@import url('https://fonts.googleapis.com/css2?family=DM+Sans:ital,opsz,wght@0,9..40,300;0,9..40,400;0,9..40,500;0,9..40,600;0,9..40,700;1,9..40,400&family=Space+Mono:wght@400;700&display=swap');

/* ─── Variables — Light Default ─── */
:root {
  --accent:       #2563EB;
  --accent-light: #EFF6FF;
  --accent-mid:   #BFDBFE;
  --accent-dark:  #1D4ED8;

  --bg:        #F8F9FA;
  --bg-white:  #FFFFFF;
  --surface:   #FFFFFF;
  --surface2:  #F3F4F6;
  --surface3:  #E9EAEC;

  --border:    #E5E7EB;
  --border2:   #D1D5DB;

  --text:         #111827;
  --text-soft:    #6B7280;
  --text-lighter: #9CA3AF;

  --nav-bg:    rgba(255,255,255,0.92);
  --shadow:    0 1px 3px rgba(0,0,0,0.08), 0 1px 2px rgba(0,0,0,0.04);
  --shadow-md: 0 4px 12px rgba(0,0,0,0.08);

  --radius:    12px;
  --radius-sm: 8px;
  --radius-xs: 6px;
  --transition: 0.18s ease;
}

html.dark {
  --accent:       #3B82F6;
  --accent-light: rgba(59,130,246,0.12);
  --accent-mid:   rgba(59,130,246,0.25);
  --accent-dark:  #60A5FA;

  --bg:       #0F1117;
  --bg-white: #161B27;
  --surface:  #1A2030;
  --surface2: #1F2737;
  --surface3: #263040;

  --border:  rgba(255,255,255,0.07);
  --border2: rgba(255,255,255,0.12);

  --text:         #F1F5F9;
  --text-soft:    #94A3B8;
  --text-lighter: #64748B;

  --nav-bg: rgba(15,17,23,0.92);
  --shadow:    0 1px 3px rgba(0,0,0,0.3);
  --shadow-md: 0 4px 16px rgba(0,0,0,0.3);
}

/* ─── Reset ─── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; }

body {
  font-family: 'DM Sans', -apple-system, BlinkMacSystemFont, sans-serif;
  background: var(--bg);
  color: var(--text);
  font-size: 15px;
  line-height: 1.6;
  min-height: 100vh;
  transition: background 0.25s ease, color 0.25s ease;
  -webkit-font-smoothing: antialiased;
}

/* ─── Nav ─── */
nav {
  position: sticky;
  top: 0;
  z-index: 100;
  background: var(--nav-bg);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
  padding: 0 24px;
  height: 56px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.nav-left  { display: flex; align-items: center; gap: 16px; }
.nav-right { display: flex; align-items: center; gap: 10px; }

.nav-logo { display: flex; align-items: center; text-decoration: none; }

.nav-logo .logo-dark  { display: block; }
.nav-logo .logo-light { display: none; }
html.dark .nav-logo .logo-dark  { display: none; }
html.dark .nav-logo .logo-light { display: block; }

.nav-logo img { height: 26px; width: auto; display: block; }

.nav-logo-text {
  font-weight: 700;
  font-size: 1rem;
  color: var(--text);
  letter-spacing: -0.2px;
}

.nav-back {
  display: flex;
  align-items: center;
  gap: 5px;
  font-size: 0.82rem;
  font-weight: 500;
  color: var(--text-soft);
  text-decoration: none;
  padding: 4px 10px;
  border-radius: var(--radius-xs);
  transition: all var(--transition);
}
.nav-back:hover { color: var(--accent); background: var(--accent-light); }
.nav-back svg   { width: 14px; height: 14px; flex-shrink: 0; }

/* ─── Theme Toggle ─── */
.theme-toggle {
  width: 40px;
  height: 22px;
  background: var(--surface3);
  border: 1px solid var(--border2);
  border-radius: 999px;
  cursor: pointer;
  display: flex;
  align-items: center;
  padding: 2px;
  transition: all var(--transition);
  flex-shrink: 0;
}
.theme-toggle:hover { border-color: var(--accent); }

