/* Modern Reset & Core CSS Design Tokens */
:root {
  --font-sans: 'Plus Jakarta Sans', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --font-mono: 'JetBrains Mono', monospace;

  /* Theme: Dark Mode (Default) - Pure Black Background (#000000) */
  --bg-main: #000000;
  --bg-gradient: radial-gradient(at 0% 0%, rgba(239, 68, 68, 0.18) 0px, transparent 45%),
                 radial-gradient(at 100% 100%, rgba(220, 38, 38, 0.12) 0px, transparent 45%);
  --card-bg: rgba(18, 18, 18, 0.94);
  --card-border: rgba(239, 68, 68, 0.25);
  --card-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.95);

  --text-primary: #FFFFFF;
  --text-secondary: #A1A1AA;
  --text-muted: #71717A;

  --box-bg: rgba(24, 24, 27, 0.85);
  --input-bg: rgba(9, 9, 11, 0.95);
  --input-border: rgba(255, 255, 255, 0.15);

  /* Primary Theme Brand Accent: Vibrant Red */
  --accent-red: #EF4444;
  --accent-red-hover: #DC2626;
  --accent-red-glow: rgba(239, 68, 68, 0.35);

  /* Button State Colors */
  --btn-red-bg: #EF4444;
  --btn-red-hover: #DC2626;
  --btn-red-shadow: rgba(239, 68, 68, 0.45);

  --btn-yellow-bg: #EAB308;
  --btn-yellow-hover: #CA8A04;
  --btn-yellow-shadow: rgba(234, 179, 8, 0.5);

  --btn-green-bg: #22C55E;
  --btn-green-hover: #16A34A;
  --btn-green-shadow: rgba(34, 197, 94, 0.5);

  --radius-sm: 8px;
  --radius-md: 14px;
  --radius-lg: 20px;
  --radius-pill: 9999px;
  --transition-fast: 0.2s cubic-bezier(0.4, 0, 0.2, 1);
  --transition-normal: 0.35s cubic-bezier(0.4, 0, 0.2, 1);
}

/* Day / Light Mode Overrides - High Contrast Vibrant Buttons & Cards */
body.light-mode {
  --bg-main: #F4F4F6;
  --bg-gradient: radial-gradient(at 0% 0%, rgba(220, 38, 38, 0.1) 0px, transparent 50%),
                 radial-gradient(at 100% 100%, rgba(239, 68, 68, 0.08) 0px, transparent 50%);
  --card-bg: #FFFFFF;
  --card-border: rgba(220, 38, 38, 0.25);
  --card-shadow: 0 20px 45px -10px rgba(0, 0, 0, 0.08);

  --text-primary: #09090B;
  --text-secondary: #3F3F46;
  --text-muted: #71717A;

  --box-bg: #F4F4F5;
  --input-bg: #FFFFFF;
  --input-border: rgba(0, 0, 0, 0.18);

  --accent-red: #DC2626;
  --accent-red-hover: #B91C1C;
  --btn-red-bg: #DC2626;
  --btn-red-hover: #B91C1C;
  --btn-red-shadow: rgba(220, 38, 38, 0.4);
}

body.light-mode .select-photo-dropzone-btn,
body.light-mode .action-btn.state-red:not(:disabled) {
  background: #DC2626;
  color: #FFFFFF;
  font-weight: 800;
  box-shadow: 0 8px 24px rgba(220, 38, 38, 0.38);
}

body.light-mode .select-photo-dropzone-btn:hover,
body.light-mode .action-btn.state-red:not(:disabled):hover {
  background: #B91C1C;
  box-shadow: 0 10px 28px rgba(220, 38, 38, 0.55);
}

body.light-mode .action-btn.state-disabled,
body.light-mode .action-btn:disabled {
  background: #E4E4E7;
  color: #71717A;
  border: 1px solid #D4D4D8;
  opacity: 0.7;
}

body.light-mode .mode-toggle-group {
  background: #E4E4E7;
  border-color: rgba(220, 38, 38, 0.3);
}

