/* ============================================================
   날씨콕 (Weather-Kok) Landing Page Styles
   Brand: #2196F3 Sky Blue — weather-flutter 앱 테마와 정합
   - Light: light_theme.dart  (primary #2196F3, surface #FFF, bg #E3F2FD 계열)
   - Dark : dark_theme.dart   (primary #64B5F6, surface #1E293B, bg #0D1117)
   - Gradients: splash_screen.dart _lightGradient / _darkGradient
   테마: CSS 변수 + prefers-color-scheme 기본값 + [data-theme] 수동 오버라이드
   ============================================================ */

@import url('https://fonts.googleapis.com/css2?family=Noto+Sans+KR:wght@300;400;500;700;900&display=swap');

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

/* ─── Theme Variables: Light (default, = app light_theme) ─── */
:root {
  color-scheme: light;

  --primary: #2196f3;          /* colorScheme.primary */
  --primary-strong: #1565c0;   /* hover / 짙은 파랑 (splash 3rd stop) */
  --primary-soft: #64b5f6;     /* primary-light */
  --on-primary: #ffffff;       /* colorScheme.onPrimary */
  --primary-bg: #e3f2fd;       /* surfaceContainerHighest */

  --bg: #ffffff;
  --bg-alt: #f4f8ff;
  --bg-section: #f0f6ff;
  --surface: #ffffff;          /* cardTheme.color */
  --nav-bg: rgba(255, 255, 255, 0.92);

  --text-main: #1f2937;        /* onSurface */
  --text-sub: #4b5563;         /* bodyLarge */
  --text-muted: #6b7280;       /* bodyMedium */
  --border: #d0e4f7;

  --badge-bg: rgba(33, 150, 243, 0.15);
  --badge-fg: #1565c0;
  --badge-border: #64b5f6;
  --faq-open-bg: #e3f2fd;
  --divider-accent: #e3f2fd;

  --hero-grad: linear-gradient(135deg, #e3f2fd 0%, #bbdefb 40%, #90caf9 100%);
  --hero-glow: rgba(33, 150, 243, 0.18);
  --mockup-grad: linear-gradient(160deg, #1565c0 0%, #2196f3 50%, #42a5f5 100%); /* splash light */
  --band-grad: linear-gradient(135deg, #2196f3 0%, #1565c0 100%);
  --inner-hero-grad: linear-gradient(135deg, #e3f2fd 0%, #daeeff 100%);

  --store-btn-bg: #111111;
  --store-btn-fg: #ffffff;
  --store-btn-border: transparent;
  --footer-bg: #0d1b2a;
  --img-ring: transparent;

  --shadow-sm: 0 2px 8px rgba(33, 150, 243, 0.10);
  --shadow-md: 0 6px 24px rgba(33, 150, 243, 0.15);
  --shadow-lg: 0 16px 48px rgba(33, 150, 243, 0.20);
  --btn-shadow: 0 4px 16px rgba(33, 150, 243, 0.35);
  --btn-shadow-hover: 0 8px 24px rgba(33, 150, 243, 0.45);
  --mockup-shadow: 0 24px 64px rgba(33, 150, 243, 0.4), 0 4px 12px rgba(0, 0, 0, 0.15);

  --radius: 16px;              /* cardTheme radius */
  --radius-sm: 8px;
  --radius-btn: 12px;          /* button radius (앱 버튼과 동일) */
  --radius-lg: 24px;
  --transition: 0.25s ease;
  --max-width: 1100px;
}

/* ─── Theme Variables: Dark (= app dark_theme) ─── */
/* 1) 시스템 다크 (수동 라이트 지정이 없을 때) */
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    color-scheme: dark;

    --primary: #64b5f6;          /* colorScheme.primary (dark) */
    --primary-strong: #90caf9;
    --primary-soft: #4fc3f7;     /* secondary (dark) */
    --on-primary: #0d1117;       /* onPrimary (dark) */
    --primary-bg: rgba(100, 181, 246, 0.14);

    --bg: #0d1117;               /* scaffoldBackgroundColor */
    --bg-alt: #111927;
    --bg-section: #111927;
    --surface: #1e293b;          /* cardTheme.color */
    --nav-bg: rgba(13, 17, 23, 0.88);

    --text-main: #f1f5f9;        /* onSurface */
    --text-sub: #94a3b8;         /* bodyLarge */
    --text-muted: #8091a5;
    --border: #334155;           /* dividerTheme */

