@import url('https://fonts.googleapis.com/css2?family=Roboto:wght@500;700;900&display=swap');

/* ==========================================================
   BTC QR Code Generator — "Ledger Night" theme
   Headings: Roboto | Body: Arial
   Palette: ink #0d1420, panel #152033, line #24334c,
            bitcoin orange #f7931a, text #c3cee0, white #fff
   ========================================================== */

:root {
  --ink: #0d1420;
  --panel: #152033;
  --field: #0d1626;
  --line: #24334c;
  --line-strong: #2c3d59;
  --btc: #f7931a;
  --btc-light: #ffa73d;
  --btc-dark: #b86a0a;
  --text: #c3cee0;
  --muted: #8ea0b8;
  --white: #ffffff;
}

* { box-sizing: border-box; }

html { background: var(--ink); }

body {
  margin: 0;
  min-height: 100vh;
  font-family: Arial, Helvetica, sans-serif;
  font-size: 16px;
  line-height: 1.6;
  color: var(--text);
  background-color: var(--ink);
  background-image:
    radial-gradient(ellipse 60% 40% at 50% 0%, rgba(247, 147, 26, 0.16), transparent 70%),
    linear-gradient(rgba(255, 255, 255, 0.035) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255, 255, 255, 0.035) 1px, transparent 1px);
  background-size: auto, 44px 44px, 44px 44px;
  background-position: top center, -1px -1px, -1px -1px;
}

/* ---------- Header / logo ---------- */
.logo-header {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 100%;
  padding: 28px 16px 8px;
}

.logo-header a {
  display: inline-flex;
  align-items: center;
  padding: 10px 22px;
  background: #f4f6fa;
  border-radius: 999px;
  box-shadow: 0 6px 24px rgba(0, 0, 0, 0.35);
}

.logo-img {
  height: 36px;
  display: block;
  margin: 0;
}

/* ---------- Main tool card ---------- */
.container {
  max-width: 680px;
  margin: 32px auto 0;
  padding: 40px 36px 44px;
  background: var(--panel);
  border: 1px solid var(--line);
  border-top: 4px solid var(--btc);
  border-radius: 20px;
  box-shadow: 0 30px 80px rgba(0, 0, 0, 0.45);
}

h1 {
  margin: 0 0 28px;
  padding: 0;
  border: 0;
  font-family: 'Roboto', Arial, sans-serif;
  font-size: clamp(28px, 5vw, 40px);
  font-weight: 900;
  line-height: 1.1;
  letter-spacing: -0.02em;
  text-align: center;
  color: var(--white);
}

/* Bitcoin coin above the title, drawn with CSS only */
h1::before {
  content: "B";
  display: flex;
  align-items: center;
  justify-content: center;
  width: 56px;
  height: 56px;
  margin: 0 auto 18px;
  border-radius: 50%;
  background: var(--btc);
  color: var(--white);
  font-family: 'Roboto', Arial, sans-serif;
  font-size: 32px;
  font-weight: 900;
  line-height: 1;
  transform: rotate(14deg);
  box-shadow: 0 0 0 6px rgba(247, 147, 26, 0.18);
}

/* ---------- Form ---------- */
form br { display: none; }

label {
  display: block;
  margin: 0 0 8px;
  font-family: 'Roboto', Arial, sans-serif;
  font-size: 15px;
  font-weight: 700;
  letter-spacing: 0.02em;
  color: var(--white);
}

input[type="text"],
input[type="number"] {
  display: block;
  width: 100%;
  margin: 0;
  padding: 16px 18px;
  font-family: Arial, Helvetica, sans-serif;
  font-size: 16px;
  color: var(--white);
  background: var(--field);
  border: 1px solid var(--line-strong);
  border-radius: 12px;
  transition: border-color 0.15s ease, box-shadow 0.15s ease;
}

input[type="text"]::placeholder,
input[type="number"]::placeholder {
  color: #5f7391;
}

input[type="text"]:focus,
input[type="number"]:focus {
  outline: none;
  border-color: var(--btc);
  box-shadow: 0 0 0 4px rgba(247, 147, 26, 0.22);
}

.slider-container { margin-top: 20px; }

.slider-label {
  display: flex;
  justify-content: space-between;
  margin-bottom: 5px;
  font-size: 13px;
  color: var(--muted);
}

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

.value-display {
  margin-top: 5px;
  text-align: right;
  font-size: 14px;
  color: var(--muted);
}

