/* CAVEDIVER.COM — "Survey / Water"
   Hybrid: immersive water-depth heroes (photographic) over a pale grid-ruled
   survey sheet (field notebook). Watery blue throughout.
   All tone lives in :root — change it here, nothing else moves. */
:root{
  /* water column, shallow -> deep */
  --surface:#eaf4f7;   /* sheet ground */
  --shallow:#d6e9f0;
  --mid:#4e9cbb;
  --deep:#14495f;
  --abyss:#0a2634;
  --trench:#061a24;

  --ink:#0e2a37;
  --mut:#5c7d8b;
  --rule:#bcd8e2;
  --grid:#d9eaf1;
  --line-dk:#14364a;

  --beam:#f2e9c9;      /* dive-light on water */
  --rust:#b04a2f;      /* warnings + survey stamp */
  --rust-bg:#fbeee9;

  --max:1120px; --rad:2px;
  --sans:-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,Helvetica,Arial,sans-serif;
  --mono:ui-monospace,SFMono-Regular,Menlo,Consolas,"Liberation Mono",monospace;
}
*,*::before,*::after{box-sizing:border-box}
html{-webkit-text-size-adjust:100%}
body{
  margin:0;background:var(--surface);color:var(--ink);
  font-family:var(--sans);font-size:16.5px;line-height:1.68;-webkit-font-smoothing:antialiased;
  /* survey grid */
  background-image:linear-gradient(var(--grid) 1px,transparent 1px),
                   linear-gradient(90deg,var(--grid) 1px,transparent 1px);
  background-size:28px 28px;background-position:-1px -1px;
}
img{max-width:100%;height:auto;display:block}
a{color:#1c6f8f;text-decoration:none}
a:hover{text-decoration:underline}
:focus-visible{outline:2px solid var(--rust);outline-offset:3px}
.skip{position:absolute;left:-9999px}
.skip:focus{left:12px;top:12px;z-index:100;background:var(--rust);color:#fff;padding:10px 16px}

.wrap{max-width:var(--max);margin:0 auto;padding:0 34px}
.mono{font-family:var(--mono)}

/* ---------- header: slim, technical, sits over the hero ---------- */
header.site{
  position:absolute;top:0;left:0;right:0;z-index:20;
  border-bottom:1px solid rgba(255,255,255,.16);
}
.bar{display:flex;align-items:center;gap:22px;height:60px}
.brand{display:flex;align-items:center;gap:10px;color:#fff;font-weight:600;letter-spacing:.06em;font-size:.98rem}
.brand:hover{text-decoration:none}
.brand .mark{width:26px;height:26px;flex:none}
.brand span{color:var(--beam)}
nav.main{margin-left:auto;display:flex;gap:20px;flex-wrap:wrap}
nav.main a{
  color:rgba(255,255,255,.74);font-family:var(--mono);font-size:.72rem;
  letter-spacing:.13em;text-transform:uppercase;
}
nav.main a:hover,nav.main a[aria-current="page"]{color:#fff;text-decoration:none}
nav.main a[aria-current="page"]{box-shadow:inset 0 -2px 0 var(--beam)}
@media(max-width:860px){
  .bar{height:auto;padding:12px 0;flex-wrap:wrap;gap:10px}
  nav.main{margin-left:0;width:100%;gap:14px}
}

