/* ============================================================
   yonchelee.com — shared design system
   Apple-style: oversized type, full-bleed bands, frosted glass,
   light/dark via :root[data-theme]. All tokens prefixed --yl-
   so legacy per-page :root vars never collide during migration.
   ============================================================ */

:root{
  color-scheme:light;
  /* surfaces */
  --yl-bg:#FFFFFF;
  --yl-bg-band:#F5F5F7;
  --yl-bg-elev:#FFFFFF;
  --yl-nav-glass:rgba(251,251,253,.8);
  /* ink */
  --yl-ink:#1D1D1F;
  --yl-ink-2:#424245;
  --yl-ink-3:#6E6E73;
  --yl-ink-4:#86868B;
  /* lines & shadow */
  --yl-hairline:rgba(0,0,0,.1);
  --yl-hairline-soft:rgba(0,0,0,.06);
  --yl-shadow:0 8px 30px rgba(0,0,0,.08);
  --yl-shadow-lift:0 20px 50px rgba(0,0,0,.12);
  /* accent (shared by both themes) */
  --yl-accent:linear-gradient(100deg,#FF6A00 0%,#EE0979 40%,#B63CE1 70%,#4F46E5 100%);
  --yl-accent-solid:#EE0979;
  --yl-link:#0066CC;
  /* type */
  --yl-font:'Pretendard Variable',Pretendard,-apple-system,BlinkMacSystemFont,system-ui,Roboto,sans-serif;
  --yl-mono:'DM Mono','JetBrains Mono',ui-monospace,monospace;
  --yl-display:clamp(48px,9vw,96px);
  --yl-title:clamp(32px,6vw,56px);
  --yl-headline:clamp(24px,4vw,32px);
  --yl-body:17px;
  --yl-caption:12px;
  /* misc */
  --yl-r:18px;
  --yl-r-sm:12px;
  --yl-t:.35s cubic-bezier(.16,1,.3,1);
}
:root[data-theme="dark"]{
  color-scheme:dark;
  --yl-bg:#000000;
  --yl-bg-band:#161617;
  --yl-bg-elev:#1D1D1F;
  --yl-nav-glass:rgba(22,22,23,.8);
  --yl-ink:#F5F5F7;
  --yl-ink-2:#D2D2D7;
  --yl-ink-3:#A1A1A6;
  --yl-ink-4:#86868B;
  --yl-hairline:rgba(255,255,255,.14);
  --yl-hairline-soft:rgba(255,255,255,.08);
  --yl-shadow:0 8px 30px rgba(0,0,0,.6);
  --yl-shadow-lift:0 20px 50px rgba(0,0,0,.7);
  --yl-link:#2997FF;
}

/* ---------- base ---------- */
*,*::before,*::after{margin:0;padding:0;box-sizing:border-box}
html{scroll-behavior:smooth;-webkit-text-size-adjust:100%}
body.yl-body{
  font-family:var(--yl-font);
  background:var(--yl-bg);
  color:var(--yl-ink);
  font-size:var(--yl-body);
  line-height:1.6;
  letter-spacing:-.011em;
  -webkit-font-smoothing:antialiased;
  min-height:100vh;
  transition:background-color .4s ease,color .4s ease;
}
.yl-body ::selection{background:var(--yl-ink);color:var(--yl-bg)}
.yl-body ::-webkit-scrollbar{width:8px}
.yl-body ::-webkit-scrollbar-track{background:transparent}
.yl-body ::-webkit-scrollbar-thumb{background:var(--yl-ink-4);border-radius:4px}

/* ---------- language toggle rules (shared bilingual system) ---------- */
[data-en]{display:none}
html.en [data-ko]{display:none!important}
html.en [data-en]{display:inline}
html.en span[data-en],html.en strong[data-en],html.en em[data-en]{display:inline}
html.en div[data-en],html.en p[data-en],html.en li[data-en],html.en h1[data-en],html.en h2[data-en],html.en h3[data-en]{display:block}

