/* --- Global Styles & Variables --- */
:root {
    --primary-color: #007bff;
    --secondary-color: #6c757d;
    --background-color: #f8f9fa;
    --card-background: #ffffff;
    --text-color: #212529;
    --heading-color: #000;
    --border-color: #dee2e6;
    --box-shadow: 0 4px 12px rgba(0, 0, 0, 0.08);
}

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

.container {
    max-width: 960px;
    margin: 0 auto;
    padding: 0 1.5rem;
}

/* --- Header & Footer --- */
.main-header, .main-footer {
    background-color: var(--card-background);
    padding: 1rem 0;
    border-bottom: 1px solid var(--border-color);
}
.main-footer {
    border-bottom: none;
    border-top: 1px solid var(--border-color);
    margin-top: 4rem;
    font-size: 0.9rem;
    color: var(--secondary-color);
}
.main-header .container, .main-footer .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}
.logo {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--heading-color);
    text-decoration: none;
}
.main-nav a, .footer-nav a {
    margin-left: 1.5rem;
    text-decoration: none;
    color: var(--secondary-color);
    transition: color 0.2s;
}
.main-nav a:hover, .footer-nav a:hover {
    color: var(--primary-color);
}

/* --- Homepage Styles --- */
.hero { text-align: center; padding: 4rem 1.5rem; }
.hero h1 { font-size: 2.8rem; }
.calculator-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(250px, 1fr)); gap: 1.5rem; margin-top: 3rem; text-align: left; }
.card { background: var(--card-background); border-radius: 12px; padding: 1.5rem; text-decoration: none; color: var(--text-color); box-shadow: var(--box-shadow); transition: transform 0.2s, box-shadow 0.2s; }
.card:hover { transform: translateY(-5px); box-shadow: 0 8px 20px rgba(0,0,0,0.12); }
.card h3 { margin-top: 0; color: var(--primary-color); }

/* --- Main Calculator Layout --- */
main { padding: 3rem 0; }
.calculator-container { display: grid; grid-template-columns: 1fr 1fr; gap: 2rem; background-color: var(--card-background); border-radius: 12px; box-shadow: var(--box-shadow); overflow: hidden; }
.calculator-inputs { padding: 2.5rem; }
.calculator-results { background-color: var(--primary-color); color: white; padding: 2.5rem; display: flex; flex-direction: column; justify-content: center; }

/* --- Input & Form Styles --- */
h1 { font-size: 2.25rem; font-weight: 700; color: var(--heading-color); margin-top: 0; margin-bottom: 0.5rem; }
.subtitle { color: var(--secondary-color); margin-bottom: 2.5rem; }
.input-group { margin-bottom: 1.5rem; }
.input-group label { display: block; font-weight: 600; margin-bottom: 0.5rem; }
.input-group input, .input-group select { width: 100%; padding: 0.75rem 1rem; border: 1px solid var(--border-color); border-radius: 8px; font-size: 1rem; box-sizing: border-box; }
.input-group input:focus { outline: none; border-color: var(--primary-color); box-shadow: 0 0 0 3px rgba(0, 123, 255, 0.25); }

/* --- Slider Styles --- */
.input-with-slider { display: flex; flex-direction: column; }
.input-with-slider input[type="range"] { width: 100%; margin-top: 0.75rem; -webkit-appearance: none; appearance: none; height: 8px; background: #ddd; border-radius: 5px; outline: none; opacity: 0.7; transition: opacity .2s; }
.input-with-slider input[type="range"]:hover { opacity: 1; }
.input-with-slider input[type="range"]::-webkit-slider-thumb { -webkit-appearance: none; appearance: none; width: 20px; height: 20px; background: var(--primary-color); border-radius: 50%; cursor: pointer; }
.input-with-slider input[type="range"]::-moz-range-thumb { width: 20px; height: 20px; background: var(--primary-color); border-radius: 50%; cursor: pointer; }

/* --- Results Display --- */
.calculator-results h2 { margin-top: 0; font-size: 1.5rem; font-weight: 600; opacity: 0.8; }
.result-display { display: flex; align-items: baseline; margin-bottom: 2rem; }
.result-display .currency, .result-display .unit { font-size: 2rem; font-weight: 600; margin-right: 0.5rem; }
.result-display .value { font-size: 3.5rem; font-weight: 700; line-height: 1; }
.result-display .period { font-size: 1.25rem; font-weight: 600; opacity: 0.8; margin-left: 0.5rem; }
.breakdown p { margin: 0.5rem 0; font-size: 1rem; opacity: 0.9; }

/* --- Ad Placeholders & Content Sections --- */
.adsense-placeholder { width:100%; background-color:#e9ecef; text-align:center; color: #6c757d; font-weight: bold; display: flex; align-items: center; justify-content: center; border-radius: 8px; }
.content-section { margin-top: 3rem; background: var(--card-background); padding: 2rem; border-radius: 12px; }
.content-page { background: var(--card-background); padding: 2rem; border-radius: 12px; }

/* --- Responsive Design --- */
@media (max-width: 768px) {
    .calculator-container { grid-template-columns: 1fr; }
    h1 { font-size: 1.8rem; }
    .result-display .value { font-size: 2.8rem; }
}