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

:root {
  --accent: #e05a8a;
  --accent-2: #5a9de0;
  --text: #1a1a1a;
  --subtext: #555;
  --border: #e5e5e5;
  --radius: 14px;
  --max-w: 900px;
}

html { scroll-behavior: smooth; }

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  background: #fff;
  color: var(--text);
  line-height: 1.7;
  font-size: 16px;
}

/* Layout */
.container {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 24px;
}

/* Header / Hero */
.hero {
  padding: 34px 0 8px;
  text-align: center;
}

.hero h1 {
  font-size: clamp(1.6rem, 4vw, 2.4rem);
  font-weight: 700;
  margin-bottom: 12px;
}

.hero .tagline {
  font-size: clamp(0.95rem, 2.5vw, 1.15rem);
  color: var(--subtext);
  max-width: 600px;
  margin: 0 auto;
}

/* Section title */
.section {
  padding: 56px 0;
}

.section + .section {
  border-top: 1px solid var(--border);
}

.section-label {
  font-size: 0.78rem;
  font-weight: 600;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 8px;
}

.section h2 {
  font-size: clamp(1.3rem, 3vw, 1.8rem);
  font-weight: 700;
  margin-bottom: 10px;
}

.section .desc {
  color: var(--subtext);
  font-size: 0.97rem;
  max-width: 680px;
  margin-bottom: 32px;
}

/* Feature grid */
.features {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
  gap: 16px;
  margin-bottom: 36px;
}

.feature-card {
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px;
}

.feature-card .icon {
  font-size: 1.5rem;
  margin-bottom: 10px;
}

.feature-card h3 {
  font-size: 0.97rem;
  font-weight: 600;
  margin-bottom: 4px;
}

.feature-card p {
  font-size: 0.88rem;
  color: var(--subtext);
}

/* Screenshot */
.screenshot-wrap {
  border-radius: var(--radius);
  overflow: hidden;
  border: 1px solid var(--border);
  margin-bottom: 36px;
  box-shadow: 0 4px 24px rgba(0,0,0,0.08);
}

.screenshot-wrap img {
  width: 100%;
  display: block;
}

/* Extension block */
.ext-block {
  display: flex;
  align-items: flex-start;
  gap: 24px;
  margin-bottom: 36px;
}

.ext-block img.ext-icon {
  width: 72px;
  height: 72px;
  border-radius: 16px;
  flex-shrink: 0;
  border: 1px solid var(--border);
}

.ext-block .ext-content h3 {
  font-size: 1.1rem;
  font-weight: 600;
  margin-bottom: 6px;
}

.ext-block .ext-content p {
  font-size: 0.92rem;
  color: var(--subtext);
}

/* Download button */
.btn {
  display: inline-block;
  padding: 12px 28px;
  border-radius: 50px;
  font-size: 0.95rem;
  font-weight: 600;
  text-decoration: none;
  cursor: pointer;
  transition: opacity 0.2s;
  border: none;
}

.btn:hover { opacity: 0.82; }

.btn-primary {
  background: var(--text);
  color: #fff;
}

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

.btn-group {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  align-items: center;
}

.btn-note {
  font-size: 0.8rem;
  color: var(--subtext);
}

/* Footer */
footer {
  border-top: 1px solid var(--border);
  padding: 32px 0;
  text-align: center;
  font-size: 0.85rem;
  color: var(--subtext);
}

footer a {
  color: var(--subtext);
  text-decoration: underline;
  text-underline-offset: 3px;
}

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

/* Bilingual */
.zh { display: block; }
.en { display: block; color: var(--subtext); font-size: 0.9em; }

h2 .en, h1 .en {
  font-weight: 400;
  color: var(--subtext);
}

/* Tab switcher */
.tabs {
  display: inline-flex;
  background: #f2f2f2;
  border-radius: 50px;
  padding: 4px;
  margin: 28px auto 0;
  gap: 4px;
}

.tab {
  background: transparent;
  border: none;
  border-radius: 50px;
  padding: 9px 24px;
  font-size: 0.92rem;
  font-weight: 500;
  cursor: pointer;
  color: var(--subtext);
  transition: background 0.18s, color 0.18s;
  white-space: nowrap;
}

.tab.active {
  background: #fff;
  color: var(--text);
  box-shadow: 0 1px 6px rgba(0,0,0,0.10);
  font-weight: 600;
}

.tab:hover:not(.active) {
  color: var(--text);
}

/* Hero CTA (download button area in hero) */
.hero-cta {
  margin-top: 24px;
}

.btn-group--center {
  justify-content: center;
}

/* Hidden utility */
.hidden {
  display: none !important;
}

/* Tab panel: remove top padding so it flows tightly */
.tab-panel > .section {
  padding-top: 40px;
}

/* Responsive */
@media (max-width: 600px) {
  .tabs {
    width: 100%;
    justify-content: center;
  }
  .tab {
    flex: 1;
    text-align: center;
    padding: 9px 12px;
    font-size: 0.85rem;
  }
  .ext-block {
    flex-direction: column;
    align-items: center;
    text-align: center;
  }
  .btn-group {
    justify-content: center;
  }
}