/* --- Core Reset & Variable Declarations --- */
:root {
  --bg-primary: #ffffff;
  --bg-secondary: #f9fafb;
  --text-main: #111827;
  --text-muted: #4b5563;
  --border-color: #e5e7eb;
  --accent-color: #2563eb;
  --accent-hover: #1d4ed8;
  --error-bg: #fef2f2;
  --error-text: #b91c1c;
  --font-stack: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 14px;
  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.05), 0 2px 4px -1px rgba(0, 0, 0, 0.03);
  --max-width: 1140px;
  --transition-smooth: all 0.2s ease-in-out;
}

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

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

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

/* --- Global Utilities --- */
.container {
  width: 100%;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 24px;
}

.hidden {
  display: none !important;
}

.section-title {
  font-size: 2rem;
  font-weight: 700;
  text-align: center;
  margin-bottom: 40px;
  letter-spacing: -0.02em;
}

/* --- Header & Navigation Layout --- */
.navbar {
  background-color: var(--bg-primary);
  border-bottom: 1px solid var(--border-color);
  height: 72px;
  display: flex;
  align-items: center;
}

.nav-container {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.logo {
  font-size: 1.35rem;
  font-weight: 700;
  color: var(--text-main);
  text-decoration: none;
  letter-spacing: -0.03em;
}

.nav-links {
  display: flex;
  gap: 32px;
}

.nav-links a {
  text-decoration: none;
  color: var(--text-muted);
  font-weight: 500;
  font-size: 0.95rem;
  transition: var(--transition-smooth);
}

.nav-links a:hover, .nav-links a.active {
  color: var(--text-main);
}

.menu-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 4px;
}

.menu-toggle .bar {
  width: 22px;
  height: 2px;
  background-color: var(--text-main);
  transition: var(--transition-smooth);
}

/* --- Hero Core Form Elements --- */
.hero-section {
  padding: 80px 0;
  text-align: center;
  background-color: var(--bg-secondary);
  border-bottom: 1px solid var(--border-color);
}

.hero-container h1 {
  font-size: 2.85rem;
  font-weight: 700;
  line-height: 1.2;
  letter-spacing: -0.04em;
  margin-bottom: 16px;
}

.subheading {
  font-size: 1.15rem;
  color: var(--text-muted);
  max-width: 600px;
  margin: 0 auto 40px auto;
}

.input-group {
  max-width: 640px;
  margin: 0 auto;
  display: flex;
  gap: 12px;
  background: var(--bg-primary);
  padding: 8px;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-sm);
}

.input-group input {
  flex: 1;
  border: none;
  outline: none;
  padding: 12px 16px;
  font-size: 1rem;
  font-family: var(--font-stack);
  color: var(--text-main);
  width: 100%;
}

.input-group input:focus {
  background: transparent;
}

.input-group button {
  background-color: var(--text-main);
  color: var(--bg-primary);
  border: none;
  padding: 12px 28px;
  font-weight: 600;
  font-size: 0.95rem;
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: var(--transition-smooth);
  white-space: nowrap;
}

.input-group button:hover {
  background-color: #2b3544;
}

.input-group:focus-within {
  border-color: #a1a1aa;
  box-shadow: 0 0 0 4px rgba(229, 231, 235, 0.5);
}

.error-msg {
  color: var(--error-text);
  background-color: var(--error-bg);
  display: inline-block;
  margin-top: 16px;
  padding: 8px 16px;
  border-radius: var(--radius-sm);
  font-size: 0.9rem;
  font-weight: 500;
  display: none;
}

/* --- Dynamic Workspace Tool Output Layout --- */
.tool-section {
  padding: 60px 0;
  background-color: var(--bg-primary);
}

.output-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 32px;
  margin-top: 24px;
}

.download-card {
  background: var(--bg-primary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  overflow: hidden;
  box-shadow: var(--shadow-sm);
  transition: var(--transition-smooth);
}

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

.img-container {
  width: 100%;
  aspect-ratio: 16 / 9;
  background-color: var(--bg-secondary);
  overflow: hidden;
  position: relative;
  border-bottom: 1px solid var(--border-color);
}

.img-container img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.card-info {
  padding: 20px;
}

.card-info h3 {
  font-size: 1.1rem;
  font-weight: 600;
  margin-bottom: 4px;
}

.card-res {
  font-size: 0.88rem;
  color: var(--text-muted);
  margin-bottom: 20px;
}

.download-btn {
  display: block;
  width: 100%;
  text-align: center;
  background-color: var(--bg-secondary);
  color: var(--text-main);
  border: 1px solid var(--border-color);
  padding: 10px 16px;
  border-radius: var(--radius-sm);
  text-decoration: none;
  font-weight: 600;
  font-size: 0.9rem;
  transition: var(--transition-smooth);
}

.download-btn:hover {
  background-color: var(--text-main);
  color: var(--bg-primary);
  border-color: var(--text-main);
}

/* --- Product Feature Grid --- */
.features-section {
  padding: 80px 0;
  background-color: var(--bg-secondary);
  border-top: 1px solid var(--border-color);
  border-bottom: 1px solid var(--border-color);
}

.features-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: 24px;
}

.feature-card {
  background: var(--bg-primary);
  padding: 32px;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
}

