/* ===== Reset & Base ===== */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
    --bg: #f0f2f5;
    --bg-card: #ffffff;
    --text: #1a1a2e;
    --text-secondary: #6b7280;
    --text-muted: #9ca3af;
    --primary: #2563eb;
    --primary-light: #3b82f6;
    --primary-dark: #1d4ed8;
    --primary-bg: rgba(37,99,235,0.1);
    --accent: #f59e0b;
    --border: #e5e7eb;
    --shadow: 0 2px 8px rgba(0,0,0,0.08);
    --shadow-hover: 0 8px 24px rgba(0,0,0,0.12);
    --radius: 12px;
    --radius-sm: 8px;
    --max-width: 1200px;
    --header-bg: rgba(255,255,255,0.95);
    --hero-bg: linear-gradient(135deg, #1e3a5f 0%, #2563eb 50%, #1d4ed8 100%);
    --input-bg: #ffffff;
    --output-bg: #f8fafc;
    --code-bg: #1e293b;
    --code-text: #e2e8f0;
    --overlay: rgba(0,0,0,0.5);
    --modal-bg: #ffffff;
    --footer-bg: #1e293b;
    --footer-text: #94a3b8;
}

[data-theme="dark"] {
    --bg: #0f172a;
    --bg-card: #1e293b;
    --text: #e2e8f0;
    --text-secondary: #94a3b8;
    --text-muted: #64748b;
    --border: #334155;
    --shadow: 0 2px 8px rgba(0,0,0,0.3);
    --shadow-hover: 0 8px 24px rgba(0,0,0,0.4);
    --header-bg: rgba(15,23,42,0.95);
    --hero-bg: linear-gradient(135deg, #0f172a 0%, #1e3a5f 50%, #1e293b 100%);
    --input-bg: #334155;
    --output-bg: #1e293b;
    --code-bg: #0f172a;
    --code-text: #e2e8f0;
    --overlay: rgba(0,0,0,0.7);
    --modal-bg: #1e293b;
    --footer-bg: #0f172a;
    --footer-text: #64748b;
}

html { scroll-behavior: smooth; }

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Noto Sans SC", "PingFang SC", "Microsoft YaHei", sans-serif;
    background: var(--bg);
    color: var(--text);
    line-height: 1.6;
    min-height: 100vh;
    transition: background 0.3s, color 0.3s;
}

.container { max-width: var(--max-width); margin: 0 auto; padding: 0 20px; }

/* ===== Header ===== */
.header {
    position: sticky; top: 0; z-index: 100;
    background: var(--header-bg);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--border);
    transition: background 0.3s;
}
.header-inner {
    display: flex; align-items: center;
    justify-content: center;
    height: 60px;
    gap: 24px;
}
.logo {
    font-size: 1.3rem; font-weight: 800;
    text-decoration: none; color: var(--primary);
    white-space: nowrap;
    display: flex;
    align-items: center;
    gap: 4px;
}
.nav {
    display: flex;
    gap: 4px;
}
.nav-link {
    padding: 8px 14px;
    color: var(--text-secondary);
    text-decoration: none;
    font-weight: 500;
    font-size: 0.9rem;
    border-radius: var(--radius-sm);
    transition: all 0.2s;
}
.nav-link:hover {
    color: var(--primary);
    background: var(--primary-bg);
}

.header-actions {
    display: flex;
    align-items: center;
    gap: 8px;
}

/* ===== Language Switcher ===== */
.lang-switcher {
    display: flex;
    background: var(--bg);
    border-radius: var(--radius-sm);
    border: 1px solid var(--border);
    overflow: hidden;
}
.lang-btn {
    padding: 5px 10px;
    border: none;
    background: transparent;
    color: var(--text-secondary);
    font-size: 0.78rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s;
    font-family: inherit;
}
.lang-btn:hover { color: var(--text); }
.lang-btn.active {
    background: var(--primary);
    color: white;
}

.theme-toggle, .menu-toggle {
    background: none; border: none;
    font-size: 1.15rem; cursor: pointer;
    padding: 6px 8px; border-radius: var(--radius-sm);
    color: var(--text);
    transition: background 0.2s;
}
.theme-toggle:hover, .menu-toggle:hover { background: var(--border); }
.menu-toggle { display: none; }

/* ===== Hero ===== */
.hero {
    background: var(--hero-bg);
    padding: 70px 0 50px;
    text-align: center;
    color: white;
    position: relative;
    overflow: hidden;
}
.hero::before {
    content: '';
    position: absolute;
    top: -50%;
    left: -50%;
    width: 200%;
    height: 200%;
    background: radial-gradient(ellipse at 30% 50%, rgba(255,255,255,0.05) 0%, transparent 50%),
                radial-gradient(ellipse at 70% 50%, rgba(255,255,255,0.03) 0%, transparent 50%);
    pointer-events: none;
}
.hero h1 {
    font-size: 2.6rem;
    font-weight: 800;
    margin-bottom: 10px;
    letter-spacing: -0.02em;
    position: relative;
}
.hero-sub {
    font-size: 1.1rem;
    opacity: 0.9;
    margin-bottom: 28px;
    position: relative;
}
.search-box {
    max-width: 440px;
    margin: 0 auto;
    position: relative;
}
.search-input {
    width: 100%;
    padding: 12px 20px;
    border: none;
    border-radius: 50px;
    font-size: 0.95rem;
    background: rgba(255,255,255,0.15);
    color: white;
    backdrop-filter: blur(8px);
    outline: none;
    transition: background 0.3s;
}
.search-input::placeholder { color: rgba(255,255,255,0.5); }
.search-input:focus { background: rgba(255,255,255,0.25); }

