@import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600;700&display=swap');

:root {
  --brand: #0070f3;
  --brand-dark: #0057c2;
  --brand-light: #e8f0fe;
  --surface: #ffffff;
  --surface-2: #f7f8fa;
  --surface-3: #f0f2f5;
  --border: #e4e6ea;
  --border-strong: #c8cbd0;
  --text: #111214;
  --text-secondary: #5a5f6a;
  --text-muted: #8c909a;
  --radius: 10px;
  --shadow-sm: 0 1px 3px rgba(0,0,0,0.08), 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);
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
  background-color: var(--surface-2);
  color: var(--text);
  min-height: 100vh;
  -webkit-font-smoothing: antialiased;
}

/* ── Header ── */
.logo-header {
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 0 24px;
  height: 60px;
  width: 100%;
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  z-index: 100;
}

.logo-img {
  height: 28px;
  display: block;
}

/* ── Container ── */
.container {
  max-width: 720px;
  margin: 40px auto;
  padding: 36px 40px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow-md);
}

/* ── Heading ── */
h1 {
  font-size: 20px;
  font-weight: 600;
  color: var(--text);
  border-bottom: 1px solid var(--border);
  padding-bottom: 16px;
  text-align: center;
  margin: 0 0 28px;
  letter-spacing: -0.3px;
}

/* ── Label ── */
label {
  display: block;
  font-weight: 500;
  font-size: 13px;
  color: var(--text-secondary);
  margin-bottom: 6px;
  margin-top: 20px;
}

/* ── Input ── */
input[type="text"],
input[type="number"] {
  width: 100%;
  padding: 10px 14px;
  background: var(--surface);
  border: 1px solid var(--border-strong);
  border-radius: 8px;
  font-family: 'SFMono-Regular', 'Consolas', 'Liberation Mono', monospace;
  font-size: 13px;
  color: var(--text);
  transition: border-color 0.15s, box-shadow 0.15s;
  outline: none;
  letter-spacing: 0.02em;
}

input[type="text"]:hover,
input[type="number"]:hover {
  border-color: #a0a4ad;
}

input[type="text"]:focus,
input[type="number"]:focus {
  border-color: var(--brand);
  box-shadow: 0 0 0 3px rgba(0, 112, 243, 0.12);
}

input[type="text"]::placeholder,
input[type="number"]::placeholder {
  color: var(--text-muted);
}

/* ── Button ── */
button,
.btn {
  display: block;
  margin: 24px auto 0;
  width: 100%;
  padding: 11px 20px;
  background: var(--brand);
  color: #fff;
  border: none;
  border-radius: 8px;
  font-family: inherit;
  font-size: 14px;
  font-weight: 600;
  letter-spacing: 0.3px;
  cursor: pointer;
  transition: background 0.15s, transform 0.1s, box-shadow 0.15s;
  text-decoration: none;
  text-align: center;
}

button:hover,
.btn:hover {
  background: var(--brand-dark);
  box-shadow: 0 2px 8px rgba(0, 112, 243, 0.3);
}

button:active,
.btn:active {
  transform: scale(0.99);
}

/* ── Slider ── */
.slider-container {
  margin-top: 20px;
}

.slider-label {
  display: flex;
  justify-content: space-between;
  font-size: 12px;
  color: var(--text-muted);
  margin-bottom: 6px;
}

input[type="range"] {
  width: 100%;
  accent-color: var(--brand);
  cursor: pointer;
}

.value-display {
  text-align: right;
  font-size: 13px;
  color: var(--brand);
  margin-top: 4px;
  font-weight: 500;
}

/* ── SEO Section ── */
.seo-section {
  max-width: 680px;
  margin: 48px auto;
  padding: 0 20px;
  font-family: 'Inter', sans-serif;
  line-height: 1.75;
  color: var(--text-secondary);
}

.seo-section h2,
.seo-section h3 {
  color: var(--text);
  font-weight: 600;
  margin-top: 32px;
  margin-bottom: 10px;
  font-size: 16px;
}

.seo-section p {
  margin-bottom: 14px;
  font-size: 14px;
}

.seo-section ul {
  padding-left: 20px;
  margin-bottom: 14px;
}

.seo-section ul li {
  margin-bottom: 6px;
  font-size: 14px;
  color: var(--text-secondary);
}

.seo-section ul li::marker {
  color: var(--brand);
}

.seo-section strong {
  color: var(--text);
}

/* ── Result box ── */
.result-box {
  margin-top: 20px;
  font-size: 15px;
  color: var(--text);
}

/* ── Info block ── */
.info-block {
  max-width: 520px;
  margin: 28px auto;
  padding: 18px 24px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow-sm);
}

.info-block .label {
  font-weight: 600;
  font-size: 11px;
  text-transform: uppercase;
  letter-spacing: 0.7px;
  color: var(--text-muted);
  margin-bottom: 8px;
}

.info-block .value p {
  margin: 5px 0;
  font-size: 14px;
  color: var(--text-secondary);
}

.info-block a {
  color: var(--brand);
  text-decoration: none;
}

.info-block a:hover {
  text-decoration: underline;
}

/* ── Footer ── */
.footer {
  margin: 48px auto 0;
  padding-bottom: 40px;
  font-size: 13px;
  text-align: center;
  color: var(--text-muted);
  max-width: 680px;
}

/* ── Mobile ── */
@media (max-width: 600px) {
  .container {
    margin: 12px;
    padding: 24px 20px;
  }

  .seo-section {
    padding: 0 16px;
  }
}