/* ========== 导航栏按钮 ========== */
.nav-btn {
    display: inline-flex;
    align-items: center;
    gap: 0.375rem;
    padding: 0.5rem 1rem;
    font-size: 0.875rem;
    font-weight: 500;
    color: #475569;
    border-radius: 0.5rem;
    transition: all 0.2s ease;
    background: transparent;
    border: none;
    cursor: pointer;
}
.nav-btn:hover {
    color: #2563EB;
    background: #EFF6FF;
}
.nav-btn-active {
    color: #2563EB;
    background: #EFF6FF;
}

/* ========== 下拉菜单 ========== */
.nav-dropdown {
    position: absolute;
    top: 100%;
    left: 0;
    min-width: 180px;
    margin-top: 0.25rem;
    background: white;
    border-radius: 0.75rem;
    box-shadow: 0 10px 40px rgba(0,0,0,0.12), 0 0 0 1px rgba(0,0,0,0.04);
    padding: 0.5rem;
    opacity: 0;
    visibility: hidden;
    transform: translateY(-4px);
    transition: all 0.2s ease;
    z-index: 100;
}
.group:hover .nav-dropdown {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

/* ========== 下拉菜单项 ========== */
.nav-dropdown-item {
    display: flex;
    align-items: center;
    gap: 0.625rem;
    padding: 0.625rem 0.875rem;
    font-size: 0.875rem;
    color: #475569;
    border-radius: 0.5rem;
    transition: all 0.15s ease;
    text-decoration: none;
}
.nav-dropdown-item:hover {
    color: #2563EB;
    background: #EFF6FF;
}
.nav-dropdown-item-active {
    color: #2563EB;
    background: #EFF6FF;
    font-weight: 500;
}

/* ========== 移动端菜单项 ========== */
.mobile-nav-item {
    display: block;
    padding: 0.625rem 0.75rem;
    font-size: 0.875rem;
    color: #475569;
    border-radius: 0.5rem;
    transition: all 0.15s ease;
    text-decoration: none;
}
.mobile-nav-item:hover {
    color: #2563EB;
    background: #EFF6FF;
}
.mobile-nav-item-active {
    color: #2563EB;
    background: #EFF6FF;
    font-weight: 500;
}

/* ========== 工具卡片 ========== */
.tool-card {
    display: block;
    background: white;
    border-radius: 1rem;
    padding: 1.75rem;
    border: 1px solid #E2E8F0;
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    text-decoration: none;
    color: inherit;
}
.tool-card:hover {
    transform: translateY(-4px);
    box-shadow: 0 20px 40px rgba(37, 99, 235, 0.1), 0 0 0 1px rgba(37, 99, 235, 0.08);
    border-color: #BFDBFE;
}
.tool-card-icon {
    width: 48px;
    height: 48px;
    border-radius: 0.75rem;
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 1rem;
    font-size: 1.5rem;
}
.tool-card-title {
    font-size: 1.05rem;
    font-weight: 600;
    color: #1E293B;
    margin-bottom: 0.375rem;
}
.tool-card-desc {
    font-size: 0.8125rem;
    color: #94A3B8;
    line-height: 1.5;
}

/* ========== 功能页面容器 ========== */
.tool-page {
    max-width: 640px;
    margin: 0 auto;
    padding: 2.5rem 1.5rem;
}
.tool-page-title {
    font-size: 1.75rem;
    font-weight: 700;
    color: #1E293B;
    text-align: center;
    margin-bottom: 0.5rem;
}
.tool-page-desc {
    font-size: 0.9375rem;
    color: #94A3B8;
    text-align: center;
    margin-bottom: 2rem;
}

/* ========== 输入框 & 按钮 ========== */
.tool-input {
    width: 100%;
    padding: 0.875rem 1rem;
    font-size: 0.9375rem;
    color: #1E293B;
    background: #F8FAFC;
    border: 1.5px solid #E2E8F0;
    border-radius: 0.75rem;
    transition: all 0.2s ease;
    outline: none;
    resize: vertical;
    font-family: inherit;
}
.tool-input:focus {
    border-color: #2563EB;
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
    background: white;
}
.tool-input::placeholder {
    color: #CBD5E1;
}

