*,*::before,*::after{box-sizing:border-box;margin:0;padding:0}
:root{
  --primary:#18181b;
  --primary-dark:#09090b;
  --accent:#2563eb;
  --accent-light:#dbeafe;
  --bg:#fafafa;
  --card:#fff;
  --text:#18181b;
  --text-secondary:#71717a;
  --text-tertiary:#a1a1aa;
  --border:#f4f4f5;
  --border-hover:#e4e4e7;
  --radius:16px;
  --radius-sm:10px;
  --shadow:0 1px 2px rgba(0,0,0,.04);
  --shadow-md:0 2px 8px rgba(0,0,0,.06);
  --shadow-lg:0 8px 24px rgba(0,0,0,.08);
  --font:-apple-system,BlinkMacSystemFont,'Inter','Segoe UI',Roboto,sans-serif;
}

/* DARK MODE */
[data-theme="dark"]{
  --primary:#fafafa;
  --primary-dark:#e4e4e7;
  --accent:#60a5fa;
  --accent-light:#1e3a5f;
  --bg:#0a0a0b;
  --card:#141415;
  --text:#fafafa;
  --text-secondary:#a1a1aa;
  --text-tertiary:#52525b;
  --border:#1f1f23;
  --border-hover:#27272a;
  --shadow:0 1px 2px rgba(0,0,0,.2);
  --shadow-md:0 2px 8px rgba(0,0,0,.3);
  --shadow-lg:0 8px 24px rgba(0,0,0,.4);
}

body{font-family:var(--font);background:var(--bg);color:var(--text);line-height:1.6;min-height:100vh;-webkit-font-smoothing:antialiased;transition:background .3s,color .3s}
a{color:var(--text);text-decoration:none}
a:hover{color:var(--accent)}

/* NAV */
.nav{
  background:rgba(255,255,255,.85);
  backdrop-filter:blur(12px);-webkit-backdrop-filter:blur(12px);
  border-bottom:1px solid var(--border);
  padding:0 2rem;
  height:56px;
  display:flex;align-items:center;gap:1.5rem;
  position:sticky;top:0;z-index:100;
}
[data-theme="dark"] .nav{background:rgba(10,10,11,.85)}
.nav-logo{font-weight:700;font-size:1.125rem;color:var(--text);letter-spacing:-.02em;flex-shrink:0}
.nav-links{display:flex;gap:0;flex:1}
.nav-links a{padding:.5rem .75rem;font-size:.8125rem;color:var(--text-secondary);transition:color .15s;white-space:nowrap;font-weight:500;border-radius:6px}
.nav-links a:hover{color:var(--text);text-decoration:none}
.nav-links a.active{color:var(--text);background:var(--bg)}
[data-theme="dark"] .nav-links a.active{background:var(--border)}

/* Theme toggle */
.theme-toggle{
  flex-shrink:0;
  width:36px;height:36px;
  display:flex;align-items:center;justify-content:center;
  background:var(--bg);border:1px solid var(--border-hover);
  border-radius:50%;cursor:pointer;font-size:1rem;
  color:var(--text-secondary);transition:all .15s;
}
.theme-toggle:hover{color:var(--text);border-color:var(--text-tertiary)}

/* LAYOUT */
.page{max-width:880px;margin:0 auto;padding:3rem 1.5rem 2rem}
.page h1{font-size:2.25rem;font-weight:700;letter-spacing:-.03em;margin-bottom:.25rem}
.page .subtitle{color:var(--text-secondary);margin-bottom:2.5rem;font-size:1.0625rem;font-weight:400}

/* HERO (homepage) */
.hero{padding:4rem 0 1rem;text-align:center}
.hero h1{font-size:2.75rem;letter-spacing:-.04em;line-height:1.15;margin-bottom:.75rem}
.hero .subtitle{font-size:1.125rem;max-width:480px;margin:0 auto 2.5rem}

/* CARD */
.card{background:var(--card);border:1px solid var(--border);border-radius:var(--radius);padding:2rem;margin-bottom:1.25rem;transition:border-color .2s,background .3s}
.card:hover{border-color:var(--border-hover)}
.card h2{font-size:1.125rem;font-weight:600;margin-bottom:1rem;letter-spacing:-.01em}

/* FORM ELEMENTS */
label{display:block;font-weight:500;margin-bottom:.4rem;font-size:.8125rem;color:var(--text-secondary);text-transform:uppercase;letter-spacing:.04em}
input,select{
  width:100%;padding:.625rem .875rem;
  border:1px solid var(--border-hover);border-radius:var(--radius-sm);
  font-size:.9375rem;font-family:var(--font);
  background:var(--bg);color:var(--text);
  transition:border-color .15s,box-shadow .15s,background .3s;
}
input:focus,select:focus{outline:none;border-color:var(--accent);box-shadow:0 0 0 3px rgba(37,99,235,.1);background:var(--card)}
input::placeholder{color:var(--text-tertiary)}
.form-group{margin-bottom:1.25rem}
.form-row{display:grid;grid-template-columns:1fr 1fr;gap:1rem}

