/* ============================================
   Sellermetrics — Global Styles
   Color Palette: White / Gray / Black + Accent
   ============================================ */

/* ---- CSS Variables ---- */
:root {
  --color-bg: #ffffff;
  --color-surface: #f8f9fa;
  --color-surface-hover: #f1f3f5;
  --color-border: #e9ecef;
  --color-primary: #1a1a2e;
  --color-accent: #4f46e5;
  --color-accent-hover: #4338ca;
  --color-text: #1a1a2e;
  --color-text-muted: #6b7280;
  --color-success: #059669;
  --color-danger: #dc2626;
  --shadow-sm: 0 1px 4px rgba(0, 0, 0, 0.06);
  --shadow-md: 0 2px 12px rgba(0, 0, 0, 0.08);
  --shadow-lg: 0 4px 24px rgba(0, 0, 0, 0.12);
  --radius: 8px;
  --radius-lg: 12px;
  --transition: 0.2s ease;
  --font: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
}

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

html {
  scroll-behavior: smooth;
  font-size: 16px;
}

body {
  font-family: var(--font);
  background-color: var(--color-bg);
  color: var(--color-text);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

a {
  color: var(--color-accent);
  text-decoration: none;
  transition: color var(--transition);
}

a:hover { color: var(--color-accent-hover); }

img { max-width: 100%; display: block; }

/* ---- Typography ---- */
h1 { font-size: clamp(1.75rem, 4vw, 2.5rem); font-weight: 700; line-height: 1.2; }
h2 { font-size: clamp(1.4rem, 3vw, 2rem); font-weight: 700; line-height: 1.3; }
h3 { font-size: clamp(1.1rem, 2vw, 1.35rem); font-weight: 600; }
h4 { font-size: 1rem; font-weight: 600; }
p  { color: var(--color-text-muted); }

/* ---- Layout ---- */
.container {
  width: 100%;
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 1.25rem;
}

section { padding: 3rem 0; }

/* ---- Header / Nav ---- */
.site-header {
  background: var(--color-bg);
  border-bottom: 1px solid var(--color-border);
  position: sticky;
  top: 0;
  z-index: 100;
  box-shadow: var(--shadow-sm);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 60px;
  gap: 1rem;
}

.logo {
  font-size: 1.4rem;
  font-weight: 800;
  color: var(--color-primary);
  letter-spacing: -0.5px;
  white-space: nowrap;
}

.logo span { color: var(--color-accent); }

.site-nav {
  display: flex;
  align-items: center;
  gap: 0.25rem;
  flex-wrap: wrap;
}

.site-nav a {
  font-size: 0.85rem;
  font-weight: 500;
  color: var(--color-text-muted);
  padding: 0.35rem 0.75rem;
  border-radius: var(--radius);
  transition: background var(--transition), color var(--transition);
  white-space: nowrap;
}

.site-nav a:hover,
.site-nav a.active {
  background: var(--color-surface-hover);
  color: var(--color-accent);
}

/* Hamburger */
.nav-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 6px;
}

.nav-toggle span {
  display: block;
  width: 22px;
  height: 2px;
  background: var(--color-primary);
  border-radius: 2px;
  transition: all var(--transition);
}

/* ---- Hero ---- */
.hero {
  background: linear-gradient(135deg, #1a1a2e 0%, #16213e 60%, #0f3460 100%);
  color: #fff;
  padding: 4rem 0 3rem;
  text-align: center;
}

.hero h1 { color: #fff; margin-bottom: 1rem; }

.hero p {
  color: rgba(255,255,255,0.75);
  font-size: 1.1rem;
  max-width: 600px;
  margin: 0 auto 2rem;
}

/* ---- Buttons ---- */
.btn {
  display: inline-block;
  padding: 0.65rem 1.5rem;
  border-radius: var(--radius);
  font-weight: 600;
  font-size: 0.9rem;
  cursor: pointer;
  transition: all var(--transition);
  border: none;
  text-align: center;
}

.btn-primary {
  background: var(--color-accent);
  color: #fff;
}

.btn-primary:hover {
  background: var(--color-accent-hover);
  color: #fff;
  transform: translateY(-1px);
  box-shadow: 0 4px 12px rgba(79,70,229,0.3);
}