body.light-mode .mode-btn {
  color: #3F3F46;
  font-weight: 700;
}

body.light-mode .mode-btn:hover {
  color: #09090B;
}

body.light-mode .mode-btn.active {
  background: #DC2626;
  color: #FFFFFF;
  box-shadow: 0 4px 14px rgba(220, 38, 38, 0.35);
}

body.light-mode .unit-toggle {
  background: #E4E4E7;
}

body.light-mode .unit-btn {
  color: #52525B;
}

body.light-mode .unit-btn.active {
  background: #DC2626;
  color: #FFFFFF;
}

body.light-mode .config-box {
  background: #FFFFFF;
  border-color: rgba(220, 38, 38, 0.22);
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.03);
}

body.light-mode .dropzone {
  background: #FAFAFA;
  border-color: rgba(220, 38, 38, 0.3);
}

body.light-mode .dropzone:hover {
  background: rgba(220, 38, 38, 0.05);
}

body.light-mode .nav-tab {
  color: #3F3F46;
}

body.light-mode .nav-tab:hover,
body.light-mode .nav-tab.active {
  color: #DC2626;
  background: rgba(220, 38, 38, 0.1);
  border-color: rgba(220, 38, 38, 0.25);
}

body.light-mode .theme-toggle-btn {
  background: rgba(220, 38, 38, 0.1);
  border-color: rgba(220, 38, 38, 0.25);
  color: #DC2626;
}

body.light-mode .seo-article-card {
  background: #FFFFFF;
  border-color: rgba(220, 38, 38, 0.22);
}

body.light-mode .use-case-box,
body.light-mode .faq-accordion-item {
  background: #F4F4F5;
  border-color: rgba(220, 38, 38, 0.2);
}

body.light-mode .faq-question {
  color: #09090B;
}

body.light-mode .faq-accordion-item[open] {
  border-color: #DC2626;
  box-shadow: 0 4px 16px rgba(220, 38, 38, 0.12);
}

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

html, body {
  width: 100%;
  min-height: 100dvh;
  font-family: var(--font-sans);
  background-color: var(--bg-main);
  background-image: var(--bg-gradient);
  color: var(--text-primary);
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
  transition: background-color 0.3s ease, color 0.3s ease;
}

/* Centered Viewport Container */
.app-viewport {
  width: 100%;
  max-width: 860px;
  margin: 0 auto;
  min-height: 100vh;
  min-height: 100dvh;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: flex-start;
  padding: 1.25rem 1rem;
  gap: 1.25rem;
  overflow-y: auto;
}

/* External Top Navigation Header */
.app-header {
  width: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  padding-bottom: 0.85rem;
  border-bottom: 1px solid var(--card-border);
  flex-wrap: wrap;
}

.brand-link {
  display: flex;
  align-items: center;
  gap: 0.85rem;
  text-decoration: none;
  color: inherit;
}

.brand-logo {
  width: 42px;
  height: 42px;
  border-radius: var(--radius-sm);
  object-fit: cover;
  box-shadow: 0 0 16px rgba(239, 68, 68, 0.4);
  border: 1px solid rgba(239, 68, 68, 0.4);
}

/* KB Photoresizer Header Title in Red Gradient */
.brand-name {
  font-size: 1.85rem;
  font-weight: 800;
  letter-spacing: -0.03em;
  background: linear-gradient(135deg, #FF4D4D 0%, #EF4444 60%, #DC2626 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.header-right {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.top-nav {
  display: flex;
  align-items: center;
  gap: 0.35rem;
}

.nav-tab {
  background: transparent;
  border: 1px solid transparent;
  color: var(--text-secondary);
  font-size: 0.875rem;
  font-weight: 600;
  padding: 0.45rem 0.85rem;
  border-radius: var(--radius-pill);
  cursor: pointer;
  text-decoration: none;
  transition: var(--transition-fast);
}

.nav-tab:hover, .nav-tab.active {
  color: #FFFFFF;
  background: rgba(239, 68, 68, 0.15);
  border-color: rgba(239, 68, 68, 0.3);
}

