/* ===== RESET & BASE ===== */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; font-size: 16px; }
body { font-family: 'Segoe UI', system-ui, -apple-system, sans-serif; background: #f8f9fa; color: #2d3436; line-height: 1.6; }
a { text-decoration: none; color: inherit; }
img { max-width: 100%; display: block; }

/* ===== VARIABLES ===== */
:root {
  --primary: #1a1a2e;
  --secondary: #16213e;
  --accent: #4a9ede;
  --accent-dark: #2980b9;
  --green: #00b894;
  --light: #f8f9fa;
  --white: #ffffff;
  --gray: #636e72;
  --gray-light: #dfe6e9;
  --shadow: 0 4px 20px rgba(0,0,0,0.1);
  --shadow-lg: 0 8px 40px rgba(0,0,0,0.15);
  --radius: 12px;
  --radius-sm: 8px;
}

/* ===== HEADER / NAV ===== */
.site-header {
  position: sticky; top: 0; z-index: 100;
  background: var(--primary);
  box-shadow: 0 2px 12px rgba(0,0,0,0.3);
}
.nav-container {
  max-width: 1200px; margin: 0 auto;
  padding: 0 24px;
  display: flex; align-items: center; justify-content: space-between;
  height: 64px;
}
.nav-logo {
  display: flex; align-items: center; gap: 10px;
  font-size: 1.25rem; font-weight: 700; color: var(--white);
}
.nav-logo .logo-icon {
  width: 36px; height: 36px; background: var(--accent);
  border-radius: 8px; display: flex; align-items: center; justify-content: center;
  font-size: 1.1rem;
}
.nav-links { display: flex; align-items: center; gap: 8px; }
.nav-links a {
  color: rgba(255,255,255,0.85);
  padding: 8px 14px; border-radius: 6px;
  font-size: 0.9rem; font-weight: 500;
  transition: all 0.2s;
}
.nav-links a:hover { color: #fff; background: rgba(255,255,255,0.1); }
.nav-links a.active { color: #fff; background: var(--accent); }
.nav-cta {
  background: var(--accent) !important; color: #fff !important;
  padding: 8px 18px !important; border-radius: 20px !important;
}
.nav-cta:hover { background: var(--accent-dark) !important; }
.nav-toggle { display: none; flex-direction: column; gap: 5px; cursor: pointer; padding: 8px; }
.nav-toggle span { width: 22px; height: 2px; background: #fff; border-radius: 2px; transition: 0.3s; }

/* ===== HERO ===== */
.hero {
  background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 50%, #0f3460 100%);
  padding: 60px 24px 80px;
  text-align: center; color: #fff;
  position: relative; overflow: hidden;
}
.hero::before {
  content: ''; position: absolute; inset: 0;
  background: radial-gradient(circle at 70% 50%, rgba(74,158,222,0.15) 0%, transparent 60%);
}
.hero-content { max-width: 800px; margin: 0 auto; position: relative; }
.hero-badge {
  display: inline-flex; align-items: center; gap: 6px;
  background: rgba(74,158,222,0.2); border: 1px solid rgba(74,158,222,0.4);
  color: #7ecbf0; padding: 6px 16px; border-radius: 20px;
  font-size: 0.8rem; font-weight: 600; letter-spacing: 0.05em; text-transform: uppercase;
  margin-bottom: 20px;
}
.hero h1 { font-size: clamp(2rem, 5vw, 3.2rem); font-weight: 800; line-height: 1.2; margin-bottom: 18px; }
.hero h1 span { color: var(--accent); }
.hero p { font-size: 1.1rem; color: rgba(255,255,255,0.8); max-width: 580px; margin: 0 auto 30px; }
.hero-btns { display: flex; gap: 12px; justify-content: center; flex-wrap: wrap; }
.btn-primary {
  background: var(--accent); color: #fff; border: none;
  padding: 14px 28px; border-radius: 30px; font-size: 1rem; font-weight: 600;
  cursor: pointer; transition: all 0.2s; display: inline-flex; align-items: center; gap: 8px;
}
.btn-primary:hover { background: var(--accent-dark); transform: translateY(-2px); box-shadow: 0 6px 20px rgba(74,158,222,0.4); }
.btn-secondary {
  background: transparent; color: #fff;
  border: 2px solid rgba(255,255,255,0.4);
  padding: 12px 26px; border-radius: 30px; font-size: 1rem; font-weight: 600;
  cursor: pointer; transition: all 0.2s; display: inline-flex; align-items: center; gap: 8px;
}
.btn-secondary:hover { border-color: #fff; background: rgba(255,255,255,0.1); }

