:root {
    --primary-blue: #2C3E50;
    --accent-orange: #E67E22;
    --light-bg: #F8FAFC;
    --text-dark: #334155;
    --white: #FFFFFF;
}

body {
    font-family: 'Inter', sans-serif;
    line-height: 1.6;
    color: var(--text-dark);
    background-color: var(--light-bg);
    margin: 0;
}

header {
    background: var(--primary-blue);
    color: var(--white);
    padding: 1rem 5%;
}

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

.logo {
    font-size: 1.5rem;
    font-weight: bold;
    letter-spacing: -1px;
}

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

nav ul {
    list-style: none;
    display: flex;
    gap: 20px;
}

nav a {
    color: var(--white);
    text-decoration: none;
    font-weight: 500;
}

.hero {
    background: linear-gradient(rgba(44, 62, 80, 0.9), rgba(44, 62, 80, 0.9)), url('https://images.unsplash.com/photo-1541888946425-d81bb19240f5?auto=format&fit=crop&q=80&w=1000'); /* Professional construction/work site theme */
    background-size: cover;
    color: white;
    padding: 80px 10%;
    text-align: center;
}

.cta-button {
    background: var(--accent-orange);
    padding: 15px 30px;
    border-radius: 5px;
    color: white;
    text-decoration: none;
    font-weight: bold;
    display: inline-block;
    margin-top: 20px;
}

.tool-container {
    padding: 50px 10%;
    background: var(--white);
    margin: 40px auto;
    max-width: 800px;
    border-radius: 12px;
    box-shadow: 0 4px 15px rgba(0,0,0,0.05);
}

.instructor-note {
    font-style: italic;
    border-left: 4px solid var(--accent-orange);
    padding-left: 15px;
    margin-bottom: 30px;
}

.calculator-card label {
    display: block;
    margin-top: 15px;
    font-weight: bold;
}

.calculator-card input {
    width: 100%;
    padding: 12px;
    margin-top: 5px;
    border: 1px solid #DDD;
    border-radius: 4px;
}

.calculator-card button {
    width: 100%;
    background: var(--primary-blue);
    color: white;
    border: none;
    padding: 15px;
    margin-top: 20px;
    border-radius: 4px;
    cursor: pointer;
    font-weight: bold;
}

.results-box {
    margin-top: 25px;
    padding: 20px;
    background: #E8F4FD;
    border-radius: 8px;
    text-align: center;
}

.article-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 30px;
    padding: 50px 10%;
}

article {
    background: white;
    padding: 25px;
    border-radius: 8px;
    border-bottom: 4px solid var(--primary-blue);
}

.printable-banner {
    background: #27ae60;
    color: white;
    padding: 40px 10%;
    text-align: center;
}

.print-btn {
    background: white;
    color: #27ae60;
    border: none;
    padding: 10px 25px;
    font-weight: bold;
    cursor: pointer;
    border-radius: 4px;
}

footer {
    text-align: center;
    padding: 40px;
    background: #DDD;
    font-size: 0.8rem;
}

.disclaimer {
    max-width: 600px;
    margin: 10px auto;
    color: #666;
}