:root {
    --bg-color: #17212b;
    --surface-color: #242f3d;
    --surface-hover: #2c3847;
    --surface-active: #2b5278;
    --primary-color: #5288c1;
    --primary-hover: #4576a8;
    --primary-color-rgb: 82, 136, 193;
    --secondary-color: #64b5f6;
    --text-primary: #f5f5f5;
    --text-secondary: #7f91a4;
    --text-muted: #5d6c7e;
    --border-color: #0e1621;
    --danger-color: #ff595a;
    --success-color: #4caf50;

    /* Message Bubbles */
    --msg-out-bg: #2b5278;
    --msg-in-bg: #182533;

    /* Glassmorphism */
    --glass-bg: rgba(36, 47, 61, 0.85);
    --glass-border: 1px solid rgba(255, 255, 255, 0.05);
    --glass-shadow: 0 4px 12px rgba(0, 0, 0, 0.5);
    --blur-amount: 20px;

    /* Spacing & Radius */
    --radius-sm: 6px;
    --radius-md: 10px;
    --radius-lg: 16px;
    --radius-xl: 20px;

    /* Dark Glass Palette (Global) */
    --bg-main: #0a0a0a;
    --bg-glass: rgba(20, 20, 20, 0.55);
    --bg-glass-heavy: rgba(20, 20, 20, 0.85);
    --border-glass: rgba(255, 255, 255, 0.06);
    --shadow-deep: 0 20px 40px rgba(0, 0, 0, 0.6);
    --font-main: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

* {
    box-sizing: border-box;
}

body {
    margin: 0;
    padding: 0;
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-primary);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* Glass Panel Utility */
.glass-panel {
    background: rgba(36, 47, 61, 0.7);
    backdrop-filter: blur(var(--blur-amount));
    -webkit-backdrop-filter: blur(var(--blur-amount));
    border: 1px solid rgba(255, 255, 255, 0.05);
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.3);
    border-radius: var(--radius-md);
}

/* Enhanced Button Styles */
button {
    font-family: inherit;
    cursor: pointer;
    user-select: none;
    -webkit-tap-highlight-color: transparent;
}

.fluent-btn,
.btn,
button.btn-primary,
button.btn-secondary,
button.btn-danger,
.modal-btn,
.input-button,
.session-button,
.btn-terminate-all {
    background: #455977;
    border: none;
    color: #fff;
    padding: 12px 24px;
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    font-size: 14px;
    font-weight: 500;
    position: relative;
    overflow: hidden;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    min-height: 44px;
    /* Touch-friendly */
}

.fluent-btn::before,
.btn::before,
.modal-btn::before {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    width: 0;
    height: 0;
    border-radius: 50%;
    background: rgba(255, 255, 255, 0.2);
    transform: translate(-50%, -50%);
    transition: width 0.6s, height 0.6s;
}

.fluent-btn:hover::before,
.btn:hover::before,
.modal-btn:hover::before {
    width: 300px;
    height: 300px;
}

.fluent-btn:hover,
.btn:hover,
.btn-primary:hover {
    background: var(--primary-hover);
    transform: translateY(-2px);
    box-shadow: 0 8px 24px rgba(var(--primary-color-rgb), 0.4);
}

.fluent-btn:active,
.btn:active {
    transform: translateY(0);
    box-shadow: 0 2px 8px rgba(var(--primary-color-rgb), 0.3);
}

/* Secondary Button */
.fluent-btn.secondary,
.btn-secondary {
    background: transparent;
    border: 1px solid var(--border-color);
    color: var(--text-primary);
}

.fluent-btn.secondary:hover,
.btn-secondary:hover {
    background: rgba(255, 255, 255, 0.05);
    border-color: var(--primary-color);
    box-shadow: 0 4px 16px rgba(0, 0, 0, 0.2);
}

/* Danger Button */
.btn-danger,
.modal-btn-confirm {
    background: var(--danger-color);
    color: #fff;
}

.btn-danger:hover,
.modal-btn-confirm:hover {
    background: #ff3d3e;
    box-shadow: 0 8px 24px rgba(255, 89, 90, 0.4);
}

/* Cancel Button */
.modal-btn-cancel {
    background: rgba(255, 255, 255, 0.05);
    border: 1px solid var(--border-color);
    color: var(--text-primary);
}

