:root {

  --color-bg: #fdfbf7;
  --color-bg-alt: #f6f1ea;
  --color-surface: #fff;
  --color-text: #2c2416;
  --color-text-secondary: #6b5e4f;
  --color-text-muted: #9a8d7f;
  --color-border: #e8e0d5;
  --color-border-light: #f0ebe4;

  --color-primary: #c17d4f;
  --color-primary-dark: #a6683e;
  --color-primary-light: #f5e6d8;

  --color-success: #5a8f7b;
  --color-success-light: #e8f4ef;
  --color-warning: #d4a84b;
  --color-warning-light: #fdf6e8;
  --color-info: #6a8fba;
  --color-info-light: #e8f1f8;

  --font-heading: "PingFang SC", "Noto Serif SC", "Source Han Serif SC", "STSong", Georgia, "Times New Roman", serif;
  --font-body: "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Noto Sans SC", system-ui, -apple-system, sans-serif;

  --space-xs: .25rem;
  --space-sm: .5rem;
  --space-md: 1rem;
  --space-lg: 1.25rem;
  --space-xl: 1.75rem;
  --space-2xl: 2.25rem;
  --space-3xl: 2.75rem;

  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;
  --radius-xl: 24px;
  --radius-full: 9999px;

  --shadow-sm: 0 2px 8px rgba(44, 36, 22, .06);
  --shadow-md: 0 4px 16px rgba(44, 36, 22, .08);
  --shadow-lg: 0 8px 32px rgba(44, 36, 22, .1);

  --header-height: 56px;
  --content-max-width: 1200px;
  --content-narrow: 800px;

  --ease-out: cubic-bezier(0.16, 1, .3, 1);
  --duration-fast: 150ms;
  --duration-normal: 300ms;
  --duration-slow: 500ms;
}

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

html {
  font-size: 16px;
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--header-height) + 20px);
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: var(--font-body);
  color: var(--color-text);
  background: var(--color-bg);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

::selection {
  background: var(--color-primary-light);
  color: var(--color-primary-dark);
}

h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-heading);
  font-weight: 700;
  line-height: 1.25;
  letter-spacing: -0.02em;
  color: var(--color-text);
}

h1 { font-size: clamp(2rem, 5vw, 3.5rem); }
h2 { font-size: clamp(1.5rem, 3.5vw, 2.5rem); }
h3 { font-size: clamp(1.25rem, 2.5vw, 1.75rem); }
h4 { font-size: 1.25rem; }

p {
  max-width: 65ch;
  color: var(--color-text-secondary);
}

a {
  color: var(--color-primary-dark);
  text-decoration: none;
  transition: color var(--duration-fast) var(--ease-out);
}

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

.container {
  width: 100%;
  max-width: var(--content-max-width);
  margin: 0 auto;
  padding: 0 var(--space-xl);
}

.container-narrow {
  max-width: var(--content-narrow);
}

.section {
  padding: var(--space-3xl) 0;
}

.breadcrumb-nav {
  padding: calc(var(--header-height) + var(--space-sm)) 0 0;
  min-height: 92px;
}

.breadcrumb-nav ol {
  max-width: var(--content-max-width);
  margin: 0 auto;
  padding: 0 var(--space-lg);
  list-style: none;
  display: flex;
  flex-wrap: wrap;
  font-size: .85rem;
  color: var(--color-text-muted);
}

.breadcrumb-nav li:not(:last-child)::after {
  content: '>';
  margin: 0 var(--space-xs);
  color: var(--color-border);
}

.breadcrumb-nav a {
  color: var(--color-primary-dark);
  text-decoration: none;
}

.breadcrumb-nav a:hover {
  text-decoration: underline;
}

.section-alt {
  background: var(--color-bg-alt);
}

.section-sm {
  padding: var(--space-xl) 0;
}

.header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  height: var(--header-height);
  background: rgba(253, 251, 247, .85);
  backdrop-filter: blur(20px) saturate(180%);
  -webkit-backdrop-filter: blur(20px) saturate(180%);
  border-bottom: 1px solid var(--color-border-light);
  transition: all var(--duration-normal) var(--ease-out);
}

.header.scrolled {
  box-shadow: var(--shadow-sm);
  background: rgba(253, 251, 247, .95);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 100%;
  max-width: var(--content-max-width);
  margin: 0 auto;
  padding: 0 var(--space-xl);
}