/* ---------- nav ---------- */
nav.yl-nav{
  position:fixed;top:0;left:0;right:0;z-index:999;
  height:48px;padding:0 max(22px,env(safe-area-inset-left));
  display:flex;align-items:center;gap:26px;
  background:var(--yl-nav-glass);
  backdrop-filter:blur(20px) saturate(180%);
  -webkit-backdrop-filter:blur(20px) saturate(180%);
  border-bottom:1px solid var(--yl-hairline-soft);
  overflow-x:auto;scrollbar-width:none;
}
nav.yl-nav::-webkit-scrollbar{display:none}
nav.yl-nav .logo{
  font-size:18px;font-weight:600;letter-spacing:-.4px;white-space:nowrap;
  text-decoration:none;
  background:var(--yl-accent);
  -webkit-background-clip:text;background-clip:text;-webkit-text-fill-color:transparent;
}
nav.yl-nav a:not(.logo){
  font-size:12.5px;font-weight:450;letter-spacing:-.1px;white-space:nowrap;
  color:var(--yl-ink-2);text-decoration:none;
  transition:color var(--yl-t);opacity:.92;
}
nav.yl-nav a:not(.logo):hover{color:var(--yl-ink);opacity:1}
nav.yl-nav a.on{color:var(--yl-ink);font-weight:600}
.yl-nav__spacer{margin-left:auto}
.yl-nav__ctrl{display:flex;align-items:center;gap:10px;flex-shrink:0}

/* theme toggle */
.theme-toggle{
  width:30px;height:30px;border-radius:50%;border:1px solid var(--yl-hairline);
  background:transparent;color:var(--yl-ink-2);cursor:pointer;
  display:inline-flex;align-items:center;justify-content:center;
  font-size:14px;line-height:1;transition:all var(--yl-t);flex-shrink:0;
}
.theme-toggle:hover{color:var(--yl-ink);border-color:var(--yl-ink-3);transform:rotate(15deg)}

/* lang toggle */
.lang-toggle{
  display:inline-flex;align-items:center;gap:2px;padding:3px;border-radius:980px;
  background:var(--yl-hairline-soft);border:1px solid var(--yl-hairline);
  font-family:var(--yl-mono);font-size:11px;flex-shrink:0;
}
.lang-toggle button{
  padding:3px 9px;border:none;border-radius:980px;background:transparent;
  color:var(--yl-ink-3);font-family:inherit;font-size:11px;font-weight:500;
  cursor:pointer;transition:all .2s;letter-spacing:.5px;
}
.lang-toggle button.active{background:var(--yl-bg-elev);color:var(--yl-ink);box-shadow:0 1px 4px rgba(0,0,0,.12)}
.lang-toggle button:hover:not(.active){color:var(--yl-ink)}

/* ---------- breadcrumbs ---------- */
.yl-crumbs{
  max-width:1024px;margin:0 auto;padding:64px 24px 0;
  font-size:12px;color:var(--yl-ink-3);display:flex;align-items:center;gap:7px;flex-wrap:wrap;
}
.yl-crumbs a{color:var(--yl-ink-3);text-decoration:none;transition:color var(--yl-t)}
.yl-crumbs a:hover{color:var(--yl-ink)}
.yl-crumbs .sep{color:var(--yl-ink-4);font-size:10px}
.yl-crumbs .cur{color:var(--yl-ink);font-weight:500}

/* ---------- layout ---------- */
.yl-wrap{max-width:740px;margin:0 auto;padding:0 24px}
.yl-wrap--wide{max-width:1024px;margin:0 auto;padding:0 24px}
main.yl-main{padding-top:48px}

/* full-bleed bands */
.yl-band{padding:110px 0;background:var(--yl-bg)}
.yl-band--soft{background:var(--yl-bg-band)}
.yl-band--dark{background:#000;color:#F5F5F7}
.yl-band--dark .yl-eyebrow{color:#86868B}
.yl-band--hero{min-height:calc(100svh - 48px);display:flex;align-items:center;padding:80px 0}
.yl-band--tight{padding:72px 0}

