:root {
  --bg: #ffffff;
  --bg-subtle: #f7f8fa;
  --text: #1a1d21;
  --text-muted: #5c6370;
  --border: #e8eaef;
  --accent: #2563eb;
  --accent-soft: rgba(37, 99, 235, 0.08);
  --shadow: 0 1px 2px rgba(15, 23, 42, 0.06);
  --shadow-lg: 0 12px 40px rgba(15, 23, 42, 0.08);
  --radius: 12px;
  --font-sans: "DM Sans", "Noto Sans SC", system-ui, -apple-system, sans-serif;
  --font-brand: "Fredoka", "Noto Sans SC", system-ui, sans-serif;
}

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

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: var(--font-sans);
  font-size: 1rem;
  line-height: 1.65;
  color: var(--text);
  background: var(--bg);
  -webkit-font-smoothing: antialiased;
}

.container {
  width: min(1120px, 100% - 2.5rem);
  margin-inline: auto;
}

/* Header */
.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  background: rgba(255, 255, 255, 0.85);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  min-height: 64px;
}

.logo {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 1.25rem;
  letter-spacing: -0.02em;
  color: var(--text);
  text-decoration: none;
}

.logo span {
  font-family: var(--font-brand);
  font-weight: 600;
}

.app-icon {
  display: block;
  object-fit: contain;
}

.app-icon--header {
  width: 32px;
  height: 32px;
  border-radius: 8px;
  flex-shrink: 0;
}

.app-icon--hero {
  width: clamp(72px, 18vw, 96px);
  height: auto;
  aspect-ratio: 1;
  border-radius: 22px;
  box-shadow: var(--shadow-lg);
  margin-bottom: 0.75rem;
}

.app-icon--footer {
  width: 28px;
  height: 28px;
  border-radius: 7px;
  flex-shrink: 0;
}

.nav {
  display: flex;
  gap: 1.5rem;
  margin-left: auto;
  margin-right: 1rem;
}

.nav a {
  color: var(--text-muted);
  text-decoration: none;
  font-size: 0.9375rem;
  font-weight: 500;
  transition: color 0.15s ease;
}

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

.lang-switch {
  display: inline-flex;
  padding: 3px;
  background: var(--bg-subtle);
  border: 1px solid var(--border);
  border-radius: 999px;
}

.lang-btn {
  border: none;
  background: transparent;
  font: inherit;
  font-size: 0.8125rem;
  font-weight: 600;
  padding: 0.35rem 0.85rem;
  border-radius: 999px;
  cursor: pointer;
  color: var(--text-muted);
  transition: background 0.15s ease, color 0.15s ease;
}

.lang-btn[aria-pressed="true"] {
  background: var(--bg);
  color: var(--text);
  box-shadow: var(--shadow);
}

.lang-btn:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

/* Hero — 左右分栏：文案 + 截图轮播 */
.hero {
  padding: clamp(2.5rem, 6vw, 4.5rem) 0 clamp(2.5rem, 5vw, 3.5rem);
  background: linear-gradient(180deg, var(--bg-subtle) 0%, var(--bg) 55%);
  border-bottom: 1px solid var(--border);
}

.hero-split {
  display: grid;
  grid-template-columns: minmax(0, 1.08fr) minmax(280px, 0.92fr);
  gap: clamp(1.75rem, 4vw, 3rem);
  align-items: start;
}

.hero-copy {
  min-width: 0;
}

.hero-features {
  margin-top: 2rem;
  padding-top: 1.75rem;
  border-top: 1px solid var(--border);
}

.hero-features .section-title {
  margin-bottom: 1rem;
  scroll-margin-top: 5rem;
}

.hero-copy .feature-card {
  padding: 1.15rem 1rem;
}

.hero-shots {
  min-width: 0;
  scroll-margin-top: 5rem;
  position: sticky;
  top: 5rem;
}

.shots-heading {
  margin: 0 0 0.35rem;
  font-size: clamp(1.125rem, 2vw, 1.35rem);
  font-weight: 700;
  letter-spacing: -0.02em;
}

.shots-sub {
  margin: 0 0 1rem;
  font-size: 0.9375rem;
  color: var(--text-muted);
  line-height: 1.55;
}

.hero-title {
  margin: 0 0 1rem;
  font-family: var(--font-brand);
  font-size: clamp(2.5rem, 6vw, 3.5rem);
  font-weight: 600;
  letter-spacing: -0.03em;
  line-height: 1.1;
}

.hero-lead {
  margin: 0 0 1.25rem;
  font-size: 1.0625rem;
  color: var(--text-muted);
  line-height: 1.75;
}

.section-title {
  margin: 0 0 0.5rem;
  font-size: clamp(1.5rem, 3vw, 1.75rem);
  font-weight: 700;
  letter-spacing: -0.02em;
}

/* Features */
.feature-grid {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 1.25rem;
}

/* 必须写在 .feature-grid 之后，且双类选择器覆盖 auto-fill + min 280px，否则窄左栏会只能排一列 */
.feature-grid.feature-grid--hero {
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 0.75rem;
}

.feature-card {
  padding: 1.5rem 1.35rem;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  transition: border-color 0.2s ease, box-shadow 0.2s ease;
}

