/* ============================
   TelegramPCDL - 仿 Telegram 官方风格
   参考 ytelegram.com 设计
   ============================ */

:root {
  --blue: #0088cc;
  --blue-dark: #006699;
  --blue-light: #e5f2fa;
  --blue-pale: #f0f8ff;
  --green: #4dab53;
  --green-dark: #3d8b42;
  --white: #ffffff;
  --bg: #ffffff;
  --bg-gray: #f2f2f2;
  --bg-dark: #222222;
  --bg-footer: #1a1a1a;
  --text: #000000;
  --text-dark: #222222;
  --text-body: #444444;
  --text-muted: #999999;
  --text-light: #bbbbbb;
  --text-white: #ffffff;
  --border: #e0e0e0;
  --border-light: #eeeeee;
  --radius: 12px;
  --radius-sm: 8px;
  --radius-pill: 50px;
  --shadow-card: 0 2px 8px rgba(0,0,0,0.06);
  --shadow-hover: 0 4px 20px rgba(0,0,0,0.1);
  --shadow-btn: 0 2px 6px rgba(0,136,204,0.3);
  --font: 'Noto Sans SC', -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Helvetica Neue', Arial, sans-serif;
  --font-mono: 'DM Mono', 'Courier New', monospace;
  --max-w: 1140px;
  --transition: 0.2s ease;
}

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

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

body {
  font-family: var(--font);
  color: var(--text-body);
  background: var(--bg);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}

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

a {
  color: var(--blue);
  text-decoration: none;
  transition: color var(--transition);
}
a:hover { color: var(--blue-dark); }

ul, ol { list-style: none; }

h1, h2, h3, h4, h5, h6 {
  color: var(--text-dark);
  font-weight: 700;
  line-height: 1.3;
}

.container {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 20px;
}

/* ============================
   HEADER
   ============================ */
.header {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 1000;
  background: var(--blue);
  height: 56px;
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 56px;
}

.logo {
  display: flex;
  align-items: center;
  gap: 0;
  text-decoration: none;
  color: var(--text-white);
  height: 56px;
}

.logo-img {
  height: 28px;
  width: auto;
}

.logo-text {
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--text-white);
  margin-left: 8px;
  letter-spacing: -0.01em;
}

.nav {
  display: flex;
  align-items: center;
  gap: 0;
}

.nav a {
  color: rgba(255,255,255,0.85);
  padding: 16px 15px;
  font-size: 0.9rem;
  font-weight: 500;
  transition: all var(--transition);
  display: flex;
  align-items: center;
  height: 56px;
  border-bottom: 3px solid transparent;
}

.nav a:hover,
.nav a.active {
  color: #fff;
  background: rgba(255,255,255,0.1);
  border-bottom-color: rgba(255,255,255,0.6);
}

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

.nav-dropdown-content {
  display: none;
  position: absolute;
  top: 56px;
  left: 50%;
  transform: translateX(-50%);
  min-width: 170px;
  background: var(--white);
  border-radius: var(--radius-sm);
  padding: 6px;
  box-shadow: 0 4px 24px rgba(0,0,0,0.12);
  z-index: 200;
}

.nav-dropdown:hover .nav-dropdown-content {
  display: block;
  animation: fadeIn 0.15s ease;
}

.nav-dropdown-content a {
  display: block;
  padding: 10px 16px;
  height: auto;
  color: var(--text-body);
  font-size: 0.88rem;
  border-bottom: none;
  border-radius: 6px;
}

.nav-dropdown-content a:hover,
.nav-dropdown-content a.active {
  background: var(--blue-light);
  color: var(--blue);
  border-bottom: none;
}

/* Mobile */
.menu-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 8px;
}

.menu-toggle span {
  display: block;
  width: 22px; height: 2px;
  background: #fff;
  border-radius: 1px;
  transition: all var(--transition);
}

