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

:root {
  --blue: #2563eb;
  --blue-dark: #1d4ed8;
  --blue-light: #eff6ff;
  --gray-50: #f8fafc;
  --gray-100: #f1f5f9;
  --gray-200: #e2e8f0;
  --gray-600: #475569;
  --gray-700: #334155;
  --gray-900: #0f172a;
  --green: #16a34a;
  --red: #dc2626;
  --white: #ffffff;
  --radius: 12px;
  --shadow: 0 1px 3px rgba(0,0,0,.08), 0 4px 16px rgba(0,0,0,.06);
}

body {
  font-family: system-ui, -apple-system, sans-serif;
  background: var(--gray-50);
  color: var(--gray-900);
  line-height: 1.6;
  min-height: 100vh;
}

a { color: var(--blue); text-decoration: none; }
a:hover { text-decoration: underline; }

/* NAV */
nav {
  background: var(--white);
  border-bottom: 1px solid var(--gray-200);
  padding: 0 1.5rem;
  position: sticky;
  top: 0;
  z-index: 100;
}
.nav-inner {
  max-width: 900px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 56px;
}
.logo {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--blue);
  letter-spacing: -0.5px;
  text-decoration: none;
}
.logo:hover { text-decoration: none; }
.logo span { color: var(--gray-700); }
nav ul { display: flex; gap: 1.5rem; list-style: none; }
nav ul a { color: var(--gray-700); font-size: .9rem; font-weight: 500; }
nav ul a:hover { color: var(--blue); text-decoration: none; }

/* MAIN */
main {
  max-width: 900px;
  margin: 0 auto;
  padding: 2rem 1.5rem 4rem;
}

/* HERO */
.hero {
  text-align: center;
  padding: 3rem 0 2.5rem;
}
.hero h1 {
  font-size: 2.4rem;
  font-weight: 800;
  color: var(--gray-900);
  line-height: 1.2;
  letter-spacing: -1px;
}
.hero p {
  color: var(--gray-600);
  font-size: 1.1rem;
  margin-top: .75rem;
}

/* SITE INTRO */
.site-intro {
  max-width: 700px;
  margin: 0 auto 1.5rem;
  text-align: center;
}
.site-intro p {
  color: var(--gray-600);
  font-size: .95rem;
  line-height: 1.75;
}

/* TOOL GRID */
.section-title {
  font-size: 1rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: .08em;
  color: var(--gray-600);
  margin: 2.5rem 0 1rem;
}
.tool-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 1rem;
}
.tool-card {
  background: var(--white);
  border: 1px solid var(--gray-200);
  border-radius: var(--radius);
  padding: 1.25rem 1.5rem;
  display: flex;
  flex-direction: column;
  gap: .4rem;
  transition: box-shadow .15s, border-color .15s;
  cursor: pointer;
}
.tool-card:hover {
  box-shadow: var(--shadow);
  border-color: var(--blue);
  text-decoration: none;
}
.tool-card .icon { font-size: 1.5rem; }
.tool-card h3 { font-size: 1rem; font-weight: 600; color: var(--gray-900); }
.tool-card p { font-size: .85rem; color: var(--gray-600); }
.tool-card .badge {
  display: inline-block;
  font-size: .7rem;
  font-weight: 600;
  padding: .15rem .5rem;
  border-radius: 99px;
  margin-top: .25rem;
  background: #fef3c7;
  color: #92400e;
}
.badge.new { background: #dcfce7; color: #166534; }

/* CALCULATOR PAGE */
.calc-page { max-width: 700px; }
.calc-header { margin-bottom: 2rem; }
.calc-header h1 { font-size: 1.9rem; font-weight: 800; letter-spacing: -.5px; }
.calc-header p { color: var(--gray-600); margin-top: .4rem; }
.breadcrumb { font-size: .85rem; color: var(--gray-600); margin-bottom: 1rem; }
.breadcrumb a { color: var(--gray-600); }

