:root {
    --purple-900: #1a1a2e;
    --purple-800: #25253e;
    --purple-700: #4c1d95;
    --purple-600: #6d28d9;
    --purple-500: #7c3aed;
    --purple-400: #8b5cf6;
    --purple-300: #a78bfa;
    --purple-200: #c4b5fd;
    --purple-100: #ddd6fe;
    --cyan-500: #06b6d4;
    --cyan-400: #22d3ee;
    --cyan-300: #67e8f9;
    --bg-primary: #1a1a2e;
    --bg-secondary: #1e1e36;
    --bg-card: rgba(30, 30, 54, 0.65);
    --bg-card-hover: rgba(30, 30, 54, 0.8);
    --surface: rgba(26, 26, 46, 0.85);
    --text: #e2e8f0;
    --text-secondary: #a1a1b5;
    --text-muted: #7c7c96;
    --border: rgba(139, 92, 246, 0.15);
    --border-active: rgba(139, 92, 246, 0.35);
    --success: #10b981;
    --success-bg: rgba(16, 185, 129, 0.08);
    --success-border: rgba(16, 185, 129, 0.25);
    --warning: #f59e0b;
    --warning-bg: rgba(245, 158, 11, 0.08);
    --warning-border: rgba(245, 158, 11, 0.25);
    --error: #ef4444;
    --error-bg: rgba(239, 68, 68, 0.08);
    --error-border: rgba(239, 68, 68, 0.25);
    --shadow: 0 4px 24px rgba(0,0,0,0.3);
    --shadow-glow: 0 0 16px rgba(139,92,246,0.1);
    --radius: 10px;
}

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

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

body::before {
    content: '';
    position: fixed;
    top: 0; left: 0; right: 0; bottom: 0;
    background:
        radial-gradient(ellipse at 20% 50%, rgba(109,40,217,0.06) 0%, transparent 50%),
        radial-gradient(ellipse at 80% 0%, rgba(6,182,212,0.04) 0%, transparent 40%);
    pointer-events: none;
    z-index: 0;
}

.container {
    max-width: 1400px;
    margin: 0 auto;
    padding: 0 2rem 3rem;
    position: relative;
    z-index: 1;
}

@media (max-width: 768px) {
    .container {
        padding: 0 1rem 2rem;
    }
}

header {
    padding: 1rem 0 0.75rem;
    margin-bottom: 1.5rem;
    position: relative;
}

.site-header {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    justify-content: space-between;
    gap: 0.75rem;
    padding: 0.75rem 0;
    border-bottom: 1px solid var(--border);
    position: relative;
}

.site-header::after {
    content: '';
    position: absolute;
    bottom: -1px;
    left: 10%;
    right: 10%;
    height: 1px;
    background: linear-gradient(90deg, transparent, var(--purple-500), transparent);
}

.site-header .brand {
    display: flex;
    align-items: center;
    text-decoration: none;
    margin-bottom: 0;
}

.site-header h1 {
    font-size: 1.625rem;
    font-weight: 800;
    letter-spacing: -0.02em;
    margin: 0;
}

.site-header .subtitle {
    width: 100%;
    text-align: center;
    color: var(--text-muted);
    font-size: 0.875rem;
    margin: 0.25rem 0 0;
}

.site-header .badge-row {
    width: 100%;
    justify-content: center;
    margin-top: 0.375rem;
}

.site-nav {
    display: flex;
    align-items: center;
    gap: 0.25rem;
}

.site-nav .nav-link {
    color: var(--text-muted);
    text-decoration: none;
    font-size: 0.875rem;
    padding: 0.35rem 0.65rem;
    border-radius: 6px;
    transition: all 0.2s;
}

.site-nav .nav-link:hover {
    color: var(--text);
    background: rgba(139, 92, 246, 0.08);
}

.site-nav .nav-link.active {
    color: var(--purple-300);
    background: rgba(139, 92, 246, 0.1);
}

header:not(.site-header) {
    text-align: center;
}

header:not(.site-header)::after {
    content: '';
    position: absolute;
    bottom: -1px;
    left: 30%;
    right: 30%;
    height: 1px;
    background: linear-gradient(90deg, transparent, var(--purple-500), transparent);
}