/* BUTTONS */
.btn{
  display:inline-flex;align-items:center;justify-content:center;
  padding:.625rem 1.25rem;
  background:var(--primary);color:var(--bg);
  border:none;border-radius:var(--radius-sm);
  font-size:.875rem;font-weight:600;font-family:var(--font);
  cursor:pointer;transition:all .15s;width:100%;
  letter-spacing:-.01em;
}
.btn:hover{opacity:.85;transform:translateY(-1px);box-shadow:var(--shadow-md)}
.btn:active{transform:translateY(0)}
.btn-secondary{background:var(--bg);color:var(--text);border:1px solid var(--border-hover)}
.btn-secondary:hover{background:var(--card);border-color:#d4d4d8;transform:translateY(-1px);opacity:1}
[data-theme="dark"] .btn-secondary:hover{border-color:var(--text-tertiary)}

/* RESULTS */
.result{
  background:var(--bg);
  border:1px solid var(--border);
  border-radius:var(--radius);
  padding:1.5rem;margin-top:1.5rem;
  display:none;transition:background .3s;
}
.result.show{display:block}
.result-row{display:flex;justify-content:space-between;align-items:center;padding:.625rem 0;border-bottom:1px solid var(--border)}
.result-row:last-child{border-bottom:none}
.result-label{color:var(--text-secondary);font-size:.875rem}
.result-value{font-weight:700;font-size:1rem;color:var(--text);font-variant-numeric:tabular-nums}
.result-big{font-size:2.25rem;font-weight:800;color:var(--text);text-align:center;padding:1.25rem 0;letter-spacing:-.03em;font-variant-numeric:tabular-nums}

/* CHART */
.chart-container{display:flex;justify-content:center;padding:1.5rem 0}
.chart-container canvas{max-width:220px;max-height:220px;width:100%;height:auto}
.chart-legend{display:flex;gap:1.25rem;justify-content:center;flex-wrap:wrap;padding:.5rem 0}
.chart-legend-item{display:flex;align-items:center;gap:.4rem;font-size:.8125rem;color:var(--text-secondary)}
.chart-legend-dot{width:10px;height:10px;border-radius:50%;flex-shrink:0}

/* AD SLOTS */
.ad-slot{
  background:var(--bg);
  border:1px dashed var(--border-hover);
  border-radius:var(--radius-sm);
  padding:1.25rem;text-align:center;
  color:var(--text-tertiary);font-size:.75rem;
  margin:1.5rem 0;
  letter-spacing:.02em;text-transform:uppercase;
}

/* HOMEPAGE GRID */
.calc-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(250px,1fr));gap:1rem}
.calc-card{
  background:var(--card);
  border:1px solid var(--border);
  border-radius:var(--radius);
  padding:1.75rem;
  transition:all .2s ease;
  text-decoration:none;color:var(--text);
  display:flex;flex-direction:column;
}
.calc-card:hover{
  border-color:var(--border-hover);
  box-shadow:var(--shadow-lg);
  transform:translateY(-3px);
  text-decoration:none;
}
.calc-card .icon{
  width:44px;height:44px;
  display:flex;align-items:center;justify-content:center;
  border-radius:12px;
  font-size:1.25rem;
  margin-bottom:1rem;
  background:var(--bg);
  border:1px solid var(--border);
}
.calc-card h3{font-size:1rem;font-weight:600;margin-bottom:.375rem;letter-spacing:-.01em}
.calc-card p{color:var(--text-secondary);font-size:.8125rem;line-height:1.55;flex:1}

/* RELATED CALCULATORS */
.related-section{margin-top:2.5rem}
.related-section h2{font-size:1rem;font-weight:600;margin-bottom:1rem;color:var(--text-secondary)}
.related-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(240px,1fr));gap:.75rem}
.related-card{
  display:flex;align-items:center;gap:1rem;
  padding:1rem 1.25rem;
  background:var(--card);border:1px solid var(--border);
  border-radius:var(--radius-sm);
  transition:all .15s;color:var(--text);
}
.related-card:hover{border-color:var(--border-hover);box-shadow:var(--shadow-md);transform:translateY(-1px);text-decoration:none}
.related-icon{font-size:1.25rem;flex-shrink:0}
.related-card strong{display:block;font-size:.875rem;margin-bottom:.125rem}
.related-card span{font-size:.75rem;color:var(--text-secondary)}

/* FAQ */
.faq-section{margin-top:2rem}
.faq-section h2{font-size:1rem;font-weight:600;margin-bottom:1rem;color:var(--text-secondary)}
.faq-item{border-bottom:1px solid var(--border);padding:1rem 0}
.faq-item:last-child{border-bottom:none}
.faq-q{font-weight:600;font-size:.9375rem;margin-bottom:.375rem;cursor:pointer;display:flex;justify-content:space-between;align-items:center}
.faq-q::after{content:'+';font-size:1.25rem;color:var(--text-tertiary);transition:transform .2s}
.faq-item.open .faq-q::after{transform:rotate(45deg)}
.faq-a{color:var(--text-secondary);font-size:.875rem;line-height:1.7;max-height:0;overflow:hidden;transition:max-height .3s ease}
.faq-item.open .faq-a{max-height:300px}