    --badge-bg: rgba(100, 181, 246, 0.16);
    --badge-fg: #90caf9;
    --badge-border: rgba(100, 181, 246, 0.45);
    --faq-open-bg: rgba(100, 181, 246, 0.12);
    --divider-accent: rgba(100, 181, 246, 0.25);

    --hero-grad: linear-gradient(135deg, #0d1117 0%, #0a2e63 55%, #0d47a1 100%); /* splash dark tones */
    --hero-glow: rgba(100, 181, 246, 0.10);
    --mockup-grad: linear-gradient(160deg, #1565c0 0%, #0d47a1 55%, #0a2e63 100%); /* splash dark */
    --band-grad: linear-gradient(135deg, #1565c0 0%, #0d47a1 100%);
    --inner-hero-grad: linear-gradient(135deg, #111927 0%, #0f2440 100%);

    --store-btn-bg: #1e293b;
    --store-btn-fg: #f1f5f9;
    --store-btn-border: #334155;
    --footer-bg: #0a0f17;
    --img-ring: rgba(255, 255, 255, 0.16);

    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.35);
    --shadow-md: 0 6px 24px rgba(0, 0, 0, 0.45);
    --shadow-lg: 0 16px 48px rgba(0, 0, 0, 0.55);
    --btn-shadow: 0 4px 16px rgba(13, 71, 161, 0.45);
    --btn-shadow-hover: 0 8px 24px rgba(13, 71, 161, 0.6);
    --mockup-shadow: 0 24px 64px rgba(0, 0, 0, 0.55), 0 4px 12px rgba(0, 0, 0, 0.35);
  }
}

/* 2) 수동 다크 (토글 → localStorage → data-theme) — 시스템 설정보다 우선 */
:root[data-theme="dark"] {
  color-scheme: dark;

  --primary: #64b5f6;
  --primary-strong: #90caf9;
  --primary-soft: #4fc3f7;
  --on-primary: #0d1117;
  --primary-bg: rgba(100, 181, 246, 0.14);

  --bg: #0d1117;
  --bg-alt: #111927;
  --bg-section: #111927;
  --surface: #1e293b;
  --nav-bg: rgba(13, 17, 23, 0.88);

  --text-main: #f1f5f9;
  --text-sub: #94a3b8;
  --text-muted: #8091a5;
  --border: #334155;

  --badge-bg: rgba(100, 181, 246, 0.16);
  --badge-fg: #90caf9;
  --badge-border: rgba(100, 181, 246, 0.45);
  --faq-open-bg: rgba(100, 181, 246, 0.12);
  --divider-accent: rgba(100, 181, 246, 0.25);

  --hero-grad: linear-gradient(135deg, #0d1117 0%, #0a2e63 55%, #0d47a1 100%);
  --hero-glow: rgba(100, 181, 246, 0.10);
  --mockup-grad: linear-gradient(160deg, #1565c0 0%, #0d47a1 55%, #0a2e63 100%);
  --band-grad: linear-gradient(135deg, #1565c0 0%, #0d47a1 100%);
  --inner-hero-grad: linear-gradient(135deg, #111927 0%, #0f2440 100%);

  --store-btn-bg: #1e293b;
  --store-btn-fg: #f1f5f9;
  --store-btn-border: #334155;
  --footer-bg: #0a0f17;
  --img-ring: rgba(255, 255, 255, 0.16);

  --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.35);
  --shadow-md: 0 6px 24px rgba(0, 0, 0, 0.45);
  --shadow-lg: 0 16px 48px rgba(0, 0, 0, 0.55);
  --btn-shadow: 0 4px 16px rgba(13, 71, 161, 0.45);
  --btn-shadow-hover: 0 8px 24px rgba(13, 71, 161, 0.6);
  --mockup-shadow: 0 24px 64px rgba(0, 0, 0, 0.55), 0 4px 12px rgba(0, 0, 0, 0.35);
}

html {
  scroll-behavior: smooth;
  font-size: 16px;
}

body {
  font-family: 'Noto Sans KR', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  color: var(--text-main);
  background: var(--bg);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  transition: background-color var(--transition), color var(--transition);
}

a {
  color: var(--primary);
  text-decoration: none;
  transition: color var(--transition);
}