.brand {
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 0.375rem;
}

header h1, .site-header h1 {
    font-size: 1.625rem;
    font-weight: 800;
    letter-spacing: -0.02em;
    margin: 0;
}

.logo-text {
    background: linear-gradient(135deg, var(--purple-300), var(--cyan-400));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.logo-text .slash {
    color: var(--purple-500);
    -webkit-text-fill-color: var(--purple-500);
    font-weight: 400;
    padding: 0 0.1em;
}

header .subtitle {
    color: var(--text-muted);
    font-size: 0.875rem;
}

.badge-row {
    display: flex;
    justify-content: center;
    gap: 0.375rem;
    margin-top: 0.75rem;
    flex-wrap: wrap;
}

.badge {
    display: inline-flex;
    background: rgba(139, 92, 246, 0.08);
    border: 1px solid rgba(139, 92, 246, 0.18);
    padding: 0.2rem 0.65rem;
    border-radius: 999px;
    font-size: 0.625rem;
    font-weight: 600;
    color: var(--purple-300);
    letter-spacing: 0.05em;
    text-transform: uppercase;
}

.layout-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1.25rem;
    align-items: start;
}

@media (max-width: 900px) {
    .layout-grid {
        grid-template-columns: 1fr;
    }
}

.card {
    background: var(--bg-card);
    backdrop-filter: blur(8px);
    -webkit-backdrop-filter: blur(8px);
    border-radius: var(--radius);
    border: 1px solid var(--border);
    padding: 1.5rem;
    transition: border-color 0.2s, box-shadow 0.2s, background 0.2s;
    box-shadow: var(--shadow);
}

.card:hover {
    border-color: var(--border-active);
    box-shadow: var(--shadow), var(--shadow-glow);
    background: var(--bg-card-hover);
}

.card.full {
    grid-column: 1 / -1;
}

.card h2 {
    font-size: 0.8125rem;
    font-weight: 700;
    margin-bottom: 1rem;
    color: var(--purple-200);
    display: flex;
    align-items: center;
    gap: 0.5rem;
    text-transform: uppercase;
    letter-spacing: 0.06em;
}

.card h2 .icon {
    width: 1.5rem;
    height: 1.5rem;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    background: linear-gradient(135deg, var(--purple-600), var(--purple-400));
    border-radius: 5px;
    font-size: 0.6875rem;
    flex-shrink: 0;
    box-shadow: 0 0 6px rgba(139,92,246,0.25);
}

.section-desc {
    color: var(--text-secondary);
    font-size: 0.8125rem;
    margin-bottom: 1rem;
    line-height: 1.5;
}

.form-group {
    margin-bottom: 0.875rem;
}

.form-group label {
    display: block;
    font-weight: 600;
    margin-bottom: 0.3rem;
    color: var(--text);
    font-size: 0.78125rem;
    letter-spacing: 0.01em;
}

.form-group label small {
    font-weight: 400;
    color: var(--text-muted);
}

.form-group input[type="number"] {
    width: 100%;
    padding: 0.65rem 0.75rem;
    border: 1.5px solid var(--border);
    border-radius: 8px;
    font-size: 0.875rem;
    transition: border-color 0.2s, box-shadow 0.2s;
    font-family: inherit;
    background: rgba(10, 10, 20, 0.4);
    color: var(--text);
    -moz-appearance: textfield;
    appearance: textfield;
}

.form-group input[type="number"]::-webkit-inner-spin-button,
.form-group input[type="number"]::-webkit-outer-spin-button {
    -webkit-appearance: none;
    margin: 0;
}

.form-group input[type="number"]:focus {
    outline: none;
    border-color: var(--purple-500);
    box-shadow: 0 0 0 3px rgba(139,92,246,0.12);
}

.form-group input[type="number"]::placeholder {
    color: var(--text-muted);
    font-size: 0.8125rem;
}

.form-group textarea,
.form-group input[type="text"],
.form-group input[type="email"],
.form-group input[type="password"],
.form-group input[type="url"],
.form-group input[type="file"] {
    width: 100%;
    padding: 0.65rem 0.75rem;
    border: 1.5px solid var(--border);
    border-radius: 8px;
    font-size: 0.875rem;
    transition: border-color 0.2s, box-shadow 0.2s;
    font-family: inherit;
    background: rgba(10, 10, 20, 0.4);
    color: var(--text);
}

