:root {
    --bg-color: #F2F2F7;
    --surface-color: #FFFFFF;
    --primary-color: #000000;
    --primary-hover: #333333;
    --secondary-color: #86868B;
    --text-color: #1D1D1F;
    --border-color: #D2D2D7;
    --error-color: #FF3B30;
    --success-color: #34C759;
    --font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    --shadow-sm: 0 1px 3px rgba(0,0,0,0.05);
    --shadow-md: 0 4px 6px rgba(0,0,0,0.05);
    --radius: 12px;
}

body {
    background-color: var(--bg-color);
    color: var(--text-color);
    font-family: var(--font-family);
    margin: 0;
    padding: 0;
    line-height: 1.5;
    -webkit-font-smoothing: antialiased;
}

header {
    background-color: rgba(255, 255, 255, 0.8);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    padding: 1rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    border-bottom: 1px solid var(--border-color);
    position: sticky;
    top: 0;
    z-index: 100;
}

h1 {
    margin: 0;
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--primary-color);
    letter-spacing: -0.5px;
}

.mode-badge {
    padding: 0.35rem 0.75rem;
    border-radius: 20px;
    font-size: 0.75rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.mode-guest {
    background-color: var(--error-color);
    color: #fff;
}

.mode-master {
    background-color: var(--success-color);
    color: #fff;
}

main {
    padding: 1.5rem;
    max-width: 720px;
    margin: 0 auto;
}

.card {
    background-color: var(--surface-color);
    border-radius: var(--radius);
    padding: 1.5rem;
    margin-bottom: 1.5rem;
    box-shadow: var(--shadow-sm);
    border: 1px solid rgba(0,0,0,0.02);
}

.hidden {
    display: none;
}

h2 {
    font-size: 1.1rem;
    margin-top: 0;
    margin-bottom: 1rem;
    color: var(--primary-color);
    font-weight: 600;
}

input, textarea {
    width: 100%;
    margin-bottom: 1rem;
    padding: 0.85rem;
    border-radius: 10px;
    border: 1px solid var(--border-color);
    background-color: #F8F8FA;
    color: var(--text-color);
    box-sizing: border-box;
    font-family: var(--font-family);
    font-size: 1rem;
    transition:  0.2s;
    outline: none;
    resize: none;
}

textarea#recipient-key,
textarea#message-input, 
#output-area {
    font-family: "SF Mono", "Menlo", "Monaco", "Courier New", monospace;
    font-size: 0.9rem;
}

input:focus, textarea:focus {
    border-color: #999;
    background-color: #fff;
}

button {
    width: 100%;
    margin-bottom: 1rem;
    padding: 0.85rem;
    border-radius: 10px;
    background-color: var(--primary-color);
    color: #fff;
    border: none;
    font-weight: 600;
    font-size: 1rem;
    cursor: pointer;
    transition: all 0.2s ease;
}

button:hover {
    background-color: var(--primary-hover);
    transform: translateY(-1px);
}

button:active {
    transform: translateY(0);
}

button.secondary {
    background-color: #E5E5EA;
    color: #000;
}

button.attention {
    background-color: #f59f00;
    color: #fff;
}

button.dangerous {
    background-color: #FF3B30;
    color: #fff;
}

button.secondary:hover {
    background-color: #D1D1D6;
}

label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 500;
    font-size: 0.9rem;
    color: var(--secondary-color);
}

.nav-tabs {
    display: flex;
    justify-content: center;
    background-color: #E5E5EA;
    padding: 3px;
    border-radius: 10px;
    margin-bottom: 2rem;
}

.nav-tab {
    flex: 1;
    text-align: center;
    padding: 0.5rem;
    cursor: pointer;
    border-radius: 7px;
    color: var(--text-color);
    font-size: 0.9rem;
    font-weight: 500;
    transition: all 0.2s ease;
}

.nav-tab.active {
    background-color: #FFFFFF;
    box-shadow: 0 1px 3px rgba(0,0,0,0.1);
    font-weight: 600;
}

#output-area {
    word-break: break-all;
    white-space: pre-wrap;
    background: #F8F8FA;
    padding: 1rem;
    border-radius: 10px;
    border: 1px solid var(--border-color);
    color: var(--text-color);
    min-height: 100px;
}