.menu-toggle.active span:nth-child(1) { transform: rotate(45deg) translate(5px, 5px); }
.menu-toggle.active span:nth-child(2) { opacity: 0; }
.menu-toggle.active span:nth-child(3) { transform: rotate(-45deg) translate(5px, -5px); }

/* ============================
   BREADCRUMB
   ============================ */
.breadcrumb {
  padding-top: 56px;
  background: var(--bg-gray);
}

.breadcrumb-inner {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 12px 0;
  font-size: 0.84rem;
  color: var(--text-muted);
}

.breadcrumb-inner a { color: var(--text-muted); }
.breadcrumb-inner a:hover { color: var(--blue); }
.breadcrumb-inner .sep { color: #ccc; }
.breadcrumb-inner .current { color: var(--text-dark); font-weight: 500; }

/* ============================
   HERO (首页)
   ============================ */
.hero {
  padding: 100px 0 70px;
  background: linear-gradient(135deg, var(--blue) 0%, var(--blue-dark) 100%);
  text-align: center;
}

.hero-title {
  font-size: 2.5rem;
  font-weight: 800;
  color: #fff;
  margin-bottom: 16px;
  letter-spacing: -0.02em;
}

.hero-subtitle {
  font-size: 1.1rem;
  color: rgba(255,255,255,0.75);
  max-width: 560px;
  margin: 0 auto 32px;
  line-height: 1.8;
}

.hero-buttons {
  display: flex;
  gap: 12px;
  justify-content: center;
  flex-wrap: wrap;
  margin-bottom: 40px;
}

.hero-stats {
  display: flex;
  gap: 48px;
  justify-content: center;
  padding-top: 28px;
  border-top: 1px solid rgba(255,255,255,0.15);
}

.hero-stat .num {
  font-size: 1.5rem;
  font-weight: 800;
  color: #fff;
  font-family: var(--font-mono);
}

.hero-stat .lbl {
  font-size: 0.8rem;
  color: rgba(255,255,255,0.5);
  margin-top: 2px;
}

/* ============================
   PAGE HERO (内页)
   ============================ */
.page-hero {
  background: var(--blue);
  padding: 72px 0 44px;
  text-align: center;
}

.page-hero h1 {
  font-size: 1.9rem;
  color: #fff;
  margin-bottom: 10px;
}

.page-hero p {
  color: rgba(255,255,255,0.7);
  font-size: 1rem;
  margin-bottom: 24px;
}

/* ============================
   BUTTONS
   ============================ */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 12px 28px;
  border-radius: var(--radius-pill);
  font-size: 0.95rem;
  font-weight: 600;
  font-family: var(--font);
  border: none;
  cursor: pointer;
  transition: all var(--transition);
  text-decoration: none;
  white-space: nowrap;
}

.btn-blue {
  background: var(--blue);
  color: #fff;
  box-shadow: var(--shadow-btn);
}
.btn-blue:hover {
  background: var(--blue-dark);
  transform: translateY(-1px);
  color: #fff;
}

.btn-green {
  background: var(--green);
  color: #fff;
}
.btn-green:hover {
  background: var(--green-dark);
  transform: translateY(-1px);
  color: #fff;
}

.btn-white {
  background: #fff;
  color: var(--blue);
}
.btn-white:hover {
  background: #f0f0f0;
  color: var(--blue-dark);
}

.btn-outline {
  background: transparent;
  border: 1.5px solid rgba(255,255,255,0.4);
  color: #fff;
}
.btn-outline:hover {
  border-color: #fff;
  background: rgba(255,255,255,0.1);
  color: #fff;
}

.btn-outline-blue {
  background: transparent;
  border: 1.5px solid var(--blue);
  color: var(--blue);
}
.btn-outline-blue:hover {
  background: var(--blue);
  color: #fff;
}

.btn-lg {
  padding: 15px 36px;
  font-size: 1.05rem;
}

.btn-icon { font-size: 1.1rem; }

/* ============================
   SECTIONS
   ============================ */
.section {
  padding: 60px 0;
}

