* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    font-family: 'Segoe UI', Arial, sans-serif;
}

body {
    background: #f5f7fa;
    padding: 10px;
    color: #333;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    background: white;
    padding: 20px;
    border-radius: 12px;
    box-shadow: 0 0 20px rgba(0,0,0,0.1);
}

h1, h2, h3 {
    color: #2c3e50;
    margin: 15px 0;
    text-align: center;
}

.form-group {
    margin: 15px 0;
}

label {
    display: block;
    margin: 8px 0 4px;
    font-weight: 600;
    color: #34495e;
}

input, select, button, textarea {
    width: 100%;
    padding: 10px;
    border: 1px solid #ddd;
    border-radius: 8px;
    font-size: 14px;
}

button {
    background: #3498db;
    color: white;
    cursor: pointer;
    font-weight: bold;
    transition: 0.3s;
    margin: 5px 0;
    border: none;
    border-radius: 6px;
    padding: 8px 16px;
    font-size: 14px;
}

button:hover {
    background: #2980b9;
}

.tabs {
    display: flex;
    gap: 8px;
    flex-wrap: wrap;
    margin: 15px 0;
    overflow-x: auto;
    padding: 5px 0;
}

.tab {
    padding: 8px 16px;
    background: #ecf0f1;
    border-radius: 6px;
    cursor: pointer;
    font-weight: 600;
    white-space: nowrap;
}

.tab.active {
    background: #3498db;
    color: white;
}

.tab-content {
    display: none;
}

.tab-content.active {
    display: block;
}

.error {
    color: #e74c3c;
    background: #fadbd8;
    padding: 12px;
    border-radius: 8px;
    margin: 15px 0;
}

.success {
    color: #27ae60;
    background: #d5f5e3;
    padding: 12px;
    border-radius: 8px;
    margin: 15px 0;
}

table {
    width: 100%;
    border-collapse: collapse;
    margin: 15px 0;
    font-size: 13px;
}

th, td {
    border: 1px solid #ddd;
    padding: 8px;
    text-align: left;
}

th {
    background: #f8f9fa;
    font-weight: 600;
}

.btn-group {
    display: flex;
    gap: 8px;
    flex-wrap: wrap;
    margin: 15px 0;
}

.btn {
    padding: 8px 16px;
    border: none;
    border-radius: 6px;
    cursor: pointer;
    font-weight: 600;
    font-size: 14px;
}

.btn-primary { background: #3498db; color: white; }
.btn-success { background: #27ae60; color: white; }
.btn-danger { background: #e74c3c; color: white; }
.btn-warning { background: #f39c12; color: white; }
.btn-export { background: #9b59b6; color: white; }
.btn-undo { background: #8e44ad; color: white; }

.hidden {
    display: none;
}

.status {
    padding: 10px;
    margin: 10px 0;
    border-radius: 6px;
}

.status.success {
    background: #d5f5e3;
    color: #27ae60;
}

.status.error {
    background: #fadbd8;
    color: #e74c3c;
}

.load-item {
    background: #f0f0f0;
    padding: 10px;
    margin: 5px 0;
    border-radius: 6px;
    position: relative;
}

.subject-tag {
    display: inline-block;
    background: #e3f2fd;
    padding: 5px 10px;
    margin: 5px;
    border-radius: 15px;
}

.teacher-block {
    background: #f9f9f9;
    padding: 15px;
    margin: 15px 0;
    border-radius: 8px;
}

.period-entry {
    display: flex;
    gap: 5px;
    margin: 5px 0;
    align-items: center;
}

.draggable {
    cursor: move;
    background: #e3f2fd;
    padding: 5px;
    border: 1px solid #bbdefb;
    border-radius: 4px;
}

.dropzone {
    min-height: 30px;
    background: #fff;
    border: 1px dashed #ddd;
}

.schedule-table {
    margin-bottom: 30px;
}

.shift-header {
    background: #3498db;
    color: white;
    padding: 10px;
    border-radius: 6px;
    margin: 20px 0 10px;
}

.loads-table {
    width: 100%;
    border-collapse: collapse;
    margin: 10px 0;
}

.loads-table th, .loads-table td {
    border: 1px solid #ddd;
    padding: 8px;
    text-align: center;
}

.loads-table th {
    background: #f1f1f1;
}

@media (max-width: 768px) {
    .container {
        padding: 10px;
    }
    .btn-group {
        flex-direction: column;
    }
    input, select, button {
        font-size: 14px;
        padding: 8px;
    }
    .tabs {
        padding: 5px 0;
    }
    .tab {
        padding: 6px 12px;
        font-size: 14px;
    }
    table {
        font-size: 12px;
    }
    th, td {
        padding: 6px;
    }
}