:root {
    --primary-color: #4a6fa5;
    --secondary-color: #6c757d;
    --success-color: #28a745;
    --light-color: #f8f9fa;
    --dark-color: #343a40;
    --border-color: #dee2e6;
}

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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    line-height: 1.6;
    color: var(--dark-color);
    background-color: #f5f7fa;
    padding: 20px;
}

.container {
    max-width: 800px;
    margin: 0 auto;
    background: white;
    border-radius: 10px;
    box-shadow: 0 0 20px rgba(0, 0, 0, 0.1);
    overflow: hidden;
}

header {
    background-color: var(--primary-color);
    color: white;
    padding: 20px;
    text-align: center;
}

header h1 {
    margin-bottom: 10px;
}

main {
    padding: 20px;
}

.upload-area {
    margin-bottom: 20px;
}

.drop-zone {
    border: 2px dashed var(--secondary-color);
    border-radius: 5px;
    padding: 40px 20px;
    text-align: center;
    cursor: pointer;
    transition: all 0.3s ease;
    margin-bottom: 20px;
}

.drop-zone:hover {
    border-color: var(--primary-color);
    background-color: rgba(74, 111, 165, 0.05);
}

.drop-zone__prompt {
    font-size: 1.2rem;
    color: var(--secondary-color);
}

.drop-zone__input {
    display: none;
}

.options {
    margin-bottom: 20px;
}

.option-group {
    margin-bottom: 15px;
}

.option-group label {
    display: block;
    margin-bottom: 5px;
    font-weight: 500;
}

.option-group input[type="range"] {
    width: 100%;
    margin-bottom: 5px;
}

.btn {
    display: inline-block;
    background-color: var(--primary-color);
    color: white;
    border: none;
    padding: 10px 20px;
    border-radius: 5px;
    cursor: pointer;
    font-size: 1rem;
    transition: background-color 0.3s;
    width: 100%;
    margin-bottom: 10px;
}

.btn:hover {
    background-color: #3a5a8a;
}

.btn.secondary {
    background-color: var(--secondary-color);
}

.btn.secondary:hover {
    background-color: #5a6268;
}

.btn:disabled {
    background-color: #cccccc;
    cursor: not-allowed;
}

.results {
    display: none;
}

.file-list {
    margin-bottom: 20px;
}

.file-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 15px;
    border: 1px solid var(--border-color);
    border-radius: 5px;
    margin-bottom: 10px;
    background-color: var(--light-color);
}

.file-info {
    flex: 1;
}

.file-name {
    font-weight: 500;
    margin-bottom: 5px;
}

.file-stats {
    display: flex;
    justify-content: space-between;
    font-size: 0.9rem;
    color: var(--secondary-color);
}

.file-savings {
    color: var(--success-color);
    font-weight: 500;
}

.download-btn {
    background-color: var(--success-color);
    color: white;
    border: none;
    padding: 5px 10px;
    border-radius: 3px;
    cursor: pointer;
    margin-left: 10px;
}

.loading {
    text-align: center;
    padding: 40px 0;
}

.spinner {
    border: 5px solid rgba(74, 111, 165, 0.2);
    border-radius: 50%;
    border-top: 5px solid var(--primary-color);
    width: 50px;
    height: 50px;
    animation: spin 1s linear infinite;
    margin: 0 auto 20px;
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

footer {
    text-align: center;
    padding: 15px;
    background-color: var(--light-color);
    color: var(--secondary-color);
    font-size: 0.9rem;
}

@media (max-width: 600px) {
    body {
        padding: 10px;
    }
    
    .file-item {
        flex-direction: column;
        align-items: flex-start;
    }
    
    .download-btn {
        margin-left: 0;
        margin-top: 10px;
        width: 100%;
    }
}