/* ---------- hero: descend through the water column ---------- */
.hero{
  position:relative;overflow:hidden;color:#fff;
  background:linear-gradient(180deg,var(--deep) 0%,var(--abyss) 55%,var(--trench) 100%);
}
.hero .bg{position:absolute;inset:0;object-fit:cover;width:100%;height:100%;opacity:.42;filter:saturate(.55) contrast(1.05)}
.hero::before{ /* caustic light from the surface */
  content:"";position:absolute;inset:0;pointer-events:none;
  background:
    radial-gradient(120% 60% at 50% -10%, rgba(226,244,250,.30), transparent 62%),
    radial-gradient(60% 40% at 18% 0%, rgba(120,200,225,.16), transparent 70%);
}
.hero::after{ /* dive-light shaft */
  content:"";position:absolute;top:-14%;left:62%;width:min(560px,70vw);height:130%;
  transform:translateX(-50%) rotate(6deg);pointer-events:none;filter:blur(3px);
  background:conic-gradient(from 176deg at 50% 0%,
    transparent 0deg, rgba(242,233,201,.13) 5deg, rgba(242,233,201,.03) 12deg, transparent 19deg);
}
.hero .wrap{position:relative;z-index:2;padding:132px 34px 62px}
.hero h1{
  font-size:clamp(2.3rem,5.6vw,4rem);line-height:1.02;letter-spacing:-.035em;
  margin:0 0 16px;font-weight:600;max-width:19ch;text-wrap:balance;
}
.hero .lede{font-size:1.14rem;line-height:1.6;max-width:52ch;color:rgba(255,255,255,.88);margin:0;font-weight:300}
.eyebrow{
  font-family:var(--mono);font-size:.7rem;letter-spacing:.22em;text-transform:uppercase;
  color:var(--rust);margin:0 0 16px;   /* default: on the pale sheet */
}
.hero .eyebrow{color:var(--beam)}      /* cream only over the dark water hero */
/* depth ticks down the hero edge */
.hero .ticks{
  position:absolute;right:26px;top:96px;bottom:26px;width:52px;z-index:2;
  font-family:var(--mono);font-size:.6rem;letter-spacing:.1em;color:rgba(255,255,255,.42);
  display:flex;flex-direction:column;justify-content:space-between;text-align:right;
}
.hero .ticks i{font-style:normal;position:relative;padding-right:12px}
.hero .ticks i::after{content:"";position:absolute;right:0;top:50%;width:7px;height:1px;background:rgba(255,255,255,.4)}
@media(max-width:820px){.hero .ticks{display:none}.hero .wrap{padding-top:116px}}

.cta{display:flex;gap:12px;flex-wrap:wrap;margin-top:26px}
.btn{display:inline-block;padding:11px 22px;font-family:var(--mono);font-size:.74rem;
  letter-spacing:.14em;text-transform:uppercase;border:1px solid transparent;border-radius:var(--rad)}
.btn-primary{background:var(--beam);color:#12303d;font-weight:700}
.btn-primary:hover{background:#fff;text-decoration:none}
.btn-ghost{border-color:rgba(255,255,255,.4);color:#fff}
.btn-ghost:hover{border-color:#fff;text-decoration:none}

/* ---------- the sheet ---------- */
main{position:relative}
section{padding:56px 0;border-bottom:1px solid var(--rule)}
section:last-of-type{border-bottom:0}
.section-head{max-width:66ch;margin-bottom:30px}
h2{font-size:1.5rem;letter-spacing:-.018em;margin:0 0 .5rem;font-weight:700}
h3{font-size:1.02rem;margin:0 0 .45rem;font-weight:700;letter-spacing:-.005em}
p{margin:0 0 1.05rem}
.lede{font-size:1.1rem;color:#224a5b;max-width:62ch}
.muted{color:var(--mut)}
.small{font-size:.86rem}

/* legibility scrim so hero copy holds up over a light map image */
.hero .wrap::before{
  content:"";position:absolute;inset:0 auto 0 -40vw;width:140vw;z-index:-1;
  background:linear-gradient(90deg,rgba(6,26,36,.86) 0%,rgba(6,26,36,.62) 46%,rgba(6,26,36,0) 78%);
}
.hero .wrap{isolation:isolate}

.grid{display:grid;gap:0;align-items:start}
.g2{grid-template-columns:repeat(auto-fit,minmax(320px,1fr));gap:34px}
.g3{grid-template-columns:repeat(auto-fit,minmax(290px,1fr));gap:0}

/* entries read as rows on a sheet, not cards */
.card{
  background:rgba(255,255,255,.62);
  border:1px solid var(--rule);
  padding:22px 24px;margin:-1px 0 0 -1px;
}
.card h3 a{color:var(--ink)}
.card p:last-child{margin-bottom:0}
.card .tag{
  display:block;font-family:var(--mono);font-size:.64rem;letter-spacing:.16em;
  text-transform:uppercase;color:var(--rust);margin-bottom:.5rem;
}

/* survey stamp */
.stamp{
  display:inline-block;border:1.5px solid var(--rust);color:var(--rust);
  font-family:var(--mono);font-size:.64rem;letter-spacing:.18em;text-transform:uppercase;
  padding:5px 11px;transform:rotate(-1.2deg);font-weight:700;
}

/* warnings */
.alert{border:1px solid var(--rust);border-left-width:4px;background:var(--rust-bg);padding:17px 20px;margin:0 0 8px}
.alert h3{color:var(--rust);font-family:var(--mono);font-size:.74rem;letter-spacing:.14em;text-transform:uppercase;margin-bottom:.5rem}
.alert p{margin:0 0 .7rem;color:#4a2a22}
.alert p:last-child{margin-bottom:0}