.theme-toggle-knob {
  width: 16px;
  height: 16px;
  border-radius: 50%;
  background: var(--accent);
  transition: transform 0.25s ease;
  position: relative;
  flex-shrink: 0;
}
.theme-toggle-knob::after {
  content: '';
  position: absolute;
  inset: 0;
  background: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='10' height='10' viewBox='0 0 24 24' fill='none' stroke='white' stroke-width='2.5' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpath d='M21 12.79A9 9 0 1 1 11.21 3 7 7 0 0 0 21 12.79z'/%3E%3C/svg%3E") center/10px no-repeat;
}
html.dark .theme-toggle-knob { transform: translateX(18px); }
html.dark .theme-toggle-knob::after {
  background: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='10' height='10' viewBox='0 0 24 24' fill='none' stroke='white' stroke-width='2.5' stroke-linecap='round' stroke-linejoin='round'%3E%3Ccircle cx='12' cy='12' r='5'/%3E%3Cline x1='12' y1='1' x2='12' y2='3'/%3E%3Cline x1='12' y1='21' x2='12' y2='23'/%3E%3Cline x1='4.22' y1='4.22' x2='5.64' y2='5.64'/%3E%3Cline x1='18.36' y1='18.36' x2='19.78' y2='19.78'/%3E%3Cline x1='1' y1='12' x2='3' y2='12'/%3E%3Cline x1='21' y1='12' x2='23' y2='12'/%3E%3Cline x1='4.22' y1='19.78' x2='5.64' y2='18.36'/%3E%3Cline x1='18.36' y1='5.64' x2='19.78' y2='4.22'/%3E%3C/svg%3E") center/10px no-repeat;
}

/* ─── Page Header ─── */
.page-header {
  padding: 40px 24px 28px;
  max-width: 700px;
  margin: 0 auto;
}
.breadcrumb {
  font-size: 0.78rem;
  color: var(--text-lighter);
  margin-bottom: 12px;
  display: flex;
  align-items: center;
  gap: 6px;
}
.breadcrumb a { color: var(--text-lighter); text-decoration: none; transition: color var(--transition); }
.breadcrumb a:hover { color: var(--accent); }

.page-header h1 {
  font-size: clamp(1.6rem, 4vw, 2.1rem);
  font-weight: 700;
  line-height: 1.2;
  letter-spacing: -0.4px;
  margin-bottom: 8px;
  color: var(--text);
}
.page-header h1 .accent { color: var(--accent); }
.page-header p {
  color: var(--text-soft);
  font-size: 0.93rem;
  max-width: 480px;
  line-height: 1.65;
}

/* ─── Calc Wrapper ─── */
.calc-wrapper {
  max-width: 700px;
  margin: 0 auto;
  padding: 0 24px 80px;
}

/* ─── Cards ─── */
.calc-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px;
  margin-bottom: 16px;
  box-shadow: var(--shadow);
}
.calc-card-title {
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--text-lighter);
  text-transform: uppercase;
  letter-spacing: 0.7px;
  margin-bottom: 18px;
}

/* ─── Form ─── */
.form-group { margin-bottom: 14px; }
.form-group:last-child { margin-bottom: 0; }

label {
  display: block;
  font-size: 0.85rem;
  font-weight: 500;
  color: var(--text);
  margin-bottom: 5px;
}

input[type="number"],
input[type="text"],
input[type="date"],
select {
  width: 100%;
  background: var(--surface2);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 10px 13px;
  font-family: 'DM Sans', sans-serif;
  font-size: 0.93rem;
  color: var(--text);
  outline: none;
  transition: border-color var(--transition), box-shadow var(--transition), background var(--transition);
  appearance: none;
  -webkit-appearance: none;
}
input:focus, select:focus {
  border-color: var(--accent);
  background: var(--bg-white);
  box-shadow: 0 0 0 3px var(--accent-light);
}
input::placeholder { color: var(--text-lighter); }

select {
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='7' viewBox='0 0 12 7'%3E%3Cpath d='M1 1l5 5 5-5' stroke='%239CA3AF' stroke-width='1.5' fill='none' stroke-linecap='round' stroke-linejoin='round'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 12px center;
  padding-right: 36px;
  cursor: pointer;
}
select option { background: var(--surface2); color: var(--text); }

.form-row   { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; }
.form-row-3 { display: grid; grid-template-columns: 1fr 1fr 1fr; gap: 10px; }

/* ─── Seg Control ─── */
.seg-control {
  display: flex;
  background: var(--surface2);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 3px;
  gap: 3px;
}
.seg-control input[type="radio"] { display: none; }
.seg-control label {
  flex: 1;
  text-align: center;
  padding: 7px 8px;
  border-radius: var(--radius-xs);
  cursor: pointer;
  font-size: 0.84rem;
  font-weight: 500;
  color: var(--text-soft);
  letter-spacing: 0;
  text-transform: none;
  margin: 0;
  transition: all var(--transition);
  white-space: nowrap;
}
.seg-control input[type="radio"]:checked + label {
  background: var(--bg-white);
  color: var(--accent);
  font-weight: 600;
  box-shadow: var(--shadow);
}

