-weight: 800;
  font-size: 1.05rem;
  letter-spacing: -0.01em;
}
.primary-nav {
  display: flex;
  gap: 2.1rem;
  position: absolute;
  left: 50%;
  transform: translateX(-50%);
}
.primary-nav a {
  font-size: 0.92rem;
  font-weight: 500;
  color: var(--text-secondary);
  position: relative;
  padding: 0.4rem 0.1rem;
  transition: color var(--dur-fast) var(--ease);
}
.primary-nav a::after {
  content: '';
  position: absolute;
  left: 0; right: 100%; bottom: -2px;
  height: 2px;
  background: var(--accent);
  transition: right var(--dur-base) var(--ease);
}
.primary-nav a:hover { color: var(--text-primary); }
.primary-nav a:hover::after { right: 0; }

.header-actions { display: flex; align-items: center; gap: 0.75rem; }
.theme-toggle {
  width: 38px; height: 38px;
  display: grid; place-items: center;
  border-radius: 50%;
  color: var(--text-secondary);
  transition: background-color var(--dur-fast) var(--ease), color var(--dur-fast) var(--ease);
}
.theme-toggle:hover { background: var(--surface-hover); color: var(--text-primary); }
.theme-toggle .icon { width: 19px; height: 19px; }
.icon-moon { display: none; }
[data-theme="light"] .icon-sun { display: none; }
[data-theme="light"] .icon-moon { display: block; }

.header-cta { display: inline-flex; }

.menu-toggle {
  display: none;
  width: 38px; height: 38px;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 5px;
}
.menu-toggle span {
  width: 20px; height: 1.6px;
  background: var(--text-primary);
  border-radius: 2px;
  transition: transform var(--dur-fast) var(--ease), opacity var(--dur-fast) var(--ease);
}
.menu-toggle.is-open span:nth-child(1) { transform: translateY(6.6px) rotate(45deg); }
.menu-toggle.is-open span:nth-child(2) { opacity: 0; }
.menu-toggle.is-open span:nth-child(3) { transform: translateY(-6.6px) rotate(-45deg); }

/* ============================================================
   Hero
   ============================================================ */
.hero {
  position: relative;
  min-height: 100vh;
  display: grid;
  grid-template-columns: 1.05fr 0.95fr;
  align-items: center;
  gap: 2rem;
  max-width: var(--container);
  margin: 0 auto;
  padding: calc(72px + 3rem) var(--gutter) 4rem;
}
.hero-inner { max-width: 620px; }
.hero-title {
  font-family: var(--font-display);
  font-size: var(--fs-hero);
  font-weight: 800;
  letter-spacing: -0.02em;
  line-height: 1.05;
  margin: 0 0 1.5rem;
  color: var(--text-primary);
}
.hero-subtitle {
  font-size: 1.08rem;
  color: var(--text-secondary);
  max-width: 540px;
  margin-bottom: 2.2rem;
}
.hero-actions { display: flex; gap: 0.9rem; flex-wrap: wrap; }

.hero-visual { position: relative; display: flex; align-items: center; justify-content: center; height: 100%; }
.orb-stage { position: relative; width: min(420px, 80vw); aspect-ratio: 1; display: grid; place-items: center; }
.orb-core {
  position: absolute;
  width: 62%; height: 62%;
  border-radius: 50%;
  background: radial-gradient(circle at 32% 28%, hsl(213 100% 68%), hsl(213 100% 45%) 55%, hsl(213 90% 30%) 100%);
  filter: blur(0.3px);
  box-shadow: 0 30px 90px -20px hsla(213, 100%, 50%, 0.55);
  animation: orb-breathe 7s ease-in-out infinite;
}
.orb-ring {
  position: absolute;
  border-radius: 50%;
  border: 1px solid var(--border-strong);
}
.orb-ring-1 { width: 100%; height: 100%; animation: orb-spin 26s linear infinite; }
.orb-ring-2 { width: 82%; height: 82%; border-style: dashed; opacity: 0.5; animation: orb-spin 40s linear infinite reverse; }
.orb-logo {
  position: relative;
  width: 34%;
  filter: drop-shadow(0 12px 30px hsla(213, 100%, 45%, 0.45));
  border-radius: 50%;
  animation: orb-float 6s ease-in-out infinite;
}
@keyframes orb-spin { to { transform: rotate(360deg); } }
@keyframes orb-breathe { 0%, 100% { transform: scale(1); } 50% { transform: scale(1.045); } }
@keyframes orb-float { 0%, 100% { transform: translateY(0); } 50% { transform: translateY(-10px); } }

.scroll-cue {
  position: absolute;
  bottom: 2.2rem; left: 50%;
  transform: translateX(-50%);
  width: 26px; height: 40px;
  border: 1.5px solid var(--border-strong);
  border-radius: 20px;
  display: grid;
  place-items: start center;
  padding-top: 7px;
}
.scroll-cue span {
  width: 3px; height: 7px;
  border-radius: 2px;
  background: var(--text-tertiary);
  animation: cue-drop 1.8s ease-in-out infinite;
}
@keyframes cue-drop {
  0% { opacity: 0; transform: translateY(0); }
  30% { opacity: 1; }
  70% { opacity: 1; }
  100% { opacity: 0; transform: translateY(10px); }
}

