:root {
  --ink: #1c1917;
  --muted: #78716c;
  --line: #e7e2d9;
  --paper: #f6f3ee;
  --card: #fffcf8;
  --accent: #9a3412;
  --accent-hover: #7c2d12;
  --shadow: 0 18px 50px rgba(68, 48, 24, 0.08);
}

* {
  box-sizing: border-box;
}

html,
body {
  height: 100%;
}

body {
  margin: 0;
  color: var(--ink);
  background:
    radial-gradient(circle at 12% 8%, rgba(154, 52, 18, 0.08), transparent 28%),
    linear-gradient(180deg, #fbf8f3 0%, var(--paper) 100%);
  font-family: "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
}

.page {
  width: min(1040px, calc(100% - 32px));
  margin: 0 auto;
  padding: 36px 0 56px;
}

.header {
  display: flex;
  align-items: flex-end;
  justify-content: space-between;
  gap: 24px;
  margin-bottom: 28px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 16px;
  min-width: 0;
}

.logo {
  width: 52px;
  height: 52px;
  flex: none;
  padding: 8px;
  border-radius: 14px;
  background: var(--ink);
  color: #fff;
}

.brand h1 {
  margin: 0 0 4px;
  font-size: 28px;
  line-height: 1.2;
  letter-spacing: 0.02em;
}

.brand p {
  margin: 0;
  color: var(--muted);
  font-size: 14px;
}

.nav {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
}

.nav a {
  color: var(--ink);
  text-decoration: none;
  font-size: 13px;
  padding: 8px 12px;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: rgba(255, 252, 248, 0.8);
}

.nav a:hover {
  border-color: #d6cfc3;
  background: #fff;
}

.panel {
  display: grid;
  grid-template-columns: minmax(0, 1.05fr) minmax(320px, 0.95fr);
  gap: 20px;
  align-items: stretch;
}

.card {
  background: var(--card);
  border: 1px solid rgba(231, 226, 217, 0.9);
  border-radius: 20px;
  box-shadow: var(--shadow);
  padding: 24px;
}

.card h2 {
  margin: 0 0 18px;
  font-size: 16px;
  letter-spacing: 0.08em;
}

.field {
  display: block;
  margin-bottom: 16px;
}

.field span {
  display: block;
  margin-bottom: 8px;
  font-size: 13px;
  color: #44403c;
}

textarea {
  width: 100%;
  resize: vertical;
  min-height: 96px;
  padding: 12px 14px;
  border: 1px solid var(--line);
  border-radius: 12px;
  background: #fff;
  color: var(--ink);
  font: inherit;
  font-size: 15px;
  line-height: 1.6;
  outline: none;
  transition: border-color 0.15s ease, box-shadow 0.15s ease;
}

#intorduceVal {
  min-height: 72px;
}

textarea:focus {
  border-color: #c4b8a8;
  box-shadow: 0 0 0 4px rgba(154, 52, 18, 0.08);
}

.generate {
  width: 100%;
  margin-top: 4px;
  border: 0;
  border-radius: 12px;
  padding: 13px 16px;
  background: var(--accent);
  color: #fff;
  font: inherit;
  font-size: 15px;
  letter-spacing: 0.04em;
  cursor: pointer;
}

.generate:hover {
  background: var(--accent-hover);
}

.generate:active {
  transform: translateY(1px);
}

.hint {
  margin: 12px 0 0;
  color: var(--muted);
  font-size: 12px;
  line-height: 1.6;
}

.preview-card {
  display: flex;
  flex-direction: column;
}

.preview-frame {
  flex: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 360px;
  padding: 20px;
  border-radius: 16px;
  background:
    linear-gradient(180deg, rgba(255, 255, 255, 0.4), rgba(255, 255, 255, 0.1)),
    repeating-linear-gradient(0deg, transparent, transparent 15px, rgba(120, 113, 108, 0.06) 16px),
    repeating-linear-gradient(90deg, transparent, transparent 15px, rgba(120, 113, 108, 0.06) 16px),
    #f3efe8;
}

#QRcode {
  position: relative;
  width: 100%;
}

#QRcode canvas {
  display: block;
  max-width: 100%;
  height: auto;
  margin: 0 auto;
  background: #fff;
  border-radius: 8px;
  box-shadow: 0 10px 30px rgba(68, 48, 24, 0.12);
}

.QR-download {
  display: block;
  margin-top: 16px;
  padding: 12px 16px;
  border: 1px solid var(--ink);
  border-radius: 12px;
  color: var(--ink);
  text-align: center;
  text-decoration: none;
  font-size: 15px;
  background: #fff;
}

.QR-download:hover {
  background: var(--ink);
  color: #fff;
}

@media (max-width: 820px) {
  .page {
    width: min(100% - 24px, 1040px);
    padding-top: 20px;
  }

  .header {
    flex-direction: column;
    align-items: flex-start;
  }

  .panel {
    grid-template-columns: 1fr;
  }

  .brand h1 {
    font-size: 24px;
  }

  .preview-frame {
    min-height: 280px;
  }
}