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

img {
  max-width: 100%;
  display: block;
}

ul { list-style: none; }

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

:focus-visible {
  outline: 2px solid var(--primary);
  outline-offset: 2px;
}

/* 다크 모드에서 앱 아이콘/로고 이미지에 은은한 테두리 */
img.logo-icon,
img.download-app-icon {
  box-shadow: 0 0 0 1px var(--img-ring);
}

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

.section {
  padding: 80px 0;
}

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

.section-title {
  font-size: 2rem;
  font-weight: 700;
  color: var(--text-main);
  margin-bottom: 12px;
  letter-spacing: -0.01em;
}

.section-sub {
  font-size: 1.05rem;
  color: var(--text-sub);
  margin-bottom: 48px;
}

/* ─── Navigation ─── */
nav {
  position: sticky;
  top: 0;
  z-index: 1000;
  background: var(--nav-bg);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
  box-shadow: var(--shadow-sm);
  transition: background-color var(--transition), border-color var(--transition);
}

.nav-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 16px 24px;
  max-width: var(--max-width);
  margin: 0 auto;
}

.nav-logo {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 700;
  font-size: 1.25rem;
  color: var(--text-main);
  text-decoration: none;
}

.nav-logo .logo-icon {
  font-size: 1.6rem;
}

.nav-logo .logo-text {
  color: var(--primary);
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 8px;
}

.nav-links a {
  padding: 6px 14px;
  border-radius: var(--radius-sm);
  color: var(--text-sub);
  font-size: 0.92rem;
  font-weight: 500;
  transition: all var(--transition);
}

.nav-links a:hover {
  color: var(--primary);
  background: var(--primary-bg);
}

.nav-right {
  display: flex;
  align-items: center;
  gap: 12px;
}

/* Theme Toggle */
.theme-toggle {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 38px;
  height: 38px;
  padding: 0;
  border: 1.5px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--surface);
  color: var(--text-sub);
  font-size: 1.05rem;
  line-height: 1;
  cursor: pointer;
  transition: all var(--transition);
}

.theme-toggle:hover {
  border-color: var(--primary);
  color: var(--primary);
}

/* Language Dropdown */
.lang-dropdown {
  position: relative;
}

.lang-btn {
  display: flex;
  align-items: center;
  gap: 6px;
  padding: 7px 14px;
  border: 1.5px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--surface);
  color: var(--text-sub);
  font-size: 0.9rem;
  font-family: inherit;
  font-weight: 500;
  cursor: pointer;
  transition: all var(--transition);
}

.lang-btn:hover {
  border-color: var(--primary);
  color: var(--primary);
}

.lang-btn .arrow {
  font-size: 0.7rem;
  transition: transform var(--transition);
}

.lang-dropdown.open .lang-btn .arrow {
  transform: rotate(180deg);
}

.lang-menu {
  display: none;
  position: absolute;
  top: calc(100% + 8px);
  right: 0;
  min-width: 140px;
  background: var(--surface);
  border: 1.5px solid var(--border);
  border-radius: var(--radius-sm);
  box-shadow: var(--shadow-md);
  overflow: hidden;
  z-index: 100;
}

.lang-dropdown.open .lang-menu {
  display: block;
}

.lang-menu a {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 10px 16px;
  color: var(--text-sub);
  font-size: 0.9rem;
  font-weight: 500;
  transition: all var(--transition);
}

.lang-menu a:hover,
.lang-menu a.active {
  background: var(--primary-bg);
  color: var(--primary);
}

/* Hamburger (mobile) */
.hamburger {
  display: none;
  flex-direction: column;
  gap: 5px;
  cursor: pointer;
  padding: 4px;
  background: none;
  border: none;
}

.hamburger span {
  display: block;
  width: 22px;
  height: 2px;
  background: var(--text-main);
  border-radius: 2px;
  transition: all var(--transition);
}

/* ─── Hero ─── */
.hero {
  background: var(--hero-grad);
  padding: 100px 0 80px;
  overflow: hidden;
  position: relative;
  transition: background var(--transition);
}

.hero::before {
  content: '';
  position: absolute;
  top: -80px;
  right: -80px;
  width: 480px;
  height: 480px;
  background: radial-gradient(circle, var(--hero-glow) 0%, transparent 70%);
  border-radius: 50%;
  pointer-events: none;
}