/* ---------- typography ---------- */
.yl-eyebrow{
  font-family:var(--yl-mono);font-size:11px;letter-spacing:4px;text-transform:uppercase;
  color:var(--yl-ink-3);display:block;margin-bottom:22px;
}
.yl-display{
  font-size:var(--yl-display);font-weight:700;line-height:1.04;letter-spacing:-.02em;
  color:var(--yl-ink);
}
.yl-title{
  font-size:var(--yl-title);font-weight:700;line-height:1.08;letter-spacing:-.018em;
  color:var(--yl-ink);
}
.yl-headline{
  font-size:var(--yl-headline);font-weight:600;line-height:1.15;letter-spacing:-.014em;
  color:var(--yl-ink);
}
.yl-band--dark .yl-display,.yl-band--dark .yl-title,.yl-band--dark .yl-headline{color:#F5F5F7}
.grad{
  background:var(--yl-accent);
  -webkit-background-clip:text;background-clip:text;-webkit-text-fill-color:transparent;color:transparent;
  font-style:normal;
}
.yl-lede{font-size:clamp(17px,2.4vw,21px);color:var(--yl-ink-2);line-height:1.55;font-weight:400}
.yl-band--dark .yl-lede{color:#A1A1A6}
.yl-sub{font-size:14px;color:var(--yl-ink-3);line-height:1.7}

/* section header block */
.yl-sec-head{margin-bottom:48px}
.yl-sec-head .yl-title{margin-bottom:12px}
.yl-sec-head--center{text-align:center}

/* ---------- buttons & links ---------- */
.yl-btn{
  display:inline-flex;align-items:center;gap:8px;
  padding:12px 24px;border-radius:980px;border:none;cursor:pointer;
  background:var(--yl-ink);color:var(--yl-bg);
  font-family:var(--yl-font);font-size:14.5px;font-weight:500;letter-spacing:-.1px;
  text-decoration:none;transition:all var(--yl-t);
}
.yl-btn:hover{transform:scale(1.03);box-shadow:var(--yl-shadow)}
.yl-btn--ghost{
  background:transparent;color:var(--yl-ink);
  border:1px solid var(--yl-ink-3);
}
.yl-btn--ghost:hover{border-color:var(--yl-ink);box-shadow:none}
.yl-btn--accent{background:var(--yl-accent);color:#fff}
.yl-band--dark .yl-btn{background:#F5F5F7;color:#000}
.yl-band--dark .yl-btn--ghost{background:transparent;color:#F5F5F7;border-color:#6E6E73}
.yl-band--dark .yl-btn--ghost:hover{border-color:#F5F5F7}
.yl-arrow{
  display:inline-flex;align-items:center;gap:5px;
  color:var(--yl-link);font-size:15px;font-weight:450;text-decoration:none;
  transition:gap var(--yl-t);
}
.yl-arrow::after{content:'›';font-size:17px;transition:transform var(--yl-t)}
.yl-arrow:hover{text-decoration:underline}
.yl-arrow:hover::after{transform:translateX(3px)}

/* ---------- showcase tiles (Apple product-tile style) ---------- */
.yl-tiles{display:grid;gap:18px;grid-template-columns:repeat(auto-fit,minmax(280px,1fr))}
.yl-tile{
  position:relative;border-radius:var(--yl-r);overflow:hidden;
  background:var(--yl-bg-elev);border:1px solid var(--yl-hairline-soft);
  padding:48px 36px 44px;text-align:center;text-decoration:none;color:var(--yl-ink);
  display:flex;flex-direction:column;align-items:center;gap:10px;
  transition:transform var(--yl-t),box-shadow var(--yl-t);
  box-shadow:var(--yl-shadow);
}
.yl-tile:hover{transform:translateY(-4px) scale(1.01);box-shadow:var(--yl-shadow-lift)}
.yl-tile .ic{font-size:44px;line-height:1;margin-bottom:8px}
.yl-tile h3{font-size:24px;font-weight:700;letter-spacing:-.4px;color:var(--yl-ink)}
.yl-tile p{font-size:14px;color:var(--yl-ink-3);line-height:1.5;max-width:300px}
.yl-tile .yl-arrow{margin-top:10px}
.yl-tile--dark{background:#000;border-color:rgba(255,255,255,.1)}
.yl-tile--dark h3,.yl-tile--dark{color:#F5F5F7}
.yl-tile--dark p{color:#A1A1A6}

