/* ============================================ */
/* HOW TO CALCULATE PERCENTAGE OF SALES - BLOG CSS */
/* ============================================ */

/* ============================================ */
/* CSS VARIABLES & RESET */
/* ============================================ */
:root {
  --bg: #ffffff;
  --bg-secondary: #f8fafc;
  --bg-card: #ffffff;
  --text: #1e293b;
  --text-secondary: #64748b;
  --text-muted: #94a3b8;
  --border: #e2e8f0;
  --accent: #2563eb;
  --accent-light: #dbeafe;
  --accent-dark: #1d4ed8;
  --radius: 8px;
  --shadow: 0 1px 3px rgba(0, 0, 0, 0.05);
  --positive: #16a34a;
  --negative: #dc2626;
}

[data-theme="dark"] {
  --bg: #0f172a;
  --bg-secondary: #1e293b;
  --bg-card: #1e293b;
  --text: #f1f5f9;
  --text-secondary: #cbd5e1;
  --text-muted: #94a3b8;
  --border: #334155;
  --accent: #3b82f6;
  --accent-light: #1e3a8a;
  --accent-dark: #60a5fa;
  --shadow: 0 1px 3px rgba(0, 0, 0, 0.3);
  --positive: #22c55e;
  --negative: #ef4444;
}

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

html {
  scroll-behavior: smooth;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
}

img {
  max-width: 100%;
  height: auto;
}

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

a:hover {
  text-decoration: underline;
}

.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 20px;
}

.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

/* ============================================ */
/* NAVBAR */
/* ============================================ */
.navbar {
  background: var(--bg-card);
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  z-index: 1000;
  box-shadow: var(--shadow);
}

.nav-container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 20px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
}

.nav-logo {
  font-size: 1.35rem;
  font-weight: 800;
  color: var(--accent);
  text-decoration: none;
}

.nav-toggle {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: 8px;
}

.hamburger {
  display: block;
  width: 24px;
  height: 2px;
  background: var(--text);
  position: relative;
}

.hamburger::before,
.hamburger::after {
  content: '';
  position: absolute;
  width: 24px;
  height: 2px;
  background: var(--text);
  left: 0;
}

.hamburger::before { top: -8px; }
.hamburger::after { top: 8px; }

.nav-menu {
  display: flex;
  list-style: none;
  gap: 8px;
  align-items: center;
}

.nav-menu li { list-style: none; }

.nav-menu a {
  padding: 8px 14px;
  color: var(--text);
  font-weight: 500;
  font-size: 0.95rem;
  border-radius: var(--radius);
  transition: all 0.15s ease;
  text-decoration: none;
  display: inline-block;
}

.nav-menu a:hover,
.nav-menu a.active {
  background: var(--bg-secondary);
  color: var(--accent);
  text-decoration: none;
}

.nav-dropdown { position: relative; }
.dropdown-toggle { cursor: pointer; }

.dropdown-menu {
  position: absolute;
  top: 100%;
  left: 0;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 12px;
  min-width: 260px;
  box-shadow: 0 10px 25px rgba(0, 0, 0, 0.1);
  display: none;
  z-index: 100;
}

.nav-dropdown:hover .dropdown-menu { display: block; }

.dropdown-category { padding: 8px 0; }

.category-label {
  display: block;
  font-size: 0.75rem;
  font-weight: 700;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.5px;
  padding: 4px 8px;
  margin-bottom: 4px;
}

.dropdown-tools { list-style: none; }
.dropdown-tools li { list-style: none; }

.dropdown-tools a {
  display: block;
  padding: 6px 12px;
  font-size: 0.9rem;
  color: var(--text-secondary);
}

.dropdown-tools a:hover {
  background: var(--bg-secondary);
  color: var(--accent);
}

.dropdown-divider {
  height: 1px;
  background: var(--border);
  margin: 8px 0;
}

.view-all {
  display: block;
  padding: 8px 12px;
  font-weight: 600;
  color: var(--accent);
  text-align: center;
}