.hero-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 48px;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 24px;
  position: relative;
}

.hero-content {
  flex: 1;
  max-width: 560px;
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  background: var(--badge-bg);
  color: var(--badge-fg);
  font-size: 0.82rem;
  font-weight: 600;
  padding: 5px 14px;
  border-radius: 100px;
  margin-bottom: 20px;
  letter-spacing: 0.03em;
}

.hero-title {
  font-size: 3.2rem;
  font-weight: 900;
  line-height: 1.2;
  color: var(--text-main);
  margin-bottom: 20px;
  letter-spacing: -0.02em;
}

.hero-title .highlight {
  color: var(--primary);
}

.hero-slogan {
  font-size: 1.15rem;
  color: var(--text-sub);
  margin-bottom: 36px;
  line-height: 1.7;
  font-weight: 400;
}

.hero-actions {
  display: flex;
  align-items: center;
  gap: 16px;
  flex-wrap: wrap;
}

.btn-primary {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  background: var(--primary);
  color: var(--on-primary);
  font-size: 1rem;
  font-weight: 600;
  padding: 14px 28px;
  border-radius: var(--radius-btn);
  border: none;
  cursor: pointer;
  transition: all var(--transition);
  box-shadow: var(--btn-shadow);
  text-decoration: none;
  font-family: inherit;
}

.btn-primary:hover {
  background: var(--primary-strong);
  color: var(--on-primary);
  transform: translateY(-2px);
  box-shadow: var(--btn-shadow-hover);
}

.btn-secondary {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  background: transparent;
  color: var(--primary);
  font-size: 0.95rem;
  font-weight: 600;
  padding: 13px 24px;
  border-radius: var(--radius-btn);
  border: 2px solid var(--primary);
  cursor: pointer;
  transition: all var(--transition);
  text-decoration: none;
  font-family: inherit;
}

.btn-secondary:hover {
  background: var(--primary-bg);
  color: var(--primary);
}


.hero-visual {
  flex: 0 0 auto;
  display: flex;
  align-items: center;
  justify-content: center;
}

.hero-mockup {
  width: 260px;
  height: 420px;
  background: var(--mockup-grad);
  border-radius: 36px;
  box-shadow: var(--mockup-shadow);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 32px 20px;
  position: relative;
  overflow: hidden;
}

.hero-mockup::before {
  content: '';
  position: absolute;
  top: -40px;
  right: -40px;
  width: 180px;
  height: 180px;
  background: rgba(255,255,255,0.08);
  border-radius: 50%;
}

.mockup-weather-icon {
  font-size: 5rem;
  margin-bottom: 12px;
  filter: drop-shadow(0 4px 12px rgba(0,0,0,0.2));
}

.mockup-temp {
  font-size: 3.5rem;
  font-weight: 900;
  color: #fff;
  letter-spacing: -0.02em;
  line-height: 1;
}

.mockup-city {
  font-size: 1rem;
  color: rgba(255,255,255,0.85);
  margin-top: 8px;
  font-weight: 500;
}

.mockup-details {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 10px;
  margin-top: 24px;
  width: 100%;
}

.mockup-detail-item {
  background: rgba(255,255,255,0.15);
  border-radius: 12px;
  padding: 10px 12px;
  text-align: center;
}

.mockup-detail-label {
  font-size: 0.68rem;
  color: rgba(255,255,255,0.75);
  display: block;
  margin-bottom: 2px;
}

.mockup-detail-value {
  font-size: 0.95rem;
  font-weight: 700;
  color: #fff;
}

.mockup-aqi {
  margin-top: 12px;
  background: rgba(255,255,255,0.15);
  border-radius: 12px;
  padding: 10px 16px;
  width: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.mockup-aqi-label {
  font-size: 0.75rem;
  color: rgba(255,255,255,0.8);
  font-weight: 500;
}

.mockup-aqi-badge {
  background: #4caf50; /* tertiary (공기질 좋음) */
  color: #fff;
  font-size: 0.72rem;
  font-weight: 700;
  padding: 3px 10px;
  border-radius: 100px;
}

/* ─── Features ─── */
.features-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.feature-card {
  background: var(--surface);
  border: 1.5px solid var(--border);
  border-radius: var(--radius);
  padding: 32px 28px;
  transition: all var(--transition);
  position: relative;
  overflow: hidden;
}

