@import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600;700;800&display=swap');

:root {
    --primary: #006837;
    --primary-dark: #004d28;
    --primary-light: #e6f3eb;
    --secondary: #ffb81c;
    --secondary-hover: #e5a415;
    --bg: #f4f7f6;
    --card-bg: #ffffff;
    --text-main: #333;
    --text-muted: #555;
    --border: #e0e6e2;
    --radius: 10px;
    --shadow: 0 4px 15px rgba(0,0,0,0.05);
}

* { margin: 0; padding: 0; box-sizing: border-box; font-family: 'Inter', sans-serif; }
body { background: var(--bg); color: var(--text-main); line-height: 1.6; }
a { color: var(--primary); text-decoration: none; font-weight: 500; }
a:hover { text-decoration: underline; }

.container { max-width: 1100px; margin: 0 auto; padding: 0 20px; }

/* Header */
.top-strip { background: var(--primary); color: #fff; padding: 10px 0; font-size: 0.9rem; }
.top-strip-flex { display: flex; justify-content: space-between; }
.text-yellow { color: var(--secondary); }

.gepco-header { background: #fff; box-shadow: 0 2px 10px rgba(0,0,0,0.1); position: sticky; top: 0; z-index: 1000; }
.header-main { display: flex; justify-content: space-between; align-items: center; padding: 15px 20px; }
.gepco-brand { display: flex; align-items: center; gap: 15px; text-decoration: none !important; }
.brand-logo-circle { width: 60px; height: 60px; border-radius: 50%; border: 2px solid var(--primary); display: flex; align-items: center; justify-content: center; overflow: hidden; background: #fff; }
.brand-logo-img { max-width: 100%; height: auto; }
.brand-name { display: flex; flex-direction: column; }
.main-title { font-size: 1.5rem; font-weight: 800; color: var(--primary); line-height: 1.2; }
.sub-title { font-size: 0.85rem; color: var(--text-muted); font-weight: 500; }

.main-nav { display: flex; gap: 20px; }
.nav-item { color: var(--text-main); font-weight: 600; padding: 10px 15px; border-radius: 6px; transition: 0.2s; }
.nav-item:hover, .nav-item.active { background: var(--primary-light); color: var(--primary); text-decoration: none; }

/* Hero Tool Section */
.tool-hero-section { background: linear-gradient(135deg, #f4f7f6 0%, #e6f3eb 100%); padding: 50px 0; }
.tool-card-box { background: #fff; border-radius: var(--radius); padding: 40px; box-shadow: var(--shadow); max-width: 800px; margin: 0 auto; text-align: center; border: 1px solid var(--border); }
.official-badge { display: inline-block; background: var(--primary-light); color: var(--primary); padding: 6px 15px; border-radius: 20px; font-weight: 700; font-size: 0.9rem; margin-bottom: 15px; }
.tool-header h2 { font-size: 2rem; color: var(--text-main); margin-bottom: 10px; font-weight: 800; }

.tool-tabs { display: flex; justify-content: center; gap: 10px; margin: 25px 0; }
.tab-btn { background: #f0f0f0; border: none; padding: 12px 25px; border-radius: 6px; font-weight: 600; cursor: pointer; color: var(--text-muted); font-size: 1rem; }
.tab-btn.active { background: var(--primary); color: #fff; }

.input-row { display: flex; gap: 15px; max-width: 600px; margin: 0 auto; }
.field-wrap { flex: 1; position: relative; display: flex; align-items: center; }
.field-icon { position: absolute; left: 15px; color: #888; font-size: 1.2rem; }
.tool-input { width: 100%; padding: 16px 50px 16px 45px; border: 2px solid #ccc; border-radius: 8px; font-size: 1.1rem; font-family: monospace; font-weight: bold; outline: none; transition: 0.2s; }
.tool-input:focus { border-color: var(--primary); }
.digit-count { position: absolute; right: 15px; font-size: 0.9rem; color: #888; font-weight: bold; }
.btn-check-submit { background: var(--secondary); color: #000; border: none; padding: 0 30px; font-size: 1.1rem; font-weight: 800; border-radius: 8px; cursor: pointer; box-shadow: 0 4px 6px rgba(255, 184, 28, 0.3); transition: 0.2s; }
.btn-check-submit:hover { background: var(--secondary-hover); transform: translateY(-2px); }