/* ---------- compact cards ---------- */
.yl-cards{display:grid;gap:14px;grid-template-columns:repeat(auto-fill,minmax(230px,1fr))}
.yl-card{
  display:flex;align-items:flex-start;gap:14px;
  padding:20px;border-radius:var(--yl-r-sm);
  background:var(--yl-bg-elev);border:1px solid var(--yl-hairline-soft);
  text-decoration:none;color:var(--yl-ink);
  transition:transform var(--yl-t),box-shadow var(--yl-t),border-color var(--yl-t);
}
.yl-band--soft .yl-card{box-shadow:0 1px 4px rgba(0,0,0,.04)}
.yl-card:hover{transform:translateY(-2px);box-shadow:var(--yl-shadow);border-color:var(--yl-hairline)}
.yl-card .ic{font-size:24px;line-height:1.2;flex-shrink:0}
.yl-card .name{font-size:15px;font-weight:600;letter-spacing:-.2px;color:var(--yl-ink);margin-bottom:3px}
.yl-card .desc{font-size:12.5px;color:var(--yl-ink-3);line-height:1.45}
.yl-card .tag{
  font-family:var(--yl-mono);font-size:9px;letter-spacing:1.5px;text-transform:uppercase;
  color:var(--yl-ink-4);display:block;margin-top:7px;
}

/* ---------- learn path steps ---------- */
.yl-steps{display:grid;gap:14px;grid-template-columns:repeat(auto-fit,minmax(220px,1fr));counter-reset:step}
.yl-step{
  position:relative;padding:26px 22px;border-radius:var(--yl-r-sm);
  background:var(--yl-bg-elev);border:1px solid var(--yl-hairline-soft);
  text-decoration:none;color:var(--yl-ink);counter-increment:step;
  transition:transform var(--yl-t),box-shadow var(--yl-t);
}
.yl-step:hover{transform:translateY(-2px);box-shadow:var(--yl-shadow)}
.yl-step::before{
  content:counter(step,decimal-leading-zero);
  font-family:var(--yl-mono);font-size:11px;letter-spacing:2px;color:var(--yl-ink-4);
  display:block;margin-bottom:12px;
}
.yl-step .name{font-size:16px;font-weight:600;letter-spacing:-.2px;margin-bottom:5px}
.yl-step .desc{font-size:13px;color:var(--yl-ink-3);line-height:1.5}

/* ---------- article prose (guides) ---------- */
.yl-prose{max-width:740px;margin:0 auto;padding:48px 24px 96px}
.yl-prose h1{font-size:var(--yl-title);font-weight:700;letter-spacing:-.018em;line-height:1.1;margin:24px 0 16px}
.yl-prose h2{font-size:26px;font-weight:700;letter-spacing:-.3px;margin:56px 0 16px}
.yl-prose h3{font-size:19px;font-weight:600;margin:36px 0 12px}
.yl-prose p{margin:0 0 18px;color:var(--yl-ink-2);line-height:1.75}
.yl-prose li{margin:0 0 10px;color:var(--yl-ink-2);line-height:1.7}
.yl-prose ul,.yl-prose ol{padding-left:24px;margin-bottom:18px}
.yl-prose code{font-family:var(--yl-mono);font-size:.86em;background:var(--yl-bg-band);border:1px solid var(--yl-hairline-soft);border-radius:5px;padding:1px 6px}
.yl-prose pre{background:var(--yl-bg-band);border:1px solid var(--yl-hairline-soft);border-radius:var(--yl-r-sm);padding:18px 20px;overflow-x:auto;margin-bottom:20px}
.yl-prose pre code{background:none;border:none;padding:0}
.yl-prose a{color:var(--yl-link)}
.yl-prose blockquote{border-left:3px solid var(--yl-hairline);padding-left:18px;color:var(--yl-ink-3);margin-bottom:18px}

