:root{--primary-color: #0073e6;--dark-blue: #0d253f;--light-gray: #f4f4f4;--text-color: #333;--light-text: #ffffff;--container-width: 1280px}body{font-family:Roboto,sans-serif;margin:0;padding:0;line-height:1.6;background-color:var(--light-gray);color:var(--text-color);font-size:16px}main p{text-align:justify}.container{max-width:var(--container-width);margin:0 auto;padding:0 20px}main.container{width:100%!important;max-width:var(--container-width)!important;padding:0 20px!important}header{background-color:var(--dark-blue);color:var(--light-text);padding:40px 0;text-align:center}.header-content{display:flex;flex-direction:column;align-items:center;gap:40px}@media(min-width:768px){.header-content{flex-direction:row;text-align:left}}.cover-image{flex-shrink:0}.cover-image img{max-width:300px;height:auto;border-radius:8px;box-shadow:0 10px 20px #0003}.header-text{flex:1}.header-text h1{font-size:2.5em;margin:0 0 10px;font-weight:700;color:#fff!important}.header-text h2{font-size:1.5em;margin:0 0 20px;font-weight:300;color:#a0c8e8}.header-text .subtitle{font-size:1.2em;margin-bottom:30px;font-weight:400}.release-note{font-size:.9em;margin-top:15px!important;opacity:.8}main section{padding:60px 0;border-bottom:1px solid #ddd}main section:last-child{border-bottom:none}h2{text-align:center;font-size:2.2em;margin-bottom:40px}#table-of-contents .summary-grid{display:grid;grid-template-columns:1fr;gap:30px}@media(min-width:768px){#table-of-contents .summary-grid{grid-template-columns:repeat(2,1fr)}}#table-of-contents h4{margin-top:0;color:var(--dark-blue);border-bottom:2px solid var(--primary-color);padding-bottom:10px}#table-of-contents ul{list-style:none;padding:0;margin:0}#table-of-contents li{margin-bottom:8px;font-size:.95em}#author .author-content p{text-indent:1.5em}#for-who .for-who-cards{display:grid;grid-template-columns:1fr;gap:30px}@media(min-width:768px){#for-who .for-who-cards{grid-template-columns:repeat(3,1fr)}}#for-who .card{background-color:#fff;padding:25px;border-radius:8px;box-shadow:0 4px 6px #0000001a;text-align:center}#for-who .card h3{margin-top:0;color:var(--primary-color)}.author-photo{width:150px;height:150px;border-radius:50%;display:block;margin:0 auto 30px;box-shadow:0 4px 10px #0003;object-fit:cover;border:3px solid var(--dark-blue)}#author .author-content p:first-of-type{text-indent:0}footer{background-color:var(--dark-blue);color:var(--light-text);text-align:center;padding:20px 0;margin-top:40px}.button{display:inline-block;padding:15px 30px;background-color:var(--primary-color);color:var(--light-text);text-decoration:none;border-radius:5px;font-weight:700;transition:background-color .3s ease}.button:hover{background-color:#005bb5}.purchase-info{background-color:#ffffff1a;border-radius:8px;padding:20px;margin-bottom:20px}.purchase-info h3{margin-top:0;color:#93c5fd}.price{font-size:1.8em;font-weight:300;margin:10px 0}.price del{font-size:.6em;color:#ef4444;margin-right:10px}.price strong{font-weight:700;color:#34d399}.discount-badge{background-color:#10b981;color:#fff;font-size:.6rem;font-weight:700;padding:3px 8px;border-radius:9999px;margin-left:10px;vertical-align:middle;text-transform:uppercase}.primary-buy-button{display:block;text-align:center;font-size:1.2em;padding:18px 30px}.small-text{font-size:.8em;opacity:.8;margin-top:5px}.international-stores{margin-top:20px}.international-stores h4{margin-bottom:5px;font-size:1em}.international-stores a{color:#60a5fa;text-decoration:none}.international-stores a:hover{text-decoration:underline}.toc-columns{display:flex;flex-direction:column;gap:20px}@media(min-width:768px){.toc-columns{flex-direction:row;gap:60px}}.toc-column{flex:1}#contents h3{color:var(--dark-blue);border-bottom:2px solid var(--primary-color);padding-bottom:5px;margin-top:0}#contents ul{list-style-type:none;padding-left:0}#contents ul li{padding:8px 0;border-bottom:1px solid #eee}#contents ul li strong{color:var(--dark-blue)}#mastery{background-color:#fff}#mastery ul{list-style:none;padding-left:0;margin-top:40px}#mastery li{font-size:1.1em;padding-left:35px;position:relative;margin-bottom:20px}#mastery li:before{content:"✓";position:absolute;left:0;top:0;color:#10b981;font-size:1.5em;font-weight:700;line-height:1}