/* Day/Dark Theme Toggle Button */
.theme-toggle-btn {
  background: rgba(239, 68, 68, 0.12);
  border: 1px solid rgba(239, 68, 68, 0.3);
  color: var(--accent-red);
  width: 38px;
  height: 38px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  transition: var(--transition-fast);
}

.theme-toggle-btn:hover {
  transform: scale(1.08);
  border-color: var(--accent-red);
  background: var(--accent-red);
  color: #FFF;
}

/* Main Tool Box Container */
.app-card {
  width: 100%;
  background: var(--card-bg);
  backdrop-filter: blur(24px);
  -webkit-backdrop-filter: blur(24px);
  border: 1px solid var(--card-border);
  border-radius: var(--radius-lg);
  box-shadow: var(--card-shadow);
  padding: 1.75rem;
  display: flex;
  flex-direction: column;
  gap: 1rem;
  animation: fadeIn 0.4s ease-out;
  box-sizing: border-box;
}

.page-card {
  min-height: 520px;
  justify-content: flex-start;
}

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(10px); }
  to { opacity: 1; transform: translateY(0); }
}

/* "Free Resize" Title Inside Main Box */
.box-main-title {
  font-size: 1.75rem;
  font-weight: 800;
  letter-spacing: -0.02em;
  text-align: center;
  color: var(--text-primary);
  text-shadow: 0 0 16px rgba(239, 68, 68, 0.25);
  margin-bottom: -0.25rem;
}

/* Description Subtitle */
.app-description {
  font-size: 1.05rem;
  color: var(--text-secondary);
  font-weight: 600;
  text-align: center;
  line-height: 1.45;
  margin-top: -0.15rem;
  padding: 0 0.5rem;
}

/* Single-Line Centered Processing Mode Selector */
.mode-selector-wrapper {
  display: flex;
  justify-content: center;
  width: 100%;
}

.mode-toggle-group {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  background: var(--box-bg);
  padding: 0.35rem;
  border-radius: var(--radius-pill);
  border: 1px solid var(--card-border);
  gap: 0.35rem;
  max-width: 100%;
}

.mode-btn {
  background: transparent;
  border: 1px solid transparent;
  color: var(--text-secondary);
  padding: 0.45rem 1rem;
  border-radius: var(--radius-pill);
  font-size: 0.825rem;
  font-weight: 600;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  transition: var(--transition-fast);
  white-space: nowrap;
}

.mode-btn:hover {
  color: var(--text-primary);
}

.mode-btn.active {
  background: var(--accent-red);
  color: #FFFFFF;
  box-shadow: 0 4px 14px var(--accent-red-glow);
}

/* Config Grid */
.config-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0.85rem;
}

.config-box {
  background: var(--box-bg);
  border: 1px solid var(--card-border);
  border-radius: var(--radius-md);
  padding: 0.85rem 1rem;
  display: flex;
  flex-direction: column;
  gap: 0.6rem;
  transition: var(--transition-normal);
}

.config-box.inactive {
  opacity: 0.4;
  pointer-events: none;
  filter: grayscale(0.5);
}

.config-box-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.config-box-header h3 {
  font-size: 0.95rem;
  font-weight: 700;
  color: var(--text-primary);
}

.status-indicator {
  font-size: 0.65rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  padding: 0.15rem 0.5rem;
  border-radius: var(--radius-pill);
  background: rgba(239, 68, 68, 0.15);
  color: #F87171;
  border: 1px solid rgba(239, 68, 68, 0.35);
}

.status-indicator.muted {
  background: rgba(125, 125, 125, 0.1);
  color: var(--text-muted);
  border-color: rgba(125, 125, 125, 0.15);
}

/* Format Selection Bar */
.format-bar {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.75rem;
  width: 100%;
  margin: 0.25rem 0;
  flex-wrap: wrap;
}

.format-bar-label {
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text-secondary);
}