/* ---------- footer ---------- */
footer.yl-footer{
  background:var(--yl-bg-band);border-top:1px solid var(--yl-hairline-soft);
  font-size:12px;color:var(--yl-ink-3);
}
.yl-footer__grid{
  max-width:1024px;margin:0 auto;padding:40px 24px 20px;
  display:grid;gap:28px;grid-template-columns:repeat(auto-fit,minmax(140px,1fr));
}
.yl-footer__col h4{
  font-size:12px;font-weight:600;color:var(--yl-ink);margin-bottom:10px;letter-spacing:-.1px;
}
.yl-footer__col a{
  display:block;color:var(--yl-ink-3);text-decoration:none;padding:3.5px 0;transition:color var(--yl-t);
}
.yl-footer__col a:hover{color:var(--yl-ink)}
.yl-footer__legal{
  max-width:1024px;margin:0 auto;padding:16px 24px 28px;
  border-top:1px solid var(--yl-hairline-soft);
  display:flex;justify-content:space-between;gap:12px;flex-wrap:wrap;
  font-family:var(--yl-mono);font-size:11px;color:var(--yl-ink-4);
}
.yl-footer__legal a{color:var(--yl-ink-3);text-decoration:none}
.yl-footer__legal a:hover{color:var(--yl-ink)}
/* slim variant for leaf pages */
footer.yl-footer--slim{padding:22px 24px;text-align:center}
footer.yl-footer--slim p{font-family:var(--yl-mono);font-size:11px}
footer.yl-footer--slim a{color:var(--yl-ink-3);text-decoration:none;margin:0 8px}
footer.yl-footer--slim a:hover{color:var(--yl-ink)}

/* ---------- scroll reveal ---------- */
.sr{opacity:0;transform:translateY(26px);transition:opacity .7s ease,transform .7s cubic-bezier(.16,1,.3,1)}
.sr.visible{opacity:1;transform:translateY(0)}
.sr-d1{transition-delay:.1s}
.sr-d2{transition-delay:.2s}
.sr-d3{transition-delay:.3s}

/* ---------- app scope: keep tool apps light inside dark chrome ---------- */
.yl-app-scope{color-scheme:light;background:#fff;color:#1D1D1F}

/* ---------- icon system (SVG sprite at /assets/icons.svg) ---------- */
.yl-ic{
  display:inline-flex;align-items:center;justify-content:center;flex-shrink:0;
  width:38px;height:38px;border-radius:10px;
  background:var(--yl-ic-bg,var(--yl-hairline-soft));color:var(--yl-ic-c,var(--yl-ink));
}
.yl-ic svg{width:20px;height:20px;stroke:currentColor;fill:none;stroke-width:1.8;stroke-linecap:round;stroke-linejoin:round}
.yl-tile .yl-ic{width:64px;height:64px;border-radius:16px;margin-bottom:10px}
.yl-tile .yl-ic svg{width:30px;height:30px;stroke-width:1.6}
.ic-orange{--yl-ic-c:#FF7A1A;--yl-ic-bg:rgba(255,106,0,.12)}
.ic-pink{--yl-ic-c:#F0288A;--yl-ic-bg:rgba(238,9,121,.1)}
.ic-purple{--yl-ic-c:#B63CE1;--yl-ic-bg:rgba(182,60,225,.12)}
.ic-indigo{--yl-ic-c:#6366F1;--yl-ic-bg:rgba(79,70,229,.12)}
.theme-toggle svg{width:15px;height:15px;stroke:currentColor;fill:none;stroke-width:1.8;stroke-linecap:round;stroke-linejoin:round}
.theme-toggle .tt-sun,.theme-toggle .tt-moon{display:none;line-height:0}
:root[data-theme="dark"] .theme-toggle .tt-sun{display:inline-flex}
:root:not([data-theme="dark"]) .theme-toggle .tt-moon{display:inline-flex}

/* ---------- divider ---------- */
.yl-divider{height:1px;background:var(--yl-hairline-soft);border:none}

/* ---------- responsive ---------- */
@media(max-width:640px){
  nav.yl-nav{gap:18px;padding:0 16px}
  nav.yl-nav a:not(.logo){font-size:11.5px}
  .yl-band{padding:72px 0}
  .yl-band--hero{padding:56px 0}
  .yl-tile{padding:36px 24px}
}

/* ---------- reduced motion ---------- */
@media(prefers-reduced-motion:reduce){
  *,*::before,*::after{animation-duration:.01ms!important;transition-duration:.01ms!important}
  .sr{opacity:1;transform:none}
  html{scroll-behavior:auto}
}