:root{
--primary:#007AFF;
--bg:#ffffff;
--text:#1d1d1f;
--muted:#6e6e73;
--card-border:#e5e5ea;
--underweight: #FFCC00;
--normal: #34C759;
--overweight: #FF9500;
--obese: #FF3B30;
--rainbow:linear-gradient(45deg,#ff9a9e,#fad0c4,#ffecd2,#a1c4fd,#c2e9fb,#d4fc79,#84fab0)
}

*{margin:0;padding:0;box-sizing:border-box}

body{
font-family:-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,sans-serif;
background:var(--bg); color:var(--text); min-height:100vh;
display:flex; flex-direction:column; text-align: center;
}

main{
flex:1; display:flex; flex-direction: column; align-items:center; justify-content:center; padding:30px 16px;
}

.calc-box{width:100%; max-width:550px; position: relative; z-index: 1;}

.rainbow-wrapper {
    padding: 4px; border-radius: 30px; background: var(--rainbow);
    background-size: 300%; animation: rainbowMove 6s linear infinite; margin-bottom: 40px;
}
@keyframes rainbowMove{ 0%{background-position:0% 50%} 50%{background-position:100% 50%} 100%{background-position:0% 50%} }

.result-card{ background:#fff; border-radius:26px; padding:40px 20px; border:none; position:relative; }

.input-row { display: flex; gap: 15px; margin-bottom: 25px; }
.input-group { flex: 1; }
label{ font-size:.7rem; font-weight:900; color:var(--primary); text-transform:uppercase; letter-spacing:1px; margin-bottom:8px; display:block; }
input{ width:100%; padding:16px; border-radius:14px; border:1px solid var(--card-border); font-size:1.1rem; font-weight:700; background:#fafafa; outline:none; text-align: center; }

.val-bmi{ font-size:clamp(3.5rem, 15vw, 5rem); font-weight:900; letter-spacing:-4px; line-height: 1; transition: 0.3s; }
.label-bmi{ font-size:.75rem; font-weight:900; opacity:.3; letter-spacing:3px; margin-bottom:15px; text-transform: uppercase; }
#bmi-status { font-weight: 800; font-size: 1.2rem; margin-bottom: 25px; text-transform: uppercase; letter-spacing: 1px; }

.info-line{ font-size:0.9rem; font-weight:800; color:var(--text); margin-top: 15px; border-top: 1px solid #f2f2f7; padding-top: 20px; }

.gauge-container { margin-top: 20px; }
.gauge-bar {
    height: 10px; width: 100%; background: #f2f2f7;
    border-radius: 10px; overflow: hidden; display: flex;
}
.segment { height: 100%; transition: 0.3s; }

.action-row{ margin-top:30px; display:flex; gap:12px; justify-content:center; }
.action-btn{ flex: 1; max-width: 180px; padding:14px; border-radius:14px; border:1px solid var(--card-border); background:#fff; font-size:.75rem; font-weight:800; cursor:pointer; color:var(--primary); transition: 0.2s; box-shadow: 0 4px 12px rgba(0,0,0,0.04); }
.action-btn:active { transform: scale(0.96); }

/* SEO Content Sections */
.guide-container { width: 75%; margin: 40px auto; padding: 60px 30px; background: rgba(255,255,255,0.7); border-radius: 45px; border: 1px solid var(--card-border); backdrop-filter: blur(20px); }
.guide-container h2 { font-size: 2.2rem; font-weight: 900; color: var(--primary); margin-bottom: 25px; letter-spacing: -1.5px; }
.guide-container h3 { font-size: 1.4rem; font-weight: 800; margin: 30px 0 15px; border-left: 5px solid var(--primary); padding-left: 15px; }
.guide-container p { font-size: 1.1rem; line-height: 1.8; color: #444; margin-bottom: 20px; font-weight: 500; }
.guide-container ul { list-style: none; margin: 20px 0; }
.guide-container li { margin-bottom: 12px; font-weight: 600; color: #333; position: relative; padding-left: 25px; }
.guide-container li::before { content: '→'; position: absolute; left: 0; color: var(--primary); }
.guide-container .example { background: #f7f7f9; border-left: 4px solid var(--primary); padding: 20px; margin: 20px 0; border-radius: 0 8px 8px 0; font-family: monospace; color: #555; text-align: left; }

.faq-section { width: 75%; margin: 40px auto; padding: 0 15px; text-align: left; }
.faq-section h2 { font-size: 2.2rem; font-weight: 900; color: var(--primary); margin-bottom: 25px; text-align: center; letter-spacing: -1.5px; }
.faq-item { border-bottom: 1px solid var(--card-border); margin-bottom: 15px; }
.faq-question { width: 100%; background: none; border: none; text-align: left; padding: 15px 0; font-size: 1.1rem; font-weight: 700; cursor: pointer; position: relative; padding-right: 30px; color: var(--text); }
.faq-question::after { content: '+'; position: absolute; right: 5px; top: 50%; transform: translateY(-50%); font-size: 1.5rem; font-weight: 300; color: var(--primary); transition: transform 0.3s; }
.faq-item.active .faq-question::after { transform: translateY(-50%) rotate(45deg); }
.faq-answer { max-height: 0; overflow: hidden; transition: max-height 0.4s ease-out; }
.faq-answer p { font-size: 1rem; line-height: 1.7; color: #444; padding: 0 0 20px; font-weight: 500; }

.other-tools-section { width: 75%; margin: 60px auto; text-align: center; padding: 0 15px; }
.other-tools-section h2 { font-size: 2.2rem; font-weight: 900; color: var(--primary); margin-bottom: 30px; letter-spacing: -1.5px; }
.tools-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(200px, 1fr)); gap: 15px; }
.tool-link { display: block; padding: 20px; background: #fff; border: 1px solid var(--card-border); border-radius: 16px; text-decoration: none; color: var(--text); font-weight: 700; font-size: 0.9rem; transition: all 0.3s; }
.tool-link:hover { transform: translateY(-5px); box-shadow: 0 10px 20px rgba(0,0,0,0.07); border-color: var(--primary); color: var(--primary); }

.disclaimer { padding: 40px; text-align: center; font-size: 0.75rem; color: #999; font-weight: 600; line-height: 1.6; }

@media (max-width: 1024px) {
    .guide-container, .faq-section, .other-tools-section { width: 95%; }
}