:root {
    --primary-color: #00b4d8;
    --secondary-color: #0077b6;
    --background-start: #caf0f8;
    --background-end: #90e0ef;
    --text-color: #333;
    --card-bg: #ffffff;
}

body {
    margin: 0;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: linear-gradient(135deg, var(--background-start), var(--background-end));
    min-height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    color: var(--text-color);
}

.container {
    width: 100%;
    max-width: 800px;
    padding: 20px;
}

header {
    text-align: center;
    margin-bottom: 40px;
}

header h1 {
    font-size: 3em;
    color: var(--secondary-color);
    margin: 0;
    text-shadow: 2px 2px 4px rgba(0,0,0,0.1);
}

header p {
    font-size: 1.2em;
    color: #555;
}

.offer-card {
    background: var(--card-bg);
    border-radius: 20px;
    box-shadow: 0 10px 30px rgba(0,0,0,0.1);
    overflow: hidden;
    display: flex;
    flex-direction: column;
}

@media (min-width: 768px) {
    .offer-card {
        flex-direction: row;
    }
}

.image-container {
    flex: 1;
    background: #f0f0f0;
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
}

.product-img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    display: block;
}

.content {
    flex: 1;
    padding: 40px;
    display: flex;
    flex-direction: column;
    justify-content: center;
}

h2 {
    color: var(--secondary-color);
    margin-top: 0;
}

.promo-form {
    margin-top: 20px;
    display: flex;
    flex-direction: column;
    gap: 10px;
}

label {
    font-weight: bold;
    font-size: 0.9em;
    color: #666;
}

input[type="text"] {
    padding: 12px;
    border: 2px solid #ddd;
    border-radius: 8px;
    font-size: 1em;
    transition: border-color 0.3s;
}

input[type="text"]:focus {
    border-color: var(--primary-color);
    outline: none;
}

button {
    padding: 12px;
    background: var(--primary-color);
    color: white;
    border: none;
    border-radius: 8px;
    font-size: 1em;
    cursor: pointer;
    transition: background 0.3s, transform 0.1s;
}

button:hover {
    background: var(--secondary-color);
}

button:active {
    transform: scale(0.98);
}

.result-area {
    margin-top: 20px;
    padding: 15px;
    border-radius: 8px;
    background: #f9f9f9;
    border: 1px solid #eee;
}

.hidden {
    display: none;
}

.flag-box {
    margin-top: 10px;
    padding: 10px;
    background: #ffe0e0;
    border: 1px solid #ffcccc;
    border-radius: 5px;
    color: #d8000c;
    font-family: monospace;
    word-break: break-all;
}

footer {
    text-align: center;
    margin-top: 40px;
    font-size: 0.8em;
    color: #777;
}