.theme-toggle {
  background: none;
  border: none;
  cursor: pointer;
  padding: 8px;
  font-size: 1.1rem;
  border-radius: var(--radius);
}

.nav-theme-item { list-style: none; }

@media (max-width: 900px) {
  .nav-toggle { display: block; }
  .nav-menu {
    position: absolute;
    top: 64px;
    left: 0;
    right: 0;
    background: var(--bg-card);
    flex-direction: column;
    padding: 20px;
    border-top: 1px solid var(--border);
    display: none;
    align-items: stretch;
    gap: 4px;
    box-shadow: 0 10px 25px rgba(0, 0, 0, 0.1);
  }
  .nav-menu.active { display: flex; }
  .nav-dropdown:hover .dropdown-menu {
    position: static;
    display: block;
    box-shadow: none;
    border: none;
    padding-left: 16px;
  }
  .nav-menu a { display: block; width: 100%; }
}

/* ============================================ */
/* ARTICLE */
/* ============================================ */
.blog-article {
  padding: 40px 0 60px;
}

.article-header {
  max-width: 800px;
  margin: 0 auto 40px;
  text-align: center;
}

.article-category {
  display: inline-block;
  padding: 6px 14px;
  background: var(--accent-light);
  color: var(--accent);
  font-weight: 600;
  font-size: 0.85rem;
  border-radius: 20px;
  margin-bottom: 16px;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.article-header h1 {
  font-size: 2.3rem;
  line-height: 1.3;
  margin-bottom: 20px;
  color: var(--text);
  font-weight: 800;
}

.article-meta {
  display: flex;
  justify-content: center;
  flex-wrap: wrap;
  gap: 20px;
  font-size: 0.9rem;
  color: var(--text-secondary);
  margin-bottom: 24px;
}

.article-intro {
  font-size: 1.1rem;
  line-height: 1.75;
  color: var(--text-secondary);
  text-align: left;
  padding: 20px 0;
  border-top: 1px solid var(--border);
  border-bottom: 1px solid var(--border);
}

/* ============================================ */
/* TABLE OF CONTENTS */
/* ============================================ */
.article-toc {
  max-width: 800px;
  margin: 0 auto 48px;
  padding: 24px 28px;
  background: var(--bg-secondary);
  border-left: 4px solid var(--accent);
  border-radius: var(--radius);
}

.article-toc h2 {
  font-size: 1.15rem;
  margin-bottom: 12px;
  color: var(--text);
  font-weight: 700;
}

.article-toc ol {
  margin-left: 20px;
  line-height: 2;
  color: var(--text-secondary);
}

.article-toc li {
  padding: 2px 0;
}

.article-toc a {
  color: var(--accent);
  text-decoration: none;
  font-weight: 500;
}

.article-toc a:hover {
  text-decoration: underline;
}

/* ============================================ */
/* ARTICLE SECTIONS */
/* ============================================ */
.article-section {
  max-width: 800px;
  margin: 0 auto 48px;
}

.article-section h2 {
  font-size: 1.8rem;
  margin-bottom: 20px;
  color: var(--text);
  padding-bottom: 12px;
  border-bottom: 2px solid var(--border);
  font-weight: 700;
}

.article-section h3 {
  font-size: 1.3rem;
  margin: 28px 0 12px;
  color: var(--text);
  font-weight: 700;
}

.article-section p {
  font-size: 1.05rem;
  line-height: 1.8;
  color: var(--text-secondary);
  margin-bottom: 16px;
}

.article-section ul,
.article-section ol {
  margin-left: 24px;
  line-height: 1.9;
  color: var(--text-secondary);
  margin-bottom: 16px;
}

.article-section li {
  padding: 4px 0;
}

.article-section strong {
  color: var(--text);
  font-weight: 700;
}

.article-section code {
  background: var(--bg-secondary);
  padding: 2px 8px;
  border-radius: 4px;
  font-family: 'Courier New', monospace;
  font-size: 0.9rem;
  color: var(--accent);
  font-weight: 600;
}

