/* =========================================================
   CorrosionMaster — Studio Minimalist
   ========================================================= */

:root{
  --paper:#FBFAF7;
  --surface:#FFFFFF;
  --line:#ECE9E3;
  --line-strong:#DEDACF;
  --ink:#1A1815;
  --ink-2:#6E685F;
  --ink-3:#A39C92;
  --brass:#A87C4F;
  --brass-soft:#C9A877;
  --shadow:0 1px 2px rgba(26,24,21,.04), 0 8px 30px rgba(26,24,21,.04);
  --shadow-lift:0 2px 4px rgba(26,24,21,.05), 0 18px 50px rgba(26,24,21,.07);
  --serif:'Fraunces',Georgia,'Times New Roman',serif;
  --sans:'Inter',-apple-system,BlinkMacSystemFont,'PingFang SC','Microsoft YaHei',sans-serif;
  --mono:'JetBrains Mono','SF Mono',Consolas,monospace;
}

*{margin:0;padding:0;box-sizing:border-box}

html{scroll-behavior:smooth}

body{
  font-family:var(--sans);
  background:var(--paper);
  color:var(--ink);
  line-height:1.65;
  -webkit-font-smoothing:antialiased;
  text-rendering:optimizeLegibility;
}

::selection{background:var(--brass);color:#fff}

/* ---------- NAV ---------- */
.nav{
  position:sticky;top:0;z-index:1000;
  background:rgba(251,250,247,.82);
  backdrop-filter:saturate(180%) blur(14px);
  border-bottom:1px solid var(--line);
}
.nav-inner{
  max-width:1180px;margin:0 auto;
  padding:18px 32px;
  display:flex;align-items:center;justify-content:space-between;gap:24px;
}
.brand{display:flex;align-items:center;gap:10px;text-decoration:none;color:var(--ink)}
.brand-mark{color:var(--brass);display:flex;transition:transform .5s ease}
.brand:hover .brand-mark{transform:rotate(90deg)}
.brand-word{font-family:var(--serif);font-weight:500;font-size:19px;letter-spacing:-.01em}
.brand-studio{
  font-size:10px;letter-spacing:.28em;color:var(--ink-3);
  border:1px solid var(--line-strong);padding:2px 7px;border-radius:2px;font-weight:600;
}
.nav-links{display:flex;gap:30px}
.nav-link{
  text-decoration:none;color:var(--ink-2);font-size:14px;font-weight:500;
  position:relative;padding:2px 0;transition:color .25s;
}
.nav-link::after{
  content:"";position:absolute;left:0;bottom:-3px;height:1px;width:0;
  background:var(--brass);transition:width .3s ease;
}
.nav-link:hover{color:var(--ink)}
.nav-link:hover::after{width:100%}
.nav-status{display:flex;align-items:center;gap:7px;font-size:12px;color:var(--ink-2)}
.nav-status .dot{width:7px;height:7px;border-radius:50%;background:#3Fae6b;box-shadow:0 0 0 3px rgba(63,174,107,.15);animation:pulse 2.4s ease-in-out infinite}
@keyframes pulse{0%,100%{opacity:1}50%{opacity:.4}}

/* ---------- HERO ---------- */
.hero{padding:120px 32px 96px;text-align:center}
.hero-inner{max-width:880px;margin:0 auto}
.eyebrow{
  display:inline-flex;align-items:center;gap:14px;
  font-size:11px;letter-spacing:.32em;color:var(--ink-2);font-weight:600;margin-bottom:34px;
}
.eyebrow-line{width:42px;height:1px;background:var(--brass);display:inline-block}
.hero-title{
  font-family:var(--serif);font-weight:400;
  font-size:clamp(40px,6.2vw,76px);line-height:1.06;letter-spacing:-.02em;
  color:var(--ink);margin-bottom:30px;
}
.hero-title em{font-style:italic;color:var(--brass);font-weight:300}
.hero-sub{
  font-size:clamp(15px,1.6vw,18px);color:var(--ink-2);
  max-width:620px;margin:0 auto 46px;line-height:1.85;font-weight:300;
}
.hero-meta{
  display:flex;align-items:center;justify-content:center;gap:26px;flex-wrap:wrap;
}
.meta-item{display:flex;flex-direction:column;gap:3px}
.meta-k{font-size:11px;letter-spacing:.18em;color:var(--ink-3);text-transform:uppercase}
.meta-v{font-family:var(--mono);font-size:14px;color:var(--ink);font-weight:500}
.meta-sep{width:1px;height:30px;background:var(--line-strong)}