/* ===== STATS BAR ===== */
.stats-bar {
  background: #fff; border-bottom: 1px solid var(--gray-light);
  padding: 20px 24px;
}
.stats-inner {
  max-width: 1200px; margin: 0 auto;
  display: flex; justify-content: center; gap: 60px; flex-wrap: wrap;
}
.stat-item { text-align: center; }
.stat-number { font-size: 1.8rem; font-weight: 800; color: var(--accent); }
.stat-label { font-size: 0.8rem; color: var(--gray); text-transform: uppercase; letter-spacing: 0.05em; }

/* ===== CALCULATOR SECTION ===== */
.calculator-section {
  max-width: 1200px; margin: 0 auto;
  padding: 60px 24px;
  display: grid; grid-template-columns: 1fr 1fr; gap: 60px; align-items: start;
}
.calc-intro h2 { font-size: 1.8rem; font-weight: 700; margin-bottom: 12px; }
.calc-intro p { color: var(--gray); margin-bottom: 20px; font-size: 1.05rem; }
.feature-list { list-style: none; display: flex; flex-direction: column; gap: 10px; }
.feature-list li {
  display: flex; align-items: center; gap: 10px;
  font-size: 0.95rem; color: #2d3436;
}
.feature-list li::before {
  content: '✓'; width: 22px; height: 22px; border-radius: 50%;
  background: #e8f5e9; color: #27ae60; font-size: 0.75rem; font-weight: 700;
  display: flex; align-items: center; justify-content: center; flex-shrink: 0;
}

/* ===== TI-84 CALCULATOR UI ===== */
.ti84-wrapper {
  display: flex; justify-content: center; align-items: flex-start;
}
.ti84-body {
  width: 280px;
  background: linear-gradient(180deg, #2a2a2a 0%, #1e1e1e 100%);
  border-radius: 12px 12px 30px 30px;
  padding: 16px 14px 24px;
  box-shadow: 0 20px 60px rgba(0,0,0,0.5), inset 0 1px 0 rgba(255,255,255,0.1);
  position: relative;
}
.ti84-screen-bezel {
  background: #111;
  border-radius: 6px;
  padding: 8px;
  margin-bottom: 12px;
  border: 2px solid #333;
}
.ti84-screen {
  background: #b8c89e;
  border-radius: 4px;
  height: 140px;
  display: flex; flex-direction: column;
  font-family: 'Courier New', monospace;
  overflow: hidden; position: relative;
}
.screen-content {
  flex: 1; padding: 6px 8px;
  display: flex; flex-direction: column; justify-content: flex-end;
  gap: 2px;
}
.screen-line {
  font-size: 0.7rem; color: #1a2a00;
  white-space: nowrap; overflow: hidden; text-overflow: ellipsis;
}
.screen-expr { font-size: 0.8rem; color: #1a2a00; text-align: right; }
.screen-result { font-size: 1.1rem; font-weight: bold; color: #0a1400; text-align: right; margin-top: 2px; }
.screen-cursor { display: inline-block; width: 8px; height: 11px; background: #1a2a00; animation: blink 1s step-end infinite; vertical-align: middle; }
@keyframes blink { 0%,100%{opacity:1} 50%{opacity:0} }
.screen-graph-canvas { position: absolute; inset: 0; }

/* Calculator brand */
.ti84-brand {
  text-align: center; padding: 4px 0 6px;
  font-size: 0.55rem; font-weight: 700; letter-spacing: 0.12em;
  color: #888; text-transform: uppercase;
}

/* Mode indicator */
.ti84-mode-row {
  display: flex; justify-content: center; gap: 8px; margin-bottom: 8px;
}
.mode-btn {
  background: none; border: 1px solid #555; color: #aaa;
  padding: 3px 10px; border-radius: 4px; font-size: 0.6rem;
  cursor: pointer; transition: all 0.2s; font-family: inherit;
}
.mode-btn.active { background: var(--accent); border-color: var(--accent); color: #fff; }

