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

body {
    font-family: -apple-system, BlinkMacSystemFont, Roboto, sans-serif;
    background: #f0f4f8;
    padding: 40px 20px;
}

#app {
    max-width: 1200px;
    margin: 0 auto;
}

header {
    text-align: center;
    margin-bottom: 30px;
}

h1 {
    font-size: 38px;
    font-weight: 700;
    letter-spacing: 2px;
    color: #1a202c;
    margin-bottom: 6px;
}

.subtitle {
    color: #718096;
    font-size: 15px;
    letter-spacing: 1px;
}

.main-nav {
    display: flex;
    gap: 4px;
    justify-content: center;
    background: white;
    border-radius: 12px;
    padding: 6px;
    margin-bottom: 28px;
    box-shadow: 0 2px 8px rgba(0,0,0,0.06);
    border: 1px solid #e2e8f0;
}

.nav-btn {
    padding: 10px 32px;
    border: none;
    border-radius: 8px;
    background: transparent;
    color: #4a5568;
    font-size: 15px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.25s;
}

.nav-btn:hover {
    background: #f7fafc;
    color: #2b6cb0;
}

.nav-btn.active {
    background: #2b6cb0;
    color: white;
}

.nav-btn.active:hover {
    background: #1a4f8b;
    color: white;
}

.section-content {
    display: none;
}

.section-content.active {
    display: block;
}

.filter-bar {
    display: flex;
    gap: 16px;
    margin-bottom: 24px;
    flex-wrap: wrap;
    align-items: center;
}

.search-box {
    position: relative;
    flex: 1;
    min-width: 200px;
    max-width: 320px;
}

.search-input {
    width: 100%;
    padding: 10px 24px 10px 40px;
    background: white;
    border: 2px solid #e2e8f0;
    border-radius: 30px;
    font-size: 15px;
    color: #1a202c;
    transition: all 0.2s;
}

.search-input:focus {
    outline: none;
    border-color: #2b6cb0;
    box-shadow: 0 0 0 3px rgba(43, 108, 176, 0.1);
}

.search-input::placeholder {
    color: #a0aec0;
}

.search-box::before {
    content: "🔍";
    position: absolute;
    left: 14px;
    top: 50%;
    transform: translateY(-50%);
    font-size: 14px;
    pointer-events: none;
}

.view-toggle {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 44px;
    height: 44px;
    background: white;
    border: 2px solid #e2e8f0;
    border-radius: 30px;
    cursor: pointer;
    transition: all 0.2s;
}

.view-toggle:hover {
    border-color: #2b6cb0;
}

.view-icon {
    font-size: 18px;
    color: #4a5568;
}

.case-list-view {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.case-list-item {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 16px;
    background: #f7fafc;
    border-radius: 8px;
    border-left: 4px solid #2b6cb0;
    padding: 14px 20px;
    transition: all 0.2s;
}

.case-list-item:hover {
    background: #edf2f7;
}

.case-list-content {
    display: flex;
    align-items: center;
    gap: 24px;
    flex: 1;
    min-width: 0;
}

.case-list-main {
    display: flex;
    flex-direction: column;
    gap: 4px;
    flex: 1;
    min-width: 0;
}

.case-list-title {
    font-size: 16px;
    font-weight: 600;
    color: #1a202c;
}

.case-list-company {
    font-size: 13px;
    color: #718096;
}

.case-list-meta {
    display: flex;
    gap: 6px;
    flex-wrap: wrap;
    flex-shrink: 0;
}

.case-list-item .btn-detail {
    flex-shrink: 0;
}

.category-dropdown {
    position: relative;
    display: inline-block;
}

.level-dropdown {
    position: relative;
    display: inline-block;
}

.dropdown-toggle {
    display: flex;
    align-items: center;
    gap: 8px;
    padding: 10px 24px;
    background: white;
    border: 2px solid #e2e8f0;
    border-radius: 30px;
    font-size: 15px;
    font-weight: 500;
    color: #1a202c;
    cursor: pointer;
    transition: all 0.2s;
}

.filter-label {
    color: #718096;
    font-weight: 600;
}

.filter-value {
    color: #1a202c;
    font-weight: 700;
}

.dropdown-toggle:hover {
    border-color: #2b6cb0;
}

.arrow {
    font-size: 12px;
    transition: transform 0.25s;
    color: #718096;
}

.dropdown-menu {
    display: none;
    position: absolute;
    top: calc(100% + 6px);
    left: 0;
    min-width: 180px;
    background: white;
    border: 1px solid #e2e8f0;
    border-radius: 12px;
    box-shadow: 0 8px 24px rgba(0,0,0,0.10);
    list-style: none;
    padding: 8px 0;
    z-index: 100;
}

