/* ==========================================================================
   VPNDN — base.css
   1. design tokens     2. reset        3. typography   4. layout
   5. buttons           6. header       7. footer       8. reveal
   9. accessibility     10. responsive guards
   ========================================================================== */

/* ------------------------------------------------------------------ 1. tokens */
:root{
  /* surfaces */
  --bg:#F6F8F5;
  --bg-top:#FBFCFA;
  --bg-bottom:#EEF3EE;
  --panel:#FFFFFF;
  --panel-2:#EDF1EC;
  --border:#DCE3DC;
  /* brand */
  --accent:#12C46B;
  --accent-deep:#0A9C56;
  --accent-dark:#077A44;
  --lime:#C6F24A;
  --mint:#DFF7E8;
  /* text */
  --ink:#121714;
  --muted:#5C665F;
  --muted-2:#7E8981;
  /* semantic */
  --success:#1AA65A;
  --warn:#D9A400;
  --error:#D93B3B;
  --white:#FFFFFF;
  /* materials */
  --hl:rgba(255,255,255,.78);
  --hl-soft:rgba(255,255,255,.34);
  --ink-veil:rgba(18,23,20,.14);
  --veil:rgba(18,23,20,.30);
  --shadow-lift:0 1px 2px rgba(18,23,20,.05);
  --shadow-tint:0 24px 60px -24px color-mix(in srgb,var(--accent) 22%,transparent);
  --shadow-panel:0 26px 64px -30px color-mix(in srgb,var(--accent) 24%,transparent);
  --shadow-soft:0 18px 44px -22px color-mix(in srgb,var(--accent) 30%,transparent);
  /* flags */
  --flag-red:#D7263D;
  --flag-blue:#1F3F8F;
  --flag-green:#1E8E4B;
  --flag-white:#FFFFFF;
  /* type */
  --font-display:'Inter','Noto Sans SC','Noto Sans JP','Noto Sans KR',system-ui,-apple-system,'PingFang SC','Microsoft YaHei',sans-serif;
  --font-body:'Inter','Noto Sans SC','Noto Sans JP','Noto Sans KR',system-ui,-apple-system,'PingFang SC','Microsoft YaHei',sans-serif;
  --font-mono:'JetBrains Mono','SFMono-Regular',Menlo,Consolas,'Liberation Mono',monospace;
  /* geometry */
  --r-pill:999px;
  --r-lg:24px;
  --r-md:14px;
  --r-sm:8px;
  --gutter:24px;
  --wrap:1280px;
  --nav-h:50px;
  --tap:44px;
}

/* ------------------------------------------------------------------ 2. reset */
*,*::before,*::after{box-sizing:border-box}
html{
  -webkit-text-size-adjust:100%;
  scroll-behavior:smooth;
  scroll-padding-top:88px;
}
body{
  margin:0;
  background:var(--bg);
  color:var(--ink);
  font:400 15px/1.5 var(--font-body);
  -webkit-font-smoothing:antialiased;
  text-rendering:optimizeLegibility;
  overflow-x:clip;
}
img,svg,video{max-width:100%}
img{height:auto}
a{color:inherit}
button{font:inherit;color:inherit;background:none;border:0}
input,select,textarea{font:inherit;color:inherit}
h1,h2,h3,h4,h5,h6,p,figure,blockquote,dl,dd{margin:0}
ul,ol{margin:0;padding:0;list-style:none}
table{border-collapse:collapse;border-spacing:0}
strong{font-weight:700}
::selection{background:color-mix(in srgb,var(--accent) 26%,transparent)}

/* ------------------------------------------------------------------ 3. typography */
h1,h2,h3,h4{font-family:var(--font-display);line-height:1.14;letter-spacing:-.02em;font-weight:800}
h1{font-size:clamp(30px,4.6vw,52px)}
h2{font-size:clamp(23px,3vw,32px)}
h3{font-size:19px;font-weight:700;letter-spacing:-.015em}
h4{font-size:16px;font-weight:700;letter-spacing:-.01em}
p{line-height:1.7}
code,kbd,samp{font-family:var(--font-mono);overflow-wrap:anywhere;word-break:break-word}
.mono{font-family:var(--font-mono)}
.muted{color:var(--muted)}
.no-break{white-space:nowrap}
.sr-only{position:absolute;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip:rect(0 0 0 0);white-space:nowrap;border:0}
.defs{position:absolute;width:0;height:0;overflow:hidden}

/* full-page grain layer (single texture for the whole site) */
.grain{
  position:fixed;inset:0;width:100%;height:100%;
  pointer-events:none;z-index:60;opacity:.035;mix-blend-mode:multiply;
  background-image:url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='160' height='160' viewBox='0 0 160 160'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='.82' numOctaves='3' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='160' height='160' filter='url(%23n)'/%3E%3C/svg%3E");
  background-size:160px 160px;
}

