body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background-color: #f0f2f5;
    margin: 0;
    padding: 0;
    color: #333;
}

.container {
    max-width: 900px;
    margin: 40px auto;
    padding: 20px;
}

@media (max-width: 768px) {
    .container {
        margin: 20px auto;
        padding: 15px;
    }
}

.login-box {
    background: white;
    padding: 30px;
    border-radius: 8px;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
    max-width: 400px;
    margin: 100px auto;
}

@media (max-width: 576px) {
    .login-box {
        padding: 20px;
        margin: 50px auto;
    }
}

.login-box h2 {
    text-align: center;
    margin-bottom: 20px;
}

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

.form-group label {
    display: block;
    margin-bottom: 5px;
}

.dashboard-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 20px;
    flex-wrap: wrap;
    gap: 10px;
}

.dashboard-header h1 {
    margin: 0;
    font-size: 24px;
}

@media (max-width: 576px) {
    .dashboard-header {
        flex-direction: column;
        align-items: stretch;
    }

    .dashboard-header h1 {
        font-size: 20px;
        text-align: center;
    }

    .logout-btn {
        width: 100%;
    }
}

.search-container {
    background: white;
    padding: 15px;
    border-radius: 6px;
    box-shadow: 0 1px 3px rgba(0,0,0,0.1);
}

@media (max-width: 576px) {
    .search-container {
        padding: 10px;
    }
}

.tree-node {
    background: white;
    margin-bottom: 15px;
    border-radius: 6px;
    box-shadow: 0 1px 3px rgba(0,0,0,0.1);
    overflow: hidden;
}

.tree-node.hidden {
    display: none;
}

summary {
    padding: 15px;
    cursor: pointer;
    background-color: #fff;
    font-weight: bold;
    font-size: 1.1em;
    list-style: none;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

@media (max-width: 576px) {
    summary {
        padding: 12px;
        font-size: 1em;
    }
}

summary:hover {
    background-color: #f8f9fa;
}

summary::after {
    content: '+';
    font-weight: bold;
}

details[open] summary::after {
    content: '-';
}

.channel-list {
    padding: 0;
    margin: 0;
    list-style: none;
    border-top: 1px solid #eee;
}

.channel-item {
    padding: 12px 20px;
    border-bottom: 1px solid #f0f0f0;
    display: flex;
    justify-content: space-between;
    align-items: center;
    background-color: #fafafa;
    flex-wrap: wrap;
    gap: 10px;
}

@media (max-width: 576px) {
    .channel-item {
        padding: 10px 15px;
        flex-direction: column;
        align-items: stretch;
    }
}

.channel-item:last-child {
    border-bottom: none;
}

.channel-item.hidden {
    display: none;
}

.channel-info {
    display: flex;
    flex-direction: column;
    flex: 1;
    min-width: 0;
}

.channel-name {
    font-weight: 600;
    word-break: break-word;
}

.channel-url {
    font-size: 0.85em;
    color: #666;
    margin-top: 4px;
    word-break: break-all;
}

@media (max-width: 576px) {
    .channel-url {
        font-size: 0.75em;
    }
}

.copy-btn {
    padding: 6px 12px;
    font-size: 13px;
    background-color: #28a745;
    color: white;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    white-space: nowrap;
}

@media (max-width: 576px) {
    .copy-btn {
        width: 100%;
        padding: 8px 12px;
    }
}

.copy-btn:hover {
    background-color: #218838;
}

.error-msg {
    color: red;
    text-align: center;
    margin-top: 10px;
    display: none;
}