:root {
    --primary: #2c3e50;
    --secondary: #3498db;
    --accent: #e74c3c;
    --light: #ecf0f1;
    --dark: #2c3e50;
    --success: #2ecc71;
    --warning: #f39c12;
    --danger: #e74c3c;
}

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

body {
    background-color: #f5f7fa;
    color: #333;
    line-height: 1.6;
}

.container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 20px;
}

header {
    background: var(--primary);
    color: white;
    padding: 20px 0;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
}

.header-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-size: 24px;
    font-weight: bold;
}

.logo span {
    color: var(--secondary);
}

nav ul {
    display: flex;
    list-style: none;
}

nav ul li {
    margin-left: 20px;
}

nav ul li a {
    color: white;
    text-decoration: none;
    padding: 5px 10px;
    border-radius: 4px;
    transition: background 0.3s;
}

nav ul li a:hover, nav ul li a.active {
    background: rgba(255, 255, 255, 0.1);
}

.main-content {
    display: grid;
    grid-template-columns: 1fr 3fr;
    gap: 20px;
    margin-top: 20px;
}

.sidebar {
    background: white;
    border-radius: 8px;
    padding: 20px;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.05);
}

.sidebar h3 {
    margin-bottom: 15px;
    padding-bottom: 10px;
    border-bottom: 1px solid #eee;
}

.sidebar ul {
    list-style: none;
}

.sidebar ul li {
    margin-bottom: 10px;
}

.sidebar ul li a {
    color: var(--dark);
    text-decoration: none;
    display: block;
    padding: 8px;
    border-radius: 4px;
    transition: background 0.3s;
}

.sidebar ul li a:hover {
    background: #f4f6f8;
}

.content {
    background: white;
    border-radius: 8px;
    padding: 20px;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.05);
}

.tab-content {
    display: none;
}
.tab-content.active {
    display: block;
}

.card {
    background: #fff;
    border-radius: 8px;
    padding: 15px;
    margin-bottom: 20px;
    box-shadow: 0 1px 6px rgba(0,0,0,0.04);
}

.card-title {
    font-size: 18px;
    margin-bottom: 10px;
}

.calculation-form .form-group {
    margin-bottom: 12px;
}
.calculation-form label {
    display: block;
    font-size: 14px;
    margin-bottom: 6px;
}
.calculation-form input, .calculation-form select, .calculation-form textarea {
    width: 100%;
    padding: 8px 10px;
    border: 1px solid #ddd;
    border-radius: 6px;
    font-size: 14px;
}

.btn {
    display: inline-block;
    padding: 8px 12px;
    border-radius: 6px;
    background: var(--secondary);
    color: white;
    text-decoration: none;
    border: none;
    cursor: pointer;
}
.btn.btn-danger { background: var(--danger); }
.btn.btn-success { background: var(--success); }

.dashboard-stats {
    display: flex;
    gap: 12px;
}
.stat-card {
    flex: 1;
    background: linear-gradient(180deg, #fff, #fbfdff);
    border-radius: 8px;
    padding: 12px;
    text-align: center;
    box-shadow: 0 1px 6px rgba(0,0,0,0.03);
}
.stat-title { font-size: 14px; color: #666; }
.stat-number { font-size: 24px; font-weight: bold; }

.project-card {
    border-left: 4px solid var(--secondary);
    padding: 10px 12px;
    margin-bottom: 10px;
    background: #fbfdff;
}

.drawing-container {
    border: 1px dashed #ddd;
    padding: 10px;
    border-radius: 6px;
    min-height: 200px;
}

table {
    width: 100%;
    border-collapse: collapse;
}
table thead th {
    text-align: left;
    padding: 8px;
    background: #f9fbff;
    border-bottom: 1px solid #eee;
}
table tbody td {
    padding: 8px;
    border-bottom: 1px solid #f2f2f2;
}

.result-item {
    display: flex;
    justify-content: space-between;
    margin-bottom: 8px;
}