/* ------------------------------------------------------------------ 4. layout */
.wrap{
  width:100%;
  max-width:var(--wrap);
  margin-inline:auto;
  padding-inline:var(--gutter);
}
.wrap-narrow{max-width:860px}
.sec{padding-block:64px}
.sec-tight{padding-block:40px}
.sec-head{max-width:64ch;margin-bottom:28px}
.sec-head .eyebrow{margin-bottom:12px}
.lede{font-size:16px;line-height:1.75;color:var(--muted)}
.eyebrow{
  display:inline-flex;align-items:center;gap:8px;
  font:600 11.5px/1 var(--font-mono);letter-spacing:.12em;text-transform:uppercase;
  color:var(--accent-dark);
}
.eyebrow i{width:7px;height:7px;border-radius:50%;background:var(--accent);flex:none}
.link-arrow{
  display:inline-flex;align-items:center;gap:7px;
  font-weight:600;font-size:14px;color:var(--accent-dark);
  text-decoration:none;min-height:24px;
}
.link-arrow svg{width:15px;height:15px;flex:none;transition:transform .2s}
.link-arrow:hover svg{transform:translateX(3px)}
.has-decor{position:relative;overflow-x:clip}
.tilt{transform:rotate(-.4deg)}
.tilt-alt{transform:rotate(.42deg)}

/* ------------------------------------------------------------------ 5. buttons */
.btn{
  display:inline-flex;align-items:center;justify-content:center;gap:10px;
  height:48px;border-radius:var(--r-pill);
  font-size:15px;font-weight:600;font-family:var(--font-body);
  text-decoration:none;cursor:pointer;border:0;
  transition:transform .2s,box-shadow .2s,background .2s,color .2s;
}
.btn:hover,.btn.is-hover-lift{transform:translateY(-1px)}
.btn-primary{
  padding:0 6px 0 22px;color:var(--ink);
  background:linear-gradient(90deg,var(--accent) 0%,var(--accent) 62%,color-mix(in srgb,var(--accent) 60%,var(--lime)) 100%);
  box-shadow:inset 0 1px 0 var(--hl-soft),0 14px 30px -14px color-mix(in srgb,var(--accent) 60%,transparent);
}
.btn-primary:hover,.btn-primary.is-hover-lift{
  box-shadow:inset 0 1px 0 var(--hl-soft),0 18px 34px -14px color-mix(in srgb,var(--accent) 70%,transparent);
}
.btn-badge{
  width:36px;height:36px;border-radius:50%;
  background:var(--ink);color:var(--accent);
  display:grid;place-items:center;flex:none;
}
.btn-badge svg{width:16px;height:16px;display:block}
.btn-secondary{
  padding:0 22px;background:var(--panel);color:var(--ink);
  box-shadow:inset 0 0 0 1px var(--ink);
}
.btn-secondary:hover,.btn-secondary.is-hover-lift{background:var(--panel-2)}
.btn-ghost{padding:0 20px;background:transparent;color:var(--ink);box-shadow:inset 0 0 0 1px var(--border)}
.btn-ghost:hover{background:var(--panel-2)}
.btn-sm{height:38px;font-size:13.5px;padding:0 16px}
.btn-sm.btn-primary{padding:0 4px 0 16px}
.btn-sm .btn-badge{width:30px;height:30px}
.btn-sm .btn-badge svg{width:14px;height:14px}
.btn.is-disabled{opacity:.45;pointer-events:none;box-shadow:none}
.btn.is-focus{outline:2px solid var(--accent-dark);outline-offset:2px}

