:root {
    --primary-color: #00aeff;
    --background-color: #0a192f;
    --card-background-color: #112240;
    --text-color: #ccd6f6;
    --label-color: #8892b0;
    --border-color: #233554;
    --input-background: #1d2d44;
    --success-color: #64ffda;
    --error-color: #ff6489;
}

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

.container {
    max-width: 800px;
    margin-top: 40px;
}

.main-header h1 {
    color: var(--primary-color);
    font-weight: 600;
    border-bottom: 1px solid var(--border-color);
    padding-bottom: 15px;
}

.config-form {
    background-color: var(--card-background-color);
    padding: 30px;
    border-radius: 8px;
    border: 1px solid var(--border-color);
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.2);
}

.form-section {
    margin-bottom: 30px;
    padding-bottom: 20px;
    border-bottom: 1px solid var(--border-color);
}

.form-section:last-of-type {
    border-bottom: none;
    padding-bottom: 0;
}

.form-section h4 {
    color: var(--success-color);
    margin-bottom: 20px;
    font-size: 1.1rem;
    text-transform: uppercase;
    letter-spacing: 1px;
}

.form-label {
    color: var(--label-color);
    font-weight: 500;
}

.form-control {
    background-color: var(--input-background);
    border: 1px solid var(--border-color);
    color: var(--text-color);
    border-radius: 4px;
}

.form-control:focus {
    background-color: var(--input-background);
    color: var(--text-color);
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(0, 174, 255, 0.2);
}

.form-control::placeholder {
    color: var(--label-color);
    opacity: 0.7;
}

.form-check-input {
    background-color: var(--border-color);
    border-color: var(--border-color);
}

.form-check-input:checked {
    background-color: var(--primary-color);
    border-color: var(--primary-color);
}

.form-check-input:focus {
    box-shadow: 0 0 0 3px rgba(0, 174, 255, 0.2);
}

.form-actions {
    text-align: right;
    margin-top: 20px;
}

.btn-primary {
    background-color: var(--primary-color);
    border-color: var(--primary-color);
    color: var(--background-color);
    font-weight: bold;
}

.btn-glow {
    box-shadow: 0 0 8px rgba(0, 174, 255, 0.5);
    transition: box-shadow 0.3s ease-in-out;
}

.btn-glow:hover {
    box-shadow: 0 0 15px rgba(0, 174, 255, 0.8);
}

#alert-container .alert {
    border-radius: 4px;
    border-width: 2px;
}

/* Top-left Back Button Styles */
.top-left-back-button {
    position: absolute;
    top: 20px;
    left: 20px;
    z-index: 1000; /* 確保在最上層 */
}

.top-left-back-button a {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 40px;
    height: 40px;
    border-radius: 50%;
    background-color: rgba(0, 174, 255, 0.2); /* 半透明背景 */
    color: #00aeff; /* 圖示顏色 */
    font-size: 1.2em;
    text-decoration: none;
    transition: all 0.3s ease;
    box-shadow: 0 2px 5px rgba(0, 0, 0, 0.3);
}

.top-left-back-button a:hover {
    background-color: rgba(0, 174, 255, 0.4);
    color: #fff;
    box-shadow: 0 0 10px rgba(0, 174, 255, 0.8);
    transform: scale(1.05);
}