/* BulkCalculator — Physics Tools shared stylesheet
   Extends the existing BulkCalculator design tokens. Keep in sync with dev-tools/uuid-generator.html header pattern. */

:root{
  --bg:#f7f9fc;
  --card:#ffffff;
  --ink:#1a2332;
  --ink-soft:#4a5568;
  --muted:#718096;
  --border:#e2e8f0;
  --primary:#2563eb;
  --primary-dark:#1d4ed8;
  --accent:#0d9488;
  --success:#059669;
  --warn:#d97706;
  --danger:#dc2626;
  --violet:#7c3aed;
  --radius:12px;
  --shadow:0 1px 3px rgba(0,0,0,.05), 0 1px 2px rgba(0,0,0,.03);
  --shadow-md:0 4px 12px rgba(0,0,0,.06);
  --grad-hero:linear-gradient(135deg,#eff6ff 0%,#ecfeff 50%,#f5f3ff 100%);
  --grad-mech:linear-gradient(135deg,#dbeafe,#bfdbfe);
  --grad-rot:linear-gradient(135deg,#e0f2fe,#bae6fd);
  --grad-wave:linear-gradient(135deg,#ccfbf1,#99f6e4);
  --grad-elec:linear-gradient(135deg,#fef3c7,#fde68a);
  --grad-therm:linear-gradient(135deg,#fee2e2,#fecaca);
  --grad-mod:linear-gradient(135deg,#ede9fe,#ddd6fe);
  --grad-sim:linear-gradient(135deg,#dcfce7,#bbf7d0);
}

*{box-sizing:border-box}
html,body{margin:0;padding:0;overflow-x:hidden}
body{font-family:-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,Helvetica,Arial,sans-serif;background:var(--bg);color:var(--ink);line-height:1.6;font-size:16px}
a{color:var(--primary);text-decoration:none}
a:hover{text-decoration:underline}

/* ===== HEADER (matches existing BulkCalculator) ===== */
.site-header{background:#fff;border-bottom:1px solid var(--border);position:sticky;top:0;z-index:100}
.nav-wrap{max-width:1200px;margin:0 auto;padding:14px 20px;display:flex;align-items:center;justify-content:space-between;flex-wrap:wrap;gap:12px}
.brand{font-weight:700;font-size:20px;color:var(--ink);display:flex;align-items:center;gap:8px}
.brand .diamond{color:var(--primary)}
.nav-toggle{display:none;background:none;border:1px solid var(--border);padding:6px 10px;border-radius:6px;cursor:pointer;font-size:18px}
.nav-menu{display:flex;list-style:none;margin:0;padding:0;gap:6px}
.nav-menu>li{position:relative}
.nav-menu>li>a,.nav-menu>li>span{padding:8px 14px;display:block;color:var(--ink);font-weight:500;cursor:pointer;border-radius:6px}
.nav-menu>li>a:hover,.nav-menu>li>span:hover{background:#f1f5f9;text-decoration:none}
.dropdown{display:none;position:absolute;top:100%;left:0;background:#fff;border:1px solid var(--border);border-radius:8px;box-shadow:var(--shadow-md);min-width:240px;padding:8px;z-index:101}
.nav-menu>li:hover .dropdown{display:block}
.dropdown li{list-style:none}
.dropdown a{display:block;padding:8px 12px;color:var(--ink-soft);border-radius:6px;font-size:14px}
.dropdown a:hover{background:#f1f5f9;color:var(--primary);text-decoration:none}

/* Two-column Bulk-Calculators dropdown */
header .dropdown{min-width:220px;max-width:calc(100vw - 40px)}
header .nav-menu>li:first-child .dropdown{min-width:380px;grid-template-columns:1fr 1fr;padding:8px}
header .nav-menu>li:first-child:hover .dropdown{display:grid;column-gap:6px}
header .nav-menu>li:last-child .dropdown{left:auto;right:0}
header .dropdown a{font-size:13px;padding:7px 10px;line-height:1.25;white-space:normal}

/* ===== CONTAINERS ===== */
.container{max-width:1200px;margin:0 auto;padding:24px 20px 60px}
.container-narrow{max-width:980px;margin:0 auto;padding:24px 20px 60px}
.breadcrumb,.crumbs{font-size:13px;color:var(--muted);margin-bottom:18px}
.breadcrumb a,.crumbs a{color:var(--muted)}
.breadcrumb a:hover,.crumbs a:hover{color:var(--primary)}

h1{font-size:32px;margin:0 0 10px;letter-spacing:-.02em;color:var(--ink)}
h2{font-size:22px;margin:32px 0 12px;padding-left:12px;border-left:3px solid var(--primary);color:var(--ink)}
h3{font-size:18px;margin:20px 0 10px;color:var(--ink)}
h4{font-size:16px;margin:16px 0 8px}
p{margin:10px 0}
ul,ol{padding-left:22px}
li{margin:6px 0}