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

.section-title {
  font-size: 1.8rem;
  text-align: center;
  margin-bottom: 8px;
}

.section-sub {
  text-align: center;
  color: var(--text-muted);
  font-size: 1rem;
  margin-bottom: 44px;
}

/* ============================
   DOWNLOAD GRID
   ============================ */
.download-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 20px;
}

.download-card {
  background: var(--white);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 32px 24px;
  text-align: center;
  transition: all var(--transition);
}

.download-card:hover {
  border-color: var(--blue);
  box-shadow: var(--shadow-hover);
  transform: translateY(-3px);
}

.download-card-icon {
  width: 64px; height: 64px;
  margin: 0 auto 16px;
  background: var(--blue-light);
  border-radius: var(--radius);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.8rem;
}

.download-card h3 {
  font-size: 1.1rem;
  margin-bottom: 4px;
}

.download-card .ver {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  color: var(--text-muted);
  margin-bottom: 4px;
}

.download-card .size {
  font-size: 0.82rem;
  color: var(--text-muted);
  margin-bottom: 16px;
}

.download-card .btn { width: 100%; }

/* ============================
   FEATURE CARDS
   ============================ */
.feature-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 20px;
}

.feature-card {
  padding: 28px 20px;
  border-radius: var(--radius);
  background: var(--white);
  border: 1px solid var(--border-light);
  transition: all var(--transition);
}

.feature-card:hover {
  box-shadow: var(--shadow-card);
  transform: translateY(-2px);
}

.feature-card-icon {
  width: 48px; height: 48px;
  background: var(--blue-light);
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.3rem;
  margin-bottom: 14px;
}

.feature-card h3 {
  font-size: 1.02rem;
  margin-bottom: 8px;
}

.feature-card p {
  font-size: 0.9rem;
  color: var(--text-muted);
  line-height: 1.7;
}

/* ============================
   CONTENT / ARTICLE
   ============================ */
.content-section {
  padding: 44px 0 60px;
}

.content-grid {
  display: grid;
  grid-template-columns: 1fr 260px;
  gap: 36px;
  align-items: start;
}

.article {
  background: var(--white);
  border: 1px solid var(--border-light);
  border-radius: var(--radius);
  padding: 36px;
}

.article h2 {
  font-size: 1.35rem;
  margin: 32px 0 12px;
  padding-top: 24px;
  border-top: 1px solid var(--border-light);
}

.article h2:first-child {
  margin-top: 0; padding-top: 0; border-top: none;
}

.article h3 {
  font-size: 1.08rem;
  margin: 22px 0 8px;
}

.article p {
  margin-bottom: 12px;
  line-height: 1.85;
}

.article ul, .article ol {
  margin-bottom: 12px;
  padding-left: 20px;
}
.article ul { list-style: disc; }
.article ol { list-style: decimal; }
.article li { margin-bottom: 6px; line-height: 1.7; }
.article strong { color: var(--text-dark); }

.article a {
  color: var(--blue);
  text-decoration: underline;
  text-underline-offset: 3px;
}
.article a:hover { color: var(--blue-dark); }

/* Step list */
.step-list { counter-reset: step; margin: 18px 0; }

.step-item {
  counter-increment: step;
  display: flex;
  gap: 16px;
  margin-bottom: 16px;
  padding: 18px;
  background: var(--bg-gray);
  border-radius: var(--radius-sm);
  border: 1px solid var(--border-light);
}

.step-item::before {
  content: counter(step);
  flex-shrink: 0;
  width: 38px; height: 38px;
  background: var(--blue);
  color: #fff;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 0.95rem;
}

.step-content h4 {
  font-size: 0.98rem;
  margin-bottom: 4px;
}

.step-content p {
  color: var(--text-muted);
  margin-bottom: 0;
  font-size: 0.9rem;
}