/* ------------------------------------------------------------------ 6. header */
.nav-wrap{padding:8px 24px;position:relative;z-index:50}
.nav{
  position:relative;
  max-width:1280px;margin:0 auto;height:var(--nav-h);
  display:flex;align-items:center;justify-content:space-between;gap:24px;
  padding:0 8px 0 16px;
  background:var(--panel);border-radius:var(--r-pill);
  box-shadow:inset 0 0 0 1px var(--border),var(--shadow-tint);
}
.brand{
  display:inline-flex;align-items:center;gap:10px;flex:none;
  text-decoration:none;font:800 17px/1 var(--font-display);
  letter-spacing:-.02em;color:var(--ink);
}
.brand-mark{
  width:26px;height:26px;display:block;border-radius:8px;
  box-shadow:0 6px 14px -8px color-mix(in srgb,var(--accent) 60%,transparent);
}
.brand-word{white-space:nowrap}
.nav-links{display:flex;align-items:center;font-size:14px;font-weight:500;min-width:0}
.nav-links a{
  display:inline-flex;align-items:center;min-height:28px;padding:6px 0;
  text-decoration:none;color:var(--ink);transition:color .2s;
}
.nav-links a:hover{color:var(--accent-dark)}
.nav-links a + a::before{content:"·";margin:0 13px;color:var(--muted-2);font-weight:700}
.nav-links a[aria-current="page"]{color:var(--accent-dark)}
.nav-right{display:flex;align-items:center;gap:10px;margin-left:auto;flex:none}
.lang-wrap{position:relative}
.lang{
  background:none;border:0;font:inherit;font-size:13px;color:var(--muted);
  display:inline-flex;align-items:center;gap:6px;cursor:pointer;
  padding:6px 10px;border-radius:var(--r-pill);min-height:32px;
}
.lang:hover{background:var(--panel-2)}
.lang-caret{
  width:0;height:0;flex:none;
  border-left:4px solid transparent;border-right:4px solid transparent;
  border-top:5px solid var(--muted-2);
}
.lang-menu{
  position:absolute;top:calc(100% + 8px);right:0;z-index:70;
  min-width:158px;padding:6px;border-radius:var(--r-md);
  background:var(--panel);
  box-shadow:inset 0 0 0 1px var(--border),var(--shadow-panel);
  display:flex;flex-direction:column;gap:2px;
}
.lang-menu[hidden]{display:none}
.lang-menu a{
  display:flex;align-items:center;justify-content:space-between;gap:12px;
  min-height:38px;padding:9px 12px;border-radius:var(--r-sm);
  text-decoration:none;font-size:13.5px;color:var(--ink);
}
.lang-menu a:hover{background:var(--panel-2)}
.lang-menu a[aria-current="true"]{color:var(--accent-dark);font-weight:600}
.btn-login{
  display:inline-flex;align-items:center;justify-content:center;gap:8px;
  height:36px;padding:0 18px;border-radius:var(--r-pill);
  background:var(--ink);color:var(--panel);text-decoration:none;
  font-size:14px;font-weight:600;box-shadow:var(--shadow-lift);white-space:nowrap;
}
.btn-login:hover{background:var(--accent-dark)}
.nav-burger{
  display:none;width:var(--tap);height:var(--tap);min-width:var(--tap);min-height:var(--tap);
  border-radius:var(--r-pill);cursor:pointer;place-items:center;color:var(--ink);
}
.nav-burger:hover{background:var(--panel-2)}
.burger-bars{display:grid;gap:4px;width:18px}
.burger-bars i{display:block;height:2px;border-radius:2px;background:currentColor;transition:transform .25s,opacity .25s}
.nav-burger[aria-expanded="true"] .burger-bars i:nth-child(1){transform:translateY(6px) rotate(45deg)}
.nav-burger[aria-expanded="true"] .burger-bars i:nth-child(2){opacity:0}
.nav-burger[aria-expanded="true"] .burger-bars i:nth-child(3){transform:translateY(-6px) rotate(-45deg)}
.nav-drawer{
  position:absolute;top:calc(100% + 10px);left:0;right:0;z-index:60;
  display:none;flex-direction:column;gap:2px;
  padding:10px;border-radius:var(--r-lg);
  background:var(--panel);
  box-shadow:inset 0 0 0 1px var(--border),var(--shadow-panel);
  max-height:calc(100dvh - 120px);overflow-y:auto;overscroll-behavior:contain;
}
.nav-drawer.is-open{display:flex}
.drawer-list{display:flex;flex-direction:column;gap:2px}
.nav-drawer a{
  display:flex;width:100%;align-items:center;min-height:48px;
  padding:12px 14px;border-radius:var(--r-md);
  text-decoration:none;font-size:15px;font-weight:500;color:var(--ink);
}
.nav-drawer a:hover{background:var(--panel-2)}
.nav-drawer a[aria-current="page"]{
  color:var(--accent-dark);
  background:color-mix(in srgb,var(--accent) 10%,var(--white));
}
.drawer-sep{height:1px;background:var(--border);margin:8px 4px}
.drawer-label{
  font:500 11px/1 var(--font-mono);letter-spacing:.1em;text-transform:uppercase;
  color:var(--muted-2);padding:8px 14px 2px;
}
.nav-veil{position:fixed;inset:0;z-index:30;background:var(--veil);display:none}
html.nav-open .nav-veil{display:block}
html.nav-open{overflow:hidden}

