/* =============================================
   RPM Calculator - Main Stylesheet
   Fonts: Syne (headings), DM Sans (body), JetBrains Mono (code)
   ============================================= */

:root {
  --primary: #E84040;
  --primary-dark: #c02828;
  --primary-light: #ff6b6b;
  --accent: #FF8C42;
  --bg: #0a0c0f;
  --bg-card: #111418;
  --bg-elevated: #181d23;
  --border: rgba(255,255,255,0.08);
  --border-strong: rgba(255,255,255,0.14);
  --text: #e8eaf0;
  --text-muted: #8a9bb0;
  --text-dim: #5a6878;
  --white: #ffffff;
  --success: #3ddc84;
  --warning: #ffd166;
  --radius: 12px;
  --radius-lg: 20px;
  --shadow: 0 4px 24px rgba(0,0,0,0.4);
  --shadow-lg: 0 12px 48px rgba(0,0,0,0.6);
  --font-head: 'Syne', sans-serif;
  --font-body: 'DM Sans', sans-serif;
  --font-mono: 'JetBrains Mono', monospace;
  --transition: 0.25s cubic-bezier(0.4,0,0.2,1);
}

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

html { scroll-behavior: smooth; }

body {
  font-family: var(--font-body);
  background: var(--bg);
  color: var(--text);
  line-height: 1.7;
  font-size: 16px;
  overflow-x: hidden;
}

/* ---- Layout ---- */
.container { max-width: 1200px; margin: 0 auto; padding: 0 24px; }

/* ---- Typography ---- */
h1,h2,h3,h4,h5 { font-family: var(--font-head); font-weight: 700; line-height: 1.15; color: var(--white); }
h1 { font-size: clamp(2.5rem, 6vw, 4.5rem); font-weight: 800; letter-spacing: -1px; }
h2 { font-size: clamp(1.8rem, 4vw, 2.8rem); font-weight: 700; }
h3 { font-size: 1.3rem; font-weight: 600; }
p { color: var(--text-muted); margin-bottom: 1rem; }
a { color: var(--primary-light); text-decoration: none; transition: color var(--transition); }
a:hover { color: var(--primary); }
strong { color: var(--text); font-weight: 600; }
code { font-family: var(--font-mono); font-size: 0.85em; background: rgba(232,64,64,0.12); color: var(--primary-light); padding: 2px 8px; border-radius: 4px; display: block; margin: 4px 0; }

.accent { color: var(--primary); }

/* ---- Buttons ---- */
.btn {
  display: inline-flex; align-items: center; gap: 8px;
  padding: 12px 28px; border-radius: 8px; font-family: var(--font-head);
  font-weight: 600; font-size: 0.95rem; cursor: pointer; border: none;
  transition: all var(--transition); text-decoration: none; letter-spacing: 0.3px;
}
.btn-primary { background: var(--primary); color: #fff; }
.btn-primary:hover { background: var(--primary-dark); color: #fff; transform: translateY(-2px); box-shadow: 0 8px 24px rgba(232,64,64,0.4); }
.btn-outline { background: transparent; color: var(--text); border: 1.5px solid var(--border-strong); }
.btn-outline:hover { border-color: var(--primary); color: var(--primary-light); background: rgba(232,64,64,0.08); }

/* ---- Header ---- */
.site-header {
  position: fixed; top: 0; left: 0; right: 0; z-index: 1000;
  background: rgba(10,12,15,0.85); backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--border);
  transition: all var(--transition);
}
.site-header.scrolled { background: rgba(10,12,15,0.97); }

.header-inner {
  display: flex; align-items: center; justify-content: space-between;
  height: 68px;
}

.logo { display: flex; align-items: center; gap: 10px; text-decoration: none; }
.logo-icon { font-size: 1.5rem; display: inline-block; animation: spin-slow 8s linear infinite; }
@keyframes spin-slow { to { transform: rotate(360deg); } }
.logo-text { font-family: var(--font-head); font-weight: 800; font-size: 1.25rem; color: var(--white); letter-spacing: -0.5px; }
.logo-accent { color: var(--primary); }

.main-nav { display: flex; align-items: center; gap: 4px; }
.nav-link { padding: 8px 14px; border-radius: 7px; font-weight: 500; color: var(--text-muted); font-size: 0.9rem; transition: all var(--transition); }
.nav-link:hover { color: var(--white); background: rgba(255,255,255,0.07); }
.nav-cta { background: var(--primary) !important; color: #fff !important; padding: 8px 18px; }
.nav-cta:hover { background: var(--primary-dark) !important; transform: translateY(-1px); }

