:root {
    --primary-color: #4a69bd;
    --secondary-color: #f8f9fa;
    --border-color: #dee2e6;
    --text-color: #212529;
    --online-color: #28a745;
    --offline-color: #dc3545;
}

body {
    font-family: sans-serif;
    margin: 0;
    background-color: var(--secondary-color);
    color: var(--text-color);
    display: flex;
    height: 100vh;
}

.hidden { display: none !important; }

/* 로그인 모달 */
.modal {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.5);
    display: none;
    justify-content: center;
    align-items: center;
}
.modal.active { display: flex; }
.modal-content {
    background-color: white;
    padding: 2em;
    border-radius: 8px;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.2);
}
#login-form { display: flex; flex-direction: column; gap: 1em; }
#login-form input, #login-form button { padding: 0.8em; font-size: 1em; }
.error-message { color: var(--offline-color); text-align: center; }

/* 대시보드 레이아웃 */
#dashboard {
    display: flex;
    width: 100%;
    height: 100%;
}
.sidebar {
    width: 250px;
    background-color: white;
    border-right: 1px solid var(--border-color);
    padding: 1em;
    overflow-y: auto;
}
.main-content {
    flex-grow: 1;
    padding: 2em;
    overflow-y: auto;
}

/* PC 목록 */
#pc-list {
    list-style-type: none;
    padding: 0;
    margin: 0;
}
#pc-list li {
    padding: 0.8em;
    cursor: pointer;
    border-radius: 5px;
    margin-bottom: 0.5em;
    border-left: 5px solid transparent;
}
#pc-list li:hover { background-color: var(--secondary-color); }
#pc-list li.active {
    background-color: #e9ecef;
    font-weight: bold;
}
#pc-list li.online { border-left-color: var(--online-color); }
#pc-list li.offline { border-left-color: var(--offline-color); }
#pc-list li::before {
    content: '● ';
    font-size: 0.8em;
}
#pc-list li.online::before { color: var(--online-color); }
#pc-list li.offline::before { color: var(--offline-color); }

/* 탭 */
.tabs {
    display: flex;
    border-bottom: 1px solid var(--border-color);
    margin-bottom: 1em;
}
.tab-button {
    padding: 0.8em 1.2em;
    border: none;
    background: none;
    cursor: pointer;
    font-size: 1em;
    color: var(--text-color);
}
.tab-button.active {
    font-weight: bold;
    border-bottom: 3px solid var(--primary-color);
}
.tab-content { display: none; }
.tab-content.active { display: block; }

/* << 추가 >> 서브 탭 스타일 */
.sub-tabs {
    display: flex;
    margin-bottom: 1em;
    gap: 0.5em;
}
.sub-tab-button {
    padding: 0.5em 1em;
    border: 1px solid var(--border-color);
    background-color: #fff;
    border-radius: 20px;
    cursor: pointer;
}
.sub-tab-button.active {
    background-color: var(--primary-color);
    color: white;
    border-color: var(--primary-color);
}
.sub-tab-content { display: none; }
.sub-tab-content.active { display: block; }


/* 테이블 및 폼 */
table {
    width: 100%;
    border-collapse: collapse;
    margin-top: 1em;
}
th, td {
    padding: 0.8em;
    text-align: left;
    border-bottom: 1px solid var(--border-color);
}
thead { background-color: var(--secondary-color); }
/* << 추가 >> 테이블 footer 스타일 */
tfoot {
    background-color: #e9ecef;
    font-weight: bold;
}
#daily-total-usage {
    margin: 1em 0;
    font-size: 1.1em;
    font-weight: bold;
}

input[type="text"], input[type="password"], input[type="number"], input[type="date"], select {
    padding: 0.5em;
    margin-right: 0.5em;
}
button {
    padding: 0.5em 1em;
    background-color: var(--primary-color);
    color: white;
    border: none;
    border-radius: 5px;
    cursor: pointer;
}
button:hover { opacity: 0.9; }
.actions, .setting-item, .add-program-form { margin-top: 1.5em; }

/* 화면 공유 모달 */
.screen-view { width: 80%; max-width: 1200px; }
.screen-view img { width: 100%; height: auto; background-color: #eee; }
.close-btn {
    position: absolute;
    top: 10px;
    right: 25px;
    font-size: 35px;
    cursor: pointer;
}

/* 위험 구역 스타일 */
.danger-zone {
    margin-top: 2em;
    padding: 1em;
    border: 1px solid var(--offline-color);
    border-radius: 5px;
    background-color: #fdf2f2;
}
.danger-btn {
    background-color: var(--offline-color);
}
.danger-btn:hover {
    opacity: 0.8;
}