/* ---------- SECTION HEAD ---------- */
section{max-width:1180px;margin:0 auto;padding:0 32px}
.section-head{margin:0 auto 48px;max-width:760px}
.section-index{
  font-family:var(--mono);font-size:12px;color:var(--brass);
  letter-spacing:.1em;display:block;margin-bottom:14px;
}
.section-title{font-family:var(--serif);font-weight:500;font-size:clamp(28px,3.4vw,40px);letter-spacing:-.015em;margin-bottom:14px}
.section-lead{font-size:16px;color:var(--ink-2);font-weight:300;line-height:1.8}

.studio{padding-top:40px}
.method{padding-top:120px}
.reference{padding-top:120px}
.about{padding-top:120px;padding-bottom:40px}

/* ---------- STUDIO GRID ---------- */
.studio-grid{display:grid;grid-template-columns:380px 1fr;gap:28px;align-items:stretch}
.panel{
  background:var(--surface);border:1px solid var(--line);
  border-radius:4px;box-shadow:var(--shadow);position:relative;overflow:hidden;
}
.input-card{padding:34px 32px;display:flex;flex-direction:column}
.panel-label{
  font-size:11px;letter-spacing:.26em;text-transform:uppercase;color:var(--ink-3);
  font-weight:600;margin-bottom:26px;padding-bottom:16px;border-bottom:1px solid var(--line);
}

/* fields */
.field{margin-bottom:22px}
.field label{
  display:flex;justify-content:space-between;align-items:baseline;
  font-size:13px;font-weight:600;color:var(--ink);margin-bottom:9px;
}
.field-range{font-family:var(--mono);font-size:10px;color:var(--ink-3);letter-spacing:.04em}
.field input{
  width:100%;padding:13px 15px;font-family:var(--mono);font-size:16px;color:var(--ink);
  background:var(--paper);border:1px solid var(--line-strong);border-radius:3px;
  outline:none;transition:border-color .25s,box-shadow .25s,background .25s;
}
.field input::placeholder{color:var(--ink-3)}
.field input:focus{border-color:var(--brass);background:var(--surface);box-shadow:0 0 0 3px rgba(168,124,79,.12)}

/* actions */
.actions{display:flex;gap:10px;margin:6px 0 26px}
.btn-primary{
  flex:1;display:inline-flex;align-items:center;justify-content:center;gap:9px;
  padding:14px 20px;background:var(--ink);color:#fff;border:none;border-radius:3px;
  font-size:14px;font-weight:600;cursor:pointer;transition:background .25s,transform .2s;
}
.btn-primary:hover{background:var(--brass)}
.btn-primary:active{transform:translateY(1px)}
.btn-primary:disabled{opacity:.55;cursor:wait}
.btn-ghost{
  width:50px;display:inline-flex;align-items:center;justify-content:center;
  background:var(--surface);border:1px solid var(--line-strong);border-radius:3px;
  color:var(--ink-2);cursor:pointer;transition:all .25s;
}
.btn-ghost:hover{border-color:var(--brass);color:var(--brass)}

/* examples */
.examples{padding-top:22px;border-top:1px solid var(--line);display:flex;flex-wrap:wrap;gap:8px;align-items:center}
.examples-cap{font-size:11px;letter-spacing:.16em;text-transform:uppercase;color:var(--ink-3);margin-right:4px;font-weight:600}
.chip{
  padding:6px 13px;background:var(--paper);border:1px solid var(--line-strong);
  border-radius:30px;font-size:12.5px;color:var(--ink-2);cursor:pointer;transition:all .22s;
}
.chip:hover{border-color:var(--brass);color:var(--brass);background:var(--surface);transform:translateY(-1px)}

/* map */
.map-card{display:flex;flex-direction:column}
#map{width:100%;height:100%;min-height:520px;background:#eef0f0}
.map-caption{
  position:absolute;bottom:16px;left:50%;transform:translateX(-50%);z-index:500;
  background:rgba(255,255,255,.92);backdrop-filter:blur(6px);
  padding:7px 16px;border-radius:30px;font-size:12px;color:var(--ink-2);
  border:1px solid var(--line);pointer-events:none;white-space:nowrap;letter-spacing:.02em;
}