.hamburger { display: none; flex-direction: column; gap: 5px; cursor: pointer; background: none; border: none; padding: 6px; }
.hamburger span { display: block; width: 22px; height: 2px; background: var(--text); border-radius: 2px; transition: var(--transition); }

/* ---- Hero ---- */
.hero {
  min-height: 100vh; display: flex; align-items: center;
  position: relative; overflow: hidden; padding: 100px 0 60px;
}
.hero-bg {
  position: absolute; inset: 0;
  background: radial-gradient(ellipse 60% 70% at 80% 40%, rgba(232,64,64,0.12) 0%, transparent 60%),
              radial-gradient(ellipse 40% 50% at 20% 80%, rgba(255,140,66,0.07) 0%, transparent 50%),
              linear-gradient(180deg, #0a0c0f 0%, #0d1018 100%);
}
.hero-bg::before {
  content: ''; position: absolute; inset: 0;
  background-image: radial-gradient(rgba(255,255,255,0.025) 1px, transparent 1px);
  background-size: 40px 40px;
}

.hero-content {
  position: relative; z-index: 1;
  display: grid; grid-template-columns: 1fr 1fr; gap: 60px; align-items: center;
}
.hero-badge {
  display: inline-flex; align-items: center; gap: 6px;
  background: rgba(232,64,64,0.12); border: 1px solid rgba(232,64,64,0.3);
  color: var(--primary-light); padding: 6px 14px; border-radius: 100px;
  font-size: 0.85rem; font-weight: 500; margin-bottom: 1.2rem;
}
.hero-subtitle { font-size: 1.15rem; color: var(--text-muted); margin: 1.2rem 0 2rem; max-width: 500px; }
.hero-btns { display: flex; gap: 12px; flex-wrap: wrap; margin-bottom: 2.5rem; }
.hero-stats { display: flex; gap: 32px; }
.stat { display: flex; flex-direction: column; gap: 2px; }
.stat strong { font-family: var(--font-head); font-size: 1.4rem; color: var(--white); }
.stat span { font-size: 0.8rem; color: var(--text-dim); text-transform: uppercase; letter-spacing: 1px; }

/* ---- Gauge ---- */
.hero-visual { display: flex; flex-direction: column; align-items: center; gap: 20px; }
.gauge-container { position: relative; }
.gauge { width: 280px; height: 280px; position: relative; }
.gauge-face {
  width: 100%; height: 100%; border-radius: 50%;
  background: conic-gradient(from 180deg, #1a1f2b 0deg, #111418 360deg);
  border: 2px solid var(--border-strong);
  box-shadow: 0 0 60px rgba(232,64,64,0.15), inset 0 0 40px rgba(0,0,0,0.5);
  position: relative; overflow: hidden;
}
.gauge-face::before {
  content: ''; position: absolute; inset: 8px; border-radius: 50%;
  border: 1px solid rgba(255,255,255,0.05);
}
.gauge-needle {
  position: absolute; bottom: 50%; left: 50%;
  width: 3px; height: 45%; background: linear-gradient(to top, var(--primary), #ff8888);
  transform-origin: bottom center; transform: translateX(-50%) rotate(-135deg);
  border-radius: 2px; transition: transform 1.5s cubic-bezier(0.34,1.56,0.64,1);
  box-shadow: 0 0 12px rgba(232,64,64,0.8);
}
.gauge-center {
  position: absolute; bottom: calc(50% - 8px); left: calc(50% - 8px);
  width: 16px; height: 16px; background: var(--primary); border-radius: 50%;
  box-shadow: 0 0 12px rgba(232,64,64,0.8);
}
.gauge-label {
  position: absolute; bottom: 25%; left: 50%; transform: translateX(-50%);
  font-size: 0.7rem; color: var(--text-dim); text-transform: uppercase; letter-spacing: 2px; font-family: var(--font-mono);
}
.gauge-readout {
  text-align: center;
  font-family: var(--font-head); font-size: 2.2rem; font-weight: 800; color: var(--white);
  text-shadow: 0 0 30px rgba(232,64,64,0.5);
}
.gauge-readout small { display: block; font-size: 0.85rem; color: var(--text-dim); font-weight: 400; margin-top: -6px; }