/* ===== Tools Grid ===== */
.tools-section {
    padding: 50px 0;
}
.tools-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
    gap: 16px;
}
.tool-card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 24px 16px;
    text-align: center;
    cursor: pointer;
    transition: all 0.25s ease;
    box-shadow: var(--shadow);
    position: relative;
    overflow: hidden;
}
.tool-card::after {
    content: '';
    position: absolute;
    top: 0; left: 0; right: 0;
    height: 3px;
    background: var(--primary);
    transform: scaleX(0);
    transition: transform 0.3s ease;
    transform-origin: left;
}
.tool-card:hover::after { transform: scaleX(1); }
.tool-card:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-hover);
    border-color: var(--primary-light);
}
.tool-card .card-icon {
    font-size: 2.2rem;
    margin-bottom: 10px;
    display: block;
}
.tool-card h3 {
    font-size: 0.95rem;
    font-weight: 700;
    margin-bottom: 4px;
    color: var(--text);
}
.tool-card p {
    font-size: 0.8rem;
    color: var(--text-secondary);
}

/* ===== Tool Workspace ===== */
.tool-workspace {
    padding: 30px 0 50px;
}
.back-btn {
    background: var(--bg-card);
    border: 1px solid var(--border);
    padding: 8px 18px;
    border-radius: var(--radius-sm);
    cursor: pointer;
    font-size: 0.9rem;
    color: var(--text-secondary);
    margin-bottom: 20px;
    transition: all 0.2s;
}
.back-btn:hover {
    background: var(--primary);
    color: white;
    border-color: var(--primary);
}

.tool-panel {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 28px;
    box-shadow: var(--shadow);
}
.tool-panel h2 {
    font-size: 1.4rem;
    font-weight: 700;
    margin-bottom: 6px;
}
.tool-panel .tool-desc {
    color: var(--text-secondary);
    margin-bottom: 20px;
    font-size: 0.9rem;
}

.form-group { margin-bottom: 14px; }
.form-group label {
    display: block;
    font-weight: 600;
    margin-bottom: 5px;
    font-size: 0.85rem;
    color: var(--text);
}
.form-group textarea,
.form-group input[type="text"],
.form-group input[type="number"],
.form-group input[type="date"],
.form-group input[type="datetime-local"],
.form-group select {
    width: 100%;
    padding: 10px 12px;
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    font-size: 0.9rem;
    background: var(--input-bg);
    color: var(--text);
    transition: border-color 0.2s;
    outline: none;
    font-family: inherit;
}
.form-group textarea { min-height: 100px; resize: vertical; }
.form-group textarea:focus,
.form-group input:focus,
.form-group select:focus { border-color: var(--primary); }

.btn {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    padding: 10px 20px;
    border: none;
    border-radius: var(--radius-sm);
    font-size: 0.88rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s;
    font-family: inherit;
}
.btn-primary {
    background: var(--primary);
    color: white;
}
.btn-primary:hover { background: var(--primary-dark); transform: translateY(-1px); }
.btn-secondary {
    background: var(--border);
    color: var(--text);
}
.btn-secondary:hover { background: var(--text-secondary); color: white; }
.btn-success {
    background: #059669;
    color: white;
}
.btn-success:hover { background: #047857; }

.output-box {
    background: var(--output-bg);
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    padding: 14px;
    margin-top: 14px;
    min-height: 44px;
    font-family: "SF Mono", "Fira Code", "Consolas", monospace;
    font-size: 0.85rem;
    white-space: pre-wrap;
    word-break: break-all;
    position: relative;
}
.copy-btn {
    position: absolute;
    top: 6px; right: 6px;
    padding: 3px 10px;
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 4px;
    font-size: 0.75rem;
    cursor: pointer;
    color: var(--text-secondary);
    transition: all 0.2s;
    font-family: inherit;
}
.copy-btn:hover { background: var(--primary); color: white; border-color: var(--primary); }

/* ===== Ad Slot ===== */
.ad-container {
    display: flex;
    justify-content: center;
    padding: 0;
}