/* ---------- Button (chunky "key" style) ---------- */
button,
.btn {
  display: block;
  width: 100%;
  max-width: 400px;
  margin: 28px auto 0;
  padding: 16px 20px;
  font-family: 'Roboto', Arial, sans-serif;
  font-size: 16px;
  font-weight: 700;
  letter-spacing: 0.05em;
  text-align: center;
  text-decoration: none;
  color: #1a1204;
  background: var(--btc);
  border: 0;
  border-radius: 12px;
  box-shadow: 0 4px 0 var(--btc-dark), 0 14px 28px rgba(247, 147, 26, 0.25);
  cursor: pointer;
  transition: background-color 0.15s ease, transform 0.1s ease, box-shadow 0.1s ease;
}

button:hover,
.btn:hover {
  background: var(--btc-light);
}

button:active,
.btn:active {
  transform: translateY(3px);
  box-shadow: 0 1px 0 var(--btc-dark), 0 6px 14px rgba(247, 147, 26, 0.2);
}

button:focus-visible,
.btn:focus-visible,
a:focus-visible {
  outline: 3px solid var(--white);
  outline-offset: 3px;
}

/* ---------- Result block (filled by script) ---------- */
.result-box {
  margin-top: 24px;
  padding: 18px;
  font-size: 16px;
  color: var(--white);
  background: var(--field);
  border: 1px dashed var(--line-strong);
  border-radius: 12px;
  word-break: break-all;
  text-align: center;
}

/* ---------- SEO / article section ---------- */
.seo-section {
  max-width: 760px;
  margin: 64px auto 0;
  padding: 0 20px;
  font-family: Arial, Helvetica, sans-serif;
  font-size: 16px;
  line-height: 1.75;
  color: var(--text);
}

.seo-section h1,
.seo-section h2,
.seo-section h3 {
  font-family: 'Roboto', Arial, sans-serif;
  color: var(--white);
  text-align: left;
}

.seo-section h2 {
  margin: 52px 0 16px;
  padding-top: 28px;
  border-top: 1px solid var(--line);
  font-size: 26px;
  font-weight: 700;
  line-height: 1.25;
  letter-spacing: -0.01em;
}

.seo-section h3 {
  margin: 28px 0 8px;
  font-size: 18px;
  font-weight: 700;
  line-height: 1.35;
}

.seo-section p {
  margin: 0 0 20px;
}

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

.seo-section em {
  color: var(--muted);
}

.seo-section a {
  color: var(--btc);
}

.seo-section code {
  padding: 2px 7px;
  font-family: Consolas, 'Courier New', monospace;
  font-size: 0.92em;
  color: #ffb454;
  background: #1b2a42;
  border-radius: 6px;
}

/* Bullet lists: small diamonds (like blocks in a chain) */
.seo-section ul {
  margin: 0 0 20px;
  padding: 0;
  list-style: none;
}

.seo-section ul li {
  position: relative;
  margin-bottom: 10px;
  padding-left: 28px;
}

.seo-section ul li::before {
  content: "";
  position: absolute;
  left: 4px;
  top: 0.62em;
  width: 8px;
  height: 8px;
  background: var(--btc);
  transform: rotate(45deg);
}

/* Numbered lists: real sequences, numbered with orange badges */
.seo-section ol {
  margin: 0 0 20px;
  padding: 0;
  list-style: none;
  counter-reset: step;
}

.seo-section ol li {
  position: relative;
  margin-bottom: 12px;
  padding-left: 44px;
  counter-increment: step;
}

.seo-section ol li::before {
  content: counter(step);
  position: absolute;
  left: 0;
  top: 0.1em;
  width: 28px;
  height: 28px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: 'Roboto', Arial, sans-serif;
  font-size: 14px;
  font-weight: 700;
  line-height: 1;
  color: var(--btc);
  background: rgba(247, 147, 26, 0.12);
  border: 1px solid rgba(247, 147, 26, 0.45);
  border-radius: 50%;
}

/* ---------- Contact block ---------- */
.info-block {
  max-width: 760px;
  margin: 48px auto 64px;
  padding: 24px 28px;
  background: var(--panel);
  border: 1px solid var(--line);
  border-left: 4px solid var(--btc);
  border-radius: 14px;
  font-family: Arial, Helvetica, sans-serif;
}

.info-block .label {
  margin-bottom: 8px;
  font-family: 'Roboto', Arial, sans-serif;
  font-size: 18px;
  font-weight: 700;
  color: var(--white);
}

.info-block .value p {
  margin: 6px 0;
  color: var(--text);
  overflow-wrap: anywhere;
}

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

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

/* ---------- Footer ---------- */
.footer {
  max-width: 700px;
  margin: 80px auto 0;
  font-size: 14px;
  text-align: center;
  color: var(--muted);
}

/* ---------- Mobile ---------- */
@media (max-width: 600px) {
  .container {
    margin: 20px 14px 0;
    padding: 30px 20px 34px;
    border-radius: 16px;
  }

  .seo-section { margin-top: 48px; }

  .seo-section h2 { font-size: 22px; }

  .info-block { margin: 40px 14px 48px; }
}

@media (prefers-reduced-motion: reduce) {
  * { transition: none !important; }
}