.form-group textarea:focus,
.form-group input[type="text"]:focus,
.form-group input[type="email"]:focus,
.form-group input[type="password"]:focus,
.form-group input[type="url"]:focus,
.form-group input[type="file"]:focus,
.form-group input[type="number"]:focus {
    outline: none;
    border-color: var(--purple-500);
    box-shadow: 0 0 0 3px rgba(139,92,246,0.12);
}

.form-group textarea::placeholder,
.form-group input::placeholder {
    color: var(--text-muted);
    font-size: 0.8125rem;
}

.form-group small {
    display: block;
    margin-top: 0.2rem;
    color: var(--text-muted);
    font-size: 0.71875rem;
}

.input-file-wrapper {
    display: flex;
    align-items: center;
    gap: 0.625rem;
    margin-top: 0.25rem;
}

.file-upload-btn {
    padding: 0.45rem 1rem;
    font-size: 0.8125rem;
    font-weight: 600;
    border: 1.5px solid var(--purple-500);
    border-radius: 8px;
    background: rgba(139, 92, 246, 0.1);
    color: var(--purple-300);
    cursor: pointer;
    transition: all 0.2s;
    white-space: nowrap;
}

.file-upload-btn:hover {
    background: rgba(139, 92, 246, 0.2);
    border-color: var(--purple-400);
    box-shadow: 0 0 12px rgba(139, 92, 246, 0.15);
}

.file-name {
    font-size: 0.8125rem;
    color: var(--text-muted);
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
}

button {
    cursor: pointer;
    padding: 0.55rem 1.125rem;
    border: none;
    border-radius: 8px;
    font-size: 0.8125rem;
    font-weight: 600;
    transition: all 0.2s;
    font-family: inherit;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.375rem;
    letter-spacing: 0.01em;
}

.btn-primary {
    background: linear-gradient(135deg, var(--purple-600), var(--purple-500));
    color: white;
    box-shadow: 0 3px 10px rgba(109,40,217,0.3);
}

.btn-primary:hover {
    transform: translateY(-1px);
    box-shadow: 0 5px 16px rgba(109,40,217,0.4);
}

.btn-primary:active {
    transform: translateY(0);
}

.btn-primary:disabled {
    opacity: 0.45;
    cursor: not-allowed;
    transform: none;
}

.btn-secondary {
    background: rgba(139, 92, 246, 0.07);
    color: var(--purple-300);
    border: 1px solid rgba(139, 92, 246, 0.18);
}

.btn-secondary:hover {
    background: rgba(139, 92, 246, 0.14);
    border-color: rgba(139, 92, 246, 0.3);
}

.btn-small {
    padding: 0.4rem 0.8rem;
    font-size: 0.71875rem;
    background: linear-gradient(135deg, var(--purple-600), var(--purple-500));
    color: white;
}

.btn-small:hover {
    box-shadow: 0 0 10px rgba(139,92,246,0.3);
}

.button-row {
    display: flex;
    gap: 0.625rem;
    justify-content: flex-end;
    margin-top: 1rem;
}

.hidden {
    display: none !important;
}

.alert-success,
.alert-warning,
.alert-error,
.alert-info {
    width: 100%;
    padding: 0.65rem 0.875rem;
    border-radius: 8px;
    margin-bottom: 0.875rem;
    display: flex;
    align-items: flex-start;
    gap: 0.5rem;
    font-size: 0.78125rem;
    line-height: 1.5;
}

.alert-success {
    background: var(--success-bg);
    color: #6ee7b7;
    border: 1px solid var(--success-border);
}

.alert-warning {
    background: var(--warning-bg);
    color: #fcd34d;
    border: 1px solid var(--warning-border);
}

.alert-info {
    background: rgba(139, 92, 246, 0.07);
    color: var(--purple-300);
    border: 1px solid rgba(139, 92, 246, 0.18);
}

.alert-error {
    background: var(--error-bg);
    color: #fca5a5;
    border: 1px solid var(--error-border);
}

.status-icon {
    font-weight: 700;
    font-size: 0.875rem;
    flex-shrink: 0;
    line-height: 1.5;
}

.share-link-box {
    display: flex;
    gap: 0.5rem;
    margin-bottom: 0.875rem;
}

