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

:root {
  --bg: #F7F6F2;
  --surface: #FFFFFF;
  --border: rgba(0,0,0,0.08);
  --border-strong: rgba(0,0,0,0.15);
  --text: #1A1A18;
  --text-muted: #6B6B66;
  --text-faint: #9C9C96;
  --accent-bg: #1A1A18;
  --accent-text: #F7F6F2;
  --radius: 12px;
  --radius-sm: 8px;
  --tag-finance: #E8F4EE;
  --tag-finance-text: #1A5C35;
  --tag-health: #FEF0E8;
  --tag-health-text: #7A2E0A;
  --tag-math: #EEF0FE;
  --tag-math-text: #2A2E8A;
  --tag-everyday: #FEF6E8;
  --tag-everyday-text: #7A4E0A;
}

body {
  font-family: 'DM Sans', sans-serif;
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
  font-size: 15px;
  line-height: 1.6;
}

/* HEADER */
header {
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  padding: 0 2rem;
  position: sticky;
  top: 0;
  z-index: 100;
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 60px;
}

.logo {
  font-family: 'Syne', sans-serif;
  font-weight: 800;
  font-size: 1.3rem;
  letter-spacing: -0.03em;
  color: var(--text);
  text-decoration: none;
}

.logo span { color: var(--text-muted); font-weight: 400; }

.search-bar {
  display: flex;
  align-items: center;
  gap: 8px;
  background: var(--bg);
  border: 1px solid var(--border-strong);
  border-radius: 999px;
  padding: 6px 14px;
  width: 240px;
  transition: border-color 0.2s;
}

.search-bar:focus-within { border-color: var(--accent-bg); }

.search-bar input {
  background: none;
  border: none;
  outline: none;
  font-family: 'DM Sans', sans-serif;
  font-size: 13.5px;
  color: var(--text);
  width: 100%;
}

.search-bar input::placeholder { color: var(--text-faint); }

/* HERO */
.hero {
  text-align: center;
  padding: 4rem 2rem 2.5rem;
}

.hero h1 {
  font-family: 'Syne', sans-serif;
  font-weight: 800;
  font-size: clamp(2rem, 5vw, 3.2rem);
  letter-spacing: -0.04em;
  line-height: 1.1;
  margin-bottom: 0.75rem;
}

.hero p {
  color: var(--text-muted);
  font-size: 1rem;
  max-width: 420px;
  margin: 0 auto 2rem;
  font-weight: 300;
}

/* FILTERS */
.filters {
  display: flex;
  gap: 8px;
  justify-content: center;
  flex-wrap: wrap;
  padding: 0 2rem 2.5rem;
}

.filter-btn {
  font-family: 'DM Sans', sans-serif;
  font-size: 13px;
  font-weight: 500;
  padding: 6px 16px;
  border-radius: 999px;
  border: 1px solid var(--border-strong);
  background: var(--surface);
  color: var(--text-muted);
  cursor: pointer;
  transition: all 0.15s;
  text-decoration: none;
  display: inline-block;
}

.filter-btn:hover { border-color: var(--text); color: var(--text); }
.filter-btn.active { background: var(--accent-bg); color: var(--accent-text); border-color: var(--accent-bg); }

/* GRID */
.container { max-width: 1100px; margin: 0 auto; padding: 0 2rem 4rem; }

.calc-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 16px;
}

.calc-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  transition: border-color 0.2s, box-shadow 0.2s, transform 0.15s;
  text-decoration: none;
  color: inherit;
  display: block;
}

.calc-card:hover {
  border-color: var(--border-strong);
  box-shadow: 0 4px 16px rgba(0,0,0,0.08);
  transform: translateY(-1px);
}

.card-header {
  padding: 1.25rem 1.25rem 1rem;
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 12px;
}

.card-icon {
  width: 40px; height: 40px;
  border-radius: var(--radius-sm);
  display: flex; align-items: center; justify-content: center;
  font-size: 18px;
  flex-shrink: 0;
}

.card-title-area { flex: 1; }

.card-title {
  font-family: 'Syne', sans-serif;
  font-weight: 600;
  font-size: 0.95rem;
  color: var(--text);
  margin-bottom: 2px;
}

.card-desc { font-size: 12.5px; color: var(--text-muted); line-height: 1.4; }

.card-tag {
  font-family: 'DM Mono', monospace;
  font-size: 10px;
  font-weight: 500;
  padding: 3px 8px;
  border-radius: 999px;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  flex-shrink: 0;
}

.tag-finance { background: var(--tag-finance); color: var(--tag-finance-text); }
.tag-health { background: var(--tag-health); color: var(--tag-health-text); }
.tag-math { background: var(--tag-math); color: var(--tag-math-text); }
.tag-everyday { background: var(--tag-everyday); color: var(--tag-everyday-text); }