.calc-card {
  background: var(--white);
  border: 1px solid var(--gray-200);
  border-radius: var(--radius);
  padding: 2rem;
  box-shadow: var(--shadow);
}

/* FORM */
.form-group { margin-bottom: 1.25rem; }
label {
  display: block;
  font-size: .9rem;
  font-weight: 600;
  color: var(--gray-700);
  margin-bottom: .4rem;
}
input, select {
  width: 100%;
  padding: .65rem .9rem;
  border: 1.5px solid var(--gray-200);
  border-radius: 8px;
  font-size: 1rem;
  font-family: inherit;
  background: var(--white);
  color: var(--gray-900);
  transition: border-color .15s;
  appearance: none;
}
input:focus, select:focus {
  outline: none;
  border-color: var(--blue);
  box-shadow: 0 0 0 3px rgba(37,99,235,.12);
}
.input-prefix {
  position: relative;
}
.input-prefix span {
  position: absolute;
  left: .9rem;
  top: 50%;
  transform: translateY(-50%);
  color: var(--gray-600);
  font-size: 1rem;
  pointer-events: none;
}
.input-prefix input { padding-left: 1.8rem; }
.input-suffix { position: relative; }
.input-suffix span {
  position: absolute;
  right: .9rem;
  top: 50%;
  transform: translateY(-50%);
  color: var(--gray-600);
  font-size: 1rem;
  pointer-events: none;
}
.input-suffix input { padding-right: 2rem; }

.form-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1rem;
}

/* BUTTON */
.btn {
  width: 100%;
  padding: .8rem 1.5rem;
  background: var(--blue);
  color: var(--white);
  border: none;
  border-radius: 8px;
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  transition: background .15s;
  margin-top: .5rem;
}
.btn:hover { background: var(--blue-dark); }

/* RESULT */
.result-box {
  margin-top: 1.5rem;
  background: var(--blue-light);
  border: 1.5px solid #bfdbfe;
  border-radius: 10px;
  padding: 1.5rem;
  display: none;
}
.result-box.show { display: block; }
.result-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(160px, 1fr));
  gap: 1rem;
}
.result-item label {
  font-size: .8rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: .05em;
  color: #3b82f6;
  margin-bottom: .2rem;
}
.result-item .value {
  font-size: 1.6rem;
  font-weight: 800;
  color: var(--gray-900);
}
.result-item .value.green { color: var(--green); }

/* INFO SECTION */
.info-section {
  margin-top: 2.5rem;
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
}
.info-card {
  background: var(--white);
  border: 1px solid var(--gray-200);
  border-radius: var(--radius);
  padding: 1.5rem;
}
.info-card h2 { font-size: 1.1rem; font-weight: 700; margin-bottom: .75rem; }
.info-card p { color: var(--gray-600); font-size: .92rem; line-height: 1.7; }
.info-card ul {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: .4rem;
  margin-top: .5rem;
}
.info-card ul li {
  font-size: .9rem;
  color: var(--gray-600);
  padding-left: 1.2rem;
  position: relative;
}
.info-card ul li::before {
  content: "→";
  position: absolute;
  left: 0;
  color: var(--blue);
}

/* FOOTER */
footer {
  background: var(--white);
  border-top: 1px solid var(--gray-200);
  padding: 2rem 1.5rem;
  text-align: center;
  color: var(--gray-600);
  font-size: .875rem;
}
.footer-inner { max-width: 900px; margin: 0 auto; }
.footer-links { display: flex; justify-content: center; gap: 1.5rem; margin-bottom: .75rem; }
.footer-links a { color: var(--gray-600); font-size: .875rem; }

/* RELATED TOOLS */
.related { margin-top: 2.5rem; }
.related h2 { font-size: 1rem; font-weight: 700; margin-bottom: 1rem; color: var(--gray-700); }

@media (max-width: 600px) {
  .hero h1 { font-size: 1.7rem; }
  .form-row { grid-template-columns: 1fr; }
  .calc-card { padding: 1.25rem; }
  nav ul { display: none; }
}