.share-link-box input {
    flex: 1;
    padding: 0.85rem 1rem;
    border: 1.5px solid rgba(139, 92, 246, 0.25);
    border-radius: 8px;
    font-size: 0.875rem;
    font-family: 'SF Mono', 'Fira Code', 'Cascadia Code', 'Courier New', monospace;
    background: rgba(10, 10, 20, 0.5);
    color: var(--purple-200);
    letter-spacing: 0.01em;
    box-shadow: 0 0 12px rgba(139, 92, 246, 0.08);
}

.share-link-box input:focus {
    outline: none;
    border-color: var(--purple-500);
    box-shadow: 0 0 16px rgba(139, 92, 246, 0.15);
}

.secret-key-section {
    margin-top: 1rem;
}

.secret-key-section textarea {
    font-family: 'SF Mono', 'Fira Code', 'Cascadia Code', 'Courier New', monospace;
    background: rgba(10, 10, 20, 0.5);
    min-height: 90px;
    padding: 0.85rem 1rem;
    font-size: 0.8125rem;
    color: var(--purple-200);
    border: 1.5px solid rgba(245, 158, 11, 0.25);
    letter-spacing: 0.02em;
    width: 100%;
    border-radius: 8px;
}

.secret-key-section textarea:focus {
    outline: none;
    border-color: var(--purple-500);
    box-shadow: 0 0 12px rgba(139, 92, 246, 0.12);
}

.key-result-area {
    font-family: 'SF Mono', 'Fira Code', 'Cascadia Code', 'Courier New', monospace;
    background: rgba(10, 10, 20, 0.5) !important;
    min-height: 80px;
    padding: 0.85rem 1rem;
    font-size: 0.8125rem;
    color: var(--purple-200) !important;
    border: 1.5px solid var(--border);
    letter-spacing: 0.02em;
    width: 100%;
    border-radius: 8px;
}

.key-result-area:focus {
    outline: none;
    border-color: var(--purple-500);
    box-shadow: 0 0 12px rgba(139, 92, 246, 0.12);
}

#decryptedText {
    background: rgba(10, 10, 20, 0.4);
    padding: 0.875rem;
    border-radius: 8px;
    margin-top: 0.5rem;
    font-family: 'SF Mono', 'Fira Code', 'Cascadia Code', 'Courier New', monospace;
    white-space: pre-wrap;
    word-break: break-word;
    font-size: 0.8125rem;
    color: var(--purple-200);
    border: 1px solid var(--border);
}

.key-pair-toggle {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    cursor: pointer;
    font-size: 0.78125rem;
    color: var(--purple-300);
    background: none;
    border: none;
    padding: 0.5rem 0;
    font-weight: 500;
    transition: color 0.2s;
}

.key-pair-toggle:hover {
    color: var(--purple-200);
}

.key-pair-toggle .chevron {
    transition: transform 0.3s;
    font-size: 0.6875rem;
}

.key-pair-toggle.open .chevron {
    transform: rotate(180deg);
}

.key-pair-body {
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.35s ease;
}

.key-pair-body.open {
    max-height: 600px;
}

footer {
    text-align: center;
    margin-top: 2.5rem;
    padding-top: 1.25rem;
    border-top: 1px solid var(--border);
    color: var(--text-muted);
    font-size: 0.71875rem;
}

.toast {
    position: fixed;
    bottom: 2rem;
    left: 50%;
    transform: translateX(-50%) translateY(0.75rem);
    background: var(--bg-card);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border: 1px solid var(--border);
    color: var(--text);
    padding: 0.65rem 1.25rem;
    border-radius: 8px;
    box-shadow: var(--shadow), var(--shadow-glow);
    opacity: 0;
    transition: opacity 0.25s ease, transform 0.25s ease;
    pointer-events: none;
    z-index: 1000;
    font-size: 0.8125rem;
    font-weight: 500;
}

.toast.show {
    opacity: 1;
    transform: translateX(-50%) translateY(0);
}

.toast.success {
    border-color: var(--success-border);
    color: #6ee7b7;
}

.toast.error {
    border-color: rgba(239, 68, 68, 0.25);
    color: #fca5a5;
}

.about-section {
    margin-top: 2rem;
}

.about-toggle {
    width: 100%;
    background: var(--bg-card);
    backdrop-filter: blur(8px);
    -webkit-backdrop-filter: blur(8px);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 0.875rem 1.125rem;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: space-between;
    font-size: 0.8125rem;
    font-weight: 600;
    color: var(--purple-200);
    transition: border-color 0.2s, box-shadow 0.2s;
    gap: 0.5rem;
}