.logo {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  font-family: var(--font-heading);
  font-size: 1.35rem;
  font-weight: 700;
  color: var(--color-text);
  letter-spacing: -0.02em;
}

.logo-icon {
  width: 36px;
  height: 36px;
  border-radius: var(--radius-md);
  background: linear-gradient(135deg, var(--color-primary), var(--color-primary-dark));
  display: flex;
  align-items: center;
  justify-content: center;
  color: #fff;
  font-size: 1.1rem;
  font-weight: 700;
}

.nav {
  display: flex;
  align-items: center;
  gap: var(--space-xs);
}

.nav-link {
  display: inline-flex;
  align-items: center;
  padding: var(--space-sm) var(--space-md);
  font-size: .925rem;
  font-weight: 500;
  color: var(--color-text-secondary);
  border-radius: var(--radius-md);
  transition: all var(--duration-fast) var(--ease-out);
  position: relative;
}

.nav-link:hover {
  color: var(--color-text);
  background: var(--color-primary-light);
}

.nav-link.active {
  color: var(--color-primary-dark);
  background: var(--color-primary-light);
}

.nav-cta {
  margin-left: var(--space-md);
  padding: var(--space-sm) var(--space-lg);
  background: var(--color-primary);
  color: #fff !important;
  border-radius: var(--radius-full);
  font-weight: 600;
  font-size: .9rem;
  transition: all var(--duration-fast) var(--ease-out);
  box-shadow: 0 2px 8px rgba(193, 125, 79, .25);
}

.nav-cta:hover {
  background: var(--color-primary-dark);
  box-shadow: 0 4px 16px rgba(193, 125, 79, .35);
  transform: translateY(-1px);
}

.mobile-menu-btn {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: var(--space-sm);
  color: var(--color-text);
}

.mobile-menu-btn svg {
  width: 24px;
  height: 24px;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-sm);
  padding: var(--space-md) var(--space-xl);
  font-family: var(--font-body);
  font-size: 1rem;
  font-weight: 600;
  border: none;
  border-radius: var(--radius-full);
  cursor: pointer;
  transition: all var(--duration-fast) var(--ease-out);
  white-space: nowrap;
}

.btn-primary {
  background: var(--color-primary);
  color: #fff;
  box-shadow: 0 2px 8px rgba(193, 125, 79, .25);
}

.btn-primary:hover {
  background: var(--color-primary-dark);
  box-shadow: 0 4px 16px rgba(193, 125, 79, .35);
  transform: translateY(-1px);
}

.btn-outline {
  background: transparent;
  color: var(--color-primary-dark);
  border: 1.5px solid var(--color-primary);
}

.btn-outline:hover {
  background: var(--color-primary-light);
  border-color: var(--color-primary-dark);
}

.btn-lg {
  padding: var(--space-md) var(--space-2xl);
  font-size: 1.075rem;
}

.hero {
  position: relative;
  padding: calc(var(--header-height) + var(--space-xl)) 0 var(--space-2xl);
  overflow: hidden;
  display: flex;
  align-items: center;
}

.hero::before {
  content: '';
  position: absolute;
  top: -50%;
  right: -20%;
  width: 80%;
  height: 180%;
  background: radial-gradient(ellipse at center, var(--color-primary-light) 0%, transparent 70%);
  z-index: -1;
  opacity: .6;
}

.hero-content {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-xl);
  align-items: center;
}

.hero-text {
  display: flex;
  flex-direction: column;
  gap: var(--space-md);
}

.hero-eyebrow {
  display: inline-flex;
  align-items: center;
  gap: var(--space-sm);
  padding: var(--space-xs) var(--space-md);
  background: var(--color-primary-light);
  color: var(--color-primary-dark);
  border-radius: var(--radius-full);
  font-size: .85rem;
  font-weight: 600;
  width: fit-content;
}

.hero-title {
  font-size: clamp(2.25rem, 5.5vw, 4rem);
  line-height: 1.1;
  letter-spacing: -0.03em;
}

.hero-title .highlight {
  background: linear-gradient(135deg, var(--color-primary), var(--color-primary-dark));
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
}

