/* Dokodemo Denwa: palette and type taken from the company logo.
   Red and blue are the logo's own inks. Headings use an old-style Mincho serif to echo the logo lettering. */
:root{
  --ground:#f7f8fb; --surface:#ffffff;
  --ink:#141c33; --ink-2:#39435e; --muted:#566079;
  --line:#d3d9e6; --line-soft:#e5e9f1;
  --blue:#1c3891; --blue-deep:#142a6e; --blue-tint:#e8ecf7;
  --red:#c91818;
  --max:1180px; --rail:250px;
  --serif:"Zen Old Mincho","Hiragino Mincho ProN","Yu Mincho",Georgia,serif;
  --sans:"Zen Kaku Gothic New","Hiragino Sans","Yu Gothic",system-ui,sans-serif;
  --s-1:.8rem; --s0:1rem; --s1:1.25rem; --s2:1.563rem; --s3:1.953rem; --s4:2.441rem; --s5:3.052rem;
}
*{box-sizing:border-box}
html{-webkit-text-size-adjust:100%}
body{margin:0;background:var(--ground);color:var(--ink);font:400 var(--s0)/1.75 var(--sans)}
html[lang=ja] body{line-height:1.9}
h1,h2,h3{font-family:var(--serif);font-weight:700;color:var(--ink)}
a{color:var(--blue);text-underline-offset:.2em}
a:hover{color:var(--blue-deep)}
:focus-visible{outline:2px solid var(--red);outline-offset:2px}
.wrap{max-width:var(--max);margin:0 auto;padding-inline:clamp(16px,4vw,32px)}
.skip{position:absolute;left:-999px}.skip:focus{left:12px;top:12px;background:#fff;padding:8px 12px;z-index:99}

/* header */
.site-header{background:var(--surface);border-bottom:1px solid var(--line);position:relative;z-index:10}
.site-header .wrap{display:flex;align-items:center;gap:20px;min-height:84px}
.brand{display:flex;align-items:center;gap:14px;text-decoration:none;margin-right:auto;min-height:44px}
.brand img{height:60px;width:auto;display:block}
.brand-sub{font-size:.82rem;color:var(--muted);line-height:1.4;padding-left:14px;border-left:1px solid var(--line);max-width:11em}
.nav{display:flex;align-items:center;gap:2px}
.nav a{color:var(--ink-2);text-decoration:none;padding:8px 12px;font-size:.95rem;font-weight:500;border-bottom:2px solid transparent}
.nav a:hover{color:var(--ink)}
.nav a[aria-current=page]{color:var(--ink);border-bottom-color:var(--red)}
.nav .contact-link{margin-left:8px;background:var(--blue);color:#fff;border-radius:6px;border:0;padding:9px 16px}
.nav .contact-link:hover{background:var(--blue-deep);color:#fff}
.nav .contact-link[aria-current=page]{background:var(--blue-deep)}
.lang{display:flex;gap:2px;font-size:.84rem}
.lang a{color:var(--muted);text-decoration:none;padding:4px 7px;border-radius:4px;white-space:nowrap}
.lang a:hover{color:var(--ink)}
.lang a[aria-current=true]{color:var(--blue);font-weight:700;box-shadow:inset 0 0 0 1px var(--line)}
.nav-lang{display:none}
.menu-btn{display:none;font:inherit;font-size:.9rem;background:var(--surface);border:1px solid var(--line);border-radius:6px;padding:6px 12px;color:var(--ink);cursor:pointer;white-space:nowrap;min-height:44px;min-width:44px}
@media (max-width:900px){
  .menu-btn{display:block}
  .site-header .wrap{gap:12px;min-height:72px}
  .brand img{height:50px}
  .nav{position:absolute;top:100%;left:0;right:0;flex-direction:column;align-items:stretch;background:var(--surface);border-bottom:1px solid var(--line);padding:8px clamp(16px,4vw,32px) 16px}
  .nav:not(.open){display:none}
  .nav a{min-height:44px;display:flex;align-items:center;padding:10px 0;border-bottom:1px solid var(--line-soft)}
  .nav a[aria-current=page]{color:var(--red);border-bottom-color:var(--line-soft)}
  .nav .contact-link{margin:12px 0 0;justify-content:center;padding:12px}
  .nav .contact-link[aria-current=page]{color:#fff}
}
@media (max-width:560px){
  .brand-sub,.head-lang{display:none}
  .nav .nav-lang{display:flex;gap:6px;padding-top:14px}
  .nav .nav-lang a{border:0;padding:6px 12px;min-height:44px;min-width:44px;justify-content:center}
}