.about-toggle:hover {
    border-color: var(--purple-500);
    box-shadow: var(--shadow-glow);
}

.about-toggle .chevron {
    transition: transform 0.3s ease;
    font-size: 0.6875rem;
    color: var(--text-muted);
}

.about-toggle.open .chevron {
    transform: rotate(180deg);
}

.about-content {
    background: var(--bg-card);
    backdrop-filter: blur(8px);
    -webkit-backdrop-filter: blur(8px);
    border: 1px solid var(--border);
    border-top: none;
    border-radius: 0 0 var(--radius) var(--radius);
    padding: 0 1.5rem;
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.4s ease, padding 0.3s ease;
}

.about-content.open {
    max-height: 3000px;
    padding: 1.25rem 1.5rem 1.75rem;
}

.about-content h3 {
    font-size: 0.875rem;
    font-weight: 700;
    color: var(--purple-200);
    margin: 1.125rem 0 0.5rem;
}

.about-content h3:first-child {
    margin-top: 0;
}

.about-content p,
.about-content li {
    color: var(--text-secondary);
    font-size: 0.8125rem;
    line-height: 1.7;
    margin-bottom: 0.625rem;
}

.about-content ul {
    list-style: none;
    padding: 0;
}

.about-content li {
    padding-left: 1.25rem;
    position: relative;
}

.about-content li::before {
    content: '';
    position: absolute;
    left: 0;
    top: 0.55em;
    width: 5px;
    height: 5px;
    border-radius: 50%;
    background: var(--purple-500);
    box-shadow: 0 0 4px rgba(139,92,246,0.4);
}

.about-content .crypto-chain {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    gap: 0.375rem;
    margin: 0.625rem 0;
}

.about-content .crypto-tag {
    background: rgba(139, 92, 246, 0.08);
    border: 1px solid rgba(139, 92, 246, 0.2);
    border-radius: 5px;
    padding: 0.35rem 0.7rem;
    font-size: 0.71875rem;
    font-weight: 600;
    color: var(--purple-300);
    font-family: 'SF Mono', 'Fira Code', 'Cascadia Code', 'Courier New', monospace;
}

.about-content .crypto-arrow {
    display: flex;
    align-items: center;
    color: var(--text-muted);
    font-size: 0.8125rem;
}

.flow-steps {
    background: rgba(10, 10, 20, 0.4);
    border: 1px solid var(--border);
    border-radius: 8px;
    padding: 1rem 1.25rem;
    margin: 0.75rem 0;
}

.flow-step {
    display: flex;
    align-items: flex-start;
    gap: 0.75rem;
    padding: 0.5rem 0;
    font-size: 0.8125rem;
    color: var(--text-secondary);
    line-height: 1.5;
}

.flow-step + .flow-step {
    border-top: 1px dashed rgba(139, 92, 246, 0.12);
}

.flow-step .step-num {
    width: 1.5rem;
    height: 1.5rem;
    min-width: 1.5rem;
    background: rgba(139, 92, 246, 0.12);
    border: 1px solid rgba(139, 92, 246, 0.2);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.6875rem;
    font-weight: 700;
    color: var(--purple-300);
}

.flow-step .step-side {
    color: var(--purple-300);
    font-weight: 600;
    min-width: 5rem;
}

.flow-step .step-desc {
    color: var(--text-secondary);
}

@media (max-width: 640px) {
    header {
        padding: 1.25rem 0 1rem;
    }

    header h1 {
        font-size: 1.25rem;
    }

    .card {
        padding: 1.125rem;
    }

    .button-row {
        flex-direction: column;
    }

    button {
        width: 100%;
    }

    .share-link-box {
        flex-direction: column;
    }

    .crypto-chain {
        flex-direction: column;
    }

    .crypto-arrow {
        transform: rotate(90deg);
    }

    .flow-step {
        flex-wrap: wrap;
    }
}

::placeholder { text-align: center; }
input::placeholder { text-align: center; }
textarea::placeholder { text-align: center; }