/* ============================================================
   帮帮课堂助手 — Official Website Stylesheet
   PC + Mobile Responsive
   ============================================================ */

/* --- CSS Variables --- */
:root {
  --color-primary: #4F46E5;
  --color-primary-dark: #4338CA;
  --color-primary-light: #818CF8;
  --color-accent: #6366F1;
  --color-accent-2: #8B5CF6;
  --color-bg: #FFFFFF;
  --color-bg-alt: #F8FAFC;
  --color-bg-dark: #0F172A;
  --color-text: #1E293B;
  --color-text-light: #64748B;
  --color-text-white: #F1F5F9;
  --color-border: #E2E8F0;
  --color-success: #10B981;
  --color-warning: #F59E0B;
  --color-danger: #EF4444;
  --color-info: #0EA5E9;

  --font-sans: 'Segoe UI', 'PingFang SC', 'Microsoft YaHei', 'Helvetica Neue', sans-serif;
  --shadow-sm: 0 1px 3px rgba(0,0,0,0.06), 0 1px 2px rgba(0,0,0,0.04);
  --shadow-md: 0 4px 12px rgba(0,0,0,0.08), 0 2px 4px rgba(0,0,0,0.04);
  --shadow-lg: 0 12px 32px rgba(0,0,0,0.1), 0 4px 8px rgba(0,0,0,0.06);
  --shadow-xl: 0 24px 48px rgba(0,0,0,0.12), 0 8px 16px rgba(0,0,0,0.06);
  --shadow-accent: 0 8px 24px rgba(79,70,229,0.25);
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 16px;
  --radius-xl: 24px;
  --transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  --max-width: 1200px;
  --header-h: 72px;
}

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

html {
  scroll-behavior: smooth;
  scroll-padding-top: var(--header-h);
  -webkit-font-smoothing: antialiased;
}

body {
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.6;
  color: var(--color-text);
  background: var(--color-bg);
  overflow-x: hidden;
}

img { max-width: 100%; height: auto; display: block; }
a { color: inherit; text-decoration: none; transition: var(--transition); }
ul { list-style: none; }
button { cursor: pointer; border: none; background: none; font: inherit; color: inherit; }

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

/* --- Text Gradients --- */
.text-gradient {
  background: linear-gradient(135deg, #6366F1 0%, #8B5CF6 40%, #EC4899 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
.text-gradient-light {
  background: linear-gradient(135deg, #A5B4FC 0%, #C4B5FD 50%, #F9A8D4 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

/* --- Buttons --- */
.btn {
  display: inline-flex; align-items: center; gap: 8px;
  font-weight: 600; border-radius: var(--radius-md); transition: var(--transition);
  white-space: nowrap; cursor: pointer;
}
.btn-sm { padding: 10px 20px; font-size: 14px; }
.btn-lg { padding: 14px 32px; font-size: 16px; }
.btn-block { display: flex; justify-content: center; width: 100%; }

.btn-gradient {
  background: linear-gradient(135deg, #6366F1 0%, #8B5CF6 100%);
  color: #fff; box-shadow: var(--shadow-accent);
}
.btn-gradient:hover {
  transform: translateY(-2px);
  box-shadow: 0 12px 32px rgba(79,70,229,0.35);
}
.btn-outline {
  background: transparent; color: var(--color-primary);
  border: 2px solid var(--color-border);
}
.btn-outline:hover { border-color: var(--color-primary); background: #EEF2FF; }
.btn-outline:disabled { opacity: 0.5; cursor: not-allowed; border-color: var(--color-border); color: var(--color-text-light); }
.btn-outline:disabled:hover { background: transparent; }