/* TABLE */
table{width:100%;border-collapse:collapse;font-size:.8125rem;margin-top:.75rem}
th,td{padding:.5rem .75rem;text-align:left;border-bottom:1px solid var(--border)}
th{font-weight:600;font-size:.75rem;text-transform:uppercase;letter-spacing:.04em;color:var(--text-secondary);position:sticky;top:0;background:var(--card)}
.table-wrap{max-height:400px;overflow-y:auto;border:1px solid var(--border);border-radius:var(--radius-sm)}

/* GPA rows */
.gpa-row{display:grid;grid-template-columns:2fr 1fr 1fr auto;gap:.75rem;align-items:end;margin-bottom:.75rem}
.gpa-row input,.gpa-row select{margin-bottom:0}

/* HAMBURGER */
.nav-hamburger{display:none;background:none;border:none;cursor:pointer;padding:.25rem;color:var(--text);font-size:1.5rem;line-height:1}

/* CATEGORY NAV DROPDOWN */
.nav-dropdown{position:relative}
.nav-cat{padding:.5rem .75rem;font-size:.8125rem;color:var(--text-secondary);cursor:pointer;font-weight:500;white-space:nowrap;display:block}
.nav-cat:hover{color:var(--text)}
.nav-cat::after{content:'▾';font-size:.625rem;margin-left:.25rem;opacity:.5}
.nav-dropdown-menu{display:none;position:absolute;top:100%;left:0;background:var(--card);border:1px solid var(--border);border-radius:var(--radius-sm);box-shadow:var(--shadow-lg);padding:.5rem 0;min-width:180px;z-index:200}
.nav-dropdown:hover .nav-dropdown-menu{display:block}
.nav-dropdown.open .nav-dropdown-menu{display:block}
.nav-dropdown-menu a{display:block;padding:.4rem 1rem;font-size:.8125rem;color:var(--text-secondary);white-space:nowrap}
.nav-dropdown-menu a:hover{background:var(--bg);color:var(--text);text-decoration:none}
.nav-dropdown-menu a.active{color:var(--text);font-weight:600}

/* CATEGORY TITLE (homepage) */
.category-title{font-size:1.125rem;font-weight:600;margin:2rem 0 .75rem;color:var(--text-secondary);letter-spacing:-.01em}
.category-title:first-of-type{margin-top:0}

/* AFFILIATE BOX */
.affiliate-box{border-left:3px solid var(--accent);position:relative}
.affiliate-label{font-size:.7rem;text-transform:uppercase;letter-spacing:.05em;color:var(--text-tertiary);position:absolute;top:.75rem;right:1rem}

/* EMBED SECTION */
.embed-section{margin-top:1.5rem}
.embed-code{width:100%;padding:.65rem .875rem;border:1px solid var(--border-hover);border-radius:var(--radius-sm);font-size:.75rem;font-family:monospace;background:var(--bg);color:var(--text);resize:none;height:60px}

/* EMBED MODE */
.embed-mode .nav,.embed-mode .footer,.embed-mode .ad-slot,.embed-mode .faq-section,.embed-mode .related-section,.embed-mode .affiliate-box,.embed-mode .embed-section,.embed-mode .subtitle{display:none!important}
.embed-mode .page{padding:1rem}
.embed-mode .page h1{font-size:1.5rem}

/* FOOTER */
.footer{text-align:center;padding:2.5rem 1.5rem;color:var(--text-tertiary);font-size:.75rem;border-top:1px solid var(--border);margin-top:4rem;transition:border-color .3s}
.footer a{color:var(--text-tertiary)}
.footer a:hover{color:var(--text-secondary)}

/* RESPONSIVE */
@media(max-width:640px){
  .nav{padding:.75rem 1rem;height:auto;flex-wrap:wrap;gap:.5rem}
  .nav-logo{order:0}
  .nav-hamburger{display:block;order:1;margin-left:auto}
  .theme-toggle{order:2}
  .nav-links{order:3;width:100%;display:none;flex-direction:column;gap:0;padding:.5rem 0;border-top:1px solid var(--border);margin-top:.5rem}
  .nav-links.open{display:flex}
  .nav-dropdown{position:static}
  .nav-cat{padding:.75rem 0;font-size:.9rem;border-bottom:1px solid var(--border)}
  .nav-dropdown-menu{position:static;box-shadow:none;border:none;border-radius:0;padding:0 0 .5rem 1rem;min-width:auto}
  .nav-dropdown:hover .nav-dropdown-menu{display:none}
  .nav-dropdown.open .nav-dropdown-menu{display:block}
  .nav-dropdown-menu a{padding:.5rem 0;font-size:.8125rem}
  .page{padding:2rem 1rem}
  .page h1{font-size:1.75rem}
  .hero h1{font-size:2rem}
  .hero .subtitle{font-size:1rem}
  .form-row{grid-template-columns:1fr}
  .calc-grid{grid-template-columns:1fr}
  .related-grid{grid-template-columns:1fr}
  .gpa-row{grid-template-columns:1fr 1fr}
  .result-big{font-size:1.75rem}
}