/* ===== HERO ===== */
.phys-hero{background:var(--grad-hero);border-bottom:1px solid var(--border)}
.phys-hero-inner{max-width:1200px;margin:0 auto;padding:50px 20px 40px;text-align:center}
.phys-hero h1{font-size:2.4rem;margin:0 0 12px;background:linear-gradient(90deg,#2563eb,#0d9488,#7c3aed);-webkit-background-clip:text;background-clip:text;color:transparent}
.phys-hero p{font-size:1.1rem;color:var(--ink-soft);max-width:780px;margin:0 auto 20px}
.phys-hero .badges{display:flex;flex-wrap:wrap;gap:8px;justify-content:center}
.phys-hero .badge{background:#fff;border:1px solid var(--border);color:var(--primary);padding:5px 12px;border-radius:999px;font-size:12px;font-weight:600;box-shadow:var(--shadow)}

/* ===== SEARCH ===== */
.phys-search{max-width:720px;margin:24px auto 0;position:relative}
.phys-search input{width:100%;padding:14px 18px 14px 44px;border:1px solid var(--border);border-radius:999px;font-size:15px;background:#fff;box-shadow:var(--shadow)}
.phys-search input:focus{outline:none;border-color:var(--primary);box-shadow:0 0 0 3px rgba(37,99,235,.15)}
.phys-search::before{content:"🔍";position:absolute;left:16px;top:50%;transform:translateY(-50%);font-size:16px}

/* ===== CATEGORY SECTION ===== */
.cat-block{max-width:1200px;margin:40px auto 0;padding:0 20px}
.cat-head{display:flex;align-items:center;gap:14px;margin-bottom:14px}
.cat-icon{width:44px;height:44px;border-radius:12px;display:flex;align-items:center;justify-content:center;font-size:22px;flex-shrink:0}
.cat-head h2{margin:0;padding:0;border:none;font-size:1.4rem}
.cat-head .cat-sub{color:var(--muted);font-size:.95rem;margin:2px 0 0}
.cat-icon.mech{background:var(--grad-mech);color:#1e40af}
.cat-icon.rot{background:var(--grad-rot);color:#0369a1}
.cat-icon.wave{background:var(--grad-wave);color:#0f766e}
.cat-icon.elec{background:var(--grad-elec);color:#b45309}
.cat-icon.therm{background:var(--grad-therm);color:#b91c1c}
.cat-icon.mod{background:var(--grad-mod);color:#6d28d9}
.cat-icon.sim{background:var(--grad-sim);color:#166534}

.tool-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(260px,1fr));gap:14px;margin-top:6px}
.tool{background:var(--card);border:1px solid var(--border);border-radius:var(--radius);padding:16px;box-shadow:var(--shadow);transition:transform .15s ease,box-shadow .15s ease,border-color .15s;display:block;color:inherit;text-decoration:none}
.tool:hover{transform:translateY(-2px);box-shadow:var(--shadow-md);border-color:#c7d2fe;text-decoration:none}
.tool .ico{font-size:1.5rem;line-height:1;margin-bottom:8px}
.tool h3{font-size:1rem;margin:0 0 4px;color:var(--primary)}
.tool p{font-size:.88rem;color:var(--muted);margin:0}

/* ===== TOOL PAGE LAYOUT ===== */
.tool-card{background:var(--card);border:1px solid var(--border);border-radius:var(--radius);padding:24px;box-shadow:var(--shadow);margin:18px 0}
.tool-tagline{color:var(--muted);margin:-4px 0 18px}
.field{margin-bottom:14px}
.field label{display:block;font-weight:600;font-size:14px;margin-bottom:6px;color:var(--ink)}
.field .hint{font-size:12px;color:var(--muted);margin-top:4px}
.field-row{display:grid;grid-template-columns:1fr 140px;gap:10px}
.field-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(220px,1fr));gap:14px}

input[type=text],input[type=number],input[type=date],input[type=email],input[type=password],select,textarea{
  width:100%;padding:10px 12px;border:1px solid var(--border);border-radius:8px;font-size:15px;
  font-family:inherit;background:#fff;color:var(--ink);transition:border-color .15s,box-shadow .15s;
}
input:focus,select:focus,textarea:focus{outline:none;border-color:var(--primary);box-shadow:0 0 0 3px rgba(37,99,235,.15)}
input[type=number]::-webkit-inner-spin-button,input[type=number]::-webkit-outer-spin-button{opacity:1}
textarea{resize:vertical;min-height:120px;font-family:ui-monospace,SFMono-Regular,Menlo,Consolas,monospace;font-size:13px}

