* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}

body {
  background-color: #f4f7f6;
  color: #333;
  display: flex;
  flex-direction: column;
  align-items: center;
  padding: 20px;
}

.container {
  max-width: 600px;
  width: 100%;
  background: #ffffff;
  padding: 30px;
  border-radius: 12px;
  box-shadow: 0 4px 15px rgba(0,0,0,0.05);
  margin: 20px 0;
}

header {
  text-align: center;
  margin-bottom: 25px;
}

header h1 {
  color: #2c3e50;
  font-size: 1.8rem;
  margin-bottom: 8px;
}

header p {
  color: #7f8c8d;
  font-size: 0.95rem;
}

.drop-zone {
  border: 2px dashed #3498db;
  border-radius: 8px;
  padding: 40px 20px;
  text-align: center;
  cursor: pointer;
  background: #f8fbfe;
  transition: 0.3s;
}

.drop-zone:hover {
  background: #eef6fd;
}

.drop-zone span {
  color: #3498db;
  font-weight: bold;
}

.controls-section {
  margin-top: 20px;
}

.preview-box {
  text-align: center;
  margin-bottom: 20px;
}

.preview-box img {
  max-width: 100%;
  max-height: 250px;
  border-radius: 6px;
}

.setting-group {
  margin-bottom: 15px;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

select, input[type="range"] {
  padding: 6px 12px;
  border-radius: 4px;
  border: 1px solid #ccc;
}

button, .download-btn {
  display: block;
  width: 100%;
  padding: 12px;
  background-color: #2ecc71;
  color: white;
  text-align: center;
  border: none;
  border-radius: 6px;
  font-size: 1rem;
  font-weight: bold;
  cursor: pointer;
  text-decoration: none;
  transition: 0.3s;
}

button:hover, .download-btn:hover {
  background-color: #27ae60;
}

.result-section {
  margin-top: 25px;
  padding-top: 20px;
  border-top: 1px solid #eee;
  text-align: center;
}

#sizeInfo {
  margin-bottom: 15px;
  font-weight: 600;
  color: #2c3e50;
}

.ad-space {
  width: 100%;
  max-width: 728px;
  height: 90px;
  background: #e0e0e0;
  display: flex;
  align-items: center;
  justify-content: center;
  color: #666;
  font-size: 0.9rem;
  border: 1px dashed #bbb;
  border-radius: 6px;
}

footer {
            margin-top: 2rem;
            text-align: center;
            color: var(--text-muted);
            font-size: 0.875rem;
            display: flex;
            justify-content: center;
            gap: 1.5rem;
        }

        footer a {
            color: var(--text-muted);
            text-decoration: none;
            transition: color 0.2s;
        }

        footer a:hover {
            color: var(--primary);
        }