.feature-card:hover {
  border-color: #d5dae3;
  box-shadow: var(--shadow-lg);
}

.feature-icon {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 2.25rem;
  height: 2.25rem;
  margin-bottom: 0.75rem;
  font-size: 1.1rem;
  background: var(--accent-soft);
  border-radius: 8px;
}

.feature-card h3 {
  margin: 0 0 0.5rem;
  font-size: 1.0625rem;
  font-weight: 600;
}

.feature-card p {
  margin: 0;
  font-size: 0.9375rem;
  color: var(--text-muted);
  line-height: 1.65;
}

/* Screenshots carousel（首屏右侧） */
.carousel {
  margin-top: 0;
}

.carousel-viewport {
  overflow: hidden;
  width: 100%;
  border-radius: calc(var(--radius) + 4px);
  border: 1px solid var(--border);
  background: var(--bg);
  box-shadow: var(--shadow-lg);
}

.carousel-track {
  display: flex;
  transition: transform 0.45s cubic-bezier(0.25, 0.8, 0.25, 1);
}

.carousel-slide {
  flex: 0 0 100%;
  min-width: 100%;
  box-sizing: border-box;
  padding: clamp(0.65rem, 2vw, 1.25rem);
  display: flex;
  justify-content: center;
  align-items: center;
}

.carousel-slide img {
  display: block;
  width: min(380px, 100%);
  height: auto;
  border-radius: 10px;
  box-shadow: 0 4px 24px rgba(15, 23, 42, 0.1);
}

.carousel-controls {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 1rem;
  margin-top: 1.25rem;
}

.carousel-btn {
  width: 44px;
  height: 44px;
  border-radius: 999px;
  border: 1px solid var(--border);
  background: var(--bg);
  font-size: 1.5rem;
  line-height: 1;
  cursor: pointer;
  color: var(--text);
  transition: background 0.15s ease, border-color 0.15s ease;
}

.carousel-btn:hover {
  background: var(--bg-subtle);
  border-color: #d5dae3;
}

.carousel-btn:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

.carousel-dots {
  display: flex;
  gap: 0.5rem;
  flex-wrap: wrap;
  justify-content: center;
}

.carousel-dot {
  width: 8px;
  height: 8px;
  border-radius: 999px;
  border: none;
  padding: 0;
  background: #c9ced8;
  cursor: pointer;
  transition: background 0.15s ease, transform 0.15s ease;
}

.carousel-dot[aria-selected="true"] {
  background: var(--accent);
  transform: scale(1.15);
}

.carousel-dot:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

/* FAQ & Contact */
.faq-section {
  padding: clamp(3rem, 7vw, 5rem) 0;
  background: var(--bg-subtle);
  border-top: 1px solid var(--border);
  scroll-margin-top: 5rem;
}

.faq-section .section-title {
  margin-bottom: 1.5rem;
}

.faq-list {
  display: flex;
  flex-direction: column;
  gap: 0.65rem;
  margin-bottom: 2.5rem;
}

.faq-item {
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--bg);
  box-shadow: var(--shadow);
}

.faq-item summary {
  cursor: pointer;
  padding: 1rem 1.15rem;
  font-weight: 600;
  font-size: 0.98rem;
  list-style: none;
}

.faq-item summary::-webkit-details-marker {
  display: none;
}

.faq-item p {
  margin: 0;
  padding: 1rem 1.15rem 1.15rem;
  color: var(--text-muted);
  font-size: 0.9375rem;
  line-height: 1.65;
}

.faq-item[open] summary {
  border-bottom: 1px solid var(--border);
  padding-bottom: 1rem;
}

.contact-block {
  padding: 1.5rem 1.35rem;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--bg);
  text-align: center;
  box-shadow: var(--shadow);
  scroll-margin-top: 5rem;
}

.contact-title {
  margin: 0 0 0.65rem;
  font-size: 1.0625rem;
  font-weight: 600;
}

.contact-email {
  font-size: 1.05rem;
  font-weight: 500;
  color: var(--accent);
  text-decoration: none;
  word-break: break-all;
}

.contact-email:hover {
  text-decoration: underline;
}

/* Footer */
.site-footer {
  padding: 2rem 0;
  border-top: 1px solid var(--border);
  background: var(--bg);
}

.footer-inner {
  text-align: center;
}

.footer-brand {
  margin: 0 0 0.35rem;
  font-size: 1rem;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.45rem;
}

.footer-brand span {
  font-family: var(--font-brand);
  font-weight: 600;
}

.footer-copy {
  margin: 0;
  font-size: 0.875rem;
  color: var(--text-muted);
}

@media (max-width: 960px) {
  .hero-split {
    grid-template-columns: 1fr;
  }

  .hero-shots {
    position: static;
    scroll-margin-top: 4.5rem;
    margin-top: 0.25rem;
    padding-top: 1.75rem;
    border-top: 1px solid var(--border);
  }
}

@media (max-width: 640px) {
  .nav {
    display: none;
  }

  .header-inner {
    min-height: 56px;
  }
}

body.lang-en {
  font-family: "DM Sans", system-ui, -apple-system, sans-serif;
}