.dropdown-menu.open {
    display: block;
}

.dropdown-item {
    padding: 10px 24px;
    font-size: 14px;
    color: #4a5568;
    cursor: pointer;
    transition: all 0.15s;
}

.dropdown-item:hover {
    background: #ebf8ff;
    color: #2b6cb0;
}

.dropdown-item.active {
    background: #2b6cb0;
    color: white;
}

.dropdown-item.active:hover {
    background: #1a4f8b;
}

.case-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 24px;
}

.case-card {
    background: white;
    padding: 24px;
    border-radius: 12px;
    box-shadow: 0 2px 8px rgba(0,0,0,0.06);
    border: 1px solid #e2e8f0;
    transition: all 0.2s;
}

.case-card:hover {
    box-shadow: 0 8px 24px rgba(0,0,0,0.10);
    transform: translateY(-4px);
}

.badge {
    display: inline-block;
    background: #ebf8ff;
    color: #2b6cb0;
    font-size: 12px;
    font-weight: 600;
    padding: 4px 14px;
    border-radius: 20px;
    margin-bottom: 12px;
}

.badge-secondary {
    background: #f0fdf4;
    color: #15803d;
}

.badge-tertiary {
    background: #fffbeb;
    color: #b45309;
}

.meta-tags {
    display: flex;
    gap: 6px;
    flex-wrap: wrap;
    margin-bottom: 4px;
}

.meta-tags .badge {
    margin-bottom: 0;
}

.case-card h3 {
    font-size: 18px;
    color: #1a202c;
    margin-bottom: 6px;
}

.company {
    color: #4a5568;
    font-size: 14px;
    margin-bottom: 10px;
}

.desc {
    color: #718096;
    font-size: 14px;
    line-height: 1.6;
    margin-bottom: 16px;
}

.btn-detail {
    background: none;
    border: 1px solid #cbd5e0;
    border-radius: 8px;
    padding: 6px 18px;
    color: #4a5568;
    font-size: 13px;
    cursor: pointer;
    transition: all 0.2s;
}

.btn-detail:hover {
    background: #2b6cb0;
    border-color: #2b6cb0;
    color: white;
}

.placeholder-content {
    background: white;
    padding: 40px 48px;
    border-radius: 12px;
    border: 1px solid #e2e8f0;
}

.placeholder-content h2 {
    font-size: 24px;
    color: #1a202c;
    margin-bottom: 8px;
}

.placeholder-content > p {
    color: #718096;
    font-size: 15px;
    margin-bottom: 24px;
}

.placeholder-list {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

/* ===== How To 样式（带折叠按钮） ===== */
.how-item {
    background: #f7fafc;
    border-radius: 8px;
    border-left: 4px solid #2b6cb0;
    padding: 0;
    overflow: hidden;
    transition: all 0.2s;
}

.how-question {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 14px 20px;
    font-size: 15px;
    font-weight: 600;
    color: #1a202c;
    gap: 12px;
}

.how-question span {
    flex: 1;
}

.btn-answer {
    background: #2b6cb0;
    border: none;
    color: white;
    font-size: 13px;
    font-weight: 600;
    padding: 4px 18px;
    border-radius: 20px;
    cursor: pointer;
    transition: background 0.2s;
    flex-shrink: 0;
    white-space: nowrap;
}

.btn-answer:hover {
    background: #1a4f8b;
}

.how-answer {
    padding: 0 20px 14px 20px;
    color: #2d3748;
    font-size: 15px;
    line-height: 1.7;
    display: none;
}

.how-answer.open {
    display: block;
}

/* ===== F&Q 样式（直接显示，无按钮） ===== */
.faq-item {
    background: #f7fafc;
    border-radius: 8px;
    border-left: 4px solid #2b6cb0;
    padding: 14px 20px;
}

.faq-question {
    font-size: 15px;
    color: #1a202c;
    margin-bottom: 6px;
}

.faq-answer {
    font-size: 15px;
    color: #2d3748;
    line-height: 1.7;
    padding-left: 4px;
}

.empty-msg {
    grid-column: 1 / -1;
    text-align: center;
    color: #718096;
    padding: 40px 0;
}

.error-msg {
    grid-column: 1 / -1;
    text-align: center;
    color: #e53e3e;
    padding: 40px 0;
    font-size: 16px;
}

@media (max-width: 640px) {
    .main-nav {
        flex-direction: column;
        gap: 4px;
        padding: 4px;
    }
    .nav-btn {
        padding: 10px 16px;
        font-size: 14px;
        text-align: center;
    }
    .placeholder-content {
        padding: 24px 20px;
    }
    .how-question {
        flex-wrap: wrap;
    }
    .btn-answer {
        width: 100%;
        text-align: center;
        padding: 6px;
    }
}