.tool-btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    padding: 0.75rem 1.75rem;
    font-size: 0.9375rem;
    font-weight: 600;
    color: white;
    background: linear-gradient(135deg, #3B82F6, #2563EB);
    border: none;
    border-radius: 0.75rem;
    cursor: pointer;
    transition: all 0.2s ease;
    box-shadow: 0 4px 14px rgba(37, 99, 235, 0.3);
}
.tool-btn:hover {
    background: linear-gradient(135deg, #2563EB, #1D4ED8);
    box-shadow: 0 6px 20px rgba(37, 99, 235, 0.4);
    transform: translateY(-1px);
}
.tool-btn:active {
    transform: translateY(0);
}

.tool-btn-outline {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    padding: 0.625rem 1.25rem;
    font-size: 0.8125rem;
    font-weight: 500;
    color: #475569;
    background: white;
    border: 1.5px solid #E2E8F0;
    border-radius: 0.625rem;
    cursor: pointer;
    transition: all 0.2s ease;
}
.tool-btn-outline:hover {
    color: #2563EB;
    border-color: #BFDBFE;
    background: #EFF6FF;
}

/* ========== 结果展示区 ========== */
.result-box {
    width: 100%;
    padding: 0.875rem 1rem;
    font-size: 0.9375rem;
    color: #1E293B;
    background: #F8FAFC;
    border: 1.5px solid #E2E8F0;
    border-radius: 0.75rem;
    min-height: 48px;
    word-break: break-all;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 0.75rem;
}
.result-text {
    flex: 1;
    font-family: 'SF Mono', 'Fira Code', monospace;
    font-size: 0.875rem;
    color: #1E293B;
    word-break: break-all;
}
.copy-btn {
    flex-shrink: 0;
    padding: 0.375rem 0.75rem;
    font-size: 0.75rem;
    font-weight: 500;
    color: #2563EB;
    background: #EFF6FF;
    border: 1px solid #BFDBFE;
    border-radius: 0.5rem;
    cursor: pointer;
    transition: all 0.15s ease;
    white-space: nowrap;
}
.copy-btn:hover {
    background: #2563EB;
    color: white;
}

/* ========== 标签页切换 ========== */
.tab-group {
    display: inline-flex;
    background: #F1F5F9;
    border-radius: 0.75rem;
    padding: 0.25rem;
}
.tab-item {
    padding: 0.5rem 1.25rem;
    font-size: 0.875rem;
    font-weight: 500;
    color: #64748B;
    border-radius: 0.625rem;
    cursor: pointer;
    transition: all 0.2s ease;
    border: none;
    background: transparent;
}
.tab-item:hover {
    color: #2563EB;
}
.tab-item-active {
    color: #2563EB;
    background: white;
    box-shadow: 0 1px 3px rgba(0,0,0,0.08);
}

/* ========== Hero 区域 ========== */
.hero {
    text-align: center;
    padding: 4rem 1.5rem 3rem;
    background: linear-gradient(180deg, #FFFFFF 0%, #F8FAFC 100%);
}
.hero-title {
    font-size: 2.25rem;
    font-weight: 800;
    color: #1E293B;
    letter-spacing: -0.02em;
    margin-bottom: 0.75rem;
}
.hero-subtitle {
    font-size: 1.0625rem;
    color: #94A3B8;
    max-width: 420px;
    margin: 0 auto 2rem;
    line-height: 1.6;
}

/* ========== 分区标题 ========== */
.section-title {
    font-size: 0.6875rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.1em;
    color: #94A3B8;
    margin-bottom: 1rem;
}

/* ========== 动画 ========== */
@keyframes fadeInUp {
    from { opacity: 0; transform: translateY(12px); }
    to   { opacity: 1; transform: translateY(0); }
}
.fade-in-up {
    animation: fadeInUp 0.4s ease forwards;
}