/* =============================================
   Inverse Function Calculator — Main Stylesheet
   ============================================= */

:root {
  --bg: #0a0e1a;
  --bg2: #0f1628;
  --bg3: #141d35;
  --surface: #192040;
  --surface2: #1e2850;
  --border: #2a3560;
  --border2: #354080;
  --accent: #4f8ef7;
  --accent2: #7cb3ff;
  --accent-glow: rgba(79,142,247,0.18);
  --orange: #f97316;
  --orange-light: #fb923c;
  --text: #e8edf8;
  --text2: #9ba8c8;
  --text3: #6b7aa0;
  --green: #22c55e;
  --red: #ef4444;
  --radius: 14px;
  --radius-sm: 8px;
  --shadow: 0 8px 40px rgba(0,0,0,0.5);
  --shadow-sm: 0 2px 12px rgba(0,0,0,0.3);
  --font-display: 'DM Serif Display', Georgia, serif;
  --font-body: 'DM Sans', sans-serif;
  --font-mono: 'DM Mono', 'Fira Mono', monospace;
}

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

html { scroll-behavior: smooth; }

body {
  background: var(--bg);
  color: var(--text);
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.65;
  min-height: 100vh;
}

.container {
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 24px;
}

/* ── NAV ─────────────────────────────── */
.nav {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(10,14,26,0.92);
  backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--border);
}

.nav-inner {
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 24px;
  height: 64px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.logo {
  display: flex;
  align-items: center;
  gap: 10px;
  text-decoration: none;
  color: var(--text);
}

.logo-icon {
  font-family: var(--font-display);
  font-size: 1.5rem;
  color: var(--accent);
  line-height: 1;
}

.logo-text {
  font-weight: 600;
  font-size: 1.05rem;
  letter-spacing: -0.01em;
}

.nav-links {
  list-style: none;
  display: flex;
  gap: 4px;
}

.nav-links a {
  text-decoration: none;
  color: var(--text2);
  font-size: 0.92rem;
  font-weight: 500;
  padding: 6px 14px;
  border-radius: 8px;
  transition: all 0.2s;
}

.nav-links a:hover,
.nav-links a.active {
  color: var(--text);
  background: var(--surface);
}

/* ── HERO ─────────────────────────────── */
.hero {
  position: relative;
  padding: 80px 0 64px;
  text-align: center;
  overflow: hidden;
}

.hero-bg-grid {
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(var(--border) 1px, transparent 1px),
    linear-gradient(90deg, var(--border) 1px, transparent 1px);
  background-size: 48px 48px;
  opacity: 0.25;
  mask-image: radial-gradient(ellipse 80% 60% at 50% 50%, black 40%, transparent 100%);
}

.hero::after {
  content: '';
  position: absolute;
  top: -120px; left: 50%;
  transform: translateX(-50%);
  width: 600px; height: 600px;
  background: radial-gradient(circle, rgba(79,142,247,0.12) 0%, transparent 70%);
  pointer-events: none;
}

.hero-badge {
  display: inline-block;
  background: var(--surface);
  border: 1px solid var(--border2);
  color: var(--accent2);
  font-size: 0.78rem;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  padding: 5px 14px;
  border-radius: 999px;
  margin-bottom: 24px;
}

.hero-title {
  font-family: var(--font-display);
  font-size: clamp(2.6rem, 6vw, 4.2rem);
  line-height: 1.1;
  color: var(--text);
  margin-bottom: 20px;
}

.hero-title em {
  font-style: italic;
  color: var(--accent);
}

.hero-sub {
  max-width: 560px;
  margin: 0 auto;
  color: var(--text2);
  font-size: 1.05rem;
}

/* ── MAIN ─────────────────────────────── */
.main-content {
  padding: 0 0 80px;
}

/* ── TOOL CARD ────────────────────────── */
.tool-card {
  background: var(--bg2);
  border: 1px solid var(--border);
  border-radius: 20px;
  overflow: hidden;
  margin-bottom: 64px;
  box-shadow: var(--shadow);
}

.tool-header {
  background: var(--bg3);
  border-bottom: 1px solid var(--border);
  padding: 28px 36px;
}

.tool-header h2 {
  font-family: var(--font-display);
  font-size: 1.6rem;
  color: var(--text);
  margin-bottom: 6px;
}

.tool-header p {
  color: var(--text2);
  font-size: 0.95rem;
}

.tool-body {
  padding: 36px;
  display: flex;
  flex-direction: column;
  gap: 28px;
}

/* Input Group */
.input-group label {
  display: block;
  font-weight: 600;
  font-family: var(--font-mono);
  font-size: 0.95rem;
  color: var(--accent2);
  margin-bottom: 10px;
}