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

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

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

.feature-icon {
  font-size: 2.6rem;
  margin-bottom: 16px;
  display: block;
  line-height: 1;
}

.feature-title {
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--text-main);
  margin-bottom: 8px;
}

.feature-desc {
  font-size: 0.92rem;
  color: var(--text-sub);
  line-height: 1.65;
}

/* ─── Data Source Banner ─── */
.data-source {
  background: var(--band-grad);
  padding: 60px 0;
  text-align: center;
  color: #fff;
}

.data-source-title {
  font-size: 1.6rem;
  font-weight: 700;
  margin-bottom: 12px;
}

.data-source-desc {
  font-size: 1rem;
  opacity: 0.88;
  max-width: 560px;
  margin: 0 auto 32px;
  line-height: 1.7;
}

.data-badges {
  display: flex;
  justify-content: center;
  gap: 16px;
  flex-wrap: wrap;
}

.data-badge {
  background: rgba(255,255,255,0.15);
  border: 1.5px solid rgba(255,255,255,0.3);
  border-radius: 100px;
  padding: 8px 20px;
  font-size: 0.9rem;
  font-weight: 600;
  color: #fff;
  display: flex;
  align-items: center;
  gap: 8px;
}

/* ─── AQI Info Section ─── */
.aqi-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 16px;
  margin-top: 40px;
}

.aqi-card {
  border-radius: var(--radius);
  padding: 24px 20px;
  text-align: center;
  color: #fff;
}

/* 등급 색상은 대기질 시맨틱 컬러 (앱 등급 배지와 동일 계열) — 테마 불변 */
.aqi-card.good     { background: linear-gradient(135deg, #4caf50, #66bb6a); }
.aqi-card.moderate { background: linear-gradient(135deg, #ff9800, #ffa726); }
.aqi-card.bad      { background: linear-gradient(135deg, #f44336, #ef5350); }
.aqi-card.very-bad { background: linear-gradient(135deg, #9c27b0, #ab47bc); }

.aqi-emoji {
  font-size: 2.2rem;
  margin-bottom: 8px;
}

.aqi-level {
  font-size: 1rem;
  font-weight: 700;
  margin-bottom: 4px;
}

.aqi-range {
  font-size: 0.8rem;
  opacity: 0.88;
}

/* ─── Download Section ─── */
.download {
  text-align: center;
  padding: 100px 0;
  background: var(--bg-alt);
}

.download-app-icon {
  font-size: 5rem;
  margin-bottom: 20px;
  display: block;
}

.download h2 {
  font-size: 2.2rem;
  font-weight: 800;
  margin-bottom: 12px;
  letter-spacing: -0.01em;
}

.download p {
  font-size: 1.05rem;
  color: var(--text-sub);
  margin-bottom: 40px;
  max-width: 480px;
  margin-left: auto;
  margin-right: auto;
}

.store-buttons {
  display: flex;
  justify-content: center;
  gap: 16px;
  flex-wrap: wrap;
}

.store-btn {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  background: var(--store-btn-bg);
  color: var(--store-btn-fg);
  border: 1.5px solid var(--store-btn-border);
  padding: 14px 24px;
  border-radius: var(--radius-btn);
  font-size: 0.95rem;
  font-weight: 600;
  transition: all var(--transition);
  text-decoration: none;
  opacity: 0.5;
  cursor: not-allowed;
  pointer-events: none;
}

.store-btn .store-icon {
  font-size: 1.6rem;
}

.store-btn .store-text small {
  display: block;
  font-size: 0.72rem;
  font-weight: 400;
  opacity: 0.8;
  margin-bottom: 1px;
}


/* ─── Footer (양 테마 공통 다크 톤) ─── */
footer {
  background: var(--footer-bg);
  color: rgba(255,255,255,0.65);
  padding: 60px 0 32px;
}

.footer-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 24px;
}

.footer-top {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr;
  gap: 40px;
  margin-bottom: 40px;
}

.footer-brand .footer-logo {
  font-size: 1.2rem;
  font-weight: 700;
  color: #fff;
  display: flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 12px;
  text-decoration: none;
}

.footer-brand p {
  font-size: 0.88rem;
  line-height: 1.7;
  max-width: 280px;
}

.footer-links h4 {
  font-size: 0.88rem;
  font-weight: 700;
  color: #fff;
  margin-bottom: 14px;
  text-transform: uppercase;
  letter-spacing: 0.08em;
}