/* CALCULATOR PAGE */
.calc-page { max-width: 680px; margin: 0 auto; padding: 2.5rem 2rem 4rem; }

.breadcrumb {
  font-size: 13px;
  color: var(--text-faint);
  margin-bottom: 1.5rem;
  font-family: 'DM Mono', monospace;
}

.breadcrumb a { color: var(--text-faint); text-decoration: none; }
.breadcrumb a:hover { color: var(--text); }

.calc-page h1 {
  font-family: 'Syne', sans-serif;
  font-weight: 800;
  font-size: clamp(1.6rem, 4vw, 2.2rem);
  letter-spacing: -0.03em;
  margin-bottom: 0.5rem;
}

.calc-page .subtitle {
  color: var(--text-muted);
  font-size: 0.95rem;
  margin-bottom: 2rem;
}

.calc-box {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: 2rem;
  margin-bottom: 2rem;
}

.field { margin-bottom: 1rem; }

label {
  display: block;
  font-size: 12px;
  font-weight: 500;
  color: var(--text-muted);
  margin-bottom: 5px;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  font-family: 'DM Mono', monospace;
}

input[type=number], input[type=text], input[type=date], select {
  width: 100%;
  padding: 11px 14px;
  border: 1px solid var(--border-strong);
  border-radius: var(--radius-sm);
  font-family: 'DM Sans', sans-serif;
  font-size: 15px;
  background: var(--bg);
  color: var(--text);
  outline: none;
  transition: border-color 0.15s;
  -moz-appearance: textfield;
}

input:focus, select:focus { border-color: var(--text); background: var(--surface); }

.input-row { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; }

.calc-btn {
  width: 100%;
  padding: 13px;
  background: var(--accent-bg);
  color: var(--accent-text);
  border: none;
  border-radius: var(--radius-sm);
  font-family: 'Syne', sans-serif;
  font-weight: 600;
  font-size: 0.95rem;
  cursor: pointer;
  margin-top: 0.5rem;
  transition: opacity 0.15s;
}

.calc-btn:hover { opacity: 0.82; }

.result-box {
  margin-top: 1.5rem;
  padding: 1.5rem;
  background: var(--bg);
  border-radius: var(--radius-sm);
  border: 1px solid var(--border);
  display: none;
}

.result-box.show { display: block; }

.result-label {
  font-family: 'DM Mono', monospace;
  font-size: 11px;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--text-faint);
  margin-bottom: 4px;
}

.result-value {
  font-family: 'Syne', sans-serif;
  font-weight: 700;
  font-size: 2rem;
  color: var(--text);
  line-height: 1.1;
}

.result-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
  margin-top: 1rem;
}

.result-item {
  background: var(--surface);
  border-radius: var(--radius-sm);
  padding: 0.875rem 1rem;
  border: 1px solid var(--border);
}

.result-item .result-value { font-size: 1.2rem; }

/* INFO SECTION */
.info-section { margin-top: 2.5rem; }

.info-section h2 {
  font-family: 'Syne', sans-serif;
  font-weight: 700;
  font-size: 1.2rem;
  margin-bottom: 0.75rem;
  letter-spacing: -0.02em;
}

.info-section p {
  color: var(--text-muted);
  font-size: 0.9rem;
  line-height: 1.7;
  margin-bottom: 1rem;
}

.formula-box {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 1rem 1.25rem;
  font-family: 'DM Mono', monospace;
  font-size: 13px;
  color: var(--text-muted);
  margin: 1rem 0;
}

/* RELATED */
.related-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
  gap: 10px;
  margin-top: 1rem;
}

.related-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 0.875rem 1rem;
  text-decoration: none;
  color: var(--text);
  font-size: 13.5px;
  font-weight: 500;
  transition: all 0.15s;
  display: flex;
  align-items: center;
  gap: 8px;
}

.related-card:hover { border-color: var(--border-strong); transform: translateY(-1px); }

/* FOOTER */
footer {
  border-top: 1px solid var(--border);
  padding: 2rem;
  text-align: center;
  color: var(--text-faint);
  font-size: 13px;
  font-family: 'DM Mono', monospace;
}

/* NO RESULTS */
.no-results { text-align: center; padding: 4rem 2rem; color: var(--text-muted); display: none; }
.no-results.show { display: block; }
.no-results h3 { font-family: 'Syne', sans-serif; font-size: 1.1rem; margin-bottom: 0.5rem; }

@media (max-width: 600px) {
  header { padding: 0 1rem; }
  .search-bar { width: 160px; }
  .container { padding: 0 1rem 3rem; }
  .hero { padding: 2.5rem 1rem 1.5rem; }
  .filters { padding: 0 1rem 2rem; }
  .input-row { grid-template-columns: 1fr; }
  .result-grid { grid-template-columns: 1fr; }
  .calc-page { padding: 1.5rem 1rem 3rem; }
  .calc-box { padding: 1.25rem; }
}