.input-row {
  display: flex;
  gap: 12px;
}

.input-row input {
  flex: 1;
  background: var(--surface);
  border: 1.5px solid var(--border);
  border-radius: var(--radius-sm);
  color: var(--text);
  font-family: var(--font-mono);
  font-size: 1.1rem;
  padding: 14px 18px;
  outline: none;
  transition: border-color 0.2s, box-shadow 0.2s;
}

.input-row input:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px var(--accent-glow);
}

.input-row input::placeholder { color: var(--text3); }

.input-hint {
  font-size: 0.82rem;
  color: var(--text3);
  margin-top: 8px;
}

.btn-calc {
  background: var(--accent);
  color: #fff;
  border: none;
  border-radius: var(--radius-sm);
  padding: 14px 24px;
  font-size: 0.95rem;
  font-weight: 600;
  font-family: var(--font-body);
  cursor: pointer;
  white-space: nowrap;
  transition: background 0.2s, transform 0.1s, box-shadow 0.2s;
  box-shadow: 0 4px 16px rgba(79,142,247,0.3);
}

.btn-calc:hover { background: var(--accent2); box-shadow: 0 6px 24px rgba(79,142,247,0.4); }
.btn-calc:active { transform: scale(0.98); }

/* Examples */
.examples-row {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 8px;
}

.examples-label {
  font-size: 0.84rem;
  color: var(--text3);
  font-weight: 500;
}

.chip {
  background: var(--surface);
  border: 1px solid var(--border);
  color: var(--text2);
  font-family: var(--font-mono);
  font-size: 0.85rem;
  padding: 5px 13px;
  border-radius: 999px;
  cursor: pointer;
  transition: all 0.18s;
}

.chip:hover {
  background: var(--surface2);
  border-color: var(--accent);
  color: var(--accent2);
}

/* Result Box */
.result-box {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  min-height: 100px;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 28px;
  transition: all 0.3s;
}

.result-placeholder {
  text-align: center;
  color: var(--text3);
}

.result-icon {
  font-family: var(--font-display);
  font-size: 2rem;
  color: var(--border2);
  display: block;
  margin-bottom: 8px;
}

.result-success {
  width: 100%;
  text-align: center;
}

.result-label {
  font-size: 0.85rem;
  color: var(--text3);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  margin-bottom: 10px;
}

.result-value {
  font-family: var(--font-display);
  font-size: clamp(1.4rem, 3vw, 2rem);
  color: var(--accent2);
  letter-spacing: -0.01em;
}

.result-domain {
  margin-top: 10px;
  font-size: 0.88rem;
  color: var(--text3);
}

.result-error {
  color: var(--red);
  text-align: center;
  font-size: 0.95rem;
}

/* Steps */
.steps-box {
  background: var(--bg3);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 28px 32px;
}

.steps-box h3 {
  font-size: 1rem;
  font-weight: 600;
  color: var(--text2);
  margin-bottom: 18px;
  text-transform: uppercase;
  letter-spacing: 0.06em;
}

.steps-list {
  list-style: none;
  counter-reset: step;
  display: flex;
  flex-direction: column;
  gap: 14px;
}

.steps-list li {
  counter-increment: step;
  display: flex;
  gap: 14px;
  align-items: flex-start;
}

.steps-list li::before {
  content: counter(step);
  min-width: 28px;
  height: 28px;
  background: var(--accent);
  color: #fff;
  border-radius: 50%;
  font-size: 0.8rem;
  font-weight: 700;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
  margin-top: 2px;
}

.steps-list li span {
  font-family: var(--font-mono);
  font-size: 0.9rem;
  color: var(--text);
  line-height: 1.6;
}

/* Graph */
.graph-section h3 {
  font-size: 1rem;
  font-weight: 600;
  color: var(--text2);
  margin-bottom: 16px;
  text-transform: uppercase;
  letter-spacing: 0.06em;
}

#graphCanvas {
  width: 100%;
  max-width: 600px;
  height: auto;
  background: var(--surface);
  border-radius: var(--radius-sm);
  border: 1px solid var(--border);
  display: block;
}

.graph-note {
  font-size: 0.82rem;
  color: var(--text3);
  margin-top: 10px;
}

/* ── INFO SECTION ────────────────────── */
.info-section { margin-bottom: 64px; }

.info-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 20px;
}

.info-card {
  background: var(--bg2);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 28px;
  transition: border-color 0.2s, transform 0.2s;
}

.info-card:hover {
  border-color: var(--accent);
  transform: translateY(-2px);
}