/* ---------- RESULT ---------- */
.result-wrap{max-width:1180px;margin:56px auto 0;padding:0 32px}
.result-inner{
  background:var(--surface);border:1px solid var(--line);border-radius:4px;
  box-shadow:var(--shadow-lift);padding:0;overflow:hidden;
}
.state{padding:70px 32px;text-align:center}
.state-mark{width:54px;height:54px;margin:0 auto 18px;border:1px solid var(--line-strong);border-radius:50%;display:flex;align-items:center;justify-content:center;color:var(--brass);font-family:var(--serif);font-size:24px}
.state-mark .spinner{width:22px;height:22px;border:2px solid var(--line-strong);border-top-color:var(--brass);border-radius:50%;animation:spin .8s linear infinite}
.state.err{color:#b4452e;border-color:#f0d2c8}
.state p{color:var(--ink-2);font-size:14px}

.diagnosis{padding:38px 40px 42px}
.diagnosis-head{
  display:flex;justify-content:space-between;align-items:flex-end;
  padding-bottom:26px;margin-bottom:30px;border-bottom:1px solid var(--line);
}
.dh-label{display:block;font-size:11px;letter-spacing:.2em;text-transform:uppercase;color:var(--ink-3);margin-bottom:7px}
.dh-coord{font-family:var(--mono);font-size:22px;color:var(--ink);font-weight:500}
.dh-right{font-family:var(--mono);font-size:12px;color:var(--ink-3)}

.diagnosis-grid{display:grid;grid-template-columns:1.1fr .9fr 1.4fr;gap:34px}
.diag-cap{display:block;font-size:11px;letter-spacing:.2em;text-transform:uppercase;color:var(--ink-3);margin-bottom:16px;font-weight:600}
.diag-rate .rate-figure{display:flex;align-items:baseline;gap:8px;margin-bottom:18px}
.rate-num{font-family:var(--serif);font-size:62px;line-height:.9;font-weight:500;color:var(--ink);letter-spacing:-.02em}
.rate-unit{font-family:var(--mono);font-size:14px;color:var(--ink-2)}
.rate-scale{height:5px;background:var(--line);border-radius:3px;overflow:hidden}
.rate-scale-fill{height:100%;width:0;border-radius:3px;transition:width .9s cubic-bezier(.2,.7,.2,1)}

.diag-grade{text-align:center;display:flex;flex-direction:column;align-items:center;padding:6px 0}
.grade-letter{font-family:var(--serif);font-size:84px;line-height:.85;font-weight:500;margin-bottom:12px}
.grade-name{font-size:17px;font-weight:600;color:var(--ink);margin-bottom:12px}
.grade-badge{font-family:var(--mono);font-size:12px;color:#fff;padding:5px 15px;border-radius:30px;letter-spacing:.02em}

.diag-desc{display:flex;flex-direction:column}
.desc-text{font-size:14.5px;color:var(--ink);line-height:1.8;font-weight:300;flex:1;margin-bottom:18px}
.desc-foot{padding-top:16px;border-top:1px solid var(--line);font-size:13px;color:var(--ink-2);display:flex;gap:10px;flex-wrap:wrap}
.desc-foot .examples-cap{color:var(--ink-3)}

/* detail rows */
.detail{margin-top:34px;padding-top:30px;border-top:1px solid var(--line);display:grid;grid-template-columns:1fr 1fr;gap:0 56px}
.detail-row{display:flex;justify-content:space-between;align-items:center;padding:13px 0;border-bottom:1px solid var(--line)}
.detail-row span{font-size:13px;color:var(--ink-2)}
.detail-row b{font-family:var(--mono);font-size:13.5px;color:var(--ink);font-weight:500;text-align:right}

/* ---------- METHOD ---------- */
.method-grid{display:grid;grid-template-columns:repeat(4,1fr);gap:22px}
.method-card{
  background:var(--surface);border:1px solid var(--line);border-radius:4px;
  padding:30px 26px;transition:transform .3s,box-shadow .3s,border-color .3s;
}
.method-card:hover{transform:translateY(-4px);box-shadow:var(--shadow);border-color:var(--line-strong)}
.method-no{font-family:var(--serif);font-style:italic;font-size:26px;color:var(--brass);display:block;margin-bottom:18px}
.method-card h3{font-family:var(--serif);font-weight:500;font-size:19px;margin-bottom:11px}
.method-card p{font-size:13.5px;color:var(--ink-2);line-height:1.75;font-weight:300}