/* ---- Features Strip ---- */
.features-strip { padding: 60px 0; border-top: 1px solid var(--border); }
.features-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 20px; }
.feature-card {
  background: var(--bg-card); border: 1px solid var(--border); border-radius: var(--radius);
  padding: 28px 24px; transition: all var(--transition);
}
.feature-card:hover { border-color: rgba(232,64,64,0.3); transform: translateY(-4px); box-shadow: 0 12px 40px rgba(0,0,0,0.4); }
.feature-icon { font-size: 2rem; margin-bottom: 12px; }
.feature-card h3 { font-size: 1.05rem; margin-bottom: 8px; }
.feature-card p { font-size: 0.9rem; color: var(--text-muted); margin: 0; }

/* ---- Calculator ---- */
.calculator-section { padding: 80px 0; }
.section-header { text-align: center; margin-bottom: 48px; }
.section-header p { font-size: 1.05rem; margin-top: 10px; }

.calc-wrapper {
  background: var(--bg-card); border: 1px solid var(--border); border-radius: var(--radius-lg); overflow: hidden;
}

.calc-tabs {
  display: flex; overflow-x: auto; border-bottom: 1px solid var(--border);
  background: var(--bg-elevated); scrollbar-width: none;
}
.calc-tabs::-webkit-scrollbar { display: none; }
.tab-btn {
  flex-shrink: 0; padding: 16px 24px; background: none; border: none; color: var(--text-muted);
  font-family: var(--font-body); font-size: 0.9rem; font-weight: 500; cursor: pointer;
  border-bottom: 2px solid transparent; transition: all var(--transition); white-space: nowrap;
}
.tab-btn:hover { color: var(--text); background: rgba(255,255,255,0.04); }
.tab-btn.active { color: var(--primary-light); border-bottom-color: var(--primary); background: rgba(232,64,64,0.06); }

.tab-content { display: none; padding: 40px; }
.tab-content.active { display: block; }

.calc-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 40px; }
.calc-inputs h3 { margin-bottom: 8px; }
.calc-desc { font-size: 0.9rem; color: var(--text-muted); margin-bottom: 28px; }

.input-group { margin-bottom: 20px; }
.input-group label { display: block; font-weight: 500; font-size: 0.9rem; margin-bottom: 7px; color: var(--text); }
.input-group small { display: block; font-size: 0.8rem; color: var(--text-dim); margin-top: 5px; }

.input-row { display: flex; gap: 8px; }

input[type="number"], select {
  width: 100%; padding: 11px 14px; background: var(--bg-elevated); border: 1.5px solid var(--border);
  border-radius: 8px; color: var(--text); font-family: var(--font-body); font-size: 0.95rem;
  transition: border-color var(--transition); outline: none; -moz-appearance: textfield;
}
input[type="number"]::-webkit-outer-spin-button,
input[type="number"]::-webkit-inner-spin-button { -webkit-appearance: none; }
input[type="number"]:focus, select:focus { border-color: var(--primary); box-shadow: 0 0 0 3px rgba(232,64,64,0.12); }
select { cursor: pointer; min-width: 90px; width: auto; flex-shrink: 0; }

.radio-group { display: flex; gap: 20px; }
.radio-label { display: flex; align-items: center; gap: 7px; cursor: pointer; font-size: 0.95rem; }
.radio-label input { cursor: pointer; accent-color: var(--primary); }

.tire-size-row { display: flex; align-items: center; gap: 8px; }
.tire-size-row input { flex: 1; }
.divider { color: var(--text-muted); font-weight: 600; font-size: 1.1rem; }

.calc-btn {
  width: 100%; padding: 14px; background: var(--primary); color: #fff;
  border: none; border-radius: 8px; font-family: var(--font-head); font-size: 1rem; font-weight: 600;
  cursor: pointer; transition: all var(--transition); margin-top: 8px; letter-spacing: 0.3px;
}
.calc-btn:hover { background: var(--primary-dark); transform: translateY(-2px); box-shadow: 0 8px 24px rgba(232,64,64,0.35); }
.reset-btn {
  width: 100%; padding: 10px; background: transparent; color: var(--text-muted);
  border: 1px solid var(--border); border-radius: 8px; font-size: 0.9rem;
  cursor: pointer; transition: all var(--transition); margin-top: 8px;
}
.reset-btn:hover { border-color: var(--border-strong); color: var(--text); }

