:root {
  --bg: #f4f7fb;
  --card: #ffffff;
  --text: #1f2a37;
  --muted: #4b5563;
  --accent: #0077b6;
  --accent-2: #0096c7;
  --border: #dbe4ee;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;
  color: var(--text);
  background: radial-gradient(circle at 10% 10%, #e5f4ff, var(--bg) 35%);
}

.app {
  min-height: 100vh;
  display: grid;
  grid-template-columns: minmax(320px, 420px) 1fr;
  gap: 20px;
  padding: 20px;
}

.panel {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 18px;
  box-shadow: 0 8px 30px rgba(31, 42, 55, 0.08);
}

h1 {
  margin: 0 0 8px;
  font-size: 1.65rem;
}

.subtitle {
  margin: 0 0 16px;
  color: var(--muted);
}

.form-grid {
  display: grid;
  gap: 10px;
}

.toggle-row {
  display: flex;
  gap: 14px;
  flex-wrap: wrap;
  padding: 4px 0 2px;
}

.check {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-size: 0.95rem;
}

.check input {
  width: auto;
}

label {
  display: grid;
  gap: 6px;
  font-size: 0.95rem;
}

input {
  width: 100%;
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 10px;
  font-size: 1rem;
}

button {
  border: 0;
  border-radius: 10px;
  padding: 12px;
  font-weight: 700;
  color: #fff;
  cursor: pointer;
  background: linear-gradient(90deg, var(--accent), var(--accent-2));
}

.results {
  margin-top: 16px;
  padding-top: 14px;
  border-top: 1px solid var(--border);
}

.results p {
  margin: 8px 0;
}

.viewer-wrap {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 10px;
  display: grid;
  grid-template-rows: 1fr auto;
  box-shadow: 0 8px 30px rgba(31, 42, 55, 0.08);
  min-height: 420px;
}

#viewer {
  width: 100%;
  height: 100%;
  min-height: 400px;
  border-radius: 10px;
  overflow: hidden;
  background: linear-gradient(180deg, #d9ecff, #f6fbff 70%);
}

.hint {
  text-align: center;
  color: var(--muted);
  font-size: 0.9rem;
  margin: 8px 0 2px;
}

@media (max-width: 900px) {
  .app {
    grid-template-columns: 1fr;
  }

  #viewer {
    min-height: 320px;
  }
}