/* Info / Warn boxes */
.info-box {
  background: var(--blue-light);
  border: 1px solid rgba(0,136,204,0.12);
  border-left: 3px solid var(--blue);
  border-radius: 4px;
  padding: 16px 18px;
  margin: 18px 0;
}
.info-box p { margin-bottom: 0; }

.warn-box {
  background: #fff8e1;
  border: 1px solid rgba(255,193,7,0.2);
  border-left: 3px solid #ffc107;
  border-radius: 4px;
  padding: 16px 18px;
  margin: 18px 0;
}
.warn-box p { margin-bottom: 0; }

.code-block {
  background: #1e1e1e;
  color: #d4d4d4;
  padding: 14px 18px;
  border-radius: 6px;
  overflow-x: auto;
  font-family: var(--font-mono);
  font-size: 0.84rem;
  line-height: 1.7;
  margin: 14px 0;
}

/* Table */
.article-table {
  width: 100%;
  border-collapse: collapse;
  margin: 18px 0;
  font-size: 0.9rem;
}

.article-table th {
  background: var(--blue);
  color: #fff;
  padding: 11px 14px;
  text-align: left;
  font-weight: 600;
  font-size: 0.86rem;
}

.article-table th:first-child { border-radius: 6px 0 0 0; }
.article-table th:last-child { border-radius: 0 6px 0 0; }

.article-table td {
  padding: 11px 14px;
  border-bottom: 1px solid var(--border-light);
}

.article-table tr:last-child td { border-bottom: none; }
.article-table tr:nth-child(even) { background: var(--bg-gray); }

/* Req grid */
.req-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
  margin: 18px 0;
}

.req-item {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 14px 16px;
  background: var(--bg-gray);
  border-radius: var(--radius-sm);
  border: 1px solid var(--border-light);
}

.req-item .req-icon {
  width: 36px; height: 36px;
  background: var(--blue-light);
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1rem;
  flex-shrink: 0;
}

.req-item .req-label { font-size: 0.78rem; color: var(--text-muted); }
.req-item .req-value { font-weight: 600; font-size: 0.9rem; }

/* Update list */
.update-list { margin: 18px 0; }
.update-item {
  display: flex;
  gap: 16px;
  padding: 14px 0;
  border-bottom: 1px solid var(--border-light);
}
.update-item:last-child { border-bottom: none; }

.update-date {
  flex-shrink: 0;
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--text-muted);
  padding-top: 2px;
}

.update-content h4 { font-size: 0.92rem; margin-bottom: 4px; }
.update-content p { font-size: 0.86rem; color: var(--text-muted); margin-bottom: 0; }

/* Related */
.related-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 14px;
  margin: 18px 0;
}

.related-card {
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 16px;
  background: var(--white);
  border: 1px solid var(--border-light);
  border-radius: var(--radius);
  transition: all var(--transition);
}

.related-card:hover {
  border-color: var(--blue);
  box-shadow: var(--shadow-card);
}

.related-card .rc-icon {
  width: 40px; height: 40px;
  background: var(--blue-light);
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.1rem;
  flex-shrink: 0;
}

.related-card h4 { font-size: 0.9rem; margin-bottom: 2px; }
.related-card span { font-size: 0.78rem; color: var(--text-muted); }

/* ============================
   SIDEBAR
   ============================ */
.sidebar {
  position: sticky;
  top: 72px;
}

.sidebar-card {
  background: var(--white);
  border: 1px solid var(--border-light);
  border-radius: var(--radius);
  padding: 20px;
  margin-bottom: 14px;
}

.sidebar-card h4 {
  font-size: 0.92rem;
  margin-bottom: 12px;
  padding-bottom: 10px;
  border-bottom: 1px solid var(--border-light);
}

.sidebar-card ul li { margin-bottom: 6px; }
.sidebar-card ul li a {
  color: var(--text-muted);
  font-size: 0.88rem;
  display: block;
  padding: 5px 10px;
  border-radius: 4px;
  transition: all var(--transition);
}
.sidebar-card ul li a:hover {
  background: var(--blue-light);
  color: var(--blue);
}