.hero-desc {
  font-size: 1.05rem;
  line-height: 1.65;
  color: var(--color-text-secondary);
  max-width: 520px;
}

.hero-actions {
  display: flex;
  gap: var(--space-md);
  flex-wrap: wrap;
}

.hero-stats {
  display: flex;
  gap: var(--space-2xl);
  padding-top: var(--space-md);
}

.hero-stat-value {
  font-family: var(--font-heading);
  font-size: 1.75rem;
  font-weight: 700;
  color: var(--color-primary-dark);
  line-height: 1.2;
}

.hero-stat-label {
  font-size: .85rem;
  color: var(--color-text-muted);
}

.hero-visual {
  display: flex;
  align-items: center;
  justify-content: center;
  position: relative;
}

.phone-frame {
  width: 100%;
  max-width: 280px;
  aspect-ratio: 360 / 803;
  background: #2c2416;
  border-radius: 24px;
  box-shadow:
    0 0 0 3px #3a3028,
    0 0 0 5px #1a140d,
    0 20px 60px rgba(44, 36, 22, .25);
  overflow: hidden;
  position: relative;
  padding: 7px;
  box-sizing: border-box;
}

.phone-frame picture {
  position: absolute;
  top: 7px;
  left: 7px;
  right: 7px;
  bottom: 7px;
  display: block;
}

.phone-img {
  width: 100%;
  height: 100%;
  object-fit: contain;
  border-radius: 14px;
  display: block;
}

.hero-floating-card {
  position: absolute;
  background: var(--color-surface);
  border-radius: var(--radius-lg);
  padding: var(--space-md);
  box-shadow: var(--shadow-lg);
  border: 1px solid var(--color-border-light);
  font-size: .85rem;
  font-weight: 600;
  color: var(--color-text);
}

.hero-floating-card.top {
  top: 8%;
  right: -5%;
  transform: rotate(3deg);
}

.hero-floating-card.bottom {
  bottom: 12%;
  left: -8%;
  transform: rotate(-2deg);
}

.hero-float-icon {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 28px;
  height: 28px;
  border-radius: var(--radius-sm);
  background: var(--color-success-light);
  color: var(--color-success);
  margin-right: 6px;
  font-size: .8rem;
}

.features-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(340px, 1fr));
  gap: var(--space-lg);
  margin-top: var(--space-lg);
}

.feature-card {
  background: var(--color-surface);
  border-radius: var(--radius-lg);
  padding: var(--space-xl);
  border: 1px solid var(--color-border-light);
  transition: all var(--duration-normal) var(--ease-out);
  position: relative;
  overflow: hidden;
}

.feature-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: linear-gradient(90deg, var(--color-primary), var(--color-primary-dark));
  opacity: 0;
  transition: opacity var(--duration-normal) var(--ease-out);
}

.feature-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
  border-color: var(--color-border);
}

.feature-card:hover::before {
  opacity: 1;
}

.feature-icon {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 48px;
  height: 48px;
  border-radius: var(--radius-md);
  background: var(--color-primary-light);
  color: var(--color-primary-dark);
  margin-bottom: var(--space-lg);
  font-size: 1.3rem;
}

.feature-card h3 {
  font-size: 1.2rem;
  margin-bottom: var(--space-sm);
}

.feature-card p {
  font-size: .95rem;
  line-height: 1.65;
}

.section-header {
  text-align: center;
  margin-bottom: var(--space-xl);
}

.section-header h2 {
  margin-bottom: var(--space-sm);
}

.section-header p {
  font-size: 1.05rem;
  max-width: 560px;
  margin: 0 auto;
}

.section-label {
  display: inline-block;
  padding: var(--space-xs) var(--space-md);
  background: var(--color-primary-light);
  color: var(--color-primary-dark);
  border-radius: var(--radius-full);
  font-size: .85rem;
  font-weight: 600;
  margin-bottom: var(--space-sm);
}

.stats-row {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: var(--space-xl);
  margin-top: var(--space-lg);
}

.stat-card {
  text-align: center;
  padding: var(--space-xl) var(--space-md);
  background: var(--color-surface);
  border-radius: var(--radius-lg);
  border: 1px solid var(--color-border-light);
}

.stat-value {
  font-family: var(--font-heading);
  font-size: 2.25rem;
  font-weight: 700;
  color: var(--color-primary-dark);
  line-height: 1;
  margin-bottom: var(--space-sm);
}