.btn-outline {
  background: transparent;
  color: var(--color-accent);
  border: 2px solid var(--color-accent);
}

.btn-outline:hover {
  background: var(--color-accent);
  color: #fff;
}

/* ---- Cards ---- */
.card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 1.5rem;
  box-shadow: var(--shadow-md);
  transition: box-shadow var(--transition), transform var(--transition);
}

.card:hover {
  box-shadow: var(--shadow-lg);
  transform: translateY(-2px);
}

/* Tool Cards Grid (index.html) */
.tools-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 1.5rem;
  margin-top: 2rem;
}

.tool-card {
  background: #fff;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 1.75rem 1.5rem;
  box-shadow: var(--shadow-md);
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: 0.75rem;
  transition: box-shadow var(--transition), transform var(--transition);
}

.tool-card:hover {
  box-shadow: var(--shadow-lg);
  transform: translateY(-3px);
}

.tool-card-icon {
  width: 48px;
  height: 48px;
  border-radius: var(--radius);
  background: linear-gradient(135deg, #ede9fe, #c7d2fe);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.5rem;
}

.tool-card h3 {
  color: var(--color-primary);
  font-size: 1.05rem;
}

.tool-card p {
  font-size: 0.88rem;
  color: var(--color-text-muted);
  flex: 1;
}

.tool-card .btn {
  margin-top: auto;
  width: 100%;
  text-align: center;
}

/* ---- Calculator Layout ---- */
.calc-layout {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.5rem;
  margin-top: 1.5rem;
}

.calc-form, .calc-result {
  background: #fff;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 1.75rem;
  box-shadow: var(--shadow-md);
}

.calc-form h3, .calc-result h3 {
  margin-bottom: 1.25rem;
  padding-bottom: 0.75rem;
  border-bottom: 2px solid var(--color-border);
  color: var(--color-primary);
}

/* Form Fields */
.form-group {
  margin-bottom: 1rem;
}

.form-group label {
  display: block;
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--color-text);
  margin-bottom: 0.35rem;
}

.input-wrapper {
  position: relative;
  display: flex;
  align-items: center;
}

.input-prefix {
  position: absolute;
  left: 0.75rem;
  color: var(--color-text-muted);
  font-weight: 500;
  font-size: 0.9rem;
  pointer-events: none;
}

.input-suffix {
  position: absolute;
  right: 0.75rem;
  color: var(--color-text-muted);
  font-size: 0.85rem;
  pointer-events: none;
}

.form-group input,
.form-group select {
  width: 100%;
  padding: 0.6rem 0.75rem 0.6rem 2rem;
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  font-size: 0.95rem;
  color: var(--color-text);
  background: var(--color-bg);
  transition: border-color var(--transition), box-shadow var(--transition);
  outline: none;
}

.form-group input:focus,
.form-group select:focus {
  border-color: var(--color-accent);
  box-shadow: 0 0 0 3px rgba(79,70,229,0.1);
}

.form-group select { padding-left: 0.75rem; }

.form-group input.no-prefix { padding-left: 0.75rem; }

/* Result Box */
.result-box {
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.result-item {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 0.85rem 1rem;
  background: var(--color-surface);
  border-radius: var(--radius);
  border: 1px solid var(--color-border);
}

.result-item .label {
  font-size: 0.875rem;
  color: var(--color-text-muted);
  font-weight: 500;
}

.result-item .value {
  font-size: 1.15rem;
  font-weight: 700;
  color: var(--color-text);
}

.result-item.highlight {
  background: linear-gradient(135deg, #ede9fe 0%, #e0e7ff 100%);
  border-color: #c4b5fd;
}

.result-item .value.positive { color: var(--color-success); }
.result-item .value.negative { color: var(--color-danger); }

/* ---- FAQ / Accordion ---- */
.faq-section {
  background: var(--color-surface);
  padding: 3rem 0;
}

.faq-list {
  max-width: 800px;
  margin: 1.5rem auto 0;
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.faq-item {
  background: #fff;
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  overflow: hidden;
}

.faq-question {
  width: 100%;
  text-align: left;
  padding: 1rem 1.25rem;
  background: none;
  border: none;
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--color-text);
  cursor: pointer;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 1rem;
  transition: background var(--transition);
}