.sidebar-dl {
  background: var(--blue);
  border-color: transparent;
  text-align: center;
}
.sidebar-dl h4 { color: #fff; border-bottom-color: rgba(255,255,255,0.15); }
.sidebar-dl p { color: rgba(255,255,255,0.6); font-size: 0.84rem; margin-bottom: 12px; }
.sidebar-dl .btn { width: 100%; }

/* TOC */
.toc { list-style: none; padding: 0; margin: 0; }
.toc li { margin-bottom: 3px; }
.toc a {
  display: block;
  padding: 6px 12px;
  font-size: 0.84rem;
  color: var(--text-muted);
  border-radius: 4px;
  border-left: 2px solid transparent;
  transition: all var(--transition);
}
.toc a:hover, .toc a.active {
  color: var(--blue);
  background: var(--blue-light);
  border-left-color: var(--blue);
}

/* ============================
   FAQ
   ============================ */
.faq-list {
  max-width: 760px;
  margin: 0 auto;
}

.faq-item {
  background: var(--white);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-sm);
  margin-bottom: 8px;
  overflow: hidden;
  transition: all var(--transition);
}

.faq-item:hover { border-color: rgba(0,136,204,0.15); }

.faq-question {
  width: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 16px 20px;
  background: none;
  border: none;
  cursor: pointer;
  font-family: var(--font);
  font-size: 0.96rem;
  font-weight: 600;
  color: var(--text-dark);
  text-align: left;
  gap: 12px;
}

.faq-question .icon {
  flex-shrink: 0;
  width: 24px; height: 24px;
  background: var(--blue-light);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all var(--transition);
  color: var(--blue);
  font-size: 1rem;
}

.faq-item.active .faq-question .icon {
  background: var(--blue);
  color: #fff;
  transform: rotate(45deg);
}

.faq-answer {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.3s ease;
}

.faq-answer-inner {
  padding: 0 20px 18px;
  color: var(--text-body);
  line-height: 1.8;
  font-size: 0.92rem;
}
.faq-answer-inner p { margin-bottom: 8px; }

/* ============================
   CTA
   ============================ */
.cta-section {
  background: var(--blue);
  padding: 56px 0;
  text-align: center;
}

.cta-section h2 {
  font-size: 1.7rem;
  color: #fff;
  margin-bottom: 10px;
}

.cta-section p {
  color: rgba(255,255,255,0.65);
  margin-bottom: 24px;
}

/* ============================
   FOOTER
   ============================ */
.footer {
  background: var(--bg-footer);
  padding: 44px 0 20px;
}

.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: 36px;
  margin-bottom: 36px;
}

.footer-brand p {
  color: rgba(255,255,255,0.4);
  font-size: 0.86rem;
  line-height: 1.7;
  max-width: 280px;
  margin-top: 10px;
}

.footer-col h4 {
  color: rgba(255,255,255,0.85);
  font-size: 0.9rem;
  margin-bottom: 14px;
}

.footer-col a {
  display: block;
  color: rgba(255,255,255,0.4);
  font-size: 0.86rem;
  padding: 3px 0;
  transition: color var(--transition);
}

.footer-col a:hover { color: var(--blue); }

.footer-bottom {
  padding-top: 18px;
  border-top: 1px solid rgba(255,255,255,0.08);
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 8px;
}

.footer-bottom p {
  color: rgba(255,255,255,0.3);
  font-size: 0.78rem;
}
.footer-bottom a { color: rgba(255,255,255,0.3); }
.footer-bottom a:hover { color: var(--blue); }