.feature-icon {
  font-size: 1.5rem;
  margin-bottom: 16px;
}

.feature-card h3 {
  font-size: 1.2rem;
  font-weight: 600;
  margin-bottom: 8px;
  letter-spacing: -0.01em;
}

.feature-card p {
  color: var(--text-muted);
  font-size: 0.95rem;
}

/* --- Sequential Instructions Element --- */
.how-it-works {
  padding: 80px 0;
}

.steps-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 32px;
}

.step-card {
  text-align: center;
  padding: 16px;
}

.step-number {
  width: 40px;
  height: 40px;
  background-color: var(--text-main);
  color: var(--bg-primary);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  margin: 0 auto 20px auto;
}

.step-card h3 {
  font-size: 1.2rem;
  margin-bottom: 8px;
}

.step-card p {
  color: var(--text-muted);
  font-size: 0.95rem;
}

/* --- Typographic Reading Content Architecture --- */
.seo-content-section {
  padding: 80px 0;
  border-top: 1px solid var(--border-color);
}

.reading-layout {
  max-width: 760px;
  margin: 0 auto;
}

.reading-layout h2 {
  font-size: 1.85rem;
  margin-bottom: 20px;
  letter-spacing: -0.02em;
}

.reading-layout h3 {
  font-size: 1.35rem;
  margin: 36px 0 16px 0;
  letter-spacing: -0.01em;
}

.reading-layout p {
  color: var(--text-muted);
  font-size: 1.05rem;
  margin-bottom: 24px;
}

.reading-layout ul {
  margin: 0 0 24px 24px;
  color: var(--text-muted);
}

.reading-layout li {
  margin-bottom: 8px;
  font-size: 1.05rem;
}

/* --- Dynamic Accordion UI FAQ Element --- */
.faq-section {
  padding: 60px 0 100px 0;
  background-color: var(--bg-primary);
}

.faq-accordion {
  margin-top: 32px;
  border-top: 1px solid var(--border-color);
}

.faq-item {
  border-bottom: 1px solid var(--border-color);
}

.faq-trigger {
  width: 100%;
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 24px 4px;
  background: none;
  border: none;
  text-align: left;
  font-family: var(--font-stack);
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--text-main);
  cursor: pointer;
}

.faq-icon {
  position: relative;
  width: 16px;
  height: 16px;
}

.faq-icon::before, .faq-icon::after {
  content: '';
  position: absolute;
  background-color: var(--text-muted);
  transition: transform 0.2s ease-in-out;
}

/* Horizontal line */
.faq-icon::before {
  top: 7px;
  left: 0;
  width: 16px;
  height: 2px;
}

/* Vertical line */
.faq-icon::after {
  top: 0;
  left: 7px;
  width: 2px;
  height: 16px;
}

.faq-trigger[aria-expanded="true"] .faq-icon::after {
  transform: rotate(90deg);
  opacity: 0;
}

.faq-content {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.25s cubic-bezier(0.4, 0, 0.2, 1);
}

.faq-content p {
  padding: 0 4px 24px 4px;
  color: var(--text-muted);
  font-size: 1rem;
  line-height: 1.6;
}

/* --- UI Production Footer --- */
.footer {
  background-color: var(--bg-secondary);
  border-top: 1px solid var(--border-color);
  padding: 64px 0 32px 0;
}

.footer-container {
  display: flex;
  justify-content: space-between;
  gap: 48px;
  margin-bottom: 48px;
}

.footer-brand {
  max-width: 360px;
}

.footer-logo {
  font-size: 1.25rem;
  font-weight: 700;
  margin-bottom: 12px;
  letter-spacing: -0.02em;
}

.footer-brand p {
  color: var(--text-muted);
  font-size: 0.95rem;
}

.footer-links-group {
  display: flex;
  gap: 64px;
}

.footer-col h4 {
  font-size: 0.9rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: 16px;
  color: var(--text-main);
}

.footer-col a {
  display: block;
  text-decoration: none;
  color: var(--text-muted);
  font-size: 0.95rem;
  margin-bottom: 10px;
  transition: var(--transition-smooth);
}

.footer-col a:hover {
  color: var(--text-main);
}

.footer-bottom {
  border-top: 1px solid var(--border-color);
  padding-top: 32px;
  text-align: center;
  color: var(--text-muted);
  font-size: 0.88rem;
}

/* --- Mobile Responsiveness --- */
@media (max-width: 768px) {
  .html { font-size: 15px; }
  
  .menu-toggle { display: flex; }
  
  .nav-links {
    display: none;
    flex-direction: column;
    position: absolute;
    top: 72px;
    left: 0;
    width: 100%;
    background-color: var(--bg-primary);
    border-bottom: 1px solid var(--border-color);
    padding: 24px;
    gap: 16px;
    box-shadow: var(--shadow-md);
    z-index: 1000;
  }
  
  .nav-links.active { display: flex; }
  
  .hero-container h1 { font-size: 2.1rem; }
  
  .input-group {
    flex-direction: column;
    padding: 12px;
    background: transparent;
    border: none;
    box-shadow: none;
  }
  
  .input-group input {
    background: var(--bg-primary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    margin-bottom: 8px;
  }
  
  .input-group button {
    width: 100%;
    padding: 14px;
    border-radius: var(--radius-md);
  }
  
  .footer-container {
    flex-direction: column;
    gap: 32px;
  }
  
  .footer-links-group {
    gap: 32px;
    justify-content: space-between;
  }
}