:root{--primary-color:#4361ee;--secondary-color:#3a0ca3;--accent-color:#7209b7;--light-color:#f8f9fa;--dark-color:#212529;--gray-color:#6c757d;--success-color:#4cc9f0;--warning-color:#f72585;--length-primary:#0d9488;--length-gradient:linear-gradient(135deg,#14b8a6 0%,#0d9488 100%);--border-radius:12px;--box-shadow:0 8px 24px rgba(0,0,0,0.1);--transition:all 0.3s ease}*{margin:0;padding:0;box-sizing:border-box;font-family:'Segoe UI','Microsoft YaHei',sans-serif}body{background-color:#f0f2f5;color:var(--dark-color);line-height:1.6}.container{width:100%;max-width:1200px;margin:0 auto;padding:0 20px}header{background:linear-gradient(135deg,var(--primary-color),var(--secondary-color));color:white;padding:20px 0;box-shadow:0 4px 12px rgba(0,0,0,0.1);position:sticky;top:0;z-index:100}.header-content{display:flex;justify-content:space-between;align-items:center}.logo{display:flex;align-items:center;gap:15px}.logo i{font-size:2.5rem}.logo h1{font-size:1.8rem;font-weight:700}.logo span{color:var(--success-color)}nav ul{display:flex;list-style:none;gap:25px}nav a{color:white;text-decoration:none;font-weight:600;font-size:1.1rem;padding:8px 12px;border-radius:6px;transition:var(--transition)}nav a:hover,nav a.active{background-color:rgba(255,255,255,0.2)}main{padding:40px 0}.section-title{font-size:1.8rem;margin-bottom:25px;color:var(--secondary-color);display:flex;align-items:center;gap:10px}.section-title i{color:var(--accent-color)}.tools-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(280px,1fr));gap:25px;margin-bottom:40px}.tool-card{background:white;border-radius:var(--border-radius);padding:25px;box-shadow:var(--box-shadow);transition:var(--transition);cursor:pointer;border:2px solid transparent}.tool-card:hover{transform:translateY(-5px);border-color:var(--primary-color)}.tool-card i{font-size:2.5rem;color:var(--primary-color);margin-bottom:15px}.tool-card h3{font-size:1.4rem;margin-bottom:10px;color:var(--dark-color)}.tool-card p{color:var(--gray-color);margin-bottom:20px}.use-tool-btn{background-color:var(--primary-color);color:white;border:none;padding:10px 20px;border-radius:6px;font-weight:600;cursor:pointer;transition:var(--transition);width:100%}.use-tool-btn:hover{background-color:var(--secondary-color)}.tool-detail{background:white;border-radius:var(--border-radius);padding:30px;box-shadow:var(--box-shadow);margin-top:30px;display:none}.tool-detail.active{display:block}.tool-header{display:flex;justify-content:space-between;align-items:center;margin-bottom:25px;padding-bottom:15px;border-bottom:2px solid #f0f2f5}.tool-header h2{font-size:1.6rem;color:var(--secondary-color)}.close-tool{background:none;border:none;font-size:1.5rem;color:var(--gray-color);cursor:pointer;transition:var(--transition)}.close-tool:hover{color:var(--warning-color)}.converter-wrapper{max-width:1000px;margin:0 auto}.input-section{background:var(--length-gradient);padding:30px;border-radius:var(--border-radius);margin-bottom:30px;box-shadow:0 10px 20px rgba(13,148,136,0.2);display:flex;gap:20px;align-items:center;flex-wrap:wrap;color:white}.input-group{flex:2;min-width:250px}.input-label{display:block;font-weight:700;margin-bottom:10px;font-size:0.9rem;opacity:0.95}.main-input{width:100%;padding:15px 20px;border:2px solid rgba(255,255,255,0.3);border-radius:8px;background:rgba(255,255,255,0.2);color:white;font-size:1.8rem;font-weight:700;outline:none;transition:var(--transition);font-family:'Consolas',monospace}.main-input::placeholder{color:rgba(255,255,255,0.5)}.main-input:focus{background:rgba(255,255,255,0.3);border-color:white;box-shadow:0 0 0 4px rgba(255,255,255,0.1)}.select-group{flex:1;min-width:160px}.unit-select{width:100%;padding:15px;border:2px solid rgba(255,255,255,0.3);border-radius:8px;background:white;color:var(--dark-color);font-size:1rem;font-weight:600;cursor:pointer;outline:none}.results-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(320px,1fr));gap:20px}.result-section{background:white;border:1px solid #e9ecef;border-radius:10px;overflow:hidden;box-shadow:0 2px 4px rgba(0,0,0,0.02);transition:var(--transition)}.result-section:hover{box-shadow:0 5px 15px rgba(0,0,0,0.05);border-color:var(--length-primary)}.section-head{background:#f0fdfa;padding:10px 15px;border-bottom:1px solid #e9ecef;font-weight:700;color:var(--length-primary);font-size:0.9rem;text-transform:uppercase;display:flex;align-items:center;gap:8px}.unit-row{padding:12px 15px;display:flex;justify-content:space-between;align-items:center;border-bottom:1px dashed #eee}.unit-row:last-child{border-bottom:none}.unit-info{display:flex;flex-direction:column}.unit-name{font-weight:600;color:var(--dark-color);font-size:0.95rem}.unit-symbol{font-size:0.75rem;color:var(--gray-color);font-family:'Consolas',monospace}.value-wrapper{display:flex;align-items:center;gap:10px}.value-display{font-family:'Consolas',monospace;font-weight:700;color:var(--length-primary);font-size:1rem}.copy-btn-sm{color:#ccc;cursor:pointer;transition:var(--transition);font-size:0.9rem}.copy-btn-sm:hover{color:var(--length-primary)}@media (max-width:600px){.input-section{flex-direction:column;align-items:stretch}.results-grid{grid-template-columns:1fr}}