* { margin: 0; padding: 0; box-sizing: border-box; }
body { font-family: 'Noto Serif SC', Georgia, serif; background: #F9F5F0; color: #1A1A1A; line-height: 1.8; }
.filter-bar { position: sticky; top: 0; background: rgba(249,245,240,0.95); backdrop-filter: blur(10px); border-bottom: 1px solid #D8CFC0; padding: 15px 20px; display: flex; gap: 10px; z-index: 100; flex-wrap: wrap; }
.filter-btn { padding: 8px 18px; border: 1px solid #D8CFC0; border-radius: 20px; background: transparent; cursor: pointer; font-size: 14px; transition: all 0.3s; }
.filter-btn:hover { background: #E8D5D2; }
.filter-btn.active { background: #B83A2E; color: #fff; border-color: #B83A2E; }
.question-list { max-width: 900px; margin: 20px auto; padding: 0 20px; }
.question-card { background: #FFFFFF; border: 1px solid #D8CFC0; border-radius: 8px; padding: 24px; margin-bottom: 20px; box-shadow: 0 2px 10px rgba(0,0,0,0.06); display: none; }
.question-card.visible { display: block; }
.question-header { display: flex; align-items: center; gap: 12px; margin-bottom: 16px; flex-wrap: wrap; }
.question-id { font-weight: 700; font-size: 15px; }
.question-tag { background: #E8D5D2; color: #B83A2E; padding: 2px 10px; border-radius: 12px; font-size: 13px; }
.question-marks { color: #888; font-size: 13px; }
.question-difficulty { color: #B83A2E; margin-left: auto; }
.question-body p { margin-bottom: 10px; }
.solution-box { background: #F0EBE3; border-left: 4px solid #B83A2E; padding: 16px; margin-top: 12px; border-radius: 0 6px 6px 0; }
.solution-box .tip { margin-top: 12px; padding-top: 10px; border-top: 1px dashed #D8CFC0; font-style: italic; color: #666; }