/* Diagram */
.diagram-grid { display: flex; gap: 30px; align-items: center; background: #fff; padding: 30px; border-radius: var(--radius); box-shadow: var(--shadow); border: 1px solid var(--border); margin-top: 30px; }
.bill-graphic-sample { flex: 1; background: #fdfdfd; border: 1px dashed #ccc; padding: 20px; border-radius: 8px; }
.mock-bill-header { display: flex; justify-content: space-between; border-bottom: 2px solid var(--primary); padding-bottom: 10px; margin-bottom: 15px; font-weight: bold; }
.mock-bill-ref-area { background: #fff3cd; border: 2px solid var(--secondary); padding: 15px; text-align: center; border-radius: 6px; margin-bottom: 15px; position: relative; }
.mock-bill-ref-area .label { display: block; font-size: 0.8rem; font-weight: bold; color: #856404; }
.mock-bill-ref-area .val { display: block; font-size: 1.4rem; font-weight: 900; color: #000; font-family: monospace; }
.pointer-arrow { position: absolute; bottom: -25px; right: 20px; color: var(--primary); font-weight: bold; font-size: 0.9rem; }
.diagram-info { flex: 1; }
.diagram-info h3 { color: var(--primary); margin-bottom: 15px; }

/* Main Content */
.article-section { padding: 50px 0; }
.article-box { background: #fff; border-radius: var(--radius); padding: 40px; box-shadow: var(--shadow); border: 1px solid var(--border); }
.main-h1-title { font-size: 2.2rem; color: var(--primary); margin-bottom: 25px; font-weight: 800; border-bottom: 3px solid var(--primary-light); padding-bottom: 10px; display: inline-block;}
.article-box h2 { font-size: 1.8rem; color: var(--text-main); margin: 40px 0 20px; padding-bottom: 10px; border-bottom: 2px solid var(--primary-light); }
.article-box h3 { font-size: 1.4rem; color: var(--primary-dark); margin: 25px 0 15px; }
.article-box p { margin-bottom: 20px; font-size: 1.1rem; }
.article-box ul, .article-box ol { margin-bottom: 20px; padding-left: 20px; }
.article-box li { margin-bottom: 10px; font-size: 1.1rem; }

.image-showcase { margin: 40px 0; text-align: center; }
.responsive-img { max-width: 100%; height: auto; border-radius: 12px; box-shadow: 0 8px 25px rgba(0,0,0,0.1); }

/* Calculator */
.calculator-tool { background: #fff; border: 2px solid var(--primary); border-left: 8px solid var(--primary); border-radius: 12px; padding: 30px; margin: 40px 0; text-align: center; box-shadow: var(--shadow); }
.calculator-tool h3 { color: var(--primary); margin-top:0; font-size: 1.8rem; }
.calc-input { padding: 15px; font-size: 1.1rem; border: 2px solid var(--border); border-radius: 8px; width: 100%; max-width: 350px; margin-bottom: 15px; font-weight: bold; }
.calc-input:focus { border-color: var(--primary); outline: none; }
.calc-btn { background: var(--secondary); color: #000; border: none; padding: 15px 30px; font-size: 1.1rem; font-weight: 800; border-radius: 8px; cursor: pointer; transition: 0.3s; }
.calc-btn:hover { background: var(--secondary-hover); }
.calc-result { margin-top: 25px; font-size: 1.3rem; font-weight: bold; color: #333; display: none; padding: 15px; background: var(--primary-light); border-radius: 8px; }
.calc-result span { color: var(--primary); font-size: 1.8rem; display: block; margin-top: 5px; }

/* FAQ */
.faq-box h3 { background: var(--bg); padding: 15px 20px; border-radius: 6px; border-left: 4px solid var(--primary); font-size: 1.2rem; margin-bottom: 10px; }
.faq-box p { padding: 0 20px 20px; }

/* Footer */
footer { background: var(--primary-dark); color: #fff; padding: 40px 0; text-align: center; }
.footer-links { display: flex; justify-content: center; gap: 20px; margin-top: 20px; flex-wrap: wrap; }
.footer-links a { color: #ddd; }
.footer-links a:hover { color: var(--secondary); }

/* Mobile Menu */
.mobile-toggle { display: none; background: none; border: none; font-size: 1.5rem; color: var(--text-main); cursor: pointer; }

