:root {
    --primary-color: #007bff;
    --primary-hover-color: #0056b3;
    --background-color: #f8f9fa;
    --card-background-color: #ffffff;
    --text-color: #343a40;
    --light-text-color: #6c757d;
    --border-color: #dee2e6;
    --success-color: #28a745;
}

body {
    font-family: 'Poppins', sans-serif;
    background-color: var(--background-color);
    color: var(--text-color);
    margin: 0;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    padding: 20px;
    box-sizing: border-box;
}

.container {
    background-color: var(--card-background-color);
    padding: 40px;
    border-radius: 12px;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.1);
    width: 100%;
    max-width: 600px;
    text-align: center;
}

header h1 {
    font-size: 2.5rem;
    margin-bottom: 10px;
    color: var(--primary-color);
}

header p {
    font-size: 1.1rem;
    color: var(--light-text-color);
    margin-bottom: 30px;
}

.upload-section input[type="file"] {
    display: none;
}

.upload-label {
    background-color: var(--primary-color);
    color: white;
    padding: 15px 30px;
    border-radius: 8px;
    cursor: pointer;
    display: inline-flex;
    align-items: center;
    gap: 10px;
    font-size: 1.1rem;
    transition: background-color 0.3s ease;
}

.upload-label:hover {
    background-color: var(--primary-hover-color);
}

.upload-label svg {
    width: 28px;
    height: 28px;
}

.file-name-display {
    margin-top: 15px;
    color: var(--light-text-color);
    font-style: italic;
    min-height: 20px;
}

.controls-section {
    margin-top: 30px;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 25px;
}

.controls-section.hidden {
    display: none;
}

.slider-container {
    width: 100%;
    max-width: 400px;
}

.slider-container label {
    display: block;
    margin-bottom: 10px;
    font-size: 1.1rem;
}

#volume-slider {
    width: 100%;
    cursor: pointer;
}

.download-button {
    background-color: var(--success-color);
    color: white;
    padding: 15px 30px;
    border-radius: 8px;
    border: none;
    cursor: pointer;
    display: inline-flex;
    align-items: center;
    gap: 10px;
    font-size: 1.1rem;
    transition: background-color 0.3s ease;
}

.download-button:disabled {
    background-color: #a7d7b4;
    cursor: not-allowed;
}

.download-button:not(:disabled):hover {
    background-color: #218838;
}

.download-button svg {
    width: 24px;
    height: 24px;
}

.status-message {
    margin-top: 15px;
    color: var(--primary-color);
    font-weight: 600;
}

footer {
    margin-top: 40px;
    color: var(--light-text-color);
    font-size: 0.9rem;
}