/* ------------------------------------------------------------------ 7. footer */
.site-footer{
  position:relative;margin-top:72px;overflow-x:clip;
  background:linear-gradient(180deg,var(--bg-bottom) 0%,var(--bg) 100%);
  border-top:1px solid var(--border);
}
.site-footer::before{
  content:"";position:absolute;left:50%;top:-160px;
  width:min(900px,92vw);height:360px;transform:translateX(-50%);
  border-radius:50%;pointer-events:none;
  background:radial-gradient(ellipse at 50% 50%,color-mix(in srgb,var(--accent) 7%,transparent) 0%,transparent 70%);
}
.foot-grid{
  position:relative;display:grid;gap:30px 32px;
  grid-template-columns:1.5fr 1fr 1fr 1fr;
  padding-block:56px 34px;
}
.foot-brand{display:flex;flex-direction:column;gap:12px;min-width:0}
.foot-tag{font-size:13.5px;line-height:1.7;color:var(--muted);max-width:36ch}
.foot-fact{font:500 12px/1.6 var(--font-mono);color:var(--accent-dark);letter-spacing:.01em}
.foot-col{min-width:0}
.foot-h{
  font:500 11px/1 var(--font-mono);font-size:11px;letter-spacing:.1em;
  text-transform:uppercase;color:var(--muted-2);margin-bottom:12px;
}
.foot-links{display:flex;flex-direction:column;gap:2px}
.foot-links a{
  display:inline-flex;align-items:center;min-height:26px;padding:3px 0;
  font-size:13.5px;color:var(--muted);text-decoration:none;overflow-wrap:anywhere;
}
.foot-links a:hover{color:var(--accent-dark)}
.foot-base{
  position:relative;display:flex;flex-wrap:wrap;align-items:center;
  justify-content:space-between;gap:10px 20px;
  padding-block:18px 26px;border-top:1px solid var(--border);
}
.foot-copy{margin:0;font:500 12.5px/1.5 var(--font-mono);color:var(--muted-2)}
.foot-legal{display:flex;flex-wrap:wrap;gap:6px 18px}
.foot-legal a{
  display:inline-flex;align-items:center;min-height:24px;
  font-size:12.5px;color:var(--muted);text-decoration:none;
}
.foot-legal a:hover{color:var(--accent-dark)}

/* ------------------------------------------------------------------ 8. reveal */
.reveal{opacity:1;transform:none;transition:opacity .6s ease,transform .6s cubic-bezier(.22,.61,.36,1)}
.reveal.pending{opacity:0;transform:translateY(16px)}
.reveal.shown{opacity:1;transform:none}

/* ------------------------------------------------------------------ 9. a11y */
:where(a,button,summary,[role="tab"],[role="button"],input,select,textarea):focus-visible{
  outline:2px solid var(--accent-dark);
  outline-offset:2px;
}
/* sticky toc bar compensation + judge line helper */
body:has(.toc-tabs) section[id]{scroll-margin-top:78px}

/* ------------------------------------------------------------------ 10. guards */
/* long unbreakable strings (subscription URLs, package names) never blow the line box */
code,pre,.mono,.url{overflow-wrap:anywhere;word-break:break-word}
/* server status widget: always occupies document flow, never escapes its box */
#server-status{
  display:block;position:static;max-width:100%;overflow:hidden;
  margin:24px 0;
}
#server-status > *{max-width:100%}

@media (max-width:900px){
  .nav-links{display:none}
  .nav-burger{display:grid}
  .foot-grid{grid-template-columns:1fr 1fr;gap:26px 24px}
}
@media (min-width:901px){
  .nav-drawer{display:none !important}
}
@media (max-width:640px){
  :root{--gutter:16px}
  .no-break{white-space:normal}
  .nav-wrap{padding:8px 16px}
  .lang{display:none}
  .foot-grid{grid-template-columns:1fr;gap:24px}
  .sec{padding-block:48px}
  .tilt,.tilt-alt{transform:none}
}
@media (prefers-reduced-motion:reduce){
  html{scroll-behavior:auto}
  .reveal,.reveal.pending{opacity:1;transform:none;transition:none}
  .btn:hover,.btn.is-hover-lift{transform:none}
}

/* lh:local-harden:start */
:is(h1,h2,h3,h4){text-wrap:balance}
:is(p,li,dd,dt,figcaption,blockquote,td,th){text-wrap:pretty}
html[lang|="ko"] body{word-break:keep-all;overflow-wrap:break-word}
html[lang|="ja"] :is(h1,h2,h3,h4){word-break:auto-phrase}
.lh-tscroll{overflow-x:auto;max-width:100%;-webkit-overflow-scrolling:touch}
@media (max-width:640px){.lh-tscroll :is(th,td){min-width:5.5em}}
@supports (animation-timeline:scroll()){
  .float-cta{animation:lh-fab-in linear both;animation-timeline:scroll(root);animation-range:0 70vh}
}
@keyframes lh-fab-in{0%,45%{opacity:0;visibility:hidden}100%{opacity:1;visibility:visible}}
/* lh:local-harden:end */