/* ============================================ */
/* CALLOUT */
/* ============================================ */
.article-callout {
  padding: 20px 24px;
  background: var(--bg-secondary);
  border-left: 4px solid var(--accent);
  border-radius: var(--radius);
  margin: 24px 0;
}

.article-callout h3 {
  font-size: 1.1rem;
  margin-bottom: 8px;
  color: var(--text);
  margin-top: 0;
}

.article-callout p {
  margin: 0;
  font-size: 1rem;
}

/* ============================================ */
/* TABLES */
/* ============================================ */
.article-table-wrap {
  overflow-x: auto;
  margin: 24px 0;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--bg-card);
}

.article-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.95rem;
}

.article-table th {
  background: var(--bg-secondary);
  padding: 14px 16px;
  text-align: left;
  font-weight: 700;
  color: var(--text);
  border-bottom: 2px solid var(--border);
  white-space: nowrap;
}

.article-table td {
  padding: 12px 16px;
  border-bottom: 1px solid var(--border);
  color: var(--text-secondary);
}

.article-table tr:last-child td {
  border-bottom: none;
}

.article-table tr:hover {
  background: var(--bg-secondary);
}

/* ============================================ */
/* FORMULA BOXES */
/* ============================================ */
.formula-box,
.formula-box-large {
  background: var(--bg-secondary);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px;
  margin: 20px 0;
  font-family: 'Courier New', monospace;
  text-align: center;
  overflow-x: auto;
}

.formula-box-large {
  padding: 28px;
  border-left: 4px solid var(--accent);
}

.formula-box code,
.formula-box-large code {
  font-size: 1.05rem;
  font-weight: 700;
  color: var(--accent);
  line-height: 1.8;
  display: inline-block;
}

.formula-box-large code {
  font-size: 1.15rem;
}

.formula-legend {
  list-style: none;
  padding: 20px 24px;
  background: var(--bg-secondary);
  border-radius: var(--radius);
  margin: 20px 0;
}

.formula-legend li {
  padding: 6px 0;
  color: var(--text-secondary);
}

.formula-legend strong {
  color: var(--accent);
  font-family: 'Courier New', monospace;
  font-weight: 700;
}

/* ============================================ */
/* CTA BOXES */
/* ============================================ */
.article-cta {
  margin: 32px 0;
  padding: 24px;
  background: linear-gradient(135deg, var(--accent) 0%, var(--accent-dark) 100%);
  border-radius: var(--radius);
  text-align: center;
  color: white;
}

.article-cta p {
  color: white;
  font-size: 1.05rem;
  margin-bottom: 16px;
  font-weight: 600;
}

.cta-button,
.cta-button-large {
  display: inline-block;
  padding: 14px 28px;
  background: white;
  color: var(--accent);
  font-weight: 700;
  text-decoration: none;
  border-radius: var(--radius);
  transition: transform 0.15s ease;
  border: none;
  cursor: pointer;
}

.cta-button:hover,
.cta-button-large:hover {
  transform: translateY(-2px);
  text-decoration: none;
  box-shadow: 0 8px 20px rgba(0, 0, 0, 0.15);
}

.cta-button-large {
  padding: 18px 36px;
  font-size: 1.1rem;
}

.article-cta-final {
  text-align: center;
  margin: 32px 0;
}

/* ============================================ */
/* FAQ */
/* ============================================ */
.article-section .faq-item {
  padding: 20px 0;
  border-bottom: 1px solid var(--border);
}

.article-section .faq-item:last-child {
  border-bottom: none;
}

.article-section .faq-item h3 {
  font-size: 1.15rem;
  margin-bottom: 8px;
  margin-top: 0;
  color: var(--text);
  font-weight: 700;
}

.article-section .faq-item p {
  margin: 0;
  font-size: 1rem;
  color: var(--text-secondary);
  line-height: 1.7;
}