.footer-links ul li {
  margin-bottom: 8px;
}

.footer-links ul li a {
  font-size: 0.9rem;
  color: rgba(255,255,255,0.55);
  text-decoration: none;
  transition: color var(--transition);
}

.footer-links ul li a:hover {
  color: #90caf9;
}

.footer-bottom {
  border-top: 1px solid rgba(255,255,255,0.08);
  padding-top: 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 12px;
}

.footer-bottom p {
  font-size: 0.85rem;
}

.footer-bottom a {
  color: rgba(255,255,255,0.55);
  font-size: 0.85rem;
}

.footer-bottom a:hover {
  color: #90caf9;
}

/* ─── Inner Pages (Privacy, Terms, FAQ) ─── */
.inner-hero {
  background: var(--inner-hero-grad);
  padding: 60px 0 48px;
  border-bottom: 1px solid var(--border);
}

.inner-hero h1 {
  font-size: 2.2rem;
  font-weight: 800;
  color: var(--text-main);
  margin-bottom: 8px;
  letter-spacing: -0.01em;
}

.inner-hero p {
  color: var(--text-sub);
  font-size: 1rem;
}

.inner-content {
  max-width: 760px;
  margin: 0 auto;
  padding: 60px 24px 80px;
}

.inner-content h2 {
  font-size: 1.3rem;
  font-weight: 700;
  color: var(--text-main);
  margin: 36px 0 12px;
  padding-bottom: 8px;
  border-bottom: 2px solid var(--divider-accent);
}

.inner-content h3 {
  font-size: 1.05rem;
  font-weight: 600;
  color: var(--text-main);
  margin: 20px 0 8px;
}

.inner-content p {
  font-size: 0.95rem;
  color: var(--text-sub);
  line-height: 1.8;
  margin-bottom: 12px;
}

.inner-content ul, .inner-content ol {
  padding-left: 20px;
  margin-bottom: 12px;
}

.inner-content ul { list-style: disc; }
.inner-content ol { list-style: decimal; }

.inner-content li {
  font-size: 0.95rem;
  color: var(--text-sub);
  line-height: 1.8;
  margin-bottom: 4px;
}

/* FAQ Accordion */
.faq-item {
  border: 1.5px solid var(--border);
  border-radius: var(--radius-sm);
  margin-bottom: 12px;
  overflow: hidden;
  transition: border-color var(--transition);
}

.faq-item.open {
  border-color: var(--primary-soft);
}

.faq-question {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 18px 22px;
  cursor: pointer;
  font-weight: 600;
  font-size: 1rem;
  color: var(--text-main);
  background: var(--surface);
  transition: background var(--transition);
  user-select: none;
}

.faq-item.open .faq-question {
  background: var(--faq-open-bg);
  color: var(--primary);
}

.faq-question .faq-icon {
  font-size: 1.2rem;
  font-weight: 300;
  color: var(--primary);
  transition: transform var(--transition);
  flex-shrink: 0;
}

.faq-item.open .faq-question .faq-icon {
  transform: rotate(45deg);
}

.faq-answer {
  display: none;
  padding: 0 22px 18px;
  font-size: 0.95rem;
  color: var(--text-sub);
  line-height: 1.8;
}

.faq-item.open .faq-answer {
  display: block;
}

/* ─── Responsive ─── */
@media (max-width: 900px) {
  .features-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .hero-inner {
    flex-direction: column;
    text-align: center;
  }

  .hero-title {
    font-size: 2.4rem;
  }

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

  .hero-visual {
    order: -1;
  }

  .hero-mockup {
    width: 200px;
    height: 320px;
  }

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

  .footer-top {
    grid-template-columns: 1fr 1fr;
  }
}

@media (max-width: 640px) {
  .section {
    padding: 56px 0;
  }

  .section-title {
    font-size: 1.6rem;
  }

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

  .hero-title {
    font-size: 2rem;
  }

  .hero-slogan {
    font-size: 1rem;
  }

  .nav-links {
    display: none;
  }

  .hamburger {
    display: flex;
  }

  .footer-top {
    grid-template-columns: 1fr;
  }

  .footer-bottom {
    flex-direction: column;
    text-align: center;
  }

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

  .data-badge {
    font-size: 0.82rem;
    padding: 7px 14px;
  }
}