.stat-label {
  color: var(--color-text-muted);
  font-size: .9rem;
}

.tutorial-content {
  display: grid;
  grid-template-columns: 240px 1fr;
  gap: var(--space-3xl);
  align-items: start;
}

.tutorial-sidebar {
  position: sticky;
  top: calc(var(--header-height) + var(--space-md));
}

.tutorial-sidebar nav {
  display: flex;
  flex-direction: column;
  gap: var(--space-xs);
}

.tutorial-sidebar a {
  display: block;
  padding: var(--space-sm) var(--space-md);
  color: var(--color-text-secondary);
  font-size: .9rem;
  border-radius: var(--radius-md);
  transition: all var(--duration-fast) var(--ease-out);
  border-left: 2px solid transparent;
}

.tutorial-sidebar a:hover,
.tutorial-sidebar a.active {
  color: var(--color-primary-dark);
  background: var(--color-primary-light);
  border-left-color: var(--color-primary);
}

.tutorial-body section {
  margin-bottom: var(--space-3xl);
}

.tutorial-body h2 {
  margin-bottom: var(--space-lg);
  padding-bottom: var(--space-sm);
  border-bottom: 2px solid var(--color-border-light);
}

.tutorial-body h3 {
  margin: var(--space-md) 0 var(--space-sm);
}

.tutorial-body p {
  margin-bottom: var(--space-md);
  line-height: 1.8;
}

.tutorial-body ul,
.tutorial-body ol {
  margin-bottom: var(--space-lg);
  padding-left: var(--space-xl);
}

.tutorial-body li {
  margin-bottom: var(--space-sm);
  color: var(--color-text-secondary);
  line-height: 1.7;
}

.tip-box {
  background: var(--color-info-light);
  border-left: 4px solid var(--color-info);
  padding: var(--space-md) var(--space-lg);
  border-radius: 0 var(--radius-md) var(--radius-md) 0;
  margin: var(--space-lg) 0;
}

.tip-box strong {
  color: var(--color-info);
}

.warning-box {
  background: var(--color-warning-light);
  border-left: 4px solid var(--color-warning);
  padding: var(--space-md) var(--space-lg);
  border-radius: 0 var(--radius-md) var(--radius-md) 0;
  margin: var(--space-lg) 0;
}

.warning-box strong {
  color: var(--color-warning);
}

.format-badges {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-sm);
  margin: var(--space-lg) 0;
}

.format-badge {
  display: inline-flex;
  align-items: center;
  padding: var(--space-xs) var(--space-md);
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-full);
  font-size: .85rem;
  font-weight: 500;
  color: var(--color-text-secondary);
  transition: all var(--duration-fast) var(--ease-out);
}

.format-badge:hover {
  background: var(--color-primary-light);
  border-color: var(--color-primary);
  color: var(--color-primary-dark);
}

.testimonials-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  gap: var(--space-lg);
}

.testimonial-card {
  background: var(--color-surface);
  border-radius: var(--radius-lg);
  padding: var(--space-xl);
  border: 1px solid var(--color-border-light);
  position: relative;
}

.testimonial-card::before {
  content: '\201C';
  font-family: var(--font-heading);
  font-size: 4rem;
  line-height: 1;
  color: var(--color-primary);
  opacity: .25;
  position: absolute;
  top: var(--space-md);
  left: var(--space-md);
}

.testimonial-text {
  position: relative;
  font-size: .95rem;
  line-height: 1.7;
  padding-top: var(--space-lg);
  margin-bottom: var(--space-lg);
}

.testimonial-author {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
}

.testimonial-avatar {
  width: 40px;
  height: 40px;
  border-radius: 50%;
  background: var(--color-primary-light);
  color: var(--color-primary-dark);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: .9rem;
}

.testimonial-name {
  font-weight: 600;
  font-size: .9rem;
}

.testimonial-role {
  font-size: .8rem;
  color: var(--color-text-muted);
}

.faq-list {
  max-width: var(--content-narrow);
  margin: var(--space-2xl) auto 0;
}

.faq-item {
  border: 1px solid var(--color-border-light);
  border-radius: var(--radius-lg);
  margin-bottom: var(--space-md);
  overflow: hidden;
  background: var(--color-surface);
}

