/* ============================================================
   DESIGN TOKENS — Source of Truth cho toàn bộ project
   Mọi file CSS khác PHẢI dùng var(--*) thay vì hardcode.
   ============================================================ */
:root {
    /* --- Brand Colors --- */
    --color-primary: #667eea;
    --color-primary-dark: #5a6fd8;
    --color-secondary: #764ba2;
    --color-primary-gradient: linear-gradient(135deg, #667eea 0%, #764ba2 100%);

    /* --- Semantic Colors --- */
    --color-success: #27ae60;
    --color-success-bg: #efe;
    --color-success-border: #cfc;
    --color-danger: #e74c3c;
    --color-danger-dark: #c0392b;
    --color-danger-bg: #fee;
    --color-danger-border: #fcc;
    --color-warning: #f39c12;
    --color-info: #007bff;
    --color-info-dark: #0056b3;

    /* --- Neutral / Text --- */
    --color-text: #333;
    --color-text-muted: #666;
    --color-text-light: #999;
    --color-text-lighter: #bbb;

    /* --- Backgrounds & Surfaces --- */
    --color-bg: #f0f2f5;
    --color-surface: #ffffff;
    --color-surface-alt: #f8f9fa;
    --color-surface-hover: #f0f0f0;

    /* --- Borders --- */
    --color-border: #e0e0e0;
    --color-border-light: #eee;
    --color-border-medium: #ddd;
    --color-border-dark: #ced4da;

    /* --- Interactive (Blue system - dùng trong chat/buttons) --- */
    --color-blue: #1e88e5;
    --color-blue-dark: #1976d2;
    --color-blue-light: #e3f2fd;

    /* --- Scrollbar --- */
    --color-scrollbar-track: #f1f1f1;
    --color-scrollbar-thumb: #888;
    --color-scrollbar-thumb-hover: #555;

    /* --- Font --- */
    --font-primary: 'Roboto', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    --font-size-xs: 12px;
    --font-size-sm: 13px;
    --font-size-base: 14px;
    --font-size-md: 15px;
    --font-size-lg: 16px;
    --font-size-xl: 18px;
    --font-size-2xl: 24px;

    /* --- Spacing --- */
    --space-xs: 4px;
    --space-sm: 8px;
    --space-md: 12px;
    --space-lg: 16px;
    --space-xl: 20px;
    --space-2xl: 24px;
    --space-3xl: 32px;
    --space-4xl: 40px;

    /* --- Border Radius --- */
    --radius-sm: 4px;
    --radius-md: 6px;
    --radius-lg: 8px;
    --radius-xl: 12px;
    --radius-2xl: 16px;
    --radius-full: 50%;

    /* --- Shadows --- */
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.08);
    --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 40px rgba(0, 0, 0, 0.15);
    --shadow-xl: 0 10px 40px rgba(0, 0, 0, 0.2);

    /* --- Transitions --- */
    --transition-fast: 150ms ease;
    --transition-normal: 0.3s ease;
    --transition-slow: 0.5s ease;

    /* --- Z-Index Scale --- */
    --z-dropdown: 100;
    --z-sticky: 200;
    --z-modal: 1000;
    --z-toast: 2000;
    --z-overlay: 9000;

    /* Neutral gray (Bootstrap-compatible) */
    --color-gray: #6c757d;
    --color-gray-hover: #5a6268;
}