/* Keypad */
.ti84-keys { display: flex; flex-direction: column; gap: 4px; }
.key-row { display: flex; gap: 4px; justify-content: center; }
.key {
  flex: 1; min-width: 0;
  height: 26px; border: none; border-radius: 4px;
  font-size: 0.55rem; font-weight: 600; cursor: pointer;
  transition: all 0.1s; color: #fff;
  position: relative; font-family: inherit;
  display: flex; align-items: center; justify-content: center;
  text-align: center; line-height: 1.2;
  user-select: none;
}
.key:active { transform: scale(0.92); filter: brightness(1.2); }
.key.k-dark { background: #3a3a3a; }
.key.k-blue { background: #2980b9; }
.key.k-green { background: #27ae60; }
.key.k-gray { background: #555; }
.key.k-red { background: #c0392b; }
.key.k-dark:hover { background: #4a4a4a; }
.key.k-blue:hover { background: #3498db; }
.key.k-green:hover { background: #2ecc71; }
.key.k-gray:hover { background: #666; }
.key.k-red:hover { background: #e74c3c; }
.key .key-sub { display: block; font-size: 0.45rem; opacity: 0.7; }
.key-wide { flex: 2 !important; }
.key-enter { background: #c0392b !important; height: 28px !important; font-size: 0.6rem !important; }

/* ===== FEATURES GRID ===== */
.features-section { background: var(--primary); padding: 70px 24px; }
.section-header { text-align: center; margin-bottom: 48px; }
.section-header h2 { font-size: clamp(1.6rem, 3vw, 2.2rem); font-weight: 700; color: #fff; margin-bottom: 10px; }
.section-header p { color: rgba(255,255,255,0.65); font-size: 1.05rem; max-width: 560px; margin: 0 auto; }
.features-grid {
  max-width: 1200px; margin: 0 auto;
  display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px;
}
.feature-card {
  background: rgba(255,255,255,0.06); border: 1px solid rgba(255,255,255,0.1);
  border-radius: var(--radius); padding: 28px 24px;
  transition: all 0.3s;
}
.feature-card:hover { background: rgba(255,255,255,0.1); transform: translateY(-4px); border-color: rgba(74,158,222,0.3); }
.feature-icon {
  width: 48px; height: 48px; border-radius: 12px;
  background: rgba(74,158,222,0.2); display: flex; align-items: center; justify-content: center;
  font-size: 1.4rem; margin-bottom: 16px;
}
.feature-card h3 { font-size: 1rem; font-weight: 600; color: #fff; margin-bottom: 8px; }
.feature-card p { font-size: 0.875rem; color: rgba(255,255,255,0.6); line-height: 1.6; }

/* ===== HOW IT WORKS ===== */
.how-section { padding: 70px 24px; background: #fff; }
.how-inner { max-width: 900px; margin: 0 auto; }
.how-header { text-align: center; margin-bottom: 48px; }
.how-header h2 { font-size: clamp(1.6rem, 3vw, 2.2rem); font-weight: 700; margin-bottom: 10px; }
.how-header p { color: var(--gray); }
.steps-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 32px; }
.step { text-align: center; padding: 20px; }
.step-num {
  width: 56px; height: 56px; border-radius: 50%;
  background: linear-gradient(135deg, var(--accent), var(--accent-dark));
  color: #fff; font-size: 1.3rem; font-weight: 800;
  display: flex; align-items: center; justify-content: center; margin: 0 auto 16px;
  box-shadow: 0 4px 16px rgba(74,158,222,0.4);
}
.step h3 { font-size: 1.05rem; font-weight: 600; margin-bottom: 8px; }
.step p { font-size: 0.875rem; color: var(--gray); }

/* ===== USE CASES ===== */
.usecases-section { padding: 70px 24px; background: var(--light); }
.usecases-inner { max-width: 1200px; margin: 0 auto; }
.usecases-header { text-align: center; margin-bottom: 48px; }
.usecases-header h2 { font-size: clamp(1.6rem, 3vw, 2.2rem); font-weight: 700; margin-bottom: 10px; }
.usecases-header p { color: var(--gray); }
.usecases-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 20px; }
.usecase-card {
  background: #fff; border-radius: var(--radius); padding: 24px 20px;
  text-align: center; box-shadow: var(--shadow); transition: transform 0.2s;
}
.usecase-card:hover { transform: translateY(-4px); }
.usecase-icon { font-size: 2.2rem; margin-bottom: 12px; }
.usecase-card h3 { font-size: 0.95rem; font-weight: 600; margin-bottom: 8px; }
.usecase-card p { font-size: 0.825rem; color: var(--gray); }