/* ---------- REFERENCE TABLE ---------- */
.ref-table-wrap{background:var(--surface);border:1px solid var(--line);border-radius:4px;overflow:hidden}
.ref-table{width:100%;border-collapse:collapse}
.ref-table th{
  text-align:left;padding:15px 26px;font-size:11px;letter-spacing:.16em;text-transform:uppercase;
  color:var(--ink-3);font-weight:600;background:var(--paper);border-bottom:1px solid var(--line-strong);
}
.ref-table td{padding:16px 26px;font-size:14px;color:var(--ink);border-bottom:1px solid var(--line);font-weight:300}
.ref-table tr:last-child td{border-bottom:none}
.ref-table tr:hover td{background:var(--paper)}
.ref-level{font-family:var(--serif);font-weight:600;font-size:18px}
.ref-color{display:inline-block;width:22px;height:22px;border-radius:4px;vertical-align:middle;box-shadow:inset 0 0 0 1px rgba(0,0,0,.06)}
.ref-mono{font-family:var(--mono);font-size:13px;color:var(--ink-2)}

/* ---------- ABOUT ---------- */
.about-inner{display:grid;grid-template-columns:1.4fr .9fr;gap:60px;align-items:start;border-top:1px solid var(--line);padding-top:64px}
.about-text p{font-size:16px;color:var(--ink-2);font-weight:300;line-height:1.9;margin-bottom:20px;max-width:560px}
.about-side{display:flex;flex-direction:column;gap:0;border-left:1px solid var(--line)}
.about-stat{padding:20px 0 20px 30px;border-bottom:1px solid var(--line)}
.about-stat:last-child{border-bottom:none}
.about-stat b{font-family:var(--serif);font-size:34px;font-weight:500;display:block;color:var(--ink)}
.about-stat span{font-size:13px;color:var(--ink-3)}

/* ---------- FOOTER ---------- */
.foot{margin-top:120px;border-top:1px solid var(--line);background:var(--surface)}
.foot-inner{max-width:1180px;margin:0 auto;padding:48px 32px;text-align:center}
.foot-brand{font-family:var(--serif);font-size:22px;font-weight:500;margin-bottom:16px;letter-spacing:-.01em}
.foot-brand span{font-family:var(--sans);font-size:11px;letter-spacing:.28em;color:var(--ink-3);border:1px solid var(--line-strong);padding:3px 8px;border-radius:2px;margin-left:8px;vertical-align:middle;font-weight:600}
.foot-note{font-size:12.5px;color:var(--ink-2);margin-bottom:10px;font-family:var(--mono)}
.foot-fine{font-size:12px;color:var(--ink-3)}

/* ---------- LEAFLET OVERRIDES (minimal) ---------- */
.leaflet-control-zoom{border:none!important;box-shadow:var(--shadow)!important}
.leaflet-control-zoom a{
  background:var(--surface)!important;color:var(--ink)!important;
  border:1px solid var(--line)!important;width:32px!important;height:32px!important;
  line-height:30px!important;font-size:16px!important;border-radius:3px!important;
}
.leaflet-control-zoom a:first-child{border-bottom:none!important;border-radius:3px 3px 0 0!important}
.leaflet-control-zoom a:last-child{border-radius:0 0 3px 3px!important}
.leaflet-control-zoom a:hover{color:var(--brass)!important}
.leaflet-control-attribution{
  background:rgba(255,255,255,.8)!important;font-size:10px!important;color:var(--ink-3)!important;
}
.custom-marker div{
  width:26px;height:26px;background:var(--brass);border:3px solid #fff;
  border-radius:50% 50% 50% 0;transform:rotate(-45deg);
  box-shadow:0 3px 10px rgba(26,24,21,.3);
}

/* ---------- REVEAL ANIMATION ---------- */
.reveal{opacity:0;transform:translateY(22px);transition:opacity .8s ease,transform .8s cubic-bezier(.2,.7,.2,1)}
.reveal.in{opacity:1;transform:none}