/* ==================== HEADER ==================== */
.header {
  position: fixed; top: 0; left: 0; right: 0; z-index: 1000;
  height: var(--header-h);
  background: linear-gradient(180deg,
    rgba(255,255,255,0.95) 0%,
    rgba(248,250,252,0.9) 50%,
    rgba(241,245,249,0.85) 100%);
  backdrop-filter: blur(20px) saturate(180%);
  -webkit-backdrop-filter: blur(20px) saturate(180%);
  border-bottom: 1px solid rgba(226,232,240,0.6);
  box-shadow: 0 1px 3px rgba(0,0,0,0.03), 0 1px 2px rgba(0,0,0,0.02);
  transition: var(--transition);
}
.header.scrolled {
  border-bottom-color: rgba(226,232,240,0.9);
  box-shadow: 0 1px 3px rgba(0,0,0,0.04), 0 4px 16px rgba(0,0,0,0.04);
  background: linear-gradient(180deg,
    rgba(255,255,255,0.98) 0%,
    rgba(248,250,252,0.95) 100%);
}

.header .container {
  display: flex; align-items: center; justify-content: space-between;
  height: 100%;
}

.logo {
  display: flex; align-items: center; gap: 10px; z-index: 1001;
}
.logo img { border-radius: 10px; box-shadow: 0 2px 8px rgba(79,70,229,0.15); }
.logo-text {
  font-size: 18px; font-weight: 700;
  background: linear-gradient(135deg, #1E293B 0%, #4F46E5 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
.logo-text-light {
  background: linear-gradient(135deg, #F1F5F9 0%, #A5B4FC 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.nav-list { display: flex; gap: 2px; }
.nav-link {
  padding: 8px 18px; border-radius: 10px;
  font-size: 14.5px; font-weight: 500; color: var(--color-text-light);
  transition: var(--transition); position: relative;
}
.nav-link::after {
  content: ''; position: absolute; bottom: 2px; left: 50%;
  width: 0; height: 2px; border-radius: 2px;
  background: var(--color-primary); transform: translateX(-50%);
  transition: width 0.25s ease;
}
.nav-link:hover { color: var(--color-primary); background: rgba(99,102,241,0.06); }
.nav-link:hover::after { width: 60%; }
.nav-link.active {
  color: var(--color-primary); background: rgba(99,102,241,0.08);
  font-weight: 600;
}
.nav-link.active::after { width: 60%; }

.header-cta { display: none; }

.menu-toggle {
  display: none; flex-direction: column; gap: 5px;
  padding: 10px; z-index: 1002; border-radius: 10px;
  background: rgba(99,102,241,0.06); transition: var(--transition);
}
.menu-toggle:hover { background: rgba(99,102,241,0.12); }
.menu-toggle span {
  display: block; width: 22px; height: 2px;
  background: var(--color-text); border-radius: 2px;
  transition: var(--transition); transform-origin: center;
}
.menu-toggle.active { background: rgba(99,102,241,0.1); }
.menu-toggle.active span { background: var(--color-primary); }
.menu-toggle.active span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.menu-toggle.active span:nth-child(2) { opacity: 0; transform: scale(0); }
.menu-toggle.active span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

/* Nav drawer header — hidden on desktop */
.nav-header { display: none; }

/* Mobile nav backdrop */
.nav-backdrop {
  display: none; position: fixed; inset: 0; z-index: 998;
  background: rgba(15,23,42,0.4);
  opacity: 0; transition: opacity 0.35s ease;
}
.nav-backdrop.open { opacity: 1; }

/* ==================== SLIDESHOW ==================== */
.slideshow {
  position: relative; width: 100%; height: 100vh; min-height: 600px;
  overflow: hidden; background: #0F172A;
}
.slides-track { position: relative; width: 100%; height: 100%; }
.slide {
  position: absolute; inset: 0; opacity: 0; transition: opacity 0.8s ease;
  pointer-events: none;
}
.slide.active { opacity: 1; pointer-events: auto; }