.format-toggle-group {
  display: inline-flex;
  align-items: center;
  background: var(--box-bg);
  padding: 0.25rem;
  border-radius: var(--radius-pill);
  border: 1px solid var(--card-border);
  gap: 0.25rem;
}

.format-btn {
  background: transparent;
  border: 1px solid transparent;
  color: var(--text-secondary);
  padding: 0.35rem 0.85rem;
  border-radius: var(--radius-pill);
  font-size: 0.8rem;
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition-fast);
}

.format-btn:hover {
  color: var(--text-primary);
}

.format-btn.active {
  background: var(--accent-red);
  color: #FFFFFF;
  box-shadow: 0 2px 10px var(--accent-red-glow);
}

.config-box-body {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.size-input-wrapper {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  background: var(--input-bg);
  border: 1px solid var(--input-border);
  border-radius: var(--radius-sm);
  padding: 0.35rem 0.5rem;
  transition: var(--transition-fast);
}

.size-input-wrapper:focus-within {
  border-color: var(--accent-red);
  box-shadow: 0 0 0 2px var(--accent-red-glow);
}

.size-input-wrapper input,
.dimension-field input {
  width: 100%;
  background: transparent;
  border: none;
  outline: none;
  color: var(--text-primary);
  font-family: var(--font-mono);
  font-size: 0.95rem;
  font-weight: 600;
  padding: 0.25rem;
}

.unit-toggle {
  display: flex;
  align-items: center;
  background: rgba(0, 0, 0, 0.25);
  border-radius: var(--radius-sm);
  padding: 0.15rem;
  gap: 0.15rem;
}

.unit-btn {
  background: transparent;
  border: none;
  color: var(--text-muted);
  font-family: var(--font-mono);
  font-size: 0.725rem;
  font-weight: 700;
  padding: 0.25rem 0.5rem;
  border-radius: 4px;
  cursor: pointer;
  transition: var(--transition-fast);
}

.unit-btn.active {
  background: var(--accent-red);
  color: #FFF;
}

.dimensions-row {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.dimension-field {
  flex: 1;
  background: var(--input-bg);
  border: 1px solid var(--input-border);
  border-radius: var(--radius-sm);
  padding: 0.35rem 0.5rem;
  transition: var(--transition-fast);
}

.dimension-field:focus-within {
  border-color: var(--accent-red);
  box-shadow: 0 0 0 2px var(--accent-red-glow);
}

.dimension-separator {
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--text-muted);
}

/* Upload Dropzone Section */
.upload-section {
  width: 100%;
}

.dropzone {
  width: 100%;
  border: 2px dashed var(--input-border);
  border-radius: var(--radius-md);
  padding: 1.15rem;
  text-align: center;
  background: var(--box-bg);
  cursor: pointer;
  transition: var(--transition-fast);
  position: relative;
  overflow: hidden;
}

.dropzone:hover, .dropzone.dragover {
  border-color: var(--accent-red);
  background: rgba(239, 68, 68, 0.08);
}

.dropzone-empty {
  display: flex;
  justify-content: center;
  align-items: center;
}

.select-photo-dropzone-btn {
  background: var(--btn-red-bg);
  color: #FFFFFF;
  border: none;
  padding: 0.75rem 1.75rem;
  border-radius: var(--radius-pill);
  font-size: 0.95rem;
  font-weight: 700;
  font-family: var(--font-sans);
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  box-shadow: 0 6px 18px var(--btn-red-shadow);
  transition: var(--transition-fast);
}

.select-photo-dropzone-btn:hover {
  background: var(--btn-red-hover);
  transform: translateY(-1px);
  box-shadow: 0 8px 22px rgba(239, 68, 68, 0.6);
}

/* Dropzone Preview */
.dropzone-preview {
  display: flex;
  align-items: center;
  gap: 1rem;
  text-align: left;
}

.image-preview-thumbnail {
  width: 54px;
  height: 54px;
  border-radius: var(--radius-sm);
  overflow: hidden;
  background: #000;
  border: 1px solid var(--card-border);
  flex-shrink: 0;
  display: flex;
  align-items: center;
  justify-content: center;
}

