:root {
  --bg: #f8fafc;
  --panel-bg: #ffffff;
  --panel-border: #e2e8f0;
  --text: #1e293b;
  --text-dim: #64748b;
  --accent: #6366f1;
  --accent-hover: #4f46e5;
  --input-bg: #ffffff;
  --input-border: #cbd5e1;
  --radius: 8px;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: Arial, Helvetica, sans-serif;
}

.app {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

.app-header {
  padding: 16px 24px;
  border-bottom: 1px solid var(--panel-border);
}

.app-header h1 {
  margin: 0;
  font-size: 1.4rem;
}

.app-body {
  flex: 1;
  display: flex;
  min-height: 0;
}

.preview-panel {
  flex: 1 1 60%;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 12px;
  padding: 24px;
  min-width: 0;
}

.canvas-wrap {
  width: 100%;
  height: 100%;
  min-height: 0;
  display: flex;
  align-items: center;
  justify-content: center;
}

#bannerCanvas {
  max-width: 100%;
  max-height: 70vh;
  width: auto;
  height: auto;
  background: #fff;
  box-shadow: 0 4px 16px rgba(15, 23, 42, 0.12);
  border: 1px solid var(--panel-border);
  border-radius: 4px;
}

.size-readout {
  color: var(--text-dim);
  font-size: 0.85rem;
}

.controls-panel {
  flex: 0 0 380px;
  max-width: 380px;
  border-left: 1px solid var(--panel-border);
  background: var(--panel-bg);
  padding: 20px;
  overflow-y: auto;
  display: flex;
  flex-direction: column;
  gap: 18px;
}

.control-group label {
  display: block;
  font-size: 0.8rem;
  font-weight: bold;
  color: var(--text-dim);
  margin-bottom: 6px;
  text-transform: uppercase;
  letter-spacing: 0.03em;
}

select,
textarea,
input[type="number"],
input[type="text"] {
  width: 100%;
  background: var(--input-bg);
  border: 1px solid var(--input-border);
  color: var(--text);
  border-radius: var(--radius);
  padding: 8px 10px;
  font-size: 0.95rem;
  font-family: inherit;
}

select:focus,
textarea:focus,
input:focus {
  outline: none;
  border-color: var(--accent);
}

textarea {
  resize: vertical;
  min-height: 80px;
}

.markup-guide {
  margin-top: 10px;
  background: var(--bg);
  border: 1px solid var(--panel-border);
  border-radius: var(--radius);
  padding: 8px 12px;
  font-size: 0.85rem;
  color: var(--text-dim);
}

.markup-guide summary {
  cursor: pointer;
  font-weight: bold;
  color: var(--text);
  text-transform: none;
  padding: 4px 0;
}

.markup-guide p {
  margin: 8px 0;
}

.markup-guide ul {
  margin: 8px 0;
  padding-left: 20px;
}

.markup-guide li {
  margin-bottom: 4px;
}

.markup-guide code {
  background: var(--panel-border);
  color: var(--text);
  padding: 1px 5px;
  border-radius: 4px;
  font-family: "Courier New", Courier, monospace;
  font-size: 0.85em;
}

.row-2 {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 14px;
}

.color-field {
  display: flex;
  align-items: center;
  gap: 8px;
}

input[type="color"] {
  width: 40px;
  height: 36px;
  padding: 2px;
  border: 1px solid var(--input-border);
  border-radius: var(--radius);
  background: var(--input-bg);
  cursor: pointer;
  flex: 0 0 auto;
}

.hex-input {
  flex: 1 1 auto;
  min-width: 0;
  text-transform: uppercase;
}

.inline-inputs {
  display: flex;
  align-items: center;
  gap: 8px;
}

.x-sep {
  color: var(--text-dim);
}

.button-toggle-row {
  display: flex;
  gap: 8px;
}

.toggle-btn {
  flex: 1;
  background: var(--input-bg);
  border: 1px solid var(--input-border);
  color: var(--text);
  border-radius: var(--radius);
  padding: 8px 0;
  cursor: pointer;
  font-size: 0.95rem;
}

.toggle-btn:hover {
  border-color: var(--accent-hover);
}

.toggle-btn.is-active,
.toggle-btn[aria-pressed="true"] {
  background: var(--accent);
  border-color: var(--accent);
  color: #fff;
}

.font-size-row {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 16px;
}

.step-btn {
  width: 36px;
  height: 36px;
  border-radius: 50%;
  border: 1px solid var(--input-border);
  background: var(--input-bg);
  color: var(--text);
  font-size: 1.2rem;
  cursor: pointer;
  line-height: 1;
}

.step-btn:hover {
  border-color: var(--accent-hover);
}

.font-size-input {
  width: 64px;
  text-align: center;
  font-size: 1.1rem;
  padding: 8px 4px;
}

.download-btn {
  width: 100%;
  padding: 12px;
  background: var(--accent);
  border: none;
  color: #fff;
  border-radius: var(--radius);
  font-size: 1rem;
  font-weight: bold;
  cursor: pointer;
}

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

@media (max-width: 768px) {
  .app-body {
    flex-direction: column;
  }

  .preview-panel {
    flex: 0 0 auto;
    padding: 16px;
  }

  #bannerCanvas {
    max-height: 45vh;
  }

  .controls-panel {
    flex: 1 1 auto;
    max-width: none;
    border-left: none;
    border-top: 1px solid var(--panel-border);
  }
}