:root {
  color-scheme: light;
  --page-bg: #f5f7fb;
  --card-bg: #ffffff;
  --surface-muted: #f8fafc;
  --surface-border: #dce5f0;
  --text-main: #1f2937;
  --text-muted: #6b7280;
  --primary: #1976d2;
  --primary-dark: #145ea8;
  --danger-soft: #fdeceb;
  --danger-text: #b3261e;
  --shadow-card: 0 14px 36px rgba(15, 23, 42, 0.08);
  --shadow-soft: 0 8px 20px rgba(25, 118, 210, 0.12);
  --radius-lg: 16px;
  --radius-md: 14px;
  --radius-sm: 12px;
}

* {
  box-sizing: border-box;
}

body {
  overflow: hidden;
  margin: 0;
  min-height: 100dvh;
  overflow-x: hidden;
  overflow-y: auto;
  font-family: "Segoe UI", "Noto Sans TC", sans-serif;
  color: var(--text-main);
  background:
    radial-gradient(circle at top left, rgba(25, 118, 210, 0.12), transparent 28%),
    linear-gradient(180deg, #f9fbff 0%, var(--page-bg) 100%);
}

h1,
h2 {
  margin: 0;
  letter-spacing: -0.02em;
}

h1 {
  font-size: clamp(2rem, 4vw, 2.8rem);
  line-height: 1.08;
}

h2 {
  font-size: 1.35rem;
}

label {
  display: block;
  margin-bottom: 8px;
  font-size: 0.92rem;
  font-weight: 600;
  color: var(--text-main);
}

textarea {
  width: 100%;
  min-height: 280px;
  padding: 16px 16px 20px;
  margin: 0;
  border: 1px solid var(--surface-border);
  border-radius: var(--radius-md);
  background: var(--surface-muted);
  color: var(--text-main);
  font: inherit;
  line-height: 1.6;
  resize: vertical;
  outline: none;
  transition: border-color 0.18s ease, box-shadow 0.18s ease, background 0.18s ease;
}

button {
  border: 0;
  border-radius: var(--radius-sm);
  font: inherit;
  font-weight: 700;
  cursor: pointer;
  transition: transform 0.18s ease, box-shadow 0.18s ease, background 0.18s ease, color 0.18s ease;
}

button:hover {
  transform: translateY(-2px);
}

button:active {
  transform: translateY(0);
}