.info-icon {
  font-size: 2rem;
  margin-bottom: 14px;
}

.info-card h3 {
  font-size: 1.05rem;
  font-weight: 600;
  margin-bottom: 10px;
  color: var(--text);
}

.info-card p {
  color: var(--text2);
  font-size: 0.92rem;
  line-height: 1.65;
}

/* ── TABLE ───────────────────────────── */
.table-section { margin-bottom: 64px; }

.section-title {
  font-family: var(--font-display);
  font-size: 1.8rem;
  color: var(--text);
  margin-bottom: 28px;
}

.table-wrap { overflow-x: auto; }

.ref-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.92rem;
}

.ref-table th {
  background: var(--surface);
  color: var(--text2);
  font-weight: 600;
  text-align: left;
  padding: 12px 18px;
  border-bottom: 2px solid var(--border2);
  font-size: 0.82rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
}

.ref-table td {
  padding: 12px 18px;
  border-bottom: 1px solid var(--border);
  font-family: var(--font-mono);
  font-size: 0.88rem;
  color: var(--text);
}

.ref-table tr:hover td { background: var(--surface); }

.ref-table td:last-child {
  font-family: var(--font-body);
  font-size: 0.82rem;
  color: var(--text3);
}

/* ── BLOG CTA ────────────────────────── */
.blog-cta {
  background: linear-gradient(135deg, var(--surface) 0%, var(--surface2) 100%);
  border: 1px solid var(--border2);
  border-radius: 20px;
  padding: 48px;
  margin-bottom: 0;
}

.blog-cta-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 32px;
  flex-wrap: wrap;
}

.blog-cta-text h2 {
  font-family: var(--font-display);
  font-size: 1.6rem;
  margin-bottom: 8px;
}

.blog-cta-text p {
  color: var(--text2);
  max-width: 480px;
}

.btn-secondary {
  display: inline-block;
  background: transparent;
  border: 2px solid var(--accent);
  color: var(--accent2);
  padding: 14px 28px;
  border-radius: var(--radius-sm);
  text-decoration: none;
  font-weight: 600;
  font-size: 0.95rem;
  white-space: nowrap;
  transition: all 0.2s;
}

.btn-secondary:hover {
  background: var(--accent);
  color: #fff;
}

/* ── FAQ ─────────────────────────────── */
.faq-section {
  background: var(--bg2);
  border-top: 1px solid var(--border);
  padding: 80px 0;
}

.faq-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(460px, 1fr));
  gap: 16px;
}

.faq-item {
  background: var(--bg3);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  transition: border-color 0.2s;
}

.faq-item:hover { border-color: var(--border2); }

.faq-item summary {
  padding: 18px 22px;
  cursor: pointer;
  font-weight: 600;
  font-size: 0.95rem;
  color: var(--text);
  list-style: none;
  display: flex;
  justify-content: space-between;
  align-items: center;
  user-select: none;
}

.faq-item summary::after {
  content: '+';
  font-size: 1.3rem;
  color: var(--accent);
  transition: transform 0.2s;
}

.faq-item[open] summary::after { transform: rotate(45deg); }

.faq-item p {
  padding: 0 22px 18px;
  color: var(--text2);
  font-size: 0.92rem;
  line-height: 1.65;
}

/* ── FOOTER ──────────────────────────── */
.footer {
  background: var(--bg3);
  border-top: 1px solid var(--border);
  padding: 40px 0;
}

.footer-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 24px;
}

.footer-brand p {
  color: var(--text3);
  font-size: 0.84rem;
  margin-top: 6px;
}

.footer-links {
  display: flex;
  gap: 24px;
}

.footer-links a {
  color: var(--text3);
  text-decoration: none;
  font-size: 0.88rem;
  transition: color 0.2s;
}

.footer-links a:hover { color: var(--accent2); }

/* ── BLOG PAGE STYLES ────────────────── */
.blog-hero {
  padding: 64px 0 40px;
  text-align: center;
}

.blog-hero h1 {
  font-family: var(--font-display);
  font-size: clamp(2rem, 5vw, 3.2rem);
  margin-bottom: 12px;
}

.blog-hero p {
  color: var(--text2);
  max-width: 520px;
  margin: 0 auto;
}

.blog-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: 28px;
  padding-bottom: 80px;
}

.blog-card {
  background: var(--bg2);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  text-decoration: none;
  color: inherit;
  display: flex;
  flex-direction: column;
  transition: border-color 0.2s, transform 0.2s, box-shadow 0.2s;
}

.blog-card:hover {
  border-color: var(--accent);
  transform: translateY(-3px);
  box-shadow: 0 12px 40px rgba(0,0,0,0.4);
}