/* ============================================================
   About / Experience (text + heading split)
   ============================================================ */
.about-grid, .experience-grid {
  display: grid;
  grid-template-columns: 0.85fr 1.15fr;
  gap: clamp(2rem, 6vw, 5rem);
  align-items: start;
}
.about-body, .experience-body { color: var(--text-secondary); }
.about-body p, .experience-body p { margin-bottom: 1.15rem; }
.about-body p:last-child, .experience-body p:last-child { margin-bottom: 0; }
.experience-note {
  padding-top: 1rem;
  border-top: 1px solid var(--border);
  font-size: 0.92rem;
  color: var(--text-tertiary);
}

/* ============================================================
   Skills
   ============================================================ */
.skills-panel { border: 1px solid var(--border); border-radius: var(--radius-lg); background: var(--surface); overflow: hidden; }
.skills-tabs {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
  padding: 1.1rem 1.25rem;
  border-bottom: 1px solid var(--border);
}
.skills-tab {
  padding: 0.55rem 1.05rem;
  border-radius: 999px;
  font-size: 0.86rem;
  font-weight: 600;
  color: var(--text-secondary);
  transition: background-color var(--dur-fast) var(--ease), color var(--dur-fast) var(--ease);
}
.skills-tab:hover { color: var(--text-primary); background: var(--surface-hover); }
.skills-tab.is-active { background: var(--accent); color: #fff; }

.skills-panels { padding: 2rem clamp(1.25rem, 4vw, 2.75rem) 2.4rem; }
.skills-panel-content { display: none; }
.skills-panel-content.is-active { display: block; animation: panel-in var(--dur-base) var(--ease); }
@keyframes panel-in { from { opacity: 0; transform: translateY(6px); } to { opacity: 1; transform: translateY(0); } }
.skills-desc { color: var(--text-secondary); margin-bottom: 1.4rem; font-size: 0.95rem; }
.skills-list { display: flex; flex-wrap: wrap; gap: 0.6rem; }
.skills-list li {
  padding: 0.55rem 1rem;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  font-size: 0.88rem;
  font-weight: 500;
  color: var(--text-primary);
  background: var(--surface-2);
}

/* ============================================================
   Empty state (Projects)
   ============================================================ */
.empty-state {
  border: 1px dashed var(--border-strong);
  border-radius: var(--radius-lg);
  padding: clamp(2.5rem, 6vw, 4.5rem) 2rem;
  text-align: center;
  max-width: 560px;
  margin: 0 auto;
}
.empty-state-mark {
  width: 52px; height: 52px;
  margin: 0 auto 1.4rem;
  color: var(--accent);
}
.empty-state h3 {
  font-family: var(--font-display);
  font-size: 1.25rem;
  font-weight: 700;
  margin-bottom: 0.6rem;
}
.empty-state p { color: var(--text-secondary); }

/* ============================================================
   Content / Social
   ============================================================ */
.content-grid { display: grid; grid-template-columns: 0.85fr 1.15fr; gap: clamp(2rem, 6vw, 5rem); align-items: start; }
.content-body { color: var(--text-secondary); }
.content-body > p { margin-bottom: 1.8rem; }
.social-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 0.85rem; margin-bottom: 1.6rem; }
.social-card {
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
  padding: 1.1rem 1.25rem;
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  background: var(--surface);
  transition: border-color var(--dur-fast) var(--ease), transform var(--dur-fast) var(--ease), background-color var(--dur-fast) var(--ease);
}
.social-card:hover { border-color: var(--accent); transform: translateY(-2px); background: var(--surface-hover); }
.social-label { font-family: var(--font-display); font-weight: 700; font-size: 0.95rem; color: var(--text-primary); }
.social-handle { font-size: 0.85rem; color: var(--text-tertiary); }
.text-link { color: var(--accent); font-weight: 600; font-size: 0.95rem; }
.text-link:hover { text-decoration: underline; }

/* ============================================================
   Contact
   ============================================================ */
.section-contact { padding-bottom: clamp(5rem, 12vw, 9rem); }
.contact-panel {
  border-radius: var(--radius-lg);
  border: 1px solid var(--border);
  background: linear-gradient(155deg, var(--surface) 0%, var(--bg-elevated) 100%);
  padding: clamp(2.5rem, 7vw, 5rem);
  text-align: center;
  max-width: 720px;
  margin: 0 auto;
}
.contact-sub { color: var(--text-secondary); margin: 1.1rem auto 2.2rem; max-width: 420px; }
.contact-actions { display: flex; gap: 1rem; justify-content: center; flex-wrap: wrap; }