@keyframes spin{to{transform:rotate(360deg)}}

/* ---------- RESPONSIVE ---------- */
@media (max-width:980px){
  .studio-grid{grid-template-columns:1fr}
  .method-grid{grid-template-columns:1fr 1fr}
  .diagnosis-grid{grid-template-columns:1fr;gap:30px}
  .detail{grid-template-columns:1fr;gap:0}
  .about-inner{grid-template-columns:1fr;gap:36px}
  .about-side{border-left:none;border-top:1px solid var(--line)}
  .about-stat{padding-left:0}
}
@media (max-width:680px){
  .nav-links{display:none}
  .hero{padding:80px 22px 64px}
  .method-grid{grid-template-columns:1fr}
  section{padding-left:22px;padding-right:22px}
  .result-wrap{padding-left:22px;padding-right:22px}
  .diagnosis{padding:28px 24px 32px}
  .hero-meta{gap:18px}
  .meta-sep{display:none}
  .nav-inner{padding:16px 22px}
  #map{min-height:380px}
}

/* ---------- NAV AUTH ---------- */
.nav-auth{display:flex;align-items:center;gap:10px}
.btn-nav{
  font-family:var(--sans);font-size:13px;font-weight:500;
  padding:7px 16px;border-radius:3px;cursor:pointer;
  background:transparent;border:1px solid var(--line-strong);color:var(--ink-2);
  transition:all .25s ease;white-space:nowrap;
}
.btn-nav:hover{border-color:var(--brass);color:var(--ink)}
.btn-nav-solid{background:var(--ink);border-color:var(--ink);color:#fff}
.btn-nav-solid:hover{background:var(--brass);border-color:var(--brass);color:#fff}
.nav-user{font-size:13px;color:var(--ink-2);max-width:150px;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}

/* ---------- AUTH MODAL ---------- */
.auth-overlay{
  position:fixed;inset:0;z-index:2000;
  background:rgba(26,24,21,.42);backdrop-filter:blur(4px);
  display:flex;align-items:center;justify-content:center;padding:24px;
}
.auth-modal{
  position:relative;width:100%;max-width:420px;
  background:var(--surface);border:1px solid var(--line);
  border-radius:6px;box-shadow:var(--shadow-lift);
  padding:42px 40px 36px;
  animation:authIn .35s cubic-bezier(.2,.7,.3,1);
}
@keyframes authIn{from{opacity:0;transform:translateY(14px)}to{opacity:1;transform:none}}
.auth-close{
  position:absolute;top:12px;right:16px;
  background:none;border:none;font-size:26px;line-height:1;color:var(--ink-3);cursor:pointer;
  transition:color .2s;
}
.auth-close:hover{color:var(--ink)}
.auth-head{text-align:center;margin-bottom:28px}
.auth-brand{
  font-family:var(--serif);font-size:17px;font-weight:500;color:var(--ink);
  display:inline-block;margin-bottom:18px;
}
.auth-brand span{font-size:9px;letter-spacing:.28em;color:var(--ink-3);border:1px solid var(--line-strong);padding:2px 6px;border-radius:2px;margin-left:6px;font-weight:600}
.auth-head h3{font-family:var(--serif);font-weight:500;font-size:24px;margin-bottom:8px}
.auth-head p{font-size:13px;color:var(--ink-2);font-weight:300}
.auth-form .field{margin-bottom:16px}
.auth-submit{width:100%;justify-content:center;height:46px;margin-top:10px}
.auth-switch{text-align:center;font-size:13px;color:var(--ink-2);margin-top:18px}
.auth-switch a{color:var(--brass);text-decoration:none;font-weight:500}
.auth-switch a:hover{text-decoration:underline}
.auth-msg{margin-top:16px;padding:11px 14px;border-radius:4px;font-size:13px;text-align:center;line-height:1.5}
.auth-msg.err{background:rgba(200,60,60,.08);color:#b23b3b;border:1px solid rgba(200,60,60,.18)}
.auth-msg.ok{background:rgba(63,174,107,.1);color:#2f8f55;border:1px solid rgba(63,174,107,.2)}

@media(max-width:600px){
  .auth-modal{padding:34px 24px 28px}
  .nav-auth .btn-nav{padding:6px 12px}
}