.modal-btn-cancel:hover {
    background: rgba(255, 255, 255, 0.1);
    border-color: var(--text-secondary);
}

/* Session Buttons */
.session-button {
    width: 100%;
    padding: 8px 16px;
    font-size: 12px;
    background: var(--danger-color);
    min-height: 36px;
}

.session-button.current-badge {
    background: var(--success-color);
    color: #fff;
}

.btn-terminate-all {
    width: 100%;
    background: rgba(255, 89, 90, 0.2);
    border: 1px solid var(--danger-color);
    color: var(--danger-color);
    font-weight: 600;
}

.btn-terminate-all:hover {
    background: var(--danger-color);
    color: #fff;
}

/* Input Buttons (Chat) */
.input-button {
    width: 44px;
    height: 44px;
    padding: 0;
    background: transparent;
    color: var(--text-secondary);
    border-radius: 50%;
    min-height: unset;
}

.input-button:hover {
    background: rgba(255, 255, 255, 0.05);
    color: var(--primary-color);
    transform: scale(1.1);
}

#send-btn {
    color: var(--primary-color);
}

#send-btn:hover {
    color: #fff;
    background: var(--primary-color);
}

/* Menu Items */
.menu-item {
    background: none;
    border: none;
    color: var(--text-primary);
    padding: 12px 16px;
    text-align: left;
    width: 100%;
    transition: background 0.2s;
    display: flex;
    align-items: center;
    gap: 12px;
    min-height: 44px;
}

.menu-item:hover {
    background: rgba(255, 255, 255, 0.05);
}

.menu-item.menu-exit {
    color: var(--danger-color);
    border-top: 1px solid var(--border-color);
}

.menu-item.menu-exit:hover {
    background: rgba(255, 89, 90, 0.1);
}

/* Input Fields */
.fluent-input,
input[type="text"],
input[type="password"],
input[type="number"] {
    background: rgba(0, 0, 0, 0.3);
    border: 1px solid var(--border-color);
    color: var(--text-primary);
    padding: 12px;
    border-radius: var(--radius-md);
    width: 100%;
    outline: none;
    transition: all 0.3s;
    font-size: 14px;
}

.fluent-input:focus,
input:focus {
    border-color: var(--primary-color);
    background: rgba(0, 0, 0, 0.4);
    box-shadow: 0 0 0 3px rgba(var(--primary-color-rgb), 0.1);
}

/* Animations */
@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(10px);
    }

    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes slideIn {
    from {
        transform: translateX(-100%);
    }

    to {
        transform: translateX(0);
    }
}

@keyframes slideInRight {
    from {
        transform: translateX(100%);
    }

    to {
        transform: translateX(0);
    }
}

@keyframes scaleIn {
    from {
        transform: scale(0.9);
        opacity: 0;
    }

    to {
        transform: scale(1);
        opacity: 1;
    }
}

@keyframes shimmer {
    0% {
        background-position: -1000px 0;
    }

    100% {
        background-position: 1000px 0;
    }
}

.fade-in {
    animation: fadeIn 0.3s ease;
}

.slide-in {
    animation: slideIn 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

.slide-in-right {
    animation: slideInRight 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

.scale-in {
    animation: scaleIn 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

/* Loading Spinner */
.spinner {
    width: 20px;
    height: 20px;
    border: 2px solid rgba(255, 255, 255, 0.1);
    border-top-color: var(--primary-color);
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
}

@keyframes spin {
    to {
        transform: rotate(360deg);
    }
}

/* Scrollbar */
::-webkit-scrollbar {
    width: 8px;
    height: 8px;
}

::-webkit-scrollbar-track {
    background: transparent;
}

::-webkit-scrollbar-thumb {
    background: rgba(255, 255, 255, 0.1);
    border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
    background: rgba(255, 255, 255, 0.2);
}

/* Ripple Effect */
.ripple {
    position: relative;
    overflow: hidden;
}

.ripple::after {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    width: 0;
    height: 0;
    border-radius: 50%;
    background: rgba(255, 255, 255, 0.3);
    transform: translate(-50%, -50%);
    transition: width 0.6s, height 0.6s;
}

.ripple:active::after {
    width: 300px;
    height: 300px;
}

/* Touch Feedback */
@media (hover: none) {

    .fluent-btn:active,
    .btn:active,
    .menu-item:active {
        background: var(--surface-hover);
        transform: scale(0.98);
    }
}