body {
    font-family: Arial, sans-serif;
    margin: 0;
    padding: 40px;
    background: #f5f7fa;
    color: #1f2937;
}

.container {
    max-width: 1100px;
    margin: 0 auto;
}

h1 {
    margin-bottom: 5px;
}

h2 {
    margin-top: 0;
    color: #4b5563;
}

.form-container {
    background: white;
    padding: 25px;
    border-radius: 8px;
    margin: 30px 0;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.08);
}

.form-row {
    display: flex;
    gap: 20px;
    flex-wrap: wrap;
    margin-bottom: 20px;
}

.form-field {
    display: flex;
    flex-direction: column;
    gap: 6px;
}

.form-field label {
    font-weight: bold;
}

.form-field input,
.form-field select {
    width: 90px;
    box-sizing: border-box;
    padding: 6px 8px;
    font-size: 15px;
    border: 1px solid #cbd5e1;
    border-radius: 4px;
}

#exclude_numbers {
    width: 150px;
}

.button-row {
    display: flex;
    gap: 12px;
}

button {
    width: 200px;
    height: 42px;
    padding: 10px 20px;
    font-size: 16px;
    border: none;
    border-radius: 4px;
    background: #30CAA0;
    color: white;
    cursor: pointer;
}

button:hover {
    background: #b5f7e1;
}

.error {
    background: #fee2e2;
    color: #991b1b;
    padding: 12px 15px;
    border-radius: 5px;
    margin-bottom: 20px;
}

.grid-section {
    margin-top: 35px;
}

.grid-section h3 {
    margin-bottom: 12px;
}

.grid-wrapper {
    overflow-x: auto;
}

table {
    border-collapse: collapse;
    background: white;
}

td {
    width: 50px;
    height: 45px;
    text-align: center;
    vertical-align: middle;
    border: 1px solid #9ca3af;
    font-size: 18px;
}

table tr:first-child td,
table td:first-child {
    font-weight: bold;
    background: #e5e7eb;
}

.practice-grid td:not(:first-child):not(:first-child) {
    font-size: 20px;
}

.header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 20px;
}

.header-text {
    display: flex;
    flex-direction: column;
}

.header h1 {
    margin: 0;
}

.header h2 {
    margin: 4px 0 0 0;
}

.header img {
    width: 250px;
    
    object-fit: contain;
}

footer {
    margin-top: 40px;
    padding-top: 15px;
    border-top: 1px solid #d1d5db;
    text-align: center;
    font-size: 13px;
    color: #6b7280;
}