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

:root {
  --bg-body: #f6f8fa;
  --bg-card: #ffffff;
  --bg-input: #f0f2f5;
  --text-primary: #1f2937;
  --text-secondary: #4b5563;
  --text-muted: #9ca3af;
  --border-color: #e5e7eb;
  --border-focus: #2563eb;
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.08);
  --radius: 8px;
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --font-mono: "SF Mono", "JetBrains Mono", "Cascadia Code", monospace;
  --transition: 150ms ease;
}

html {
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
}

body {
  font-family: var(--font-sans);
  background: var(--bg-body);
  color: var(--text-primary);
  line-height: 1.6;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

a {
  color: var(--border-focus);
  text-decoration: none;
}
a:hover {
  text-decoration: underline;
}

/* ============================================
   Layout & Container
   ============================================ */
.container {
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 24px;
  width: 100%;
}

/* ============================================
   Navigation
   ============================================ */
.nav {
  background: var(--bg-card);
  border-bottom: 1px solid var(--border-color);
  padding: 0 24px;
  position: sticky;
  top: 0;
  z-index: 10;
  backdrop-filter: blur(8px);
  background: rgba(255, 255, 255, 0.9);
}

.nav-inner {
  max-width: 1100px;
  margin: 0 auto;
  height: 60px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.nav-brand {
  display: flex;
  align-items: center;
  gap: 8px;
  font-weight: 600;
  font-size: 1.1rem;
  color: var(--text-primary);
  text-decoration: none;
}
.nav-brand:hover {
  text-decoration: none;
}
.brand-icon {
  font-size: 1.3rem;
}

.nav-links {
  list-style: none;
  display: flex;
  gap: 24px;
  align-items: center;
}
.nav-links a {
  color: var(--text-secondary);
  font-size: 0.9rem;
  padding: 4px 0;
  border-bottom: 2px solid transparent;
  transition: var(--transition);
}
.nav-links a:hover {
  color: var(--text-primary);
  text-decoration: none;
  border-bottom-color: var(--border-focus);
}
.nav-links a.active {
  color: var(--text-primary);
  font-weight: 500;
  border-bottom-color: var(--border-focus);
}

/* ============================================
   Main & Hero
   ============================================ */
.main {
  flex: 1;
  padding: 40px 0 60px;
}

.hero {
  margin-bottom: 32px;
}
.hero h1 {
  font-size: 1.8rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  margin-bottom: 8px;
}
.hero p {
  color: var(--text-secondary);
  font-size: 1rem;
  max-width: 600px;
}

/* ============================================
   Cards
   ============================================ */
.card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius);
  padding: 24px;
  margin-bottom: 28px;
  box-shadow: var(--shadow-sm);
  transition: box-shadow var(--transition);
}
.card:hover {
  box-shadow: var(--shadow-md);
}
.card h2 {
  font-size: 1.2rem;
  font-weight: 600;
  margin-bottom: 16px;
}

/* ============================================
   Tool Actions (Buttons)
   ============================================ */
.tool-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 16px;
}
.tool-actions.secondary {
  margin-top: 16px;
  margin-bottom: 0;
  border-top: 1px solid var(--border-color);
  padding-top: 16px;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 8px 16px;
  font-size: 0.875rem;
  font-weight: 500;
  font-family: var(--font-sans);
  border: 1px solid var(--border-color);
  border-radius: var(--radius);
  background: var(--bg-body);
  color: var(--text-secondary);
  cursor: pointer;
  transition: all var(--transition);
  line-height: 1.4;
}
.btn:hover {
  background: var(--bg-card);
  border-color: var(--text-muted);
  color: var(--text-primary);
  transform: translateY(-1px);
}
.btn:active {
  transform: translateY(0);
}

.btn-primary {
  background: var(--border-focus);
  border-color: var(--border-focus);
  color: #fff;
}
.btn-primary:hover {
  background: #1d4ed8;
  border-color: #1d4ed8;
  color: #fff;
}
.btn-secondary {
  background: var(--bg-card);
}