/* ===== Modals ===== */
.modal-overlay {
    display: none;
    position: fixed; inset: 0;
    background: var(--overlay);
    z-index: 1000;
    align-items: center;
    justify-content: center;
    padding: 20px;
    animation: fadeIn 0.2s ease;
}
.modal-overlay.active {
    display: flex;
}
.modal {
    background: var(--modal-bg);
    border-radius: 16px;
    max-width: 560px;
    width: 100%;
    max-height: 80vh;
    overflow-y: auto;
    box-shadow: 0 20px 60px rgba(0,0,0,0.3);
    animation: slideUp 0.25s ease;
}
.modal-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 20px 24px;
    border-bottom: 1px solid var(--border);
}
.modal-header h2 {
    font-size: 1.2rem;
    font-weight: 700;
}
.modal-close {
    background: none;
    border: none;
    font-size: 1.8rem;
    cursor: pointer;
    color: var(--text-secondary);
    padding: 0 4px;
    line-height: 1;
    transition: color 0.2s;
}
.modal-close:hover { color: var(--text); }
.modal-body {
    padding: 20px 24px 24px;
    font-size: 0.9rem;
    color: var(--text-secondary);
    line-height: 1.8;
}
.modal-body p { margin-bottom: 12px; }

.about-list {
    list-style: none;
    margin: 16px 0 0;
}
.about-list li {
    padding: 10px 14px;
    margin-bottom: 8px;
    background: var(--primary-bg);
    border-radius: var(--radius-sm);
    font-size: 0.88rem;
    color: var(--text);
    border-left: 3px solid var(--primary);
}

.contact-email {
    text-align: center;
    margin: 20px 0;
}
.contact-link {
    display: inline-block;
    font-size: 1.2rem;
    font-weight: 600;
    color: var(--primary);
    text-decoration: none;
    padding: 12px 24px;
    background: var(--primary-bg);
    border-radius: var(--radius-sm);
    transition: all 0.2s;
}
.contact-link:hover {
    background: var(--primary);
    color: white;
}
.contact-response {
    text-align: center;
    font-size: 0.85rem;
    color: var(--text-muted);
    margin-top: 8px;
}

@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}
@keyframes slideUp {
    from { transform: translateY(20px); opacity: 0; }
    to { transform: translateY(0); opacity: 1; }
}

/* ===== Footer ===== */
.footer {
    background: var(--footer-bg);
    color: var(--footer-text);
    padding: 40px 0 0;
    margin-top: 40px;
}
.footer-inner {
    display: flex;
    justify-content: space-between;
    gap: 40px;
    flex-wrap: wrap;
    padding-bottom: 30px;
    border-bottom: 1px solid rgba(255,255,255,0.08);
}
.footer-brand {
    flex: 1;
    min-width: 200px;
}
.footer-logo {
    font-size: 1.2rem;
    font-weight: 800;
    color: var(--primary-light);
}
.footer-desc {
    font-size: 0.85rem;
    margin-top: 8px;
    color: var(--footer-text);
}
.footer-links {
    display: flex;
    gap: 40px;
    flex-wrap: wrap;
}
.footer-col h4 {
    color: #e2e8f0;
    font-size: 0.85rem;
    font-weight: 700;
    margin-bottom: 12px;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}
.footer-link {
    display: block;
    color: var(--footer-text);
    text-decoration: none;
    font-size: 0.88rem;
    padding: 4px 0;
    transition: color 0.2s;
}
.footer-link:hover { color: var(--primary-light); }
.footer-bottom {
    text-align: center;
    padding: 20px 0;
    font-size: 0.8rem;
    color: var(--text-muted);
}

/* ===== Responsive ===== */
@media (max-width: 768px) {
    .hero { padding: 50px 0 36px; }
    .hero h1 { font-size: 1.8rem; }
    .hero-sub { font-size: 0.95rem; }
    .tools-grid {
        grid-template-columns: repeat(auto-fill, minmax(150px, 1fr));
        gap: 12px;
    }
    .tool-card { padding: 18px 12px; }
    .tool-card .card-icon { font-size: 1.8rem; }
    .tool-card h3 { font-size: 0.85rem; }
    .tool-card p { font-size: 0.75rem; }
    .nav { display: none; }
    .nav.open {
        display: flex;
        flex-direction: column;
        position: absolute;
        top: 60px;
        left: 0; right: 0;
        background: var(--header-bg);
        padding: 12px 16px;
        gap: 4px;
        border-bottom: 1px solid var(--border);
        backdrop-filter: blur(12px);
    }
    .nav.open .nav-link { padding: 10px 14px; }
    .menu-toggle { display: block; }
    .tool-panel { padding: 18px; }
    .footer-inner { flex-direction: column; gap: 24px; }
    .footer-links { gap: 24px; }
    .modal { max-height: 90vh; }
    .modal-header { padding: 16px 20px; }
    .modal-body { padding: 16px 20px; }
}

@media (max-width: 480px) {
    .hero h1 { font-size: 1.5rem; }
    .tools-grid { grid-template-columns: repeat(2, 1fr); gap: 10px; }
    .tool-card { padding: 14px 8px; }
    .tool-card h3 { font-size: 0.8rem; }
    .tool-card p { display: none; }
    .lang-btn { padding: 4px 7px; font-size: 0.7rem; }
}