/* Thiết lập cơ bản */
body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    background-color: #fef1f1;
    color: #333;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    padding: 20px;
    box-sizing: border-box;
}

.container {
    width: 100%;
    max-width: 600px;
    background-color: #ffffff;
    padding: 30px;
    border-radius: 12px;
    box-shadow: 0 10px 25px rgba(0, 0, 0, 0.05);
    border: 1px solid #ffe4e4;
}

h1 {
    text-align: center;
    color: #d90429;
    margin-bottom: 10px;
}

h2 {
    color: #e63946;
    border-bottom: 2px solid #fde0e0;
    padding-bottom: 5px;
    margin-top: 25px;
}

hr {
    border: none;
    height: 1px;
    background-color: #fde0e0;
    margin: 30px 0;
}

/* Disclaimer */
.disclaimer {
    background-color: #fffbe6;
    border: 1px solid #ffe58f;
    border-radius: 8px;
    padding: 15px;
    font-size: 0.9em;
    text-align: center;
    color: #8a6d3b;
    margin-bottom: 20px;
}

/* Biểu mẫu (Form) */
.input-group {
    margin-bottom: 15px;
}

.input-group label {
    display: block;
    margin-bottom: 5px;
    font-weight: 600;
    color: #555;
}

.input-group input[type="text"] {
    width: 100%;
    padding: 12px;
    border: 1px solid #ddd;
    border-radius: 8px;
    box-sizing: border-box; /* Quan trọng để padding không làm vỡ layout */
    font-size: 1em;
}

.input-group input[readonly] {
    background-color: #f9f9f9;
    cursor: not-allowed;
}

button {
    width: 100%;
    padding: 12px;
    background-color: #e63946;
    color: white;
    border: none;
    border-radius: 8px;
    font-size: 1em;
    font-weight: 600;
    cursor: pointer;
    transition: background-color 0.3s ease;
}

button:hover {
    background-color: #d62828;
}

/* Kết quả "Giấy Chứng Nhận" */
#result-container {
    margin-top: 30px;
}

.certificate {
    background: linear-gradient(135deg, #fffafa 0%, #fff0f0 100%);
    border: 2px dashed #e63946;
    border-radius: 12px;
    padding: 25px;
    text-align: center;
    box-shadow: 0 4px 12px rgba(230, 57, 70, 0.1);
}

.certificate h3 {
    color: #d90429;
    margin-top: 0;
    font-size: 1.4em;
}

.certificate p {
    margin: 10px 0;
    font-size: 1.1em;
    color: #444;
}

.certificate .name {
    font-size: 1.5em;
    font-weight: bold;
    color: #000;
    margin: 5px 0;
}

.certificate .and {
    font-size: 1.2em;
    font-style: italic;
    color: #e63946;
}

.certificate .date {
    font-weight: 600;
}

.certificate .code-label {
    margin-top: 20px;
    font-size: 1em;
    color: #555;
}

.certificate .code {
    font-size: 1.3em;
    font-weight: bold;
    color: #0077b6;
    background-color: #f0f8ff;
    padding: 8px 12px;
    border-radius: 6px;
    display: inline-block;
    margin-top: 5px;
}

.certificate small {
    display: block;
    margin-top: 15px;
    color: #777;
    font-style: italic;
}

/* Trạng thái ẩn/hiện và thông báo lỗi */
.hidden {
    display: none;
}

#error-message {
    text-align: center;
    color: #d90429;
    font-weight: 600;
    margin-top: 20px;
}