/* ============================================
   Panels (Textareas)
   ============================================ */
.panels {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 20px;
  margin-bottom: 4px;
}
.panel label {
  display: block;
  font-weight: 600;
  font-size: 0.875rem;
  margin-bottom: 6px;
  color: var(--text-secondary);
}
.panel textarea {
  width: 100%;
  min-height: 220px;
  padding: 12px 14px;
  font-family: var(--font-mono);
  font-size: 0.9rem;
  line-height: 1.6;
  border: 1px solid var(--border-color);
  border-radius: var(--radius);
  background: var(--bg-input);
  color: var(--text-primary);
  resize: vertical;
  transition: var(--transition);
}
.panel textarea:focus {
  outline: none;
  border-color: var(--border-focus);
  box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}
.panel textarea[readonly] {
  background: var(--bg-body);
  color: var(--text-secondary);
}

/* ============================================
   Status
   ============================================ */
.status {
  min-height: 24px;
  font-size: 0.875rem;
  color: var(--text-secondary);
  margin-top: 8px;
}
.status.success {
  color: #16a34a;
}
.status.error {
  color: #dc2626;
}

/* ============================================
   File Section
   ============================================ */
.file-row {
  display: flex;
  align-items: center;
  gap: 16px;
  flex-wrap: wrap;
}
.file-input-wrap {
  position: relative;
  display: inline-block;
}
.file-input-wrap input[type="file"] {
  position: absolute;
  left: 0;
  top: 0;
  opacity: 0;
  width: 100%;
  height: 100%;
  cursor: pointer;
}
.file-name {
  color: var(--text-secondary);
  font-size: 0.9rem;
}
.file-hint {
  margin-top: 12px;
  font-size: 0.85rem;
  color: var(--text-muted);
  background: var(--bg-body);
  padding: 8px 14px;
  border-radius: var(--radius);
  display: inline-block;
}

/* ============================================
   FAQ Page Specific
   ============================================ */
.faq-list {
  display: flex;
  flex-direction: column;
  gap: 12px;
}
.faq-item {
  border: 1px solid var(--border-color);
  border-radius: var(--radius);
  background: var(--bg-card);
}
.faq-item summary {
  padding: 16px 20px;
  font-weight: 600;
  cursor: pointer;
  list-style: none;
  display: flex;
  align-items: center;
  gap: 12px;
  color: var(--text-primary);
  user-select: none;
}
.faq-item summary::-webkit-details-marker {
  display: none;
}
.faq-item summary::before {
  content: "▶";
  font-size: 0.75rem;
  color: var(--border-focus);
  transition: transform 150ms ease;
}
.faq-item[open] summary::before {
  transform: rotate(90deg);
}
.faq-item p {
  padding: 0 20px 20px 20px;
  margin: 0;
  color: var(--text-secondary);
  line-height: 1.7;
}

/* ============================================
   404 Page
   ============================================ */
.error-404 {
  text-align: center;
  padding: 60px 20px;
}
.error-404 h1 {
  font-size: 6rem;
  font-weight: 800;
  color: var(--text-muted);
  letter-spacing: -0.05em;
  margin-bottom: 8px;
}
.error-404 p {
  font-size: 1.2rem;
  color: var(--text-secondary);
  margin-bottom: 24px;
}

/* ============================================
   Footer
   ============================================ */
.footer {
  margin-top: 40px;
  padding-top: 24px;
  border-top: 1px solid var(--border-color);
  text-align: center;
  color: var(--text-muted);
  font-size: 0.875rem;
}

/* ============================================
   Responsive
   ============================================ */
@media (max-width: 768px) {
  .panels {
    grid-template-columns: 1fr;
  }
  .nav-inner {
    flex-wrap: wrap;
    height: auto;
    padding: 12px 0;
    gap: 8px;
  }
  .nav-links {
    gap: 16px;
  }
  .hero h1 {
    font-size: 1.4rem;
  }
  .card {
    padding: 16px;
  }
  .tool-actions {
    gap: 6px;
  }
  .btn {
    padding: 6px 12px;
    font-size: 0.8rem;
  }
  .file-row {
    flex-direction: column;
    align-items: stretch;
  }
}
@media (max-width: 480px) {
  .container {
    padding: 0 16px;
  }
  .nav {
    padding: 0 16px;
  }
}