* {
  box-sizing: border-box;
}

:root {
  --bg: #f5f7fa;
  --panel: #ffffff;
  --line: #dde5ee;
  --text: #111827;
  --primary: #2563eb;
}

body {
  margin: 0;
  min-height: 100vh;
  background: var(--bg);
  color: var(--text);
  font-family:
    ui-rounded, "SF Pro Rounded", "Apple SD Gothic Neo", "Malgun Gothic",
    sans-serif;
}

.app {
  max-width: 420px;
  margin: 0 auto;
  padding: 16px;
}

h1 {
  margin: 0 0 12px;
  font-size: 26px;
  line-height: 1.2;
}

.app-title {
  text-align: center;
}

.preview-panel,
.controls-panel {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: 12px;
}

.preview-panel {
  padding: 12px;
}

.canvas-wrap {
  width: 100%;
  aspect-ratio: 1 / 1;
  border-radius: 10px;
  overflow: hidden;
  border: 1px solid var(--line);
  background: #0f172a;
}

#thumbnailCanvas {
  width: 100%;
  height: 100%;
  display: block;
}

.controls-panel {
  margin-top: 12px;
  padding: 12px;
  display: grid;
  gap: 14px;
}

.control {
  display: grid;
  gap: 8px;
}

label {
  font-weight: 700;
  font-size: 15px;
}

.preset-list {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 8px;
}

.preset-item {
  border: 2px solid transparent;
  border-radius: 10px;
  background: #edf2f7;
  padding: 4px;
  cursor: pointer;
  transition: border-color 0.15s ease;
}

.preset-item:active {
  transform: scale(0.99);
}

.preset-item.active {
  border-color: var(--primary);
}

.preset-item img {
  width: 100%;
  aspect-ratio: 1 / 1;
  border-radius: 6px;
  object-fit: cover;
  display: block;
}

input[type="text"] {
  width: 100%;
  border: 1px solid var(--line);
  border-radius: 10px;
  padding: 12px;
  font: inherit;
  background: #fff;
  color: var(--text);
  min-height: 48px;
  line-height: 1.5;
  font-size: 15px;
}

input[type="text"]::placeholder {
  color: #9ca3af;
}

button {
  border: none;
  border-radius: 10px;
  background: var(--primary);
  color: #fff;
  font-size: 17px;
  font-weight: 700;
  padding: 14px;
  cursor: pointer;
  line-height: 1.2;
}

button:active {
  transform: translateY(1px);
}