/* ============================
   BACK TO TOP
   ============================ */
.back-to-top {
  position: fixed;
  bottom: 24px; right: 24px;
  width: 42px; height: 42px;
  background: var(--blue);
  color: #fff;
  border: none;
  border-radius: 50%;
  cursor: pointer;
  font-size: 1rem;
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: var(--shadow-btn);
  opacity: 0;
  visibility: hidden;
  transform: translateY(12px);
  transition: all var(--transition);
  z-index: 100;
}
.back-to-top.visible { opacity: 1; visibility: visible; transform: translateY(0); }
.back-to-top:hover { background: var(--blue-dark); transform: translateY(-2px); }

/* ============================
   ANIMATIONS
   ============================ */
@keyframes fadeIn {
  from { opacity: 0; } to { opacity: 1; }
}

@keyframes fadeUp {
  from { opacity: 0; transform: translateY(18px); }
  to { opacity: 1; transform: translateY(0); }
}

.animate-on-scroll {
  opacity: 0;
  transform: translateY(20px);
  transition: opacity 0.5s ease, transform 0.5s ease;
}
.animate-on-scroll.animated { opacity: 1; transform: translateY(0); }

.stagger-children .animate-on-scroll:nth-child(2) { transition-delay: 0.06s; }
.stagger-children .animate-on-scroll:nth-child(3) { transition-delay: 0.12s; }
.stagger-children .animate-on-scroll:nth-child(4) { transition-delay: 0.18s; }
.stagger-children .animate-on-scroll:nth-child(5) { transition-delay: 0.24s; }
.stagger-children .animate-on-scroll:nth-child(6) { transition-delay: 0.30s; }

/* ============================
   RESPONSIVE
   ============================ */
@media (max-width: 1024px) {
  .content-grid { grid-template-columns: 1fr; }
  .sidebar {
    position: static;
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 12px;
  }
  .footer-grid { grid-template-columns: 1fr 1fr; gap: 24px; }
}

@media (max-width: 768px) {
  .menu-toggle { display: flex; }

  .nav {
    position: fixed;
    top: 56px; left: 0; right: 0;
    background: var(--blue);
    flex-direction: column;
    padding: 10px;
    gap: 0;
    transform: translateY(-100%);
    opacity: 0;
    visibility: hidden;
    transition: all var(--transition);
    border-bottom: 1px solid rgba(255,255,255,0.1);
  }

  .nav.open {
    transform: translateY(0);
    opacity: 1;
    visibility: visible;
  }

  .nav a { padding: 12px 14px; width: 100%; height: auto; border-bottom: none; border-radius: 6px; }
  .nav a:hover, .nav a.active { border-bottom: none; }

  .nav-dropdown-content {
    position: static;
    transform: none;
    box-shadow: none;
    background: rgba(0,0,0,0.08);
    margin-top: 4px;
    display: none;
  }
  .nav-dropdown.open .nav-dropdown-content { display: block; }

  .hero { padding: 80px 0 50px; }
  .hero-title { font-size: 1.7rem; }
  .hero-subtitle { font-size: 0.95rem; }
  .hero-stats { gap: 20px; flex-wrap: wrap; }
  .hero-stat .num { font-size: 1.3rem; }

  .section { padding: 44px 0; }
  .section-title { font-size: 1.5rem; }
  .download-grid { grid-template-columns: 1fr; }
  .feature-grid { grid-template-columns: 1fr; }
  .article { padding: 22px 16px; }
  .page-hero h1 { font-size: 1.5rem; }
  .sidebar { grid-template-columns: 1fr; }
  .req-grid { grid-template-columns: 1fr; }
  .footer-grid { grid-template-columns: 1fr; gap: 20px; }
  .footer-bottom { flex-direction: column; text-align: center; }
  .hero-buttons { flex-direction: column; align-items: center; }
  .hero-buttons .btn { width: 100%; max-width: 320px; }
}

@media (max-width: 480px) {
  html { font-size: 15px; }
  .container { padding: 0 14px; }
  .hero-title { font-size: 1.5rem; }
  .btn-lg { padding: 13px 24px; font-size: 0.95rem; }
}