:root {
  --bg: #0f1419;
  --card: #1a2332;
  --text: #e7ecf3;
  --muted: #8b9cb3;
  --accent: #3b82f6;
  --accent-hover: #2563eb;
  --error: #f87171;
  --border: #2d3a4f;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  font-family: "Segoe UI", system-ui, sans-serif;
  background: radial-gradient(ellipse at top, #1e293b 0%, var(--bg) 55%);
  color: var(--text);
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 1.5rem;
}

.card {
  width: 100%;
  max-width: 420px;
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: 1.75rem;
  box-shadow: 0 24px 48px rgba(0, 0, 0, 0.35);
}

header h1 {
  margin: 0 0 0.35rem;
  font-size: 1.5rem;
}

header p {
  margin: 0 0 1.5rem;
  color: var(--muted);
  font-size: 0.9rem;
  line-height: 1.45;
}

.field {
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
  margin-bottom: 1rem;
  font-size: 0.85rem;
  color: var(--muted);
}

.field input[type="file"],
.field input[type="text"],
.field input[type="number"] {
  padding: 0.65rem 0.75rem;
  border-radius: 8px;
  border: 1px solid var(--border);
  background: var(--bg);
  color: var(--text);
  font-size: 0.95rem;
}

.size-field {
  border: none;
  padding: 0;
  margin: 0 0 1rem;
}

.size-field legend {
  padding: 0;
  margin-bottom: 0.4rem;
  font-size: 0.85rem;
  color: var(--muted);
}

.size-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0.75rem;
}

.size-row label {
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
}

.hint {
  margin: 0.5rem 0 0;
  font-size: 0.8rem;
  color: var(--muted);
  line-height: 1.4;
}

.presets {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-top: 0.65rem;
}

.preset-btn {
  width: auto;
  flex: 1;
  min-width: 5.5rem;
  padding: 0.45rem 0.5rem;
  font-size: 0.8rem;
  font-weight: 500;
  background: var(--bg);
  color: var(--muted);
  border: 1px solid var(--border);
  margin-top: 0;
}

.preset-btn:hover {
  color: var(--text);
  border-color: var(--accent);
  background: rgba(59, 130, 246, 0.08);
}

.color-row {
  display: flex;
  gap: 0.5rem;
  align-items: center;
}

.color-row input[type="color"] {
  width: 48px;
  height: 40px;
  padding: 2px;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: var(--bg);
  cursor: pointer;
}

.color-row input[type="text"] {
  flex: 1;
}

button,
.btn-secondary {
  display: inline-block;
  width: 100%;
  text-align: center;
  padding: 0.75rem 1rem;
  border-radius: 8px;
  font-size: 0.95rem;
  font-weight: 600;
  cursor: pointer;
  text-decoration: none;
  border: none;
}

button {
  background: var(--accent);
  color: #fff;
  margin-top: 0.25rem;
}

button:hover:not(:disabled) {
  background: var(--accent-hover);
}

button:disabled {
  opacity: 0.6;
  cursor: not-allowed;
}

.btn-secondary {
  background: transparent;
  color: var(--accent);
  border: 1px solid var(--accent);
  margin-top: 0.75rem;
}

.btn-secondary:hover {
  background: rgba(59, 130, 246, 0.12);
}

.status {
  margin: 1rem 0 0;
  font-size: 0.9rem;
}

.status.error {
  color: var(--error);
}

.status.info {
  color: var(--muted);
}

.preview {
  margin-top: 1.5rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--border);
}

.preview h2 {
  margin: 0 0 0.75rem;
  font-size: 1rem;
}

.preview img {
  width: 100%;
  max-width: 300px;
  display: block;
  border-radius: 4px;
  border: 1px solid var(--border);
}