/* ─── Button ─── */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 7px;
  padding: 11px 22px;
  border-radius: var(--radius-sm);
  font-family: 'DM Sans', sans-serif;
  font-weight: 600;
  font-size: 0.92rem;
  cursor: pointer;
  border: none;
  transition: all var(--transition);
  text-decoration: none;
}
.btn-primary {
  background: var(--accent);
  color: #fff;
  width: 100%;
  margin-top: 8px;
}
.btn-primary:hover {
  background: var(--accent-dark);
  transform: translateY(-1px);
  box-shadow: 0 4px 12px rgba(37,99,235,0.25);
}
.btn-primary:active { transform: translateY(0); box-shadow: none; }

.btn-ghost {
  background: transparent;
  border: 1px solid var(--border2);
  color: var(--text-soft);
  font-size: 0.84rem;
  padding: 7px 14px;
}
.btn-ghost:hover { border-color: var(--accent); color: var(--accent); background: var(--accent-light); }

/* ─── Result ─── */
.result-block {
  background: var(--accent-light);
  border: 1px solid var(--accent-mid);
  border-radius: var(--radius);
  padding: 22px;
  margin-top: 16px;
  display: none;
  animation: fadeUp 0.22s ease;
}
.result-block.show { display: block; }

@keyframes fadeUp {
  from { opacity: 0; transform: translateY(8px); }
  to   { opacity: 1; transform: translateY(0); }
}

.result-label {
  font-size: 0.73rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.7px;
  color: var(--accent);
  margin-bottom: 4px;
}
.result-value {
  font-size: clamp(1.5rem, 5vw, 2.2rem);
  font-weight: 700;
  color: var(--text);
  letter-spacing: -0.4px;
  line-height: 1.15;
}
.result-value span { color: var(--accent); }
.result-sub { font-size: 0.83rem; color: var(--text-soft); margin-top: 5px; }

.result-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(130px, 1fr)); gap: 14px; }
.result-item .result-value { font-size: 1.4rem; }

/* ─── Info Box ─── */
.info-box {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 18px 20px;
  margin-top: 16px;
  box-shadow: var(--shadow);
}
.info-box h3 { font-size: 0.88rem; font-weight: 600; margin-bottom: 10px; color: var(--text); }
.info-box p, .info-box li { font-size: 0.862rem; color: var(--text-soft); line-height: 1.65; }
.info-box ul { padding-left: 16px; }
.info-box li { margin-bottom: 4px; }

/* ─── FAQ ─── */
.faq-section { margin-top: 16px; }
.faq-item {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  margin-bottom: 8px;
  overflow: hidden;
  box-shadow: var(--shadow);
}
.faq-question {
  width: 100%;
  background: none;
  border: none;
  padding: 14px 16px;
  text-align: left;
  font-family: 'DM Sans', sans-serif;
  font-size: 0.88rem;
  font-weight: 600;
  color: var(--text);
  cursor: pointer;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 12px;
  transition: color var(--transition);
}
.faq-question:hover { color: var(--accent); }
.faq-icon {
  width: 16px;
  height: 16px;
  flex-shrink: 0;
  color: var(--text-lighter);
  transition: transform 0.2s ease;
}
.faq-item.open .faq-icon { transform: rotate(45deg); color: var(--accent); }
.faq-answer {
  display: none;
  padding: 0 16px 14px;
  font-size: 0.862rem;
  color: var(--text-soft);
  line-height: 1.65;
  border-top: 1px solid var(--border);
  padding-top: 12px;
}
.faq-item.open .faq-answer { display: block; }

/* ─── Table ─── */
.calc-table { width: 100%; border-collapse: collapse; font-size: 0.862rem; }
.calc-table th {
  font-size: 0.7rem; font-weight: 600; text-transform: uppercase;
  letter-spacing: 0.5px; color: var(--text-lighter);
  padding: 8px 10px; border-bottom: 1px solid var(--border); text-align: left;
}
.calc-table td { padding: 10px; border-bottom: 1px solid var(--border); color: var(--text); }
.calc-table tr:last-child td { border-bottom: none; }
.calc-table .td-highlight { font-weight: 600; color: var(--accent); }

/* ─── Add/Remove Row ─── */
.add-row-btn {
  width: 100%; padding: 9px; background: transparent;
  border: 1px dashed var(--border2); border-radius: var(--radius-sm);
  color: var(--text-lighter); font-family: 'DM Sans', sans-serif;
  font-size: 0.85rem; cursor: pointer; transition: all var(--transition); margin-top: 8px;
}
.add-row-btn:hover { border-color: var(--accent); color: var(--accent); background: var(--accent-light); }

.remove-btn {
  background: none; border: none; color: var(--text-lighter);
  cursor: pointer; font-size: 0.88rem; padding: 3px 7px;
  border-radius: 4px; transition: all var(--transition); display: flex; align-items: center;
}
.remove-btn:hover { color: #EF4444; background: #FEF2F2; }
.remove-btn svg { width: 14px; height: 14px; }

/* ─── Divider ─── */
.divider { height: 1px; background: var(--border); margin: 16px 0; }