.slide-img {
  width: 100%; height: 100%; object-fit: cover; object-position: center;
  filter: brightness(0.35);
}
.slide-overlay {
  position: absolute; inset: 0;
  background: linear-gradient(180deg, rgba(15,23,42,0.4) 0%, rgba(15,23,42,0.7) 100%);
}
.slide-content {
  position: absolute; bottom: 0; left: 0; right: 0;
  padding: 40px 24px 120px; max-width: var(--max-width);
  margin: 0 auto;
}
.slide-tag {
  display: inline-block; padding: 4px 14px; border-radius: 20px;
  background: rgba(99,102,241,0.25); color: #A5B4FC;
  font-size: 13px; font-weight: 600; letter-spacing: 0.5px;
  margin-bottom: 16px; border: 1px solid rgba(165,180,252,0.2);
}
.slide-title {
  font-size: clamp(28px, 5vw, 52px); line-height: 1.2;
  font-weight: 800; color: #fff; margin-bottom: 16px;
}
.slide-desc {
  font-size: clamp(14px, 2vw, 17px); color: rgba(255,255,255,0.7);
  line-height: 1.7; margin-bottom: 28px; max-width: 600px;
}

.slide-arrow {
  position: absolute; top: 50%; transform: translateY(-50%);
  width: 48px; height: 48px; border-radius: 50%;
  background: rgba(255,255,255,0.12); backdrop-filter: blur(8px);
  color: #fff; display: flex; align-items: center; justify-content: center;
  transition: var(--transition); z-index: 10;
}
.slide-arrow:hover { background: rgba(255,255,255,0.22); transform: translateY(-50%) scale(1.05); }
.slide-arrow svg { width: 24px; height: 24px; }
.slide-prev { left: 20px; }
.slide-next { right: 20px; }

.slide-dots {
  position: absolute; bottom: 60px; left: 50%; transform: translateX(-50%);
  display: flex; gap: 10px; z-index: 10;
}
.slide-dot {
  width: 10px; height: 10px; border-radius: 50%;
  background: rgba(255,255,255,0.3); transition: var(--transition);
}
.slide-dot:hover { background: rgba(255,255,255,0.5); }
.slide-dot.active { background: #fff; width: 28px; border-radius: 10px; }

.slide-scroll-hint {
  position: absolute; bottom: 28px; left: 50%; transform: translateX(-50%);
  display: flex; flex-direction: column; align-items: center; gap: 4px;
  color: rgba(255,255,255,0.5); font-size: 12px;
  animation: bounceDown 2s infinite;
}
.slide-scroll-hint svg { width: 18px; height: 18px; }

@keyframes bounceDown {
  0%, 100% { transform: translateX(-50%) translateY(0); }
  50% { transform: translateX(-50%) translateY(8px); }
}

/* ==================== INTRO BANNER ==================== */
.intro-banner {
  padding: 48px 0; background: var(--color-bg);
  border-bottom: 1px solid var(--color-border);
}
.intro-grid {
  display: grid; grid-template-columns: repeat(4, 1fr); gap: 24px;
}
.intro-item {
  display: flex; flex-direction: column; align-items: center;
  text-align: center; gap: 8px;
}
.intro-icon {
  width: 56px; height: 56px; border-radius: var(--radius-md);
  background: #EEF2FF; color: var(--color-primary);
  display: flex; align-items: center; justify-content: center;
  margin-bottom: 4px;
}
.intro-icon svg { width: 28px; height: 28px; }
.intro-item strong { font-size: 22px; font-weight: 700; }
.intro-item span { font-size: 14px; color: var(--color-text-light); }

/* ==================== SECTION HEADERS ==================== */
.section-header { text-align: center; margin-bottom: 56px; }
.section-tag {
  display: inline-block; padding: 6px 18px; border-radius: 20px;
  background: #EEF2FF; color: var(--color-primary);
  font-size: 13px; font-weight: 600; margin-bottom: 16px;
  letter-spacing: 0.5px;
}
.section-tag-light {
  background: rgba(99,102,241,0.2); color: #A5B4FC;
}
.section-title {
  font-size: clamp(22px, 4vw, 36px); font-weight: 800;
  line-height: 1.3; margin-bottom: 16px;
  margin:0px 0px 5px;padding:0 0 5px;
}
.section-desc {
  font-size: 16px; color: var(--color-text-light); line-height: 1.7;
  max-width: 680px; margin: 0 auto;
}
.text-white { color: #fff; }
.text-gray { color: rgba(255,255,255,0.7); }