.image-preview-thumbnail img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.image-meta {
  flex: 1;
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
  min-width: 0;
}

.meta-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.file-name {
  font-size: 0.85rem;
  font-weight: 700;
  color: var(--text-primary);
  max-width: 240px;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.change-file-btn {
  background: rgba(239, 68, 68, 0.15);
  border: 1px solid rgba(239, 68, 68, 0.3);
  color: #F87171;
  font-size: 0.7rem;
  font-weight: 600;
  padding: 0.2rem 0.55rem;
  border-radius: var(--radius-sm);
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 0.3rem;
  transition: var(--transition-fast);
}

.change-file-btn:hover {
  background: var(--accent-red);
  color: #FFF;
}

.meta-details {
  display: flex;
  gap: 0.4rem;
  flex-wrap: wrap;
}

.meta-chip {
  font-size: 0.685rem;
  color: var(--text-muted);
  background: rgba(125, 125, 125, 0.08);
  padding: 0.15rem 0.45rem;
  border-radius: var(--radius-sm);
  border: 1px solid var(--card-border);
}

.meta-chip strong {
  color: var(--text-secondary);
  font-family: var(--font-mono);
}

.hidden {
  display: none !important;
}

/* Action Footer & Disabled/Enabled State Styling */
.app-footer {
  width: 100%;
  padding-top: 0.25rem;
}

.action-btn {
  width: 100%;
  padding: 0.85rem;
  border-radius: var(--radius-md);
  border: none;
  font-size: 0.95rem;
  font-weight: 700;
  font-family: var(--font-sans);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  transition: background-color 0.3s ease, transform 0.15s ease, box-shadow 0.3s ease, opacity 0.3s ease;
  outline: none;
  user-select: none;
}

.action-btn:active:not(:disabled) {
  transform: scale(0.985);
}

.action-btn:disabled,
.action-btn.state-disabled {
  background: rgba(125, 125, 125, 0.15);
  color: var(--text-muted);
  border: 1px solid var(--card-border);
  box-shadow: none;
  cursor: not-allowed;
  opacity: 0.5;
  pointer-events: none;
}

.action-btn.state-red:not(:disabled) {
  background: var(--btn-red-bg);
  color: #FFFFFF;
  box-shadow: 0 6px 20px var(--btn-red-shadow);
  opacity: 1;
  cursor: pointer;
  pointer-events: auto;
}

.action-btn.state-red:not(:disabled):hover {
  background: var(--btn-red-hover);
  box-shadow: 0 8px 25px rgba(239, 68, 68, 0.6);
}

.progress-bar-container {
  position: relative;
  width: 100%;
  height: 48px;
  border-radius: var(--radius-md);
  overflow: hidden;
  background: rgba(0, 0, 0, 0.3);
  border: 1px solid var(--card-border);
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: inset 0 2px 6px rgba(0, 0, 0, 0.5);
}

.progress-bar-fill {
  position: absolute;
  top: 0;
  left: 0;
  height: 100%;
  width: 0%;
  transition: width 0.15s linear, background-color 0.4s ease;
  border-radius: var(--radius-md);
}

.progress-bar-fill.state-red {
  background: var(--btn-red-bg);
  box-shadow: 0 0 16px rgba(239, 68, 68, 0.6);
}

.progress-bar-fill.state-yellow {
  background: var(--btn-yellow-bg);
  box-shadow: 0 0 18px rgba(234, 179, 8, 0.7);
}

.progress-bar-fill.state-green {
  background: var(--btn-green-bg);
  box-shadow: 0 0 20px rgba(34, 197, 94, 0.7);
}

.progress-bar-text {
  position: relative;
  z-index: 2;
  font-size: 0.95rem;
  font-weight: 800;
  color: #FFFFFF;
  font-family: var(--font-sans);
  text-shadow: 0 1px 4px rgba(0, 0, 0, 0.8);
  letter-spacing: 0.02em;
}