.calc-result-panel { display: flex; flex-direction: column; gap: 20px; }
.result-box {
  flex: 1; background: var(--bg-elevated); border: 1.5px solid var(--border); border-radius: var(--radius);
  padding: 32px; display: flex; align-items: center; justify-content: center; min-height: 200px;
}
.result-placeholder { text-align: center; }
.result-icon { font-size: 2.5rem; margin-bottom: 12px; opacity: 0.5; }
.result-placeholder p { color: var(--text-dim); margin: 0; }

.result-success { background: rgba(61,220,132,0.06) !important; border-color: rgba(61,220,132,0.2) !important; }
.result-value { text-align: center; width: 100%; }
.result-number { font-family: var(--font-head); font-size: 3.5rem; font-weight: 800; color: var(--success); line-height: 1; margin-bottom: 4px; }
.result-unit { font-size: 1rem; color: var(--text-muted); margin-bottom: 24px; }
.result-breakdown { text-align: left; border-top: 1px solid var(--border); padding-top: 16px; width: 100%; }
.result-breakdown h4 { font-size: 0.85rem; color: var(--text-dim); text-transform: uppercase; letter-spacing: 1px; margin-bottom: 10px; }
.breakdown-row { display: flex; justify-content: space-between; font-size: 0.9rem; padding: 4px 0; color: var(--text-muted); }
.breakdown-row span:last-child { color: var(--text); font-weight: 500; }

.formula-box {
  background: rgba(0,0,0,0.3); border: 1px solid var(--border); border-radius: var(--radius);
  padding: 20px;
}
.formula-box h4 { font-size: 0.8rem; text-transform: uppercase; letter-spacing: 1px; color: var(--text-dim); margin-bottom: 10px; }
.formula-box p { font-size: 0.85rem; margin-top: 8px; margin-bottom: 0; }

/* ---- Info Section ---- */
.info-section { padding: 80px 0; border-top: 1px solid var(--border); }
.info-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 60px; align-items: center; }
.info-content ul { list-style: none; margin: 1rem 0; }
.info-content ul li { padding: 6px 0; padding-left: 20px; position: relative; color: var(--text-muted); font-size: 0.95rem; }
.info-content ul li::before { content: '→'; position: absolute; left: 0; color: var(--primary); }
.info-image img { width: 100%; border-radius: var(--radius-lg); box-shadow: var(--shadow-lg); display: block; }
.img-caption { text-align: center; font-size: 0.8rem; color: var(--text-dim); margin-top: 10px; }

/* ---- Table Section ---- */
.table-section { padding: 80px 0; }
.table-wrapper { overflow-x: auto; border-radius: var(--radius); border: 1px solid var(--border); }
.rpm-table { width: 100%; border-collapse: collapse; }
.rpm-table th {
  background: var(--bg-elevated); padding: 14px 20px; text-align: left;
  font-family: var(--font-head); font-size: 0.85rem; font-weight: 600; color: var(--text-muted);
  text-transform: uppercase; letter-spacing: 0.8px; border-bottom: 1px solid var(--border);
}
.rpm-table td {
  padding: 14px 20px; border-bottom: 1px solid var(--border); color: var(--text-muted); font-size: 0.9rem;
}
.rpm-table td:first-child { color: var(--text); font-weight: 500; }
.rpm-table tr:last-child td { border-bottom: none; }
.rpm-table tr:hover td { background: rgba(255,255,255,0.025); }

/* ---- Use Cases ---- */
.use-cases { padding: 80px 0; border-top: 1px solid var(--border); }
.use-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px; }
.use-card { background: var(--bg-card); border: 1px solid var(--border); border-radius: var(--radius-lg); overflow: hidden; transition: all var(--transition); }
.use-card:hover { transform: translateY(-6px); box-shadow: var(--shadow-lg); border-color: var(--border-strong); }
.use-card img { width: 100%; height: 220px; object-fit: cover; display: block; }
.use-card-body { padding: 24px; }
.use-card-body h3 { margin-bottom: 8px; }
.use-card-body p { margin: 0; font-size: 0.9rem; }

/* ---- FAQ ---- */
.faq-section { padding: 80px 0; }
.faq-list { max-width: 800px; margin: 0 auto; }
.faq-item { border: 1px solid var(--border); border-radius: var(--radius); margin-bottom: 12px; overflow: hidden; }
.faq-question {
  width: 100%; display: flex; justify-content: space-between; align-items: center;
  padding: 20px 24px; background: var(--bg-card); border: none; color: var(--text);
  font-family: var(--font-body); font-size: 1rem; font-weight: 500; cursor: pointer;
  text-align: left; transition: all var(--transition); gap: 16px;
}
.faq-question:hover { background: var(--bg-elevated); }
.faq-icon { font-size: 1.4rem; color: var(--primary); flex-shrink: 0; transition: transform var(--transition); line-height: 1; }
.faq-item.open .faq-icon { transform: rotate(45deg); }
.faq-answer { display: none; padding: 20px 24px; background: var(--bg-elevated); border-top: 1px solid var(--border); }
.faq-item.open .faq-answer { display: block; }
.faq-answer p { margin: 0; font-size: 0.95rem; }