/* ─── Footer ─── */
footer {
  border-top: 1px solid var(--border);
  padding: 28px 24px;
  text-align: center;
  background: var(--bg-white);
}
.footer-logo-wrap { margin-bottom: 10px; display: flex; justify-content: center; }
.footer-logo-wrap .logo-dark  { display: block; }
.footer-logo-wrap .logo-light { display: none; }
html.dark .footer-logo-wrap .logo-dark  { display: none; }
html.dark .footer-logo-wrap .logo-light { display: block; }
.footer-logo-wrap img { height: 20px; width: auto; opacity: 0.6; }

.footer-text { font-size: 0.76rem; color: var(--text-lighter); margin-bottom: 12px; }
.footer-links { display: flex; justify-content: center; gap: 18px; flex-wrap: wrap; }
.footer-links a { font-size: 0.76rem; color: var(--text-lighter); text-decoration: none; transition: color var(--transition); }
.footer-links a:hover { color: var(--accent); }

/* ─── Homepage Hero ─── */
.hero { padding: 52px 24px 32px; max-width: 700px; margin: 0 auto; }
.hero-tag {
  display: inline-flex; align-items: center; gap: 6px;
  font-size: 0.75rem; font-weight: 600; color: var(--accent);
  background: var(--accent-light); border: 1px solid var(--accent-mid);
  border-radius: 999px; padding: 4px 12px; margin-bottom: 16px;
}
.hero h1 {
  font-size: clamp(1.8rem, 5vw, 2.7rem); font-weight: 700;
  line-height: 1.15; letter-spacing: -0.7px; margin-bottom: 12px; color: var(--text);
}
.hero h1 .accent { color: var(--accent); }
.hero p { font-size: 0.96rem; color: var(--text-soft); max-width: 420px; margin-bottom: 26px; line-height: 1.65; }

/* ─── Search ─── */
.search-bar { max-width: 380px; position: relative; margin-bottom: 10px; }
.search-bar input {
  width: 100%; padding: 10px 16px 10px 38px;
  background: var(--surface); border: 1px solid var(--border);
  border-radius: 999px; font-family: 'DM Sans', sans-serif;
  font-size: 0.9rem; color: var(--text); outline: none;
  box-shadow: var(--shadow); transition: all var(--transition);
}
.search-bar input:focus { border-color: var(--accent); box-shadow: 0 0 0 3px var(--accent-light); }
.search-icon {
  position: absolute; left: 13px; top: 50%; transform: translateY(-50%);
  color: var(--text-lighter); pointer-events: none; display: flex; align-items: center;
}
.search-icon svg { width: 15px; height: 15px; }

/* ─── Category ─── */
.section-label {
  font-size: 0.7rem; font-weight: 600; text-transform: uppercase;
  letter-spacing: 1px; color: var(--text-lighter);
  margin: 28px 0 10px;
  display: flex; align-items: center; gap: 10px;
}
.section-label::after { content: ''; flex: 1; height: 1px; background: var(--border); }

/* ─── Calc Grid ─── */
.calc-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(195px, 1fr)); gap: 10px; margin-bottom: 4px; }

.calc-card-link {
  display: block; background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 16px 14px; text-decoration: none;
  color: var(--text); transition: all 0.18s ease; box-shadow: var(--shadow);
}
.calc-card-link:hover { border-color: var(--accent); box-shadow: var(--shadow-md); transform: translateY(-1px); }

.card-icon { display: flex; align-items: center; margin-bottom: 10px; color: var(--accent); }
.card-icon svg { width: 18px; height: 18px; stroke-width: 1.75; }

.calc-card-name { font-size: 0.88rem; font-weight: 600; margin-bottom: 3px; color: var(--text); line-height: 1.3; }
.calc-card-desc { font-size: 0.76rem; color: var(--text-soft); line-height: 1.4; }

.badge {
  display: inline-block; font-size: 0.6rem; font-weight: 600;
  text-transform: uppercase; letter-spacing: 0.3px; padding: 2px 6px;
  border-radius: 4px; background: var(--accent-light); color: var(--accent);
  border: 1px solid var(--accent-mid); margin-top: 6px;
}

/* ─── Responsive ─── */
@media (max-width: 580px) {
  .form-row, .form-row-3 { grid-template-columns: 1fr; }
  .calc-card { padding: 16px 14px; }
  .result-block { padding: 16px 14px; }
  .page-header { padding: 24px 16px 18px; }
  .calc-wrapper { padding: 0 16px 60px; }
  nav { padding: 0 16px; }
  .hero { padding: 32px 16px 20px; }
  .result-grid { grid-template-columns: 1fr 1fr; }
  .seg-control label { font-size: 0.78rem; padding: 6px 5px; }
}