/* ===== FAQ ===== */
.faq-section { padding: 70px 24px; background: #fff; }
.faq-inner { max-width: 780px; margin: 0 auto; }
.faq-header { text-align: center; margin-bottom: 48px; }
.faq-header h2 { font-size: clamp(1.6rem, 3vw, 2.2rem); font-weight: 700; margin-bottom: 10px; }
.faq-item { border-bottom: 1px solid var(--gray-light); }
.faq-q {
  width: 100%; background: none; border: none; text-align: left;
  padding: 20px 0; font-size: 1rem; font-weight: 600; cursor: pointer;
  display: flex; justify-content: space-between; align-items: center;
  gap: 16px; color: #2d3436; font-family: inherit;
}
.faq-q .faq-arrow { font-size: 0.8rem; color: var(--accent); transition: transform 0.3s; flex-shrink: 0; }
.faq-q.open .faq-arrow { transform: rotate(180deg); }
.faq-a { display: none; padding-bottom: 18px; font-size: 0.9rem; color: var(--gray); line-height: 1.7; }
.faq-a.open { display: block; }

/* ===== BLOG SECTION (homepage) ===== */
.blog-section { padding: 70px 24px; background: var(--light); }
.blog-inner { max-width: 1200px; margin: 0 auto; }
.blog-header { text-align: center; margin-bottom: 48px; }
.blog-header h2 { font-size: clamp(1.6rem, 3vw, 2.2rem); font-weight: 700; margin-bottom: 10px; }
.blog-header p { color: var(--gray); }
.blog-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px; margin-bottom: 36px; }
.blog-card {
  background: #fff; border-radius: var(--radius); overflow: hidden;
  box-shadow: var(--shadow); transition: all 0.3s;
}
.blog-card:hover { transform: translateY(-4px); box-shadow: var(--shadow-lg); }
.blog-card-img {
  height: 160px;
  display: flex; align-items: center; justify-content: center;
  font-size: 3rem;
}
.blog-card-body { padding: 20px; }
.blog-tag {
  display: inline-block; background: rgba(74,158,222,0.1); color: var(--accent);
  font-size: 0.7rem; font-weight: 700; text-transform: uppercase; letter-spacing: 0.08em;
  padding: 3px 10px; border-radius: 20px; margin-bottom: 10px;
}
.blog-card h3 { font-size: 0.975rem; font-weight: 600; margin-bottom: 8px; line-height: 1.4; }
.blog-card p { font-size: 0.825rem; color: var(--gray); margin-bottom: 14px; line-height: 1.5; }
.blog-meta { font-size: 0.775rem; color: #b2bec3; display: flex; align-items: center; gap: 10px; }
.blog-read-more {
  text-align: center;
}
.btn-outline {
  display: inline-flex; align-items: center; gap: 8px;
  border: 2px solid var(--accent); color: var(--accent);
  padding: 12px 28px; border-radius: 30px; font-weight: 600; font-size: 0.95rem;
  transition: all 0.2s;
}
.btn-outline:hover { background: var(--accent); color: #fff; }

/* ===== FOOTER ===== */
.site-footer { background: var(--primary); color: rgba(255,255,255,0.7); padding: 48px 24px 24px; }
.footer-inner { max-width: 1200px; margin: 0 auto; }
.footer-grid { display: grid; grid-template-columns: 2fr 1fr 1fr 1fr; gap: 40px; margin-bottom: 40px; }
.footer-brand .nav-logo { margin-bottom: 14px; }
.footer-brand p { font-size: 0.875rem; line-height: 1.7; margin-bottom: 16px; }
.footer-col h4 { font-size: 0.85rem; font-weight: 700; color: #fff; text-transform: uppercase; letter-spacing: 0.08em; margin-bottom: 16px; }
.footer-col ul { list-style: none; display: flex; flex-direction: column; gap: 8px; }
.footer-col ul li a { font-size: 0.875rem; transition: color 0.2s; }
.footer-col ul li a:hover { color: #fff; }
.footer-bottom {
  border-top: 1px solid rgba(255,255,255,0.1); padding-top: 24px;
  display: flex; justify-content: space-between; align-items: center;
  flex-wrap: wrap; gap: 12px; font-size: 0.8rem;
}
.footer-bottom a { color: rgba(255,255,255,0.5); }
.footer-bottom a:hover { color: #fff; }