/* Utilities */
.flex-row {
    display: flex;
    gap: 10px;
    align-items: center;
}

.flex-between {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.mb-0 {
    margin-bottom: 0 !important;
}

.mb-1 {
    margin-bottom: 1rem;
}

.mt-1 {
    margin-top: 1rem;
}

.w-auto {
    width: auto;
}

.flex-1 {
    flex: 1;
}

.flex-2 {
    flex: 2;
}

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

.text-center {
    text-align: center;
}

.font-medium {
    font-weight: 500;
}

.separator {
    height: 1px;
    background-color: var(--border-color);
    margin: 1.5rem 0;
}

.status-error {
    background-color: rgba(255, 59, 48, 0.95) !important;
}

.status-info {
    background-color: rgba(30, 30, 30, 0.95) !important;
}

.key-item {
    padding: 1rem 0;
    border-bottom: 1px solid var(--border-color);
}

.key-header {
    margin-bottom: 0.75rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.key-name {
    font-weight: 600;
    font-size: 1.05rem;
}

.key-date {
    font-size: 0.8rem;
    color: var(--secondary-color);
}

.key-public-key {
    margin-bottom: 0.5rem;
    font-size: 0.8rem;
}

.key-actions {
    display: flex;
    gap: 10px;
}

.btn-small {
    padding: 0.6rem;
    flex: 1;
}

.bg-warning {
    background-color: #f59f00;
    color: #fff;
}

.bg-error {
    background-color: var(--error-color);
    color: #fff;
}

select {
    width: 100%;
    margin-bottom: 1rem;
    border-radius: 10px;
    border: 1px solid var(--border-color);
    background-color: #F8F8FA;
    padding: 0 10px;
    height: 42px;
    color: var(--text-color);
    font-size: 1rem;
}

.key-item {
    font-size: 0.9rem;
    padding: 0.75rem 0;
    border-bottom: 1px solid var(--border-color);
}

.key-item:last-child {
    border-bottom: none;
}

.mode-badge {
    position: relative;
    cursor: help;
}

.mode-badge::after {
    content: attr(data-tooltip);
    position: absolute;
    top: 140%;
    right: 0;
    width: 220px;
    background-color: rgba(30, 30, 30, 0.9);
    color: #fff;
    text-align: center;
    border-radius: 8px;
    padding: 10px;
    font-size: 0.75rem;
    font-weight: 400;
    text-transform: none;
    line-height: 1.4;
    z-index: 1000;
    letter-spacing: 0;
    
    opacity: 0;
    visibility: hidden;
    transform: translateY(-5px);
    transition: opacity 0.2s ease, transform 0.2s ease, visibility 0.2s;
    pointer-events: none;
    
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    box-shadow: 0 4px 12px rgba(0,0,0,0.15);
}

.mode-badge:hover::after {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

.mode-badge::before {
    content: '';
    position: absolute;
    top: 120%;
    right: 20px;
    border-width: 6px;
    border-style: solid;
    border-color: transparent transparent rgba(30, 30, 30, 0.9) transparent;
    opacity: 0;
    visibility: hidden;
    transform: translateY(-5px);
    transition: opacity 0.2s ease, transform 0.2s ease, visibility 0.2s;
    pointer-events: none;
}

.mode-badge:hover::before {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

#status-message {
    position: fixed;
    bottom: 2rem;
    left: 50%;
    transform: translateX(-50%) translateY(20px);
    background-color: rgba(30, 30, 30, 0.95);
    color: #ffffff;
    padding: 0.75rem 1.5rem;
    border-radius: 50px;
    font-size: 0.9rem;
    font-weight: 500;
    box-shadow: 0 4px 12px rgba(0,0,0,0.15);
    z-index: 2000;
    opacity: 0;
    visibility: hidden;
    transition: opacity 0.3s cubic-bezier(0.2, 0.8, 0.2, 1), transform 0.3s cubic-bezier(0.2, 0.8, 0.2, 1), visibility 0.3s;
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    text-align: center;
    max-width: 80vw;
}

#status-message.visible {
    opacity: 1;
    visibility: visible;
    transform: translateX(-50%) translateY(0);
}