/* hero */
.hero{border-bottom:1px solid var(--line);background:linear-gradient(var(--surface),var(--ground))}
.hero .wrap{display:grid;grid-template-columns:minmax(0,1.05fr) minmax(0,1fr);gap:clamp(24px,5vw,64px);align-items:center;padding-block:clamp(48px,8vw,96px)}
.hero h1{font-size:clamp(var(--s3),5vw,var(--s5));line-height:1.2;margin:0 0 .5em;max-width:14em;letter-spacing:-.005em}
html[lang=ja] .hero h1{line-height:1.4;letter-spacing:.02em}
html[lang=de] .hero h1{hyphens:auto}
.hero .lead{font-size:var(--s1);color:var(--ink-2);max-width:32em;margin:0;line-height:1.65}
.actions{display:flex;flex-wrap:wrap;gap:12px;margin-top:32px}
.btn{display:inline-block;font:inherit;font-weight:700;font-size:.98rem;text-decoration:none;padding:12px 22px;border-radius:6px;border:1px solid var(--blue);cursor:pointer;text-align:center}
.btn-solid{background:var(--blue);color:#fff}.btn-solid:hover{background:var(--blue-deep);border-color:var(--blue-deep);color:#fff}
.btn-line{background:var(--surface);color:var(--blue)}.btn-line:hover{background:var(--blue-tint);color:var(--blue-deep)}
.page-hero .wrap{display:block;padding-block:clamp(40px,6vw,72px)}
.page-hero h1{font-size:clamp(var(--s3),4vw,var(--s4))}
@media (max-width:900px){.hero .wrap{grid-template-columns:1fr}}
@media (max-width:560px){.hero .actions .btn{flex:1 1 auto}}

/* call-flow diagram: the page's one bold element */
.ladder{margin:0;background:var(--surface);border:1px solid var(--line);border-radius:10px;padding:18px 16px 12px}
.ladder svg{display:block;width:100%;height:auto}
.ladder figcaption{font-size:var(--s-1);color:var(--muted);margin-top:6px;padding-inline:4px}
.ladder .node{font:700 12px var(--sans);fill:var(--ink)}
.ladder .life{stroke:var(--line);stroke-width:1.5;stroke-dasharray:3 4}
.ladder .head{fill:var(--blue-tint);stroke:var(--blue);stroke-width:1.2}
.ladder .msg line{stroke:var(--blue);stroke-width:1.6}
.ladder .msg path{fill:var(--blue)}
.ladder .msg text{font:500 11px var(--sans);fill:var(--ink-2)}
.ladder .msg.reply line{stroke-dasharray:5 3}
.ladder .msg.final line{stroke:var(--red)}.ladder .msg.final path{fill:var(--red)}
.ladder .pulse{fill:var(--red)}
@media (prefers-reduced-motion:no-preference){
  .ladder .msg{opacity:0;animation:msg-in .35s ease-out forwards;animation-delay:calc(var(--i)*.42s + .3s)}
  @keyframes msg-in{from{opacity:0;transform:translateY(-4px)}to{opacity:1;transform:none}}
}
@media (prefers-reduced-motion:reduce){.ladder .pulse{display:none}}

/* spec rows */
.row{display:grid;grid-template-columns:var(--rail) minmax(0,1fr);gap:clamp(20px,4vw,56px);padding-block:clamp(40px,6vw,64px);border-bottom:1px solid var(--line)}
.row:last-child{border-bottom:0}
.row > h2{font-size:var(--s2);line-height:1.35;margin:0}
@media (min-width:901px){.row > h2{position:sticky;top:24px;align-self:start}}
html[lang=de] .row > h2{hyphens:auto}
.row-body{min-width:0}
.prose{max-width:36em;color:var(--ink-2)}
html[lang=ja] .prose{max-width:36em}
.prose p{margin:0 0 1.1em}
.prose p:last-child{margin-bottom:0}
h3{font-size:var(--s1);margin:0 0 .5em;line-height:1.4}
@media (max-width:900px){.row{grid-template-columns:1fr}}

.defs{margin:28px 0;display:grid;grid-template-columns:1fr 1fr;column-gap:40px;max-width:52em}
.defs:first-child{margin-top:0}
.defs div{border-top:1px solid var(--line);padding:14px 0 18px}
.defs dt{font-weight:700;margin-bottom:4px}
.defs dd{margin:0;color:var(--ink-2);font-size:.96rem}
@media (max-width:640px){.defs{grid-template-columns:1fr}}

.elements{margin:28px 0;display:grid;grid-template-columns:repeat(auto-fill,minmax(min(100%,340px),1fr));column-gap:40px}
.elements div{display:grid;grid-template-columns:92px 1fr;gap:12px;border-top:1px solid var(--line);padding:12px 0}
.elements dt{font-weight:700;font-size:.92rem;color:var(--blue);letter-spacing:.02em}
.elements dd{margin:0;font-size:.95rem;color:var(--ink-2)}
.elements dd b{display:block;color:var(--ink);font-weight:700}

.options{display:grid;grid-template-columns:repeat(3,1fr);gap:28px;margin:28px 0}
.options > div{border-top:3px solid var(--blue);padding-top:14px}
.options p{margin:0;color:var(--ink-2);font-size:.96rem}
@media (max-width:760px){.options{grid-template-columns:1fr}}

.plain{margin:0;padding-left:1.2em;color:var(--ink-2);max-width:44em}
.plain li{margin-bottom:.5em}
.plain li::marker{color:var(--red)}
.plain b{color:var(--ink);font-weight:700}