/* ===== BLOG INDEX PAGE ===== */
.page-hero {
  background: linear-gradient(135deg, var(--primary), #0f3460);
  padding: 60px 24px; text-align: center; color: #fff;
}
.page-hero h1 { font-size: clamp(1.8rem, 4vw, 2.8rem); font-weight: 800; margin-bottom: 12px; }
.page-hero p { font-size: 1.05rem; color: rgba(255,255,255,0.75); max-width: 540px; margin: 0 auto; }
.blog-index-section { padding: 60px 24px; }
.blog-index-inner { max-width: 1200px; margin: 0 auto; }
.blog-index-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 28px; }
.blog-index-card {
  background: #fff; border-radius: var(--radius); overflow: hidden;
  box-shadow: var(--shadow); transition: all 0.3s;
}
.blog-index-card:hover { transform: translateY(-4px); box-shadow: var(--shadow-lg); }
.blog-index-card .card-img {
  height: 200px;
  display: flex; align-items: center; justify-content: center;
  font-size: 4rem;
}
.blog-index-card .card-body { padding: 24px; }
.blog-index-card h2 { font-size: 1.1rem; font-weight: 700; margin-bottom: 10px; line-height: 1.4; }
.blog-index-card p { font-size: 0.875rem; color: var(--gray); margin-bottom: 16px; line-height: 1.6; }
.read-more-link {
  display: inline-flex; align-items: center; gap: 6px;
  color: var(--accent); font-size: 0.875rem; font-weight: 600;
  transition: gap 0.2s;
}
.read-more-link:hover { gap: 10px; }

/* ===== BLOG POST PAGE ===== */
.post-hero { background: linear-gradient(135deg, var(--primary), #0f3460); padding: 60px 24px; color: #fff; }
.post-hero-inner { max-width: 820px; margin: 0 auto; }
.post-hero .post-tag {
  display: inline-block; background: rgba(74,158,222,0.25); border: 1px solid rgba(74,158,222,0.5);
  color: #7ecbf0; padding: 4px 14px; border-radius: 20px; font-size: 0.75rem;
  font-weight: 700; text-transform: uppercase; letter-spacing: 0.08em; margin-bottom: 16px;
}
.post-hero h1 { font-size: clamp(1.6rem, 4vw, 2.4rem); font-weight: 800; line-height: 1.3; margin-bottom: 16px; }
.post-hero .post-meta { display: flex; align-items: center; gap: 20px; font-size: 0.875rem; color: rgba(255,255,255,0.6); flex-wrap: wrap; }
.post-body { max-width: 820px; margin: 0 auto; padding: 48px 24px 60px; }
.post-body h2 { font-size: 1.5rem; font-weight: 700; margin: 36px 0 14px; color: var(--primary); }
.post-body h3 { font-size: 1.15rem; font-weight: 600; margin: 28px 0 10px; }
.post-body p { font-size: 1rem; line-height: 1.8; color: #2d3436; margin-bottom: 18px; }
.post-body ul, .post-body ol { padding-left: 24px; margin-bottom: 18px; }
.post-body li { font-size: 1rem; line-height: 1.8; color: #2d3436; margin-bottom: 6px; }
.post-body strong { color: var(--primary); }
.post-tip {
  background: rgba(74,158,222,0.08); border-left: 4px solid var(--accent);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  padding: 16px 20px; margin: 24px 0;
}
.post-tip strong { color: var(--accent-dark); }
.post-tip p { margin: 0; font-size: 0.9rem; }
.post-cta {
  background: linear-gradient(135deg, var(--primary), #0f3460);
  border-radius: var(--radius); padding: 32px; text-align: center;
  color: #fff; margin-top: 40px;
}
.post-cta h3 { font-size: 1.3rem; margin-bottom: 10px; }
.post-cta p { font-size: 0.9rem; color: rgba(255,255,255,0.75); margin-bottom: 20px; }
.post-nav {
  display: flex; justify-content: space-between; align-items: center;
  padding: 24px 0; border-top: 1px solid var(--gray-light); margin-top: 40px;
  flex-wrap: wrap; gap: 12px;
}
.post-nav a { display: inline-flex; align-items: center; gap: 6px; color: var(--accent); font-weight: 600; font-size: 0.9rem; }