.blog-card-img {
  height: 180px;
  background: linear-gradient(135deg, var(--surface) 0%, var(--surface2) 100%);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 3.5rem;
}

.blog-card-body {
  padding: 24px;
  flex: 1;
  display: flex;
  flex-direction: column;
}

.blog-card-tag {
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--accent);
  margin-bottom: 10px;
}

.blog-card-title {
  font-family: var(--font-display);
  font-size: 1.2rem;
  color: var(--text);
  margin-bottom: 10px;
  line-height: 1.3;
}

.blog-card-excerpt {
  color: var(--text2);
  font-size: 0.88rem;
  line-height: 1.6;
  flex: 1;
}

.blog-card-meta {
  margin-top: 16px;
  font-size: 0.8rem;
  color: var(--text3);
  display: flex;
  gap: 12px;
}

/* ── BLOG POST ───────────────────────── */
.post-hero {
  padding: 64px 0 0;
}

.post-tag {
  display: inline-block;
  font-size: 0.78rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--accent);
  background: var(--surface);
  padding: 4px 12px;
  border-radius: 999px;
  margin-bottom: 20px;
}

.post-title {
  font-family: var(--font-display);
  font-size: clamp(2rem, 4vw, 3rem);
  line-height: 1.15;
  max-width: 760px;
  margin-bottom: 18px;
}

.post-meta {
  color: var(--text3);
  font-size: 0.87rem;
  margin-bottom: 48px;
  display: flex;
  gap: 16px;
  flex-wrap: wrap;
}

.post-meta span { display: flex; align-items: center; gap: 5px; }

.post-body {
  max-width: 760px;
  padding-bottom: 80px;
}

.post-body h2 {
  font-family: var(--font-display);
  font-size: 1.7rem;
  color: var(--text);
  margin: 48px 0 16px;
  padding-top: 16px;
  border-top: 1px solid var(--border);
}

.post-body h3 {
  font-size: 1.15rem;
  font-weight: 600;
  color: var(--text);
  margin: 32px 0 12px;
}

.post-body p {
  color: var(--text2);
  font-size: 1rem;
  line-height: 1.75;
  margin-bottom: 18px;
}

.post-body ul, .post-body ol {
  color: var(--text2);
  font-size: 1rem;
  line-height: 1.75;
  margin-bottom: 18px;
  padding-left: 24px;
}

.post-body li { margin-bottom: 6px; }

.post-body strong { color: var(--text); font-weight: 600; }

.post-body a {
  color: var(--accent2);
  text-decoration: underline;
  text-underline-offset: 3px;
}

.post-body .callout {
  background: var(--surface);
  border-left: 3px solid var(--accent);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  padding: 18px 22px;
  margin: 28px 0;
}

.post-body .callout p { margin: 0; }

.post-body code {
  font-family: var(--font-mono);
  background: var(--surface);
  padding: 2px 8px;
  border-radius: 4px;
  font-size: 0.9em;
  color: var(--accent2);
}

.post-cta {
  background: linear-gradient(135deg, var(--surface) 0%, var(--surface2) 100%);
  border: 1px solid var(--border2);
  border-radius: var(--radius);
  padding: 32px;
  margin: 48px 0;
  text-align: center;
}

.post-cta h3 {
  font-family: var(--font-display);
  font-size: 1.4rem;
  margin-bottom: 10px !important;
}

.post-cta p { margin-bottom: 20px !important; }

.btn-primary {
  display: inline-block;
  background: var(--accent);
  color: #fff;
  padding: 12px 24px;
  border-radius: var(--radius-sm);
  text-decoration: none;
  font-weight: 600;
  font-size: 0.95rem;
  transition: all 0.2s;
  box-shadow: 0 4px 16px rgba(79,142,247,0.3);
}

.btn-primary:hover { background: var(--accent2); }

/* ── RESPONSIVE ──────────────────────── */
@media (max-width: 700px) {
  .tool-header, .tool-body { padding: 20px; }
  .input-row { flex-direction: column; }
  .btn-calc { width: 100%; }
  .blog-cta-inner { flex-direction: column; text-align: center; }
  .faq-grid { grid-template-columns: 1fr; }
  .footer-inner { flex-direction: column; text-align: center; }
  .post-body { padding-bottom: 48px; }
}

/* Animations */
@keyframes fadeUp {
  from { opacity: 0; transform: translateY(16px); }
  to   { opacity: 1; transform: translateY(0); }
}

.tool-card { animation: fadeUp 0.5s ease both; }
.info-card { animation: fadeUp 0.5s ease both; }
.info-card:nth-child(2) { animation-delay: 0.1s; }
.info-card:nth-child(3) { animation-delay: 0.2s; }