/* ============================================================
   Footer
   ============================================================ */
.site-footer { border-top: 1px solid var(--border); padding: 3rem 0 1.5rem; }
.footer-inner {
  display: flex;
  flex-wrap: wrap;
  gap: 1.5rem;
  align-items: center;
  justify-content: space-between;
  padding-bottom: 2rem;
}
.footer-brand { display: flex; align-items: center; gap: 0.55rem; font-family: var(--font-display); font-weight: 700; }
.footer-nav { display: flex; gap: 1.4rem; flex-wrap: wrap; }
.footer-nav a, .footer-social a { font-size: 0.88rem; color: var(--text-secondary); }
.footer-nav a:hover, .footer-social a:hover { color: var(--text-primary); }
.footer-social { display: flex; gap: 1.2rem; flex-wrap: wrap; }
.footer-bottom {
  max-width: var(--container);
  margin: 0 auto;
  padding: 1.4rem var(--gutter) 0;
  border-top: 1px solid var(--border);
  font-size: 0.82rem;
  color: var(--text-tertiary);
}

/* ============================================================
   Help widget
   ============================================================ */
.help-widget { position: fixed; right: clamp(1rem, 4vw, 2rem); bottom: clamp(1rem, 4vw, 2rem); z-index: 200; }
.help-fab {
  width: 56px; height: 56px;
  border-radius: 50%;
  background: var(--accent);
  color: #fff;
  display: grid;
  place-items: center;
  box-shadow: 0 14px 30px -10px hsla(213, 100%, 45%, 0.6);
  transition: transform var(--dur-fast) var(--ease), background-color var(--dur-fast) var(--ease);
}
.help-fab:hover { transform: translateY(-2px) scale(1.03); background: var(--accent-strong); }
.help-fab svg { width: 24px; height: 24px; }
.help-fab .icon-close { display: none; }
.help-widget.is-open .help-fab .icon-help { display: none; }
.help-widget.is-open .help-fab .icon-close { display: block; }

.help-panel {
  position: absolute;
  bottom: 70px; right: 0;
  width: min(340px, 84vw);
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  box-shadow: 0 30px 60px -15px var(--shadow-color);
  overflow: hidden;
  opacity: 0;
  transform: translateY(12px) scale(0.98);
  pointer-events: none;
  transition: opacity var(--dur-base) var(--ease), transform var(--dur-base) var(--ease);
}
.help-widget.is-open .help-panel { opacity: 1; transform: translateY(0) scale(1); pointer-events: auto; }

.help-panel-header {
  display: flex; align-items: center; justify-content: space-between;
  padding: 1.1rem 1.25rem;
  border-bottom: 1px solid var(--border);
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 0.95rem;
}
.help-panel-header button { width: 26px; height: 26px; display: grid; place-items: center; color: var(--text-secondary); border-radius: 50%; }
.help-panel-header button:hover { background: var(--surface-hover); }
.help-panel-header button svg { width: 16px; height: 16px; }

.help-panel-body { padding: 1.1rem 1.25rem 1.3rem; max-height: 360px; overflow-y: auto; }
.help-intro { font-size: 0.85rem; color: var(--text-tertiary); margin-bottom: 0.9rem; }
.help-questions { display: flex; flex-direction: column; gap: 0.5rem; }
.help-question {
  text-align: left;
  padding: 0.7rem 0.9rem;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  font-size: 0.87rem;
  color: var(--text-primary);
  transition: border-color var(--dur-fast) var(--ease), background-color var(--dur-fast) var(--ease);
}
.help-question:hover { border-color: var(--accent); background: var(--surface-hover); }
.help-answer {
  margin-top: 0.9rem;
  padding: 0.9rem 1rem;
  border-radius: var(--radius-sm);
  background: var(--surface-2);
  font-size: 0.87rem;
  color: var(--text-secondary);
  border-left: 2px solid var(--accent);
  animation: panel-in var(--dur-base) var(--ease);
}
.help-back {
  margin-top: 0.9rem;
  font-size: 0.82rem;
  font-weight: 600;
  color: var(--accent);
}

/* ============================================================
   Responsive
   ============================================================ */
@media (max-width: 980px) {
  .about-grid, .experience-grid, .content-grid { grid-template-columns: 1fr; }
  .hero { grid-template-columns: 1fr; text-align: left; }
  .hero-visual { order: -1; height: 260px; margin-bottom: 1rem; }
  .orb-stage { width: 220px; }
}

@media (max-width: 820px) {
  .primary-nav {
    position: fixed;
    top: 72px; left: 0; right: 0;
    background: var(--bg-elevated);
    border-bottom: 1px solid var(--border);
    flex-direction: column;
    align-items: flex-start;
    gap: 0;
    padding: 0.5rem var(--gutter) 1rem;
    transform: translateY(-8px);
    opacity: 0;
    visibility: hidden;
    transition: opacity var(--dur-base) var(--ease), transform var(--dur-base) var(--ease), visibility var(--dur-base);
  }
  .primary-nav.is-open { opacity: 1; transform: translateY(0); visibility: visible; }
  .primary-nav a { width: 100%; padding: 0.85rem 0; border-bottom: 1px solid var(--border); }
  .primary-nav a::after { display: none; }
  .menu-toggle { display: flex; }
  .header-cta { display: none; }
  .social-grid { grid-template-columns: 1fr; }
}

@media (max-width: 560px) {
  .contact-actions { flex-direction: column; align-items: stretch; }
  .contact-actions .btn { width: 100%; }
  .help-panel { width: min(320px, 88vw); }
}