:root {
  --bg: #edf2f7;
  --panel: rgba(255, 255, 255, 0.88);
  --line: rgba(22, 28, 38, 0.08);
  --ink: #18202a;
  --muted: #617081;
  --accent: #1f7ed2;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  font-family: "Segoe UI", "Noto Sans TC", sans-serif;
  color: var(--ink);
  background:
    radial-gradient(circle at top right, rgba(125, 205, 255, 0.22), transparent 28%),
    linear-gradient(180deg, #f9fbff 0%, var(--bg) 100%);
}

.topbar {
  display: flex;
  justify-content: space-between;
  gap: 20px;
  align-items: flex-start;
  padding: 20px 24px 12px;
}

.topbar h1 {
  margin: 0 0 6px;
  font-size: 28px;
}

.topbar p {
  margin: 0;
  color: var(--muted);
}

.topbar-actions {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
}

button,
select,
input[type="file"] {
  font: inherit;
}

button {
  border: 1px solid var(--line);
  background: white;
  color: var(--ink);
  padding: 10px 14px;
  border-radius: 12px;
  cursor: pointer;
}

button.primary {
  background: var(--accent);
  color: white;
  border-color: transparent;
}

.workspace {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 380px;
  gap: 18px;
  padding: 0 24px 24px;
}

.preview-pane,
.panel {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: 20px;
  box-shadow: 0 18px 45px rgba(22, 35, 56, 0.08);
}

.preview-pane {
  padding: 16px;
  overflow: auto;
}

.preview-frame {
  width: min(100%, 980px);
  margin: 0 auto;
}

#poster-canvas {
  width: 100%;
  height: auto;
  display: block;
  border-radius: 18px;
  background: #f7f0de;
}

.control-pane {
  display: flex;
  flex-direction: column;
  gap: 14px;
  max-height: calc(100vh - 110px);
  overflow: auto;
  padding-right: 4px;
}

.panel {
  padding: 16px;
}

.panel h2 {
  margin: 0 0 12px;
  font-size: 18px;
}

.field {
  display: flex;
  flex-direction: column;
  gap: 6px;
  margin-bottom: 10px;
}

.field > span {
  font-size: 13px;
  color: var(--muted);
}

.field input[type="range"] {
  width: 100%;
}

.field.checkbox {
  flex-direction: row;
  align-items: center;
  gap: 8px;
}

.field.checkbox span {
  color: var(--ink);
}

.notes p {
  margin: 0 0 10px;
  color: var(--muted);
  line-height: 1.5;
}

@media (max-width: 1200px) {
  .workspace {
    grid-template-columns: 1fr;
  }

  .control-pane {
    max-height: none;
  }
}