/* ==================== FEATURES ==================== */
.features {
  padding: 100px 0; position: relative;
  background: var(--color-bg-alt);
}
.section-bg-dots {
  position: absolute; inset: 0; pointer-events: none;
  background-image: radial-gradient(circle, #CBD5E1 1px, transparent 1px);
  background-size: 32px 32px; opacity: 0.5;
}

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

.feature-card {
  background: #fff; border-radius: var(--radius-lg);
  padding: 36px 28px; position: relative;
  border: 1px solid var(--color-border);
  box-shadow: var(--shadow-sm);
  transition: var(--transition);
}
.feature-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
  border-color: transparent;
}
.feature-icon {
  width: 52px; height: 52px; border-radius: var(--radius-md);
  background: color-mix(in srgb, var(--c) 12%, transparent);
  color: var(--c); display: flex; align-items: center; justify-content: center;
  margin-bottom: 18px;
}
.feature-icon svg { width: 26px; height: 26px; }
.feature-card h3 { font-size: 18px; font-weight: 700; margin-bottom: 10px; }
.feature-card p { font-size: 14px; color: var(--color-text-light); line-height: 1.7; }

/* ==================== TOOLS ==================== */
.tools { padding: 100px 0; }
.tools-grid {
  display: grid; grid-template-columns: repeat(4, 1fr); gap: 16px;
}

.tool-card {
  background: #fff; border: 1px solid var(--color-border);
  border-radius: var(--radius-md); padding: 28px 20px;
  text-align: center; transition: var(--transition);
}
.tool-card:hover {
  transform: translateY(-3px); box-shadow: var(--shadow-md);
  border-color: transparent;
}
.tool-icon {
  width: 48px; height: 48px; border-radius: var(--radius-sm);
  background: color-mix(in srgb, var(--tc) 10%, transparent);
  color: var(--tc); display: flex; align-items: center; justify-content: center;
  margin: 0 auto 14px;
}
.tool-icon svg { width: 24px; height: 24px; }
.tool-card h4 { font-size: 16px; font-weight: 700; margin-bottom: 6px; }
.tool-card p { font-size: 13px; color: var(--color-text-light); }

/* ==================== LAYOUT SECTION ==================== */
.layout-section { padding: 100px 0; background: var(--color-bg); }
.layout-grid {
  display: grid; grid-template-columns: 1fr 1fr; gap: 64px; align-items: center;
}
.layout-text .section-tag { margin-bottom: 16px; }
.layout-text .section-title { margin-bottom: 20px; }
.layout-text .section-desc { margin: 0 0 28px; max-width: none; }
.layout-list { display: flex; flex-direction: column; gap: 14px; }
.layout-list li {
  display: flex; align-items: flex-start; gap: 14px;
}
.layout-dot {
  flex-shrink: 0; width: 10px; height: 10px; border-radius: 50%;
  background: var(--dot); margin-top: 7px;
}
.layout-list li strong { display: block; font-size: 15px; font-weight: 600; }
.layout-list li span { font-size: 13px; color: var(--color-text-light); }