/* numbered rules list */
.rules{list-style:none;margin:0;padding:0;counter-reset:r}
.rules li{counter-increment:r;position:relative;padding:15px 0 15px 60px;border-top:1px solid var(--rule)}
.rules li:first-child{border-top:0}
.rules li::before{
  content:counter(r,decimal-leading-zero);position:absolute;left:0;top:16px;
  font-family:var(--mono);font-size:.78rem;color:var(--rust);font-weight:700;letter-spacing:.06em;
}
.rules strong{display:block}
.rules span{color:var(--mut);font-size:.94rem}

/* spec table — dotted leaders, tabular */
.tablewrap{overflow-x:auto;border:1px solid var(--rule);background:rgba(255,255,255,.7)}
table{border-collapse:collapse;width:100%;min-width:720px;font-size:.86rem}
caption{text-align:left;padding:13px 15px;color:var(--mut);font-size:.82rem;border-bottom:1px solid var(--rule)}
th,td{padding:9px 14px;text-align:left;border-bottom:1px dotted var(--rule);white-space:nowrap}
thead th{
  background:var(--shallow);font-family:var(--mono);font-size:.64rem;letter-spacing:.11em;
  text-transform:uppercase;color:var(--deep);border-bottom:1px solid var(--deep);
}
tbody tr:hover{background:rgba(78,156,187,.09)}
td.num{font-variant-numeric:tabular-nums;font-family:var(--mono);font-size:.82rem}

/* definition rows */
.deflist{display:grid;border:1px solid var(--rule);background:rgba(255,255,255,.7)}
.deflist>div{display:grid;grid-template-columns:210px 1fr;gap:18px;padding:14px 20px;border-top:1px dotted var(--rule)}
.deflist>div:first-child{border-top:0}
.deflist dt{font-family:var(--mono);font-size:.76rem;letter-spacing:.08em;text-transform:uppercase;color:var(--deep);margin:0}
.deflist dd{margin:0}
@media(max-width:640px){.deflist>div{grid-template-columns:1fr;gap:4px}}

/* plates */
figure{margin:0 0 26px}
figure img{border:1px solid var(--rule);background:#fff;padding:9px}
figcaption{font-size:.82rem;color:var(--mut);margin-top:9px;border-left:2px solid var(--mid);padding-left:11px}

/* forms */
form.q{display:grid;gap:15px;max-width:620px}
.field{display:grid;gap:5px}
label{font-family:var(--mono);font-size:.7rem;letter-spacing:.11em;text-transform:uppercase;color:var(--deep)}
input,textarea,select{
  font:inherit;font-size:.95rem;color:var(--ink);background:#fff;
  border:1px solid var(--rule);border-radius:var(--rad);padding:10px 12px;width:100%;
}
input:focus,textarea:focus{border-color:var(--mid);outline:none}
textarea{min-height:140px;resize:vertical}
button{font:inherit;cursor:pointer}
form.q .btn-primary{background:var(--deep);color:#fff}
form.q .btn-primary:hover{background:var(--abyss)}

/* article body */
.article{max-width:74ch;margin:0 auto}
.article p{margin:0 0 1.2rem}
.article .byline{color:var(--mut);font-size:.92rem;border-bottom:1px solid var(--rule);padding-bottom:16px;margin-bottom:26px}
.article .byline strong{color:var(--ink)}
.article h2{margin-top:34px}

/* footer */
footer.site{background:var(--abyss);color:rgba(255,255,255,.72);padding:38px 0 30px;font-size:.86rem}
.fgrid{display:grid;gap:24px;grid-template-columns:repeat(auto-fit,minmax(190px,1fr));margin-bottom:26px}
footer.site h4{font-family:var(--mono);font-size:.66rem;letter-spacing:.16em;text-transform:uppercase;color:var(--beam);margin:0 0 .6rem}
footer.site ul{list-style:none;margin:0;padding:0;display:grid;gap:.4rem}
footer.site a{color:rgba(255,255,255,.72)}
footer.site a:hover{color:#fff}
.legal{border-top:1px solid rgba(255,255,255,.16);padding-top:18px;display:flex;gap:14px;
  flex-wrap:wrap;justify-content:space-between;font-family:var(--mono);font-size:.68rem;
  letter-spacing:.09em;text-transform:uppercase;color:rgba(255,255,255,.5)}

@media (prefers-reduced-motion:reduce){*{animation:none!important;transition:none!important}}