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

.faq-question::after {
  content: '+';
  font-size: 1.3rem;
  font-weight: 300;
  color: var(--color-text-muted);
  transition: transform var(--duration-normal) var(--ease-out);
}

.faq-item.open .faq-question::after {
  content: '\2212';
}

.faq-answer {
  max-height: 0;
  overflow: hidden;
  transition: max-height var(--duration-slow) var(--ease-out);
}

.faq-item.open .faq-answer {
  max-height: 500px;
}

.faq-answer-inner {
  padding: 0 var(--space-lg) var(--space-lg);
  color: var(--color-text-secondary);
  font-size: .95rem;
  line-height: 1.7;
}

.footer {
  background: var(--color-text);
  color: rgba(255,255,255,.7);
  padding: var(--space-2xl) 0;
  text-align: center;
}

.footer-brand-line {
  font-family: var(--font-heading);
  font-size: 1.2rem;
  font-weight: 700;
  color: #fff;
  margin-bottom: var(--space-xs);
}

.footer-brand-line span {
  color: var(--color-primary);
}

.footer-desc {
  font-size: .85rem;
  color: rgba(255,255,255,.5);
  max-width: 400px;
  margin: 0 auto var(--space-lg);
}

.footer-divider {
  width: 48px;
  height: 1px;
  background: rgba(255,255,255,.15);
  margin: 0 auto var(--space-lg);
}

.footer-bottom {
  font-size: .78rem;
  color: rgba(255,255,255,.35);
  display: flex;
  justify-content: center;
  gap: var(--space-md);
  flex-wrap: wrap;
}

.footer-bottom a {
  color: rgba(255,255,255,.35);
  text-decoration: underline;
}
.footer-bottom a:hover {
  color: rgba(255,255,255,.6);
}

.page-header {
  padding: calc(var(--header-height) + var(--space-lg)) 0 var(--space-lg);
  text-align: center;
  background: linear-gradient(180deg, var(--color-primary-light) 0%, transparent 100%);
}

.page-header h1 {
  margin-bottom: var(--space-sm);
}

.page-header p {
  font-size: 1rem;
  max-width: 600px;
  margin: 0 auto;
}

.about-story {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-3xl);
  align-items: center;
}

.about-story-image {
  background: var(--color-primary-light);
  border-radius: var(--radius-xl);
  aspect-ratio: 4 / 3;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 4rem;
  color: var(--color-primary);
  opacity: .6;
}

.about-story-text h2 {
  margin-bottom: var(--space-lg);
}

.about-story-text p {
  margin-bottom: var(--space-md);
  line-height: 1.8;
}

.opensource-badge {
  display: inline-flex;
  align-items: center;
  gap: var(--space-sm);
  padding: var(--space-sm) var(--space-lg);
  background: var(--color-success-light);
  color: var(--color-success);
  border-radius: var(--radius-full);
  font-weight: 600;
  font-size: .9rem;
  margin-top: var(--space-md);
}

.cta-banner {
  background: linear-gradient(135deg, var(--color-primary-dark), var(--color-primary));
  border-radius: var(--radius-xl);
  padding: var(--space-2xl) var(--space-xl);
  text-align: center;
  color: #fff;
  position: relative;
  overflow: hidden;
}

.cta-banner::before {
  content: '';
  position: absolute;
  top: -50%;
  right: -20%;
  width: 60%;
  height: 200%;
  background: radial-gradient(circle, rgba(255,255,255,.1) 0%, transparent 60%);
}

.cta-banner h2 {
  color: #fff;
  margin-bottom: var(--space-sm);
  position: relative;
}

.cta-banner p {
  color: rgba(255,255,255,.85);
  font-size: 1rem;
  max-width: 500px;
  margin: 0 auto var(--space-lg);
  position: relative;
}

.cta-banner .btn {
  background: #fff;
  color: var(--color-primary-dark);
  box-shadow: 0 4px 16px rgba(0,0,0,.2);
}

.cta-banner .btn:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 24px rgba(0,0,0,.25);
}

.comparison-table {
  width: 100%;
  border-collapse: collapse;
  margin-top: var(--space-2xl);
  background: var(--color-surface);
  border-radius: var(--radius-lg);
  overflow: hidden;
  border: 1px solid var(--color-border-light);
}