/* ============================================ */
/* CONCLUSION */
/* ============================================ */
.article-conclusion {
  max-width: 800px;
  margin: 48px auto;
  padding: 32px;
  background: var(--bg-secondary);
  border-radius: var(--radius);
  border: 1px solid var(--border);
}

.article-conclusion h2 {
  font-size: 1.8rem;
  margin-bottom: 20px;
  font-weight: 700;
}

.article-conclusion p {
  font-size: 1.05rem;
  line-height: 1.8;
  color: var(--text-secondary);
  margin-bottom: 16px;
}

/* ============================================ */
/* RELATED ARTICLES */
/* ============================================ */
.article-related {
  max-width: 800px;
  margin: 48px auto 0;
  padding: 24px;
  background: var(--bg-card);
  border-radius: var(--radius);
  border: 1px solid var(--border);
}

.article-related h2 {
  font-size: 1.4rem;
  margin-bottom: 16px;
  font-weight: 700;
}

.article-related ul {
  list-style: none;
  padding: 0;
  margin: 0;
}

.article-related li {
  padding: 10px 0;
  border-bottom: 1px solid var(--border);
  color: var(--text-secondary);
}

.article-related li:last-child {
  border-bottom: none;
}

.article-related a {
  color: var(--accent);
  font-weight: 600;
  text-decoration: none;
}

.article-related a:hover {
  text-decoration: underline;
}

/* ============================================ */
/* FOOTER */
/* ============================================ */
.footer {
  background: var(--bg-card);
  border-top: 1px solid var(--border);
  padding: 48px 0 24px;
  margin-top: 60px;
}

.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr;
  gap: 40px;
  margin-bottom: 32px;
}

.footer-brand p {
  color: var(--text-secondary);
  margin-top: 12px;
  font-size: 0.95rem;
  line-height: 1.6;
}

.footer-logo {
  font-size: 1.35rem;
  font-weight: 800;
  color: var(--accent);
}

.footer-tagline {
  font-weight: 600;
  color: var(--accent);
  margin-top: 8px;
}

.footer-nav ul {
  list-style: none;
  padding: 0;
}

.footer-nav li {
  margin-bottom: 8px;
  list-style: none;
}

.footer-nav a {
  color: var(--text-secondary);
  font-size: 0.92rem;
  text-decoration: none;
}

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

.footer-bottom {
  border-top: 1px solid var(--border);
  padding-top: 20px;
  text-align: center;
  color: var(--text-muted);
  font-size: 0.88rem;
}

.footer-privacy {
  margin-top: 6px;
  font-size: 0.82rem;
}

/* ============================================ */
/* RESPONSIVE */
/* ============================================ */
@media (max-width: 900px) {
  .footer-grid {
    grid-template-columns: 1fr;
    gap: 24px;
  }
}

@media (max-width: 768px) {
  .blog-article {
    padding: 20px 0 40px;
  }

  .article-header h1 {
    font-size: 1.85rem;
  }

  .article-section h2 {
    font-size: 1.5rem;
  }

  .article-section h3 {
    font-size: 1.15rem;
  }

  .article-meta {
    flex-direction: column;
    gap: 8px;
  }

  .article-toc {
    padding: 18px 20px;
  }

  .article-conclusion {
    padding: 24px 20px;
  }

  .article-callout {
    padding: 16px 18px;
  }

  .formula-box-large {
    padding: 20px 16px;
  }

  .formula-box-large code {
    font-size: 0.95rem;
  }

  .article-table th,
  .article-table td {
    padding: 10px 12px;
    font-size: 0.88rem;
  }

  .cta-button,
  .cta-button-large {
    display: block;
    width: 100%;
    text-align: center;
    padding: 14px 20px;
  }
}

@media (max-width: 480px) {
  .article-header h1 {
    font-size: 1.55rem;
  }

  .article-section h2 {
    font-size: 1.35rem;
  }
}