:root {
    --bg-primary: #0f172a;
    --bg-secondary: #1e293b;
    --bg-card: #334155;
    --text-primary: #f1f5f9;
    --text-secondary: #94a3b8;
    --accent: #10b981;
    --accent-hover: #059669;
    --border: #475569;
    --header-color: #ef4444;
    --payload-color: #a855f7;
    --signature-color: #10b981;
}

[data-theme="dark"] {
    --bg-primary: #0f172a;
    --bg-secondary: #1e293b;
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    background: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100vh;
}

.container {
    max-width: 1000px;
    margin: 0 auto;
    padding: 20px;
}

header {
    text-align: center;
    padding: 40px 0;
    position: relative;
}

h1 { font-size: 2.5rem; margin-bottom: 10px; }
.tagline { color: var(--text-secondary); font-size: 1.1rem; }

.dark-mode-btn {
    position: absolute;
    top: 20px;
    right: 20px;
    background: var(--bg-secondary);
    border: 1px solid var(--border);
    padding: 10px 15px;
    border-radius: 8px;
    cursor: pointer;
    font-size: 1.2rem;
}

.tabs {
    display: flex;
    gap: 10px;
    margin-bottom: 20px;
    justify-content: center;
}

.tab {
    padding: 12px 32px;
    background: var(--bg-secondary);
    border: 1px solid var(--border);
    border-radius: 8px;
    cursor: pointer;
    color: var(--text-secondary);
    font-weight: 500;
    transition: all 0.2s;
}

.tab:hover { background: var(--bg-card); }
.tab.active { background: var(--accent); border-color: var(--accent); color: white; }

.tab-content { display: none; }
.tab-content.active { display: block; }

.tool-card {
    background: var(--bg-secondary);
    border-radius: 16px;
    padding: 30px;
    margin-bottom: 30px;
}

.input-section, .secret-section, .form-group {
    margin-bottom: 20px;
}

label {
    display: block;
    margin-bottom: 8px;
    font-weight: 500;
    color: var(--text-secondary);
}

textarea, input[type="text"], select {
    width: 100%;
    padding: 14px;
    background: var(--bg-primary);
    border: 1px solid var(--border);
    border-radius: 8px;
    color: var(--text-primary);
    font-family: 'Monaco', 'Menlo', monospace;
    font-size: 14px;
    resize: vertical;
}

textarea:focus, input:focus, select:focus {
    outline: none;
    border-color: var(--accent);
}

.output-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 20px;
    margin-top: 20px;
}

.output-card {
    background: var(--bg-primary);
    border-radius: 12px;
    overflow: hidden;
}

.output-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 12px 16px;
    background: var(--bg-card);
    font-weight: 600;
}

.header-card .output-header { border-left: 4px solid var(--header-color); }
.payload-card .output-header { border-left: 4px solid var(--payload-color); }
.signature-card .output-header { border-left: 4px solid var(--signature-color); }

.output-card pre {
    padding: 16px;
    font-size: 13px;
    white-space: pre-wrap;
    word-wrap: break-word;
    max-height: 200px;
    overflow-y: auto;
}

.copy-btn {
    padding: 6px 12px;
    background: var(--bg-secondary);
    border: 1px solid var(--border);
    border-radius: 6px;
    color: var(--text-secondary);
    cursor: pointer;
    font-size: 12px;
    transition: all 0.2s;
}

.copy-btn:hover { background: var(--accent); color: white; border-color: var(--accent); }
.copy-btn.full-width { width: 100%; margin-top: 10px; padding: 12px; }

.verification-status {
    margin-top: 20px;
    padding: 16px;
    border-radius: 8px;
    display: none;
}

.verification-status.valid {
    display: block;
    background: rgba(16, 185, 129, 0.1);
    border: 1px solid var(--accent);
    color: var(--accent);
}

.verification-status.invalid {
    display: block;
    background: rgba(239, 68, 68, 0.1);
    border: 1px solid #ef4444;
    color: #ef4444;
}

.form-row {
    display: grid;
    grid-template-columns: 1fr 2fr;
    gap: 20px;
}

.encode-btn {
    width: 100%;
    padding: 14px;
    background: var(--accent);
    border: none;
    border-radius: 8px;
    color: white;
    font-size: 16px;
    font-weight: 600;
    cursor: pointer;
    margin-bottom: 20px;
    transition: background 0.2s;
}

.encode-btn:hover { background: var(--accent-hover); }

.trust-badges {
    display: flex;
    justify-content: center;
    gap: 20px;
    flex-wrap: wrap;
    margin: 40px 0;
}

.badge {
    display: flex;
    align-items: center;
    gap: 8px;
    padding: 10px 20px;
    background: var(--bg-secondary);
    border-radius: 30px;
    font-size: 14px;
}

.badge-icon { font-size: 1.2rem; }

.faq-section {
    margin-top: 40px;
}

.faq-section h2 {
    text-align: center;
    margin-bottom: 30px;
    font-size: 1.8rem;
}

.faq-item {
    background: var(--bg-secondary);
    border-radius: 10px;
    margin-bottom: 10px;
    overflow: hidden;
}

.faq-item summary {
    padding: 16px 20px;
    cursor: pointer;
    font-weight: 500;
    list-style: none;
}

.faq-item summary::-webkit-details-marker { display: none; }
.faq-item summary::after { content: '+'; float: right; }
.faq-item[open] summary::after { content: '−'; }

.faq-item p {
    padding: 0 20px 16px;
    color: var(--text-secondary);
}

footer {
    text-align: center;
    padding: 30px;
    color: var(--text-secondary);
    border-top: 1px solid var(--border);
    margin-top: 40px;
}

@media (max-width: 768px) {
    h1 { font-size: 1.8rem; }
    .form-row { grid-template-columns: 1fr; }
    .output-grid { grid-template-columns: 1fr; }
    .tabs { flex-direction: column; }
}