/* On-Page SEO Article Card Styling (Positioned below main box with distance) */
.seo-article-card {
  width: 100%;
  background: var(--card-bg);
  backdrop-filter: blur(24px);
  -webkit-backdrop-filter: blur(24px);
  border: 1px solid var(--card-border);
  border-radius: var(--radius-lg);
  box-shadow: var(--card-shadow);
  padding: 2rem 1.75rem;
  display: flex;
  flex-direction: column;
  gap: 1.75rem;
  margin-top: 2.75rem; /* Generous distance below main tool box */
}

.seo-article-header {
  border-bottom: 1px solid var(--card-border);
  padding-bottom: 1rem;
}

.seo-main-heading {
  font-size: 1.5rem;
  font-weight: 800;
  color: var(--accent-red);
  margin-bottom: 0.5rem;
}

.seo-lead {
  font-size: 0.95rem;
  line-height: 1.6;
  color: var(--text-secondary);
}

.seo-section {
  display: flex;
  flex-direction: column;
  gap: 0.85rem;
}

.seo-section h3 {
  font-size: 1.15rem;
  font-weight: 700;
  color: var(--text-primary);
}

.faq-section-title {
  font-size: 1.25rem;
  font-weight: 800;
  color: var(--accent-red);
  margin-bottom: 0.25rem;
}

.seo-section p {
  font-size: 0.875rem;
  line-height: 1.65;
  color: var(--text-secondary);
}

.seo-feature-list, .seo-steps-list {
  padding-left: 1.25rem;
  display: flex;
  flex-direction: column;
  gap: 0.6rem;
}

.seo-feature-list li, .seo-steps-list li {
  font-size: 0.875rem;
  line-height: 1.6;
  color: var(--text-secondary);
}

.seo-feature-list strong, .seo-steps-list strong {
  color: var(--text-primary);
}

.seo-use-cases-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 0.85rem;
  margin-top: 0.35rem;
}

.use-case-box {
  background: var(--box-bg);
  border: 1px solid var(--card-border);
  border-radius: var(--radius-md);
  padding: 1rem;
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
}

.use-case-box h4 {
  font-size: 0.9rem;
  font-weight: 700;
  color: var(--accent-red);
}

.use-case-box p {
  font-size: 0.8rem;
  line-height: 1.5;
  color: var(--text-secondary);
}

/* Interactive Collapsible FAQ Accordion Styling */
.seo-faq-accordion-container {
  display: flex;
  flex-direction: column;
  gap: 0.65rem;
  width: 100%;
}

.faq-accordion-item {
  background: var(--box-bg);
  border: 1px solid var(--card-border);
  border-radius: var(--radius-md);
  overflow: hidden;
  transition: var(--transition-fast);
}

.faq-accordion-item[open] {
  border-color: var(--accent-red);
  box-shadow: 0 4px 16px rgba(239, 68, 68, 0.15);
}

.faq-question {
  padding: 0.9rem 1.15rem;
  font-size: 0.9rem;
  font-weight: 700;
  color: var(--text-primary);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: space-between;
  list-style: none;
  user-select: none;
  transition: var(--transition-fast);
}

.faq-question::-webkit-details-marker,
.faq-question::marker {
  display: none;
  content: "";
}

.faq-question:hover {
  color: var(--accent-red);
}

.faq-chevron {
  transition: transform 0.25s ease;
  color: var(--accent-red);
  flex-shrink: 0;
  margin-left: 0.5rem;
}

.faq-accordion-item[open] .faq-chevron {
  transform: rotate(180deg);
}

.faq-answer {
  padding: 0 1.15rem 0.95rem 1.15rem;
  border-top: 1px solid rgba(255, 255, 255, 0.06);
  margin-top: 0.1rem;
}

.faq-answer p {
  font-size: 0.835rem;
  line-height: 1.6;
  color: var(--text-secondary);
  padding-top: 0.6rem;
}

/* Site Footer Navigation */
.site-footer {
  width: 100%;
  padding: 1.5rem 0 0.5rem 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.6rem;
  border-top: 1px solid rgba(255, 255, 255, 0.08);
}