.layout-mockup {
  background: linear-gradient(135deg, #1E293B 0%, #0F172A 100%);
  border-radius: var(--radius-xl); padding: 28px;
  box-shadow: var(--shadow-xl); position: relative;
}
.layout-screen {
  background: #fff; border-radius: var(--radius-md);
  aspect-ratio: 16 / 11; position: relative; overflow: hidden;
}
.layout-toolbar {
  position: absolute; display: flex; gap: 8px; padding: 10px;
  background: rgba(255,255,255,0.9); backdrop-filter: blur(8px);
  border-radius: var(--radius-sm); box-shadow: var(--shadow-md);
}
.layout-toolbar span {
  width: 28px; height: 28px; border-radius: 6px; background: #E2E8F0; cursor: pointer;
}
.layout-toolbar span.active, .layout-toolbar span:hover { background: var(--color-primary); }
.layout-toolbar-bottom {
  bottom: 12px; left: 50%; transform: translateX(-50%);
  flex-direction: row;
}
.layout-toolbar-right {
  right: 10px; top: 50%; transform: translateY(-50%);
  flex-direction: column; padding: 8px;
}
.layout-float-btn {
  position: absolute; right: 16px; bottom: 16px;
  width: 36px; height: 36px; border-radius: 50%;
  background: var(--color-accent); color: #fff;
  display: flex; align-items: center; justify-content: center;
  box-shadow: var(--shadow-accent);
}
.layout-float-btn svg { width: 18px; height: 18px; }
.layout-canvas {
  display: flex; align-items: center; justify-content: center;
  height: 100%; padding: 20px;
}
.layout-canvas svg { width: 100%; max-width: 300px; height: auto; }

/* ==================== DOWNLOAD ==================== */
.download {
  padding: 100px 0; position: relative;
  background: linear-gradient(180deg, #0F172A 0%, #1E293B 100%);
  overflow: hidden;
}
.download-bg { position: absolute; inset: 0; pointer-events: none; }
.download-orb {
  position: absolute; border-radius: 50%; filter: blur(120px); opacity: 0.15;
}
.dl-orb-1 { width: 500px; height: 500px; background: #6366F1; top: -200px; left: -100px; }
.dl-orb-2 { width: 400px; height: 400px; background: #8B5CF6; bottom: -150px; right: -100px; }
.dl-orb-3 { width: 300px; height: 300px; background: #EC4899; top: 50%; left: 50%; transform: translate(-50%, -50%); }

.download-grid {
  display: grid; grid-template-columns: repeat(4, 1fr); gap: 20px;
  position: relative; z-index: 1;
}

.download-card {
  background: rgba(255,255,255,0.04); border: 1px solid rgba(255,255,255,0.08);
  border-radius: var(--radius-lg); padding: 32px 24px;
  text-align: center; transition: var(--transition);
  position: relative;
}
.download-card:hover {
  background: rgba(255,255,255,0.07); border-color: rgba(255,255,255,0.15);
  transform: translateY(-3px);
}
.download-card.featured {
  border-color: rgba(99,102,241,0.3); background: rgba(99,102,241,0.08);
}
.download-card-badge {
  position: absolute; top: -12px; left: 50%; transform: translateX(-50%);
  background: linear-gradient(135deg, #6366F1, #8B5CF6);
  color: #fff; font-size: 12px; font-weight: 700;
  padding: 4px 16px; border-radius: 12px;
}
.download-os-icon { margin-bottom: 16px; }
.download-os-icon svg { width: 48px; height: 48px; }
.download-card h3 { color: #fff; font-size: 18px; font-weight: 700; margin-bottom: 8px; }
.download-desc { color: rgba(255,255,255,0.55); font-size: 14px; margin-bottom: 20px; line-height: 1.6; }
.download-card .btn-gradient { margin-bottom: 12px; }
.download-card small { color: rgba(255,255,255,0.3); font-size: 12px; display: block; }
.download-card.coming-soon { opacity: 0.7; }
.download-card.coming-soon:hover { opacity: 0.9; }
.download-card .btn-outline {
  color: rgba(255,255,255,0.5); border-color: rgba(255,255,255,0.15); margin-bottom: 12px;
}

.download-note {
  text-align: center; margin-top: 40px; color: rgba(255,255,255,0.5);
  font-size: 14px; line-height: 1.7; position: relative; z-index: 1;
}
.download-note a { color: #A5B4FC; text-decoration: underline; }
.download-note strong { color: rgba(255,255,255,0.8); }