.btn-row{display:flex;gap:10px;flex-wrap:wrap;margin-top:16px}
.btn{padding:10px 18px;border-radius:8px;font-size:15px;font-weight:600;cursor:pointer;border:1px solid transparent;transition:all .15s;font-family:inherit;display:inline-flex;align-items:center;gap:6px}
.btn-primary{background:var(--primary);color:#fff}
.btn-primary:hover{background:var(--primary-dark)}
.btn-secondary{background:#fff;color:var(--ink-soft);border-color:var(--border)}
.btn-secondary:hover{background:#f1f5f9;color:var(--ink)}
.btn-ghost{background:transparent;color:var(--primary);padding:6px 10px}
.btn-accent{background:var(--accent);color:#fff}
.btn-accent:hover{background:#0f766e}
.btn:disabled{opacity:.5;cursor:not-allowed}

/* ===== RESULTS / FORMULA / STEPS ===== */
.result-card{background:#f0f9ff;border:1px solid #bae6fd;border-radius:var(--radius);padding:20px;margin-top:18px;position:relative}
.result-card h3{margin-top:0;display:flex;align-items:center;justify-content:space-between;gap:10px}
.copy-btn{background:#fff;border:1px solid var(--border);border-radius:6px;padding:6px 10px;cursor:pointer;font-size:13px}
.copy-btn:hover{background:#f1f5f9}
.result-row{display:flex;justify-content:space-between;align-items:flex-start;padding:10px 0;border-bottom:1px dashed #cbd5e1;gap:12px;flex-wrap:wrap}
.result-row:last-child{border-bottom:none}
.result-row .lbl{font-weight:600;color:var(--ink-soft);font-size:14px}
.result-row .val{font-weight:500;color:var(--ink);text-align:right;word-break:break-all;font-family:ui-monospace,SFMono-Regular,Menlo,Consolas,monospace;font-size:14px}
.result-big{font-size:28px;font-weight:700;color:var(--primary);margin:8px 0}
.result-actions{display:flex;gap:8px;flex-wrap:wrap;margin-top:14px}

.formula-box{background:#fff;border:1px solid var(--border);border-left:4px solid var(--accent);border-radius:8px;padding:14px 16px;margin:14px 0;font-family:"Cambria Math","Latin Modern Math",Georgia,serif;font-size:16px;overflow-x:auto;line-height:1.8}
.formula-box strong{color:var(--accent)}
.formula{background:#f8fafc;border:1px solid var(--border);border-radius:6px;padding:10px 12px;font-family:ui-monospace,monospace;font-size:13px;color:var(--ink);white-space:pre-wrap}

.steps-box{background:#fefce8;border:1px solid #fde68a;border-radius:8px;padding:14px 16px;margin:14px 0}
.steps-box h4{margin:0 0 10px;color:#a16207}
.steps-box ol{margin:0;padding-left:20px}
.steps-box li{font-size:14px;color:var(--ink-soft);margin:6px 0}

.example-box{background:#ecfdf5;border:1px solid #a7f3d0;border-radius:8px;padding:14px 16px;margin:14px 0}
.example-box h4{margin:0 0 8px;color:#047857}
.example-box code,.example-box pre{background:#fff;border:1px solid #d1fae5;border-radius:6px;padding:2px 6px;font-size:13px}

.warn-box{background:#fef2f2;border:1px solid #fecaca;border-radius:8px;padding:12px 14px;margin:12px 0;color:#991b1b;font-size:14px}
.info-box{background:#eff6ff;border:1px solid #bfdbfe;border-radius:8px;padding:12px 14px;margin:12px 0;color:#1e40af;font-size:14px}

/* ===== DIAGRAMS / SIMULATIONS ===== */
.svg-wrap{background:#fff;border:1px solid var(--border);border-radius:8px;padding:10px;margin:14px 0;overflow:hidden;text-align:center}
.svg-wrap svg{max-width:100%;height:auto;display:block;margin:0 auto}
.canvas-wrap{background:#0f172a;border:1px solid var(--border);border-radius:8px;padding:0;margin:14px 0;overflow:hidden;position:relative}
.canvas-wrap canvas{display:block;width:100%;height:auto;background:#0f172a}
.sim-controls{display:flex;gap:8px;flex-wrap:wrap;margin-top:10px}
.readout{display:grid;grid-template-columns:repeat(auto-fit,minmax(140px,1fr));gap:10px;margin-top:12px}
.readout .cell{background:#f8fafc;border:1px solid var(--border);border-radius:8px;padding:10px 12px}
.readout .cell .k{font-size:12px;color:var(--muted);font-weight:600;text-transform:uppercase;letter-spacing:.04em}
.readout .cell .v{font-size:16px;font-weight:700;color:var(--primary);font-family:ui-monospace,monospace}