.footer-links {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 1rem;
  flex-wrap: wrap;
}

.footer-links a {
  color: var(--text-secondary);
  text-decoration: none;
  font-size: 0.825rem;
  font-weight: 600;
  transition: var(--transition-fast);
}

.footer-links a:hover, .footer-links a.active {
  color: var(--accent-red);
}

.footer-copy {
  font-size: 0.75rem;
  color: var(--text-muted);
}

/* Legal Text Container */
.legal-text-container {
  display: flex;
  flex-direction: column;
  gap: 1rem;
  line-height: 1.6;
}

.legal-text-container h3 {
  font-size: 1.05rem;
  font-weight: 700;
  color: var(--accent-red);
  margin-top: 0.5rem;
}

.legal-text-container p {
  font-size: 0.875rem;
  color: var(--text-secondary);
}

.inline-link {
  color: var(--accent-red);
  text-decoration: none;
  font-weight: 600;
}

.inline-link:hover {
  text-decoration: underline;
}

/* Contact Us Layout */
.contact-container {
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
  max-width: 520px;
  margin: 0 auto;
  width: 100%;
}

.contact-info-bar {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1rem;
}

.contact-info-item {
  background: var(--box-bg);
  border: 1px solid var(--card-border);
  border-radius: var(--radius-md);
  padding: 0.85rem;
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.info-icon {
  font-size: 1.35rem;
}

.contact-info-item h4 {
  font-size: 0.825rem;
  font-weight: 700;
  color: var(--text-primary);
}

.contact-info-item p {
  font-size: 0.75rem;
  color: var(--text-secondary);
}

/* Error Pages Styling */
.error-card {
  text-align: center;
  align-items: center;
  padding: 3rem 1.5rem;
  gap: 1.25rem;
  min-height: 400px;
  justify-content: center;
}

.error-badge {
  font-size: 4rem;
  font-weight: 800;
  font-family: var(--font-mono);
  background: linear-gradient(135deg, #FF4D4D 0%, #EF4444 60%, #DC2626 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  letter-spacing: -0.04em;
  text-shadow: 0 0 30px rgba(239, 68, 68, 0.3);
  line-height: 1;
}

.error-title {
  font-size: 1.75rem;
  font-weight: 800;
  color: var(--text-primary);
}

.error-subtitle {
  font-size: 0.95rem;
  color: var(--text-secondary);
  max-width: 440px;
  line-height: 1.5;
}

.error-action-btn {
  margin-top: 0.75rem;
  background: var(--btn-red-bg);
  color: #FFFFFF;
  padding: 0.75rem 1.75rem;
  border-radius: var(--radius-pill);
  font-weight: 700;
  font-size: 0.9rem;
  text-decoration: none;
  box-shadow: 0 6px 18px var(--btn-red-shadow);
  transition: var(--transition-fast);
}

.error-action-btn:hover {
  background: var(--btn-red-hover);
  transform: translateY(-2px);
  box-shadow: 0 8px 24px rgba(239, 68, 68, 0.6);
}

/* Standalone Pages Layout */
.page-content {
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
  padding-top: 0.5rem;
}

.page-title-section {
  text-align: center;
}

.page-title-section h2 {
  font-size: 1.4rem;
  font-weight: 800;
  color: var(--accent-red);
}

.page-subtitle {
  font-size: 0.875rem;
  color: var(--text-secondary);
  margin-top: 0.25rem;
}

.standalone-presets-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(230px, 1fr));
  gap: 1rem;
}

.preset-card-full {
  background: var(--box-bg);
  border: 1px solid var(--card-border);
  border-radius: var(--radius-md);
  padding: 1rem;
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  transition: var(--transition-fast);
}

.preset-card-full:hover {
  border-color: var(--accent-red);
  transform: translateY(-2px);
}

.preset-badge {
  font-size: 0.65rem;
  font-weight: 700;
  background: var(--accent-red);
  color: #FFF;
  padding: 0.15rem 0.45rem;
  border-radius: var(--radius-pill);
}