.comparison-table th,
.comparison-table td {
  padding: var(--space-md) var(--space-lg);
  text-align: left;
  border-bottom: 1px solid var(--color-border-light);
}

.comparison-table th {
  background: var(--color-bg-alt);
  font-weight: 600;
  font-size: .9rem;
  color: var(--color-text);
}

.comparison-table th:first-child {
  width: 30%;
}

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

.comparison-table .check {
  color: var(--color-success);
  font-weight: 700;
}

.comparison-table .cross {
  color: var(--color-text-muted);
}

.steps {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: var(--space-xl);
  margin-top: var(--space-2xl);
}

.step-card {
  text-align: center;
  position: relative;
}

.step-number {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 48px;
  height: 48px;
  border-radius: 50%;
  background: var(--color-primary);
  color: #fff;
  font-size: 1.2rem;
  font-weight: 700;
  margin-bottom: var(--space-md);
}

.step-card h4 {
  margin-bottom: var(--space-sm);
}

.step-card p {
  font-size: .9rem;
  margin: 0 auto;
}

.animate-on-scroll {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity .6s var(--ease-out), transform .6s var(--ease-out);
}

.animate-on-scroll.visible {
  opacity: 1;
  transform: translateY(0);
}

.animate-on-scroll.delay-1 { transition-delay: .1s; }
.animate-on-scroll.delay-2 { transition-delay: .2s; }
.animate-on-scroll.delay-3 { transition-delay: .3s; }
.animate-on-scroll.delay-4 { transition-delay: .4s; }

.back-to-top {
  position: fixed;
  bottom: var(--space-xl);
  right: var(--space-xl);
  width: 44px;
  height: 44px;
  border-radius: 50%;
  background: var(--color-primary);
  color: #fff;
  border: none;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: var(--shadow-md);
  opacity: 0;
  visibility: hidden;
  transform: translateY(10px);
  transition: all var(--duration-normal) var(--ease-out);
  z-index: 999;
}

.back-to-top.visible {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

.back-to-top:hover {
  background: var(--color-primary-dark);
  transform: translateY(-2px);
}

@media (max-width: 1024px) {
  .hero-content {
    grid-template-columns: 1fr;
    text-align: center;
  }

  .hero-desc {
    margin: 0 auto;
  }

  .hero-actions {
    justify-content: center;
  }

  .hero-stats {
    justify-content: center;
  }

  .hero-visual {
    order: -1;
  }

  .phone-frame {
    display: none;
  }

  .hero-floating-card {
    display: none;
  }

  .about-story {
    grid-template-columns: 1fr;
  }

  .tutorial-content {
    grid-template-columns: 1fr;
  }

  .tutorial-sidebar {
    display: none;
  }

  .stats-row {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 768px) {
  :root {
    --space-3xl: 2rem;
  }

  .header {
    backdrop-filter: none;
    -webkit-backdrop-filter: none;
  }

  .nav {
    position: fixed;
    top: var(--header-height);
    left: 0;
    right: 0;
    bottom: 0;
    background: #ffffff;
    flex-direction: column;
    padding: var(--space-xl);
    gap: var(--space-sm);
    transform: translateX(100%);
    transition: transform var(--duration-normal) var(--ease-out);
    z-index: 9999;
    box-shadow: -4px 0 20px rgba(0,0,0,.08);
  }

  .nav.open {
    transform: translateX(0);
  }

  .nav-link {
    width: 100%;
    padding: var(--space-md);
    font-size: 1rem;
    justify-content: center;
  }

  .nav-cta {
    width: 100%;
    text-align: center;
    margin-left: 0;
    margin-top: var(--space-md);
    justify-content: center;
  }

  .mobile-menu-btn {
    display: block;
  }

  .features-grid {
    grid-template-columns: 1fr;
  }

  .comparison-table {
    display: block;
    overflow-x: auto;
  }
}

@media (max-width: 480px) {
  .container {
    padding: 0 var(--space-md);
  }

  .hero-stats {
    flex-direction: column;
    align-items: center;
    gap: var(--space-lg);
  }

  .stats-row {
    grid-template-columns: 1fr;
  }

  .steps {
    grid-template-columns: 1fr;
  }
}