/* ===== DATA TABLE ===== */
.data-table{width:100%;border-collapse:collapse;margin:10px 0;font-size:13px}
.data-table th,.data-table td{border:1px solid var(--border);padding:6px 10px;text-align:right;font-family:ui-monospace,monospace}
.data-table th{background:#f1f5f9;font-weight:600;color:var(--ink-soft);text-align:center}
.data-table tbody tr:nth-child(even){background:#f8fafc}
.table-wrap{max-height:240px;overflow:auto;border:1px solid var(--border);border-radius:8px;margin:10px 0}

/* ===== FAQ ===== */
details{background:#fff;border:1px solid var(--border);border-radius:8px;padding:14px 16px;margin:8px 0}
details[open]{box-shadow:var(--shadow)}
summary{font-weight:600;cursor:pointer;color:var(--ink);outline:none;list-style:none;position:relative;padding-right:20px}
summary::-webkit-details-marker{display:none}
summary::after{content:"+";position:absolute;right:0;top:0;color:var(--primary);font-weight:700;font-size:20px;line-height:1}
details[open] summary::after{content:"−"}
details p{color:var(--ink-soft);margin:10px 0 0}

/* ===== PILLS / RELATED ===== */
.pills{display:flex;flex-wrap:wrap;gap:8px;margin:14px 0}
.pills a{display:inline-block;background:#f1f5f9;color:var(--ink);padding:6px 14px;border-radius:999px;font-size:13px;border:1px solid var(--border)}
.pills a:hover{background:var(--primary);color:#fff;text-decoration:none;border-color:var(--primary)}

.related{max-width:1200px;margin:40px auto;padding:24px 20px;background:#fff;border:1px solid var(--border);border-radius:var(--radius)}
.related h2{margin:0 0 12px;font-size:1.2rem;border:none;padding:0}

/* ===== FOOTER (matches existing BulkCalculator) ===== */
.site-footer{background:#0f172a;color:#cbd5e1;margin-top:60px;padding:40px 20px 20px}
.footer-grid{max-width:1200px;margin:0 auto;display:grid;grid-template-columns:repeat(auto-fit,minmax(220px,1fr));gap:30px}
.footer-col h4{color:#fff;font-size:15px;margin:0 0 12px;font-weight:600}
.footer-col ul{list-style:none;padding:0;margin:0}
.footer-col li{margin:6px 0}
.footer-col a{color:#cbd5e1;font-size:14px}
.footer-col a:hover{color:#fff}
.footer-bottom{max-width:1200px;margin:30px auto 0;padding-top:20px;border-top:1px solid #1e293b;text-align:center;font-size:13px;color:#94a3b8}
.footer-grid .footer-col:nth-child(2) ul{display:grid;grid-template-columns:1fr 1fr;column-gap:14px}
.footer-grid .footer-col:nth-child(2) li{margin:4px 0;line-height:1.3}

/* ===== RESPONSIVE ===== */
@media (max-width:820px){
  .nav-toggle{display:block}
  .nav-menu{display:none;flex-direction:column;width:100%;background:#fff;border-top:1px solid var(--border);padding:10px 0;margin-top:14px}
  .nav-menu.open{display:flex}
  .nav-menu>li>a,.nav-menu>li>span{padding:10px 16px}
  .dropdown{position:static;display:none;box-shadow:none;border:none;padding:0 0 0 16px;background:transparent}
  .nav-menu>li.open .dropdown{display:block}
  header .nav-menu>li:first-child .dropdown,
  header .dropdown{min-width:0;grid-template-columns:1fr;padding:0 0 0 16px;left:0;right:auto}
  .footer-grid .footer-col:nth-child(2) ul{grid-template-columns:1fr}
}
@media (max-width:640px){
  .phys-hero h1{font-size:1.7rem}
  .phys-hero p{font-size:1rem}
  h1{font-size:24px}
  h2{font-size:19px}
  .field-row{grid-template-columns:1fr}
  .tool-grid{grid-template-columns:1fr}
  .result-big{font-size:22px}
}

/* ===== PRINT ===== */
@media print{
  .site-header,.site-footer,.ad-container,.btn-row,.result-actions,.sim-controls,.phys-search,.nav-toggle,.pills{display:none!important}
  body{background:#fff;color:#000}
  .tool-card,.result-card,.formula-box{box-shadow:none;border:1px solid #999}
  a{color:#000;text-decoration:underline}
}

/* ===== HELPERS ===== */
.hidden{display:none!important}
.flex{display:flex;gap:10px;align-items:center}
.mt-0{margin-top:0}.mt-1{margin-top:8px}.mt-2{margin-top:16px}.mt-3{margin-top:24px}
.text-center{text-align:center}
.text-muted{color:var(--muted)}
.note{font-size:13px;color:var(--muted);margin-top:6px}