/* ==================== CONTACT ==================== */
.contact { padding: 100px 0; background: var(--color-bg-alt); }
.contact-grid {
  display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px;
}
.contact-card {
  background: #fff; border: 1px solid var(--color-border);
  border-radius: var(--radius-lg); padding: 36px 28px;
  text-align: center; transition: var(--transition);
}
.contact-card:hover { box-shadow: var(--shadow-lg); border-color: transparent; }
.contact-card.primary {
  border-color: rgba(99,102,241,0.2);
  background: linear-gradient(180deg, #EEF2FF 0%, #fff 100%);
}
.contact-icon {
  width: 56px; height: 56px; border-radius: var(--radius-md);
  background: color-mix(in srgb, var(--c) 12%, transparent);
  color: var(--c); display: flex; align-items: center; justify-content: center;
  margin: 0 auto 16px;
}
.contact-icon svg { width: 28px; height: 28px; }
.contact-card h3 { font-size: 18px; font-weight: 700; margin-bottom: 10px; }
.contact-card p { font-size: 14px; color: var(--color-text-light); line-height: 1.7; }
.contact-email {
  display: block; font-size: 20px; font-weight: 700;
  color: var(--color-primary); margin-bottom: 8px;
}

/* ==================== FOOTER ==================== */
.footer { position: relative; background: var(--color-bg-dark); }
.footer-wave {
  position: absolute; top: -1px; left: 0; right: 0;
  transform: translateY(-99%);
}
.footer-wave svg { width: 100%; height: auto; display: block; }
.footer-main { padding: 60px 0 32px; }

.footer-grid {
  display: grid; grid-template-columns: 2fr 1fr 1fr 1fr; gap: 48px;
  margin-bottom: 48px;
}
.footer-brand p {
  color: rgba(255,255,255,0.5); font-size: 14px;
  line-height: 1.7; margin-top: 16px; max-width: 280px;
}
.footer-links h4 {
  color: #fff; font-size: 15px; font-weight: 700;
  margin-bottom: 16px; letter-spacing: 0.3px;
}
.footer-links ul { display: flex; flex-direction: column; gap: 10px; }
.footer-links a {
  color: rgba(255,255,255,0.5); font-size: 14px;
  transition: var(--transition);
}
.footer-links a:hover { color: #A5B4FC; }

.footer-bottom {
  border-top: 1px solid rgba(255,255,255,0.08);
  padding-top: 24px; display: flex; justify-content: space-between;
  align-items: center; flex-wrap: wrap; gap: 8px;
  color: rgba(255,255,255,0.35); font-size: 13px;
}
.footer-bottom a { color: rgba(255,255,255,0.6); }
.footer-bottom a:hover { color: #A5B4FC; }

/* ==================== BACK TO TOP ==================== */
.back-top {
  position: fixed; bottom: 28px; right: 28px; z-index: 999;
  width: 44px; height: 44px; border-radius: 50%;
  background: var(--color-primary); color: #fff;
  display: flex; align-items: center; justify-content: center;
  box-shadow: var(--shadow-accent); opacity: 0; visibility: hidden;
  transform: translateY(12px); transition: var(--transition);
}
.back-top.visible { opacity: 1; visibility: visible; transform: translateY(0); }
.back-top:hover { transform: translateY(-3px); box-shadow: 0 12px 32px rgba(79,70,229,0.4); }
.back-top svg { width: 22px; height: 22px; }

/* ==================== ANIMATIONS ==================== */
[data-animate] {
  opacity: 0; transform: translateY(24px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}
[data-animate].animated {
  opacity: 1; transform: translateY(0);
}

/* ==================== RESPONSIVE ==================== */

/* Tablet (768px - 1024px) */
@media (max-width: 1024px) {
  .intro-grid { grid-template-columns: repeat(4, 1fr); gap: 16px; }
  .features-grid { grid-template-columns: repeat(2, 1fr); }
  .tools-grid { grid-template-columns: repeat(3, 1fr); }
  .download-grid { grid-template-columns: repeat(2, 1fr); }
  .layout-grid { gap: 36px; }
  .footer-grid { grid-template-columns: 1fr 1fr; gap: 32px; }
}

