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

:root {
    --primary-color: #4CAF50;
    --secondary-color: #2196F3;
    --warning-color: #FF9800;
    --danger-color: #f44336;
    --info-color: #00BCD4;
    --success-color: #4CAF50;
    --text-color: #333;
    --text-light: #666;
    --bg-color: #f5f5f5;
    --bg-dark: #1e1e1e;
    --border-color: #ddd;
    --header-height: 3.75rem;
    --bottom-panel-height: 15rem;
}

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

.hidden {
    display: none !important;
}

.btn {
    padding: 0.5rem 1rem;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    font-size: 0.875rem;
    transition: all 0.3s;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.375rem;
    min-width: 60px;
    min-height: 32px;
}

.btn:hover {
    opacity: 0.9;
    transform: translateY(-1px);
}

.btn:active {
    transform: translateY(0);
}

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

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

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

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

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

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

.btn-small {
    padding: 0.25rem 0.75rem;
    font-size: 0.75rem;
}

.btn-large {
    padding: 0.75rem 1.5rem;
    font-size: 1rem;
}

.icon {
    font-size: 1rem;
}

.toggle-switch {
    position: relative;
    display: inline-block;
    width: 56px;
    height: 28px;
}

.toggle-switch input {
    opacity: 0;
    width: 0;
    height: 0;
}

.toggle-switch .slider {
    position: absolute;
    cursor: pointer;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-color: #ccc;
    transition: 0.3s;
    border-radius: 28px;
}

.toggle-switch .slider:before {
    position: absolute;
    content: "";
    height: 20px;
    width: 20px;
    left: 4px;
    bottom: 4px;
    background-color: white;
    transition: 0.3s;
    border-radius: 50%;
    box-shadow: 0 2px 4px rgba(0,0,0,0.2);
}

.toggle-switch input:checked + .slider {
    background-color: #4CAF50;
}

.toggle-switch input:checked + .slider:before {
    transform: translateX(28px);
}

@keyframes pulse {
    0%, 100% {
        opacity: 1;
    }
    50% {
        opacity: 0.5;
    }
}

.page-header {
    height: auto;
    min-height: var(--header-height);
    background: var(--bg-dark);
    color: white;
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0 1.25rem;
    box-shadow: 0 0.125rem 0.625rem rgba(0, 0, 0, 0.1);
    flex-wrap: wrap;
    gap: 0.75rem;
}

.header-left,
.header-right {
    display: flex;
    align-items: center;
    gap: 1.25rem;
    flex-wrap: wrap;
}

.header-left h2 {
    font-size: 1.25rem;
    margin-right: 0.625rem;
}

.user-name,
.class-name {
    background: rgba(255, 255, 255, 0.1);
    padding: 0.25rem 0.75rem;
    border-radius: 4px;
    font-size: 0.875rem;
}

.header-center {
    display: flex;
    align-items: center;
    gap: 10px;
}

.main-content {
    flex: 1;
    display: flex;
    overflow: hidden;
    position: relative;
    min-width: 0;
}