/* ===== BREADCRUMB ===== */
.breadcrumb {
  max-width: 1200px; margin: 0 auto; padding: 12px 24px;
  font-size: 0.8rem; color: var(--gray);
  display: flex; align-items: center; gap: 6px;
}
.breadcrumb a { color: var(--accent); }
.breadcrumb span { color: #b2bec3; }

/* ===== ABOUT / EXPLAINER ===== */
.about-section { padding: 70px 24px; background: #fff; }
.about-inner { max-width: 1100px; margin: 0 auto; display: grid; grid-template-columns: 1fr 1fr; gap: 60px; align-items: center; }
.about-text h2 { font-size: clamp(1.6rem, 3vw, 2.2rem); font-weight: 700; margin-bottom: 16px; }
.about-text p { font-size: 1rem; color: var(--gray); line-height: 1.8; margin-bottom: 14px; }
.about-text p strong { color: var(--primary); }
.about-highlights { display: flex; flex-direction: column; gap: 16px; }
.highlight-item { display: flex; gap: 14px; align-items: flex-start; }
.highlight-icon { width: 44px; height: 44px; border-radius: 10px; background: rgba(74,158,222,0.1); display: flex; align-items: center; justify-content: center; font-size: 1.2rem; flex-shrink: 0; }
.highlight-text h4 { font-size: 0.95rem; font-weight: 600; margin-bottom: 4px; }
.highlight-text p { font-size: 0.85rem; color: var(--gray); line-height: 1.6; margin: 0; }

/* ===== Q&A SECTION ===== */
.qa-section { padding: 70px 24px; background: var(--light); }
.qa-inner { max-width: 1000px; margin: 0 auto; }
.qa-header { text-align: center; margin-bottom: 48px; }
.qa-header h2 { font-size: clamp(1.6rem, 3vw, 2.2rem); font-weight: 700; margin-bottom: 10px; }
.qa-header p { color: var(--gray); }
.qa-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 28px; }
.qa-card { background: #fff; border-radius: var(--radius); padding: 28px 24px; box-shadow: var(--shadow); border-top: 3px solid var(--accent); }
.qa-card .q { font-size: 1rem; font-weight: 700; color: var(--primary); margin-bottom: 12px; display: flex; gap: 10px; align-items: flex-start; }
.qa-card .q-icon { background: var(--accent); color: #fff; width: 22px; height: 22px; border-radius: 50%; font-size: 0.7rem; font-weight: 800; display: flex; align-items: center; justify-content: center; flex-shrink: 0; margin-top: 2px; }
.qa-card .a { font-size: 0.9rem; color: var(--gray); line-height: 1.7; }
.qa-card .a strong { color: var(--primary); }

/* ===== FUNCTIONS TABLE ===== */
.functions-section { padding: 70px 24px; background: var(--primary); }
.functions-inner { max-width: 1100px; margin: 0 auto; }
.functions-header { text-align: center; margin-bottom: 48px; }
.functions-header h2 { font-size: clamp(1.6rem, 3vw, 2.2rem); font-weight: 700; color: #fff; margin-bottom: 10px; }
.functions-header p { color: rgba(255,255,255,0.65); }
.functions-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 20px; }
.fn-category { background: rgba(255,255,255,0.07); border: 1px solid rgba(255,255,255,0.12); border-radius: var(--radius); padding: 22px 18px; }
.fn-category h3 { font-size: 0.8rem; font-weight: 700; color: var(--accent); text-transform: uppercase; letter-spacing: 0.08em; margin-bottom: 14px; border-bottom: 1px solid rgba(255,255,255,0.1); padding-bottom: 8px; }
.fn-list { list-style: none; display: flex; flex-direction: column; gap: 6px; }
.fn-list li { font-size: 0.82rem; color: rgba(255,255,255,0.75); display: flex; align-items: center; gap: 7px; }
.fn-list li::before { content: ''; width: 5px; height: 5px; border-radius: 50%; background: var(--accent); flex-shrink: 0; }