.faq-question:hover { background: var(--color-surface-hover); }

.faq-question .faq-icon {
  font-size: 1.25rem;
  font-weight: 300;
  color: var(--color-accent);
  flex-shrink: 0;
  transition: transform var(--transition);
}

.faq-item.open .faq-icon { transform: rotate(45deg); }

.faq-answer {
  display: none;
  padding: 0 1.25rem 1rem;
  font-size: 0.9rem;
  color: var(--color-text-muted);
  line-height: 1.7;
  border-top: 1px solid var(--color-border);
}

.faq-item.open .faq-answer { display: block; }

/* ---- Features Section ---- */
.features-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 1.25rem;
  margin-top: 2rem;
}

.feature-item {
  padding: 1.25rem;
  border-radius: var(--radius);
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  text-align: center;
}

.feature-item .icon { font-size: 2rem; margin-bottom: 0.75rem; }
.feature-item h4 { margin-bottom: 0.4rem; color: var(--color-primary); }
.feature-item p { font-size: 0.875rem; }

/* ---- Section Titles ---- */
.section-title {
  text-align: center;
  margin-bottom: 0.5rem;
  color: var(--color-primary);
}

.section-subtitle {
  text-align: center;
  color: var(--color-text-muted);
  font-size: 1rem;
  max-width: 600px;
  margin: 0 auto;
}

/* ---- Ad Placements ---- */
.ad-slot {
  width: 100%;
  margin: 1rem 0;
  min-height: 1px; /* prevents layout shift if ad fails */
}

/* ---- Footer ---- */
.site-footer {
  background: var(--color-primary);
  color: rgba(255,255,255,0.7);
  padding: 2rem 0;
  text-align: center;
}

.site-footer .footer-links {
  display: flex;
  justify-content: center;
  flex-wrap: wrap;
  gap: 1.5rem;
  margin-bottom: 1rem;
}

.site-footer a {
  color: rgba(255,255,255,0.7);
  font-size: 0.875rem;
  transition: color var(--transition);
}

.site-footer a:hover { color: #fff; }

.site-footer p {
  font-size: 0.825rem;
  color: rgba(255,255,255,0.5);
}

/* ---- Page Intro (calculator pages) ---- */
.page-intro {
  background: linear-gradient(135deg, #1a1a2e 0%, #16213e 60%, #0f3460 100%);
  color: #fff;
  padding: 2.5rem 0 2rem;
  text-align: center;
}

.page-intro h1 { color: #fff; margin-bottom: 0.6rem; }
.page-intro p { color: rgba(255,255,255,0.75); font-size: 1rem; }

/* ---- Breadcrumb ---- */
.breadcrumb {
  font-size: 0.8rem;
  color: rgba(255,255,255,0.5);
  margin-bottom: 1rem;
}

.breadcrumb a { color: rgba(255,255,255,0.6); }
.breadcrumb a:hover { color: #fff; }

/* ---- Tip Box ---- */
.tip-box {
  background: #ede9fe;
  border-left: 4px solid var(--color-accent);
  border-radius: 0 var(--radius) var(--radius) 0;
  padding: 0.85rem 1rem;
  font-size: 0.875rem;
  color: #4c1d95;
  margin-top: 1rem;
}

/* ---- Responsive ---- */
@media (max-width: 768px) {
  .nav-toggle { display: flex; }

  .site-nav {
    display: none;
    flex-direction: column;
    position: absolute;
    top: 60px;
    left: 0;
    right: 0;
    background: var(--color-bg);
    border-bottom: 1px solid var(--color-border);
    padding: 1rem;
    gap: 0.25rem;
    box-shadow: var(--shadow-lg);
    z-index: 99;
  }

  .site-nav.open { display: flex; }
  .site-nav a { padding: 0.6rem 1rem; width: 100%; }

  .calc-layout {
    grid-template-columns: 1fr;
  }

  .hero { padding: 3rem 0 2rem; }
  .page-intro { padding: 2rem 0 1.5rem; }
  section { padding: 2rem 0; }
}

@media (max-width: 480px) {
  .tools-grid { grid-template-columns: 1fr; }
  .features-grid { grid-template-columns: 1fr 1fr; }
}