/* ---- Page Hero (inner pages) ---- */
.page-hero {
  padding: 120px 0 60px; background: linear-gradient(180deg, rgba(232,64,64,0.05) 0%, transparent 100%);
  border-bottom: 1px solid var(--border); text-align: center;
}
.page-hero h1 { font-size: clamp(2rem, 5vw, 3.5rem); }
.page-hero p { max-width: 600px; margin: 1rem auto 0; font-size: 1.1rem; }
.breadcrumb { display: flex; justify-content: center; gap: 8px; margin-bottom: 20px; font-size: 0.85rem; color: var(--text-dim); }
.breadcrumb a { color: var(--text-dim); }
.breadcrumb a:hover { color: var(--primary-light); }

/* ---- Content Page ---- */
.content-page { padding: 60px 0 80px; max-width: 840px; margin: 0 auto; }
.content-page h2 { margin: 2.5rem 0 1rem; font-size: 1.6rem; }
.content-page h3 { margin: 2rem 0 0.75rem; font-size: 1.2rem; color: var(--text-muted); }
.content-page p { font-size: 0.97rem; }
.content-page ul, .content-page ol { margin: 0.75rem 0 1rem 1.5rem; color: var(--text-muted); }
.content-page li { margin-bottom: 6px; font-size: 0.95rem; }
.content-page .updated { font-size: 0.82rem; color: var(--text-dim); margin-bottom: 2rem; }

/* ---- Contact ---- */
.contact-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 48px; align-items: start; }
.contact-info-box { background: var(--bg-card); border: 1px solid var(--border); border-radius: var(--radius); padding: 32px; }
.contact-info-box h3 { margin-bottom: 20px; }
.contact-detail { display: flex; gap: 14px; align-items: flex-start; margin-bottom: 20px; }
.contact-detail-icon { font-size: 1.5rem; flex-shrink: 0; }
.contact-form-box { background: var(--bg-card); border: 1px solid var(--border); border-radius: var(--radius); padding: 32px; }
.form-group { margin-bottom: 18px; }
.form-group label { display: block; font-weight: 500; font-size: 0.9rem; margin-bottom: 7px; }
.form-group input, .form-group textarea, .form-group select {
  width: 100%; padding: 11px 14px; background: var(--bg-elevated); border: 1.5px solid var(--border);
  border-radius: 8px; color: var(--text); font-family: var(--font-body); font-size: 0.95rem;
  transition: border-color var(--transition); outline: none;
}
.form-group textarea { resize: vertical; min-height: 120px; }
.form-group input:focus, .form-group textarea:focus { border-color: var(--primary); box-shadow: 0 0 0 3px rgba(232,64,64,0.12); }
.form-submit { width: 100%; }
.form-success { display: none; background: rgba(61,220,132,0.1); border: 1px solid rgba(61,220,132,0.3); border-radius: 8px; padding: 16px; color: var(--success); text-align: center; margin-top: 16px; }

/* ---- Formulas Page ---- */
.formula-grid { display: grid; grid-template-columns: repeat(2,1fr); gap: 24px; }
.formula-card { background: var(--bg-card); border: 1px solid var(--border); border-radius: var(--radius); padding: 28px; }
.formula-card h3 { margin-bottom: 12px; font-size: 1.1rem; }
.formula-card .formula-eq { background: var(--bg-elevated); border-left: 3px solid var(--primary); padding: 14px 16px; border-radius: 0 8px 8px 0; margin: 14px 0; font-family: var(--font-mono); font-size: 0.9rem; color: var(--primary-light); }
.formula-card p { font-size: 0.88rem; margin: 0; }

/* ---- How It Works ---- */
.steps-grid { display: grid; grid-template-columns: repeat(3,1fr); gap: 28px; }
.step-card { background: var(--bg-card); border: 1px solid var(--border); border-radius: var(--radius); padding: 32px 28px; position: relative; }
.step-number { font-family: var(--font-head); font-size: 3rem; font-weight: 800; color: rgba(232,64,64,0.2); line-height: 1; margin-bottom: 12px; }
.step-card h3 { margin-bottom: 10px; }