/* tables */
.table-wrap{overflow-x:auto;background:var(--surface);border:1px solid var(--line);border-radius:8px;margin:4px 0 8px}
table{border-collapse:collapse;width:100%;min-width:680px;font-size:.92rem}
th,td{text-align:left;vertical-align:top;padding:11px 14px;border-bottom:1px solid var(--line-soft)}
thead th{font-weight:700;color:var(--muted);font-size:.84rem;background:#f1f3f8;border-bottom:1px solid var(--line)}
tbody tr:last-child td{border-bottom:0}
td{color:var(--ink-2)}
td:first-child{white-space:nowrap;color:var(--ink);font-weight:700}
td.id{color:var(--blue)}
.spec-nav{display:flex;flex-wrap:wrap;gap:6px 18px;margin-top:20px;font-size:.92rem}
@media (max-width:640px){
  .table-wrap{overflow:visible;background:none;border:0;border-radius:0}
  table,tbody,tr,td{display:block;min-width:0;width:auto}
  thead{display:none}
  tr{background:var(--surface);border:1px solid var(--line);border-radius:8px;margin-bottom:10px;padding:12px 14px}
  td{border:0;padding:3px 0}
  td:first-child{white-space:normal;font-size:1rem;padding-bottom:6px}
  td[data-label]::before{content:attr(data-label);display:block;font-size:var(--s-1);font-weight:700;color:var(--muted)}
}

/* closing call */
.closing{padding-block:clamp(40px,6vw,64px)}
.closing .wrap{display:flex;flex-wrap:wrap;gap:20px 40px;align-items:center;justify-content:space-between;padding-top:32px;position:relative}
.closing .wrap::before{content:"";position:absolute;top:0;left:clamp(16px,4vw,32px);right:clamp(16px,4vw,32px);border-top:1px solid var(--ink)}
.closing h2{font-size:var(--s2);margin:0 0 .2em}
.closing p{margin:0;color:var(--ink-2);max-width:34em}

/* form */
.form{display:grid;grid-template-columns:1fr 1fr;gap:18px 20px;max-width:44em}
.form .full{grid-column:1/-1}
@media (max-width:640px){.form{grid-template-columns:1fr}}
.field label{display:block;font-weight:700;font-size:.92rem;margin-bottom:6px}
.field .opt{color:var(--muted);font-weight:400}
.field input,.field select,.field textarea{width:100%;font:inherit;font-size:1rem;padding:10px 12px;border:1px solid var(--line);border-radius:6px;background:var(--surface);color:var(--ink)}
.field textarea{min-height:140px;resize:vertical}
.field input:focus,.field select:focus,.field textarea:focus{outline:none;border-color:var(--blue);box-shadow:0 0 0 3px rgba(28,56,145,.18)}
.hp{position:absolute;left:-5000px;width:1px;height:1px;overflow:hidden}
.notice{padding:12px 16px;border-radius:6px;margin:0 0 20px;max-width:44em}
.notice.ok{background:var(--blue-tint);border:1px solid #b9c5e6;color:var(--blue-deep)}
.notice.err{background:#fbe9e9;border:1px solid #efbcbc;color:#8f1111}
.form-note{font-size:var(--s-1);color:var(--muted);grid-column:1/-1;margin:0}
.addr{font-style:normal;color:var(--ink-2)}

/* footer */
.site-footer{background:var(--ink);color:#c3c9d8;font-size:.92rem}
.site-footer .wrap{display:grid;grid-template-columns:1.6fr 1fr 1fr;gap:32px;padding-block:48px 28px}
.foot-logo{height:64px;width:auto;display:block}
.site-footer h2{font-family:var(--sans);font-size:.95rem;color:#fff;margin:0 0 10px}
.site-footer ul{list-style:none;margin:0;padding:0;display:grid;gap:6px}
.site-footer a{color:#c3c9d8;text-decoration:none}
.site-footer a:hover{color:#fff;text-decoration:underline}
.site-footer address{font-style:normal;margin-top:16px;line-height:1.8}
.site-footer .legal{grid-column:1/-1;border-top:1px solid #2b3552;padding-top:18px;font-size:var(--s-1);color:#9aa3b8}
@media (max-width:760px){.site-footer .wrap{grid-template-columns:1fr}}

/* touch targets: 44px minimum on touch-sized screens */
@media (max-width:900px){
  .spec-nav{gap:4px 8px}
  .spec-nav a{display:inline-flex;align-items:center;min-height:44px;min-width:48px;padding-inline:4px}
  .site-footer ul{gap:0}
  .site-footer li a{display:inline-flex;align-items:center;min-height:44px;min-width:48px}
}

/* logo prominence and header text fixes */
.site-header .wrap{min-height:104px}
.brand img{height:80px}
.brand-sub{max-width:none;white-space:nowrap}
@media (max-width:1100px){.brand-sub{display:none}}
@media (max-width:900px){
  .site-header .wrap{min-height:80px}
  .brand img{height:62px}
}
html[lang=de] .hero h1{hyphens:manual}
@media (max-width:560px){html[lang=de] .hero h1{hyphens:auto}}
.brand{min-width:48px}