@media (max-width: 768px) {
    .main-nav { display: none; position: absolute; top: 100%; left: 0; width: 100%; background: #fff; flex-direction: column; padding: 20px; gap: 10px; box-shadow: 0 10px 10px rgba(0,0,0,0.1); }
    .main-nav.show { display: flex; }
    .mobile-toggle { display: block; }
    .top-strip-flex { flex-direction: column; text-align: center; gap: 5px; }
    .input-row { flex-direction: column; }
    .btn-check-submit { padding: 15px; }
    .diagram-grid { flex-direction: column; }
    .tool-header h2 { font-size: 1.6rem; }
    .article-box { padding: 25px; }
    .main-h1-title { font-size: 1.8rem; }
}

/* Advanced Calculator Styles */
.adv-calculator-wrapper {
    background: #fff;
    border: 2px solid #006837;
    border-radius: 12px;
    padding: 30px;
    margin: 40px 0;
    box-shadow: 0 4px 15px rgba(0,0,0,0.05);
}
.adv-calc-header {
    text-align: center;
    margin-bottom: 30px;
}
.adv-calc-header h2 {
    color: #006837 !important;
    font-size: 1.8rem !important;
    margin-bottom: 10px !important;
    border: none !important;
    padding: 0 !important;
}
.adv-calc-header p {
    color: #555;
    font-size: 1rem !important;
    margin-bottom: 0 !important;
}
.adv-calc-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 30px;
}
.adv-calc-form {
    display: flex;
    flex-direction: column;
    gap: 15px;
}
.form-group label {
    display: block;
    font-size: 0.95rem;
    color: #444;
    margin-bottom: 5px;
    text-align: left;
}
.calc-select, .adv-calc-form .calc-input {
    width: 100%;
    padding: 12px;
    border: 1px solid #ccc;
    border-radius: 6px;
    font-size: 1rem;
    background: #fff;
    outline: none;
    transition: 0.2s;
    font-family: inherit;
    font-weight: normal;
    max-width: none;
    margin: 0;
}
.calc-select:focus, .adv-calc-form .calc-input:focus {
    border-color: #006837;
}
.adv-calc-btn {
    background: #006837;
    color: #fff;
    border: none;
    padding: 14px 20px;
    font-size: 1.05rem;
    font-weight: bold;
    border-radius: 6px;
    cursor: pointer;
    transition: 0.3s;
    text-align: center;
    margin-top: 10px;
    align-self: flex-start;
}
.adv-calc-btn:hover {
    background: #004d28;
}
.adv-calc-result-box {
    background: #0a4f2e;
    color: #fff;
    border-radius: 8px;
    padding: 25px;
    display: flex;
    flex-direction: column;
}
.adv-calc-result-box h3 {
    color: #fff !important;
    font-size: 1.4rem !important;
    margin: 0 0 20px 0 !important;
    text-align: left;
    border: none !important;
    padding: 0 !important;
}
.result-row {
    display: flex;
    justify-content: space-between;
    margin-bottom: 12px;
    font-size: 0.95rem;
    color: #e0e0e0;
}
.res-val {
    font-weight: 600;
    color: #fff;
}
.result-divider {
    height: 1px;
    background: rgba(255,255,255,0.2);
    margin: 15px 0;
}
.total-row {
    font-size: 1.2rem;
    align-items: center;
    margin-bottom: 0;
}
.res-total-val {
    color: #ffb81c;
    font-size: 1.8rem;
    font-weight: 800;
}
@media (max-width: 768px) {
    .adv-calc-grid {
        grid-template-columns: 1fr;
    }
    .adv-calc-btn {
        align-self: stretch;
    }
}

/* Info Cards Design */
.info-cards-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 25px;
    margin: 30px 0;
}
.info-card {
    background: #fff;
    border: 1px solid var(--border);
    border-top: 4px solid var(--primary);
    border-radius: 8px;
    padding: 25px;
    box-shadow: var(--shadow);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}
.info-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 25px rgba(0,0,0,0.1);
}
.info-card h3 {
    color: var(--primary) !important;
    font-size: 1.25rem !important;
    margin-top: 0 !important;
    margin-bottom: 12px !important;
    display: flex;
    align-items: center;
    gap: 10px;
    border: none !important;
    padding-bottom: 0 !important;
}
.info-card h3 i {
    font-size: 1.5rem;
    color: var(--secondary);
}
.info-card p {
    font-size: 1.05rem;
    margin-bottom: 0 !important;
    color: #444;
}
.article-box ul li { margin-bottom: 8px; }
.article-box ol li { margin-bottom: 8px; }
.faq-box h3 { margin-top: 25px; }