/* ---- Footer ---- */
.site-footer { background: #060809; border-top: 1px solid var(--border); padding: 64px 0 0; }
.footer-top { display: grid; grid-template-columns: 2fr 1fr 1fr 1fr; gap: 40px; padding-bottom: 48px; }
.footer-brand .footer-tagline { font-size: 0.88rem; color: var(--text-dim); margin: 14px 0 20px; max-width: 280px; }
.footer-contact { display: flex; flex-direction: column; gap: 10px; }
.contact-email {
  display: inline-flex; align-items: center; gap: 8px; color: var(--text-muted); font-size: 0.9rem;
  padding: 9px 14px; background: var(--bg-card); border: 1px solid var(--border); border-radius: 8px;
  transition: all var(--transition);
}
.contact-email:hover { border-color: var(--primary); color: var(--primary-light); }
.contact-email svg { width: 16px; height: 16px; }
.footer-logo { margin-bottom: 12px; }
.footer-links-group h4 { font-family: var(--font-head); font-size: 0.85rem; text-transform: uppercase; letter-spacing: 1px; color: var(--text-dim); margin-bottom: 16px; }
.footer-links-group ul { list-style: none; }
.footer-links-group ul li { margin-bottom: 10px; }
.footer-links-group ul a { color: var(--text-dim); font-size: 0.9rem; transition: color var(--transition); }
.footer-links-group ul a:hover { color: var(--primary-light); }
.footer-bottom {
  border-top: 1px solid var(--border); padding: 20px 0;
  display: flex; justify-content: space-between; align-items: center; flex-wrap: wrap; gap: 10px;
}
.footer-bottom p { font-size: 0.82rem; color: var(--text-dim); margin: 0; }

/* ---- Sitemap ---- */
.sitemap-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 32px; }
.sitemap-section h3 { font-size: 1rem; margin-bottom: 14px; color: var(--primary-light); }
.sitemap-section ul { list-style: none; }
.sitemap-section ul li { margin-bottom: 8px; }
.sitemap-section ul a { color: var(--text-muted); font-size: 0.9rem; }
.sitemap-section ul a:hover { color: var(--primary-light); }

/* ---- Utility ---- */
.divider-line { height: 1px; background: var(--border); margin: 60px 0; }
.text-center { text-align: center; }
.mt-2 { margin-top: 2rem; }
.alert { padding: 16px 20px; border-radius: 8px; margin-bottom: 20px; font-size: 0.9rem; }
.alert-info { background: rgba(255,140,66,0.1); border: 1px solid rgba(255,140,66,0.3); color: var(--accent); }

/* ---- Responsive ---- */
@media (max-width: 1024px) {
  .features-grid { grid-template-columns: repeat(2,1fr); }
  .footer-top { grid-template-columns: 1fr 1fr; gap: 32px; }
  .formula-grid { grid-template-columns: 1fr; }
}

@media (max-width: 768px) {
  .hero-content { grid-template-columns: 1fr; gap: 40px; text-align: center; }
  .hero-subtitle { margin-left: auto; margin-right: auto; }
  .hero-btns { justify-content: center; }
  .hero-stats { justify-content: center; }
  .hero-visual { display: none; }
  .main-nav { display: none; flex-direction: column; position: absolute; top: 68px; left: 0; right: 0; background: var(--bg); border-bottom: 1px solid var(--border); padding: 16px; gap: 4px; }
  .main-nav.open { display: flex; }
  .hamburger { display: flex; }
  .calc-grid { grid-template-columns: 1fr; }
  .info-grid { grid-template-columns: 1fr; }
  .use-grid { grid-template-columns: 1fr; }
  .contact-grid { grid-template-columns: 1fr; }
  .steps-grid { grid-template-columns: 1fr; }
  .sitemap-grid { grid-template-columns: 1fr 1fr; }
  .footer-top { grid-template-columns: 1fr 1fr; }
  .footer-bottom { flex-direction: column; text-align: center; }
  .tab-content { padding: 24px 16px; }
}

@media (max-width: 480px) {
  .features-grid { grid-template-columns: 1fr; }
  .sitemap-grid { grid-template-columns: 1fr; }
  .footer-top { grid-template-columns: 1fr; }
  h1 { font-size: 2.2rem; }
}