.page { display: flex; flex-direction: column; flex: 1; }
.copyright { margin-top: auto; }
.book-main { padding: 28px 32px 42px; background: linear-gradient(130deg, #f2f9fa, #f6f7fb 55%, #fff7f4); color: #132439; flex: 1; }
.book-intro { margin-bottom: 24px; line-height: 1.7; }
.book-intro > p:nth-child(2) { font-size: 22px; font-weight: 750; margin-top: 6px; }
.book-eyebrow { color: #087e87; font-size: 12px; font-weight: 800; letter-spacing: .07em; text-transform: uppercase; }
.book-source { font-size: 14px; color: #526174; margin-top: 7px; max-width: 850px; }
.grade-tabs { display: grid; grid-template-columns: repeat(4, 1fr); gap: 12px; padding-bottom: 24px; border-bottom: 1px solid #dce4eb; }
.grade-tabs button, .publisher-tabs button { font-family: inherit; cursor: pointer; border: 1px solid #dae3e9; border-radius: 14px; font-size: 16px; font-weight: 800; min-height: 52px; padding: 12px 18px; color: #236775; background: #e8f6f5; transition: background .15s, box-shadow .15s; }
.grade-tabs button:nth-child(2) { background: #fff0ed; color: #a34842; }
.grade-tabs button:nth-child(3) { background: #eeedfc; color: #60558d; }
.grade-tabs button:nth-child(4) { background: #fff3e5; color: #905a20; }
.grade-tabs button span { display: inline-block; font-size: 12px; margin-left: 8px; font-weight: 650; }
.grade-tabs button[aria-selected="true"], .publisher-tabs button[aria-selected="true"] { color: white; background: #14283d; border-color: #14283d; box-shadow: 0 5px 12px #14283d20; }
.publisher-tabs { display: flex; flex-wrap: wrap; gap: 10px; margin: 24px 0 8px; }
.publisher-tabs button { background: #fff; color: #40536a; font-size: 14px; min-height: 46px; border-radius: 12px; }
.publisher-tabs button span { margin-left: 8px; opacity: .8; font-size: 12px; }
.book-heading { display: flex; justify-content: space-between; align-items: center; gap: 16px; margin: 28px 0 20px; }
.book-heading h2 { font-size: clamp(22px, 2.2vw, 30px); margin-top: 5px; }
.book-count { border: 1px solid #dde5eb; background: white; border-radius: 12px; padding: 10px 14px; white-space: nowrap; font-size: 13px; font-weight: 750; color: #506174; }
.book-grid { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 16px; }
.book-card { display: flex; flex-direction: column; align-items: flex-start; min-height: 184px; border-radius: 18px; background: white; border: 1px solid #dde7eb; padding: 21px; text-decoration: none; box-shadow: 0 4px 14px #14283d06; transition: transform .15s, border-color .15s, box-shadow .15s; }
.book-card:hover { transform: translateY(-3px); border-color: #0c929b; box-shadow: 0 10px 24px #14283d12; }
.book-number { background: #e8f5f5; color: #087d86; border-radius: 8px; padding: 6px 10px; font-size: 12px; font-weight: 800; }
.book-card h3 { font-size: 19px; line-height: 1.4; margin: 14px 0 20px; overflow-wrap: anywhere; }
.book-action { color: #087d86; font-size: 13px; font-weight: 800; display: flex; width: 100%; justify-content: space-between; align-items: center; margin-top: auto; gap: 12px; }
.book-action > span { background: #087d86; color: white; border-radius: 8px; padding: 6px 10px; font-size: 17px; }
.book-notice { font-size: 13px; color: #526174; margin-top: 24px; padding: 15px 18px; border: 1px solid #dce5eb; background: #ffffffa6; border-radius: 12px; line-height: 1.7; }
.book-notice a { color: #087d86; font-weight: 700; text-underline-offset: 3px; }
@media (min-width: 801px) { .book-notice { font-size: 16px; } }
.book-empty { padding: 52px 24px; text-align: center; background: white; border: 1px dashed #bdcbd6; border-radius: 18px; }
.book-empty > span { display: block; font-size: 38px; color: #8497a7; margin-bottom: 12px; }
.book-empty h3 { font-size: 20px; line-height: 1.5; }
.book-empty p { color: #526174; font-size: 14px; margin-top: 10px; line-height: 1.6; }
.book-main [hidden] { display: none !important; }
.book-main :focus-visible { outline: 3px solid #1565c0; outline-offset: 4px; }
@media (max-width: 1100px) { .book-grid { grid-template-columns: repeat(3, minmax(0, 1fr)); } }
@media (max-width: 800px) { .book-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); } .book-main { padding: 24px 20px 32px; } .grade-tabs { gap: 8px; } .grade-tabs button { padding: 12px 6px; } .grade-tabs button span { display: block; margin: 5px 0 0; } }
@media (max-width: 480px) { .book-main { padding: 22px 14px 28px; } .grade-tabs button { font-size: 14px; border-radius: 11px; } .grade-tabs button span { font-size: 10px; } .publisher-tabs { gap: 8px; } .publisher-tabs button { flex: 1 1 100%; text-align: left; display: flex; justify-content: space-between; } .book-grid { grid-template-columns: 1fr; gap: 12px; } .book-card { min-height: 165px; } .book-intro > p:nth-child(2) { font-size: 20px; } .book-heading { gap: 10px; } .book-count { padding: 8px; font-size: 12px; } }
@media (prefers-reduced-motion: reduce) { .book-card, .grade-tabs button, .publisher-tabs button { transition: none; } .book-card:hover { transform: none; } }