.use-preset-btn {
  margin-top: 0.35rem;
  background: rgba(239, 68, 68, 0.15);
  color: #F87171;
  border: 1px solid rgba(239, 68, 68, 0.3);
  padding: 0.45rem;
  border-radius: var(--radius-sm);
  font-size: 0.8rem;
  font-weight: 700;
  cursor: pointer;
  transition: var(--transition-fast);
}

.use-preset-btn:hover {
  background: var(--accent-red);
  color: #FFF;
}

.about-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1rem;
}

.about-card {
  background: var(--box-bg);
  border: 1px solid var(--card-border);
  border-radius: var(--radius-md);
  padding: 1rem;
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
}

.about-card h3 {
  color: var(--accent-red);
}

.feedback-container {
  max-width: 480px;
  margin: 0 auto;
  width: 100%;
}

.standalone-feedback-form {
  display: flex;
  flex-direction: column;
  gap: 0.85rem;
  background: var(--box-bg);
  border: 1px solid var(--card-border);
  border-radius: var(--radius-md);
  padding: 1.25rem;
}

.form-group {
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
}

.form-label {
  font-size: 0.825rem;
  font-weight: 600;
  color: var(--text-secondary);
}

.form-input, .form-textarea {
  background: var(--input-bg);
  border: 1px solid var(--input-border);
  border-radius: var(--radius-sm);
  color: var(--text-primary);
  padding: 0.55rem;
  font-family: var(--font-sans);
  font-size: 0.85rem;
  outline: none;
}

.form-input:focus, .form-textarea:focus {
  border-color: var(--accent-red);
}

.star-rating {
  display: flex;
  gap: 0.35rem;
  cursor: pointer;
}

.star {
  font-size: 1.5rem;
  color: var(--text-muted);
  transition: color 0.2s;
}

.star.active, .star:hover {
  color: #EAB308;
}

.submit-feedback-btn {
  background: var(--accent-red);
  color: #FFF;
  border: none;
  padding: 0.65rem;
  border-radius: var(--radius-sm);
  font-weight: 700;
  font-size: 0.875rem;
  cursor: pointer;
  transition: var(--transition-fast);
}

.submit-feedback-btn:hover {
  background: var(--accent-red-hover);
}

/* Responsive Viewport Rules */
@media (max-width: 767px) {
  .app-viewport {
    padding: 0.5rem 0.35rem;
    gap: 0.75rem;
  }

  .app-card, .seo-article-card {
    padding: 1.1rem 0.85rem;
    gap: 0.75rem;
  }

  .seo-article-card {
    margin-top: 1.75rem;
  }

  .box-main-title {
    font-size: 1.45rem;
  }

  .seo-main-heading {
    font-size: 1.3rem;
  }

  .app-header {
    flex-direction: row;
    align-items: center;
    justify-content: space-between;
  }

  .brand-name {
    font-size: 1.3rem;
  }

  .brand-logo {
    width: 34px;
    height: 34px;
  }

  .top-nav {
    gap: 0.15rem;
  }

  .nav-tab {
    padding: 0.35rem 0.5rem;
    font-size: 0.725rem;
  }

  .theme-toggle-btn {
    width: 32px;
    height: 32px;
  }

  .app-description {
    font-size: 0.925rem;
  }

  .mode-toggle-group {
    width: 100%;
    justify-content: space-between;
    padding: 0.25rem;
  }

  .mode-btn {
    flex: 1;
    justify-content: center;
    padding: 0.4rem 0.35rem;
    font-size: 0.75rem;
  }

  .config-grid, .about-grid, .contact-info-bar, .seo-use-cases-grid {
    grid-template-columns: 1fr;
  }

  .footer-links {
    gap: 0.6rem 0.85rem;
  }

  .file-name {
    max-width: 160px;
  }

  .select-photo-dropzone-btn {
    width: 100%;
    justify-content: center;
    padding: 0.7rem 1rem;
    font-size: 0.9rem;
  }
}