/* Mobile (< 768px) */
@media (max-width: 768px) {
  :root { --header-h: 60px; }

  .container { padding: 0 16px; }

  /* Header — right-side drawer */
  .nav-backdrop { display: block; }

  .nav-header {
    display: flex; align-items: center; justify-content: space-between;
    padding: 0 16px 14px; margin-bottom: 8px;
    border-bottom: 1px solid rgba(255,255,255,0.08);
  }
  .nav-header-title {
    font-size: 15px; font-weight: 700;
    color: rgba(255,255,255,0.8);
    letter-spacing: 0.5px;
  }
  .nav-close {
    width: 30px; height: 30px; border-radius: 8px;
    display: flex; align-items: center; justify-content: center;
    color: rgba(255,255,255,0.5); background: rgba(255,255,255,0.06);
    transition: var(--transition);
  }
  .nav-close:hover { color: #fff; background: rgba(255,255,255,0.12); }
  .nav-close svg { width: 16px; height: 16px; }

  .nav {
    position: fixed; top: 0; right: 0; bottom: 0; z-index: 999;
    width: 210px; max-width: 62vw;
    background: rgba(15,23,42,0.92);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border-left: 1px solid rgba(255,255,255,0.06);
    box-shadow: -8px 0 40px rgba(0,0,0,0.3);
    display: flex; flex-direction: column;
    padding: 80px 0 32px;
    transform: translateX(100%);
    transition: transform 0.35s cubic-bezier(0.32, 0.72, 0, 1);
  }
  .nav.open { transform: translateX(0); }

  .nav-list {
    flex-direction: column; gap: 0; width: 100%; padding: 0 10px;
  }
  .nav-link {
    font-size: 14px; padding: 12px 16px; border-radius: 10px;
    display: flex; align-items: center; gap: 10px;
    color: rgba(255,255,255,0.7); font-weight: 500;
  }
  .nav-link::after { display: none; }
  .nav-link:hover { color: #fff; background: rgba(255,255,255,0.06); }
  .nav-link.active {
    color: #fff; background: rgba(99,102,241,0.3); font-weight: 600;
  }
  .nav-link.active::after { display: none; }

  .header-cta { display: flex; margin-left: auto; margin-right: 12px; }
  .menu-toggle { display: flex; }

  /* Slideshow */
  .slideshow { height: 85vh; min-height: 500px; }
  .slide-content { padding: 32px 16px 100px; }
  .slide-arrow { width: 40px; height: 40px; }
  .slide-arrow svg { width: 20px; height: 20px; }
  .slide-prev { left: 10px; }
  .slide-next { right: 10px; }
  .slide-dots { bottom: 40px; }

  /* Intro */
  .intro-banner { padding: 32px 0; }
  .intro-grid { grid-template-columns: repeat(2, 1fr); gap: 20px; }
  .intro-item strong { font-size: 20px; }

  /* Sections */
  .features, .tools, .layout-section, .download, .contact { padding: 64px 0; }
  .section-header { margin-bottom: 40px; }

  .features-grid { grid-template-columns: 1fr; }
  .tools-grid { grid-template-columns: repeat(2, 1fr); gap: 12px; }
  .tool-card { padding: 20px 14px; }

  .layout-grid { grid-template-columns: 1fr; gap: 32px; }
  .layout-visual { order: -1; }

  .download-grid { grid-template-columns: 1fr; max-width: 360px; margin: 0 auto; }
  .contact-grid { grid-template-columns: 1fr; max-width: 400px; margin: 0 auto; }

  .footer-grid { grid-template-columns: 1fr 1fr; gap: 28px; }
  .footer-brand { grid-column: 1 / -1; }
  .footer-bottom { flex-direction: column; align-items: flex-start; }
  .back-top { bottom: 16px; right: 16px; width: 40px; height: 40px; }
}

/* Small Mobile (< 480px) */
@media (max-width: 480px) {
  .intro-grid { grid-template-columns: repeat(2, 1fr); gap: 12px; }
  .tools-grid { grid-template-columns: repeat(2, 1fr); gap: 10px; }
  .footer-grid { grid-template-columns: 1fr; gap: 24px; }
}