/* ===== TIPS SECTION ===== */
.tips-section { padding: 70px 24px; background: #fff; }
.tips-inner { max-width: 1100px; margin: 0 auto; }
.tips-header { text-align: center; margin-bottom: 48px; }
.tips-header h2 { font-size: clamp(1.6rem, 3vw, 2.2rem); font-weight: 700; margin-bottom: 10px; }
.tips-header p { color: var(--gray); }
.tips-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px; }
.tip-card { border: 1px solid var(--gray-light); border-radius: var(--radius); padding: 24px; position: relative; transition: all 0.2s; }
.tip-card:hover { border-color: var(--accent); box-shadow: var(--shadow); }
.tip-num { position: absolute; top: -14px; left: 20px; background: var(--accent); color: #fff; font-size: 0.75rem; font-weight: 800; padding: 4px 12px; border-radius: 12px; }
.tip-card h3 { font-size: 0.95rem; font-weight: 700; margin-bottom: 10px; margin-top: 4px; }
.tip-card p { font-size: 0.875rem; color: var(--gray); line-height: 1.7; }
.tip-card code { background: rgba(74,158,222,0.1); color: var(--accent-dark); padding: 1px 6px; border-radius: 4px; font-size: 0.8rem; }

/* ===== CTA BANNER ===== */
.cta-banner { background: linear-gradient(135deg, var(--accent) 0%, var(--accent-dark) 100%); padding: 60px 24px; text-align: center; }
.cta-banner h2 { font-size: clamp(1.6rem, 3vw, 2.2rem); font-weight: 800; color: #fff; margin-bottom: 12px; }
.cta-banner p { color: rgba(255,255,255,0.85); font-size: 1.05rem; max-width: 500px; margin: 0 auto 28px; }
.cta-banner .btn-white { background: #fff; color: var(--accent-dark); padding: 14px 32px; border-radius: 30px; font-weight: 700; font-size: 1rem; display: inline-flex; align-items: center; gap: 8px; transition: all 0.2s; }
.cta-banner .btn-white:hover { transform: translateY(-2px); box-shadow: 0 8px 24px rgba(0,0,0,0.2); }

/* ===== RESPONSIVE ===== */
@media (max-width: 1024px) {
  .calculator-section { grid-template-columns: 1fr; }
  .features-grid { grid-template-columns: repeat(2, 1fr); }
  .footer-grid { grid-template-columns: 1fr 1fr; }
  .usecases-grid { grid-template-columns: repeat(2, 1fr); }
  .about-inner { grid-template-columns: 1fr; gap: 36px; }
  .qa-grid { grid-template-columns: 1fr; }
  .functions-grid { grid-template-columns: repeat(2, 1fr); }
  .tips-grid { grid-template-columns: repeat(2, 1fr); }
}
@media (max-width: 768px) {
  .nav-links { display: none; flex-direction: column; position: absolute; top: 64px; left: 0; right: 0; background: var(--primary); padding: 16px 24px; border-top: 1px solid rgba(255,255,255,0.1); }
  .nav-links.open { display: flex; }
  .nav-toggle { display: flex; }
  .blog-grid { grid-template-columns: 1fr 1fr; }
  .blog-index-grid { grid-template-columns: 1fr 1fr; }
  .steps-grid { grid-template-columns: 1fr; }
  .features-grid { grid-template-columns: 1fr; }
  .usecases-grid { grid-template-columns: repeat(2, 1fr); }
  .stats-inner { gap: 32px; }
  .footer-grid { grid-template-columns: 1fr; gap: 24px; }
}
@media (max-width: 520px) {
  .blog-grid { grid-template-columns: 1fr; }
  .blog-index-grid { grid-template-columns: 1fr; }
  .usecases-grid { grid-template-columns: 1fr 1fr; }
  .footer-bottom { flex-direction: column; text-align: center; }
  .functions-grid { grid-template-columns: 1fr 1fr; }
  .tips-grid { grid-template-columns: 1fr; }
  .qa-grid { grid-template-columns: 1fr; }
}