:root {
    --primary-color: #4a6baf;
    --secondary-color: #f9f9f9;
    --accent-color: #e63946;
    --text-color: #333;
    --light-gray: #f1f1f1;
    --medium-gray: #ddd;
    --success-color: #2ecc71;
    --error-color: #e74c3c;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    line-height: 1.6;
    color: var(--text-color);
    background-color: var(--light-gray);
}

.container {
    max-width: 800px;
    margin: 0 auto;
    padding: 20px;
}

.hidden {
    display: none !important;
}

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

header h1 {
    color: var(--primary-color);
    margin-bottom: 10px;
}

.card {
    background-color: white;
    border-radius: 8px;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
    padding: 30px;
    margin-bottom: 30px;
}

h2 {
    color: var(--primary-color);
    margin-bottom: 20px;
}

#math-problem {
    font-size: 1.5rem;
    margin: 20px 0;
    text-align: center;
    font-weight: bold;
}

.form-group {
    display: flex;
    margin-bottom: 15px;
}

input {
    flex: 1;
    padding: 12px;
    border: 1px solid var(--medium-gray);
    border-radius: 4px;
    font-size: 16px;
}

input:focus {
    outline: none;
    border-color: var(--primary-color);
}

button {
    background-color: var(--primary-color);
    color: white;
    border: none;
    border-radius: 4px;
    padding: 12px 20px;
    cursor: pointer;
    font-size: 16px;
    transition: background-color 0.3s;
}

button:hover {
    background-color: #3a5998;
}

button:disabled {
    background-color: var(--medium-gray);
    cursor: not-allowed;
}

.form-group button {
    margin-left: 10px;
}

#drop-area {
    border: 2px dashed var(--medium-gray);
    border-radius: 4px;
    padding: 40px;
    text-align: center;
    margin-bottom: 20px;
    transition: border-color 0.3s;
}

#drop-area.highlight {
    border-color: var(--primary-color);
    background-color: rgba(74, 107, 175, 0.05);
}

#select-file-btn {
    margin-top: 15px;
}

#file-info {
    margin: 15px 0;
}

.file-details {
    display: flex;
    align-items: center;
    padding: 10px;
    border: 1px solid var(--medium-gray);
    border-radius: 4px;
}

.file-details .file-icon {
    margin-right: 10px;
    color: var(--primary-color);
}

.file-details .file-size {
    color: #777;
    margin-left: auto;
}



#convert-btn {
    width: 100%;
    padding: 15px;
    font-weight: bold;
}

.progress-bar {
    height: 20px;
    background-color: var(--light-gray);
    border-radius: 10px;
    margin: 20px 0;
    overflow: hidden;
}

.progress-fill {
    height: 100%;
    background-color: var(--primary-color);
    width: 0;
    transition: width 0.3s;
}

#progress-status {
    text-align: center;
}

.buttons {
    display: flex;
    gap: 10px;
}

.buttons button {
    flex: 1;
}

#download-excel-btn {
    background-color: var(--success-color);
    margin-right: 10px;
}

#download-excel-btn:hover {
    background-color: #2e7d32;
}

#error-message {
    color: var(--error-color);
    margin-bottom: 20px;
}

#try-again-btn {
    background-color: var(--error-color);
}

#try-again-btn:hover {
    background-color: #c0392b;
}

footer {
    text-align: center;
    margin-top: 30px;
    color: #777;
    font-size: 14px;
}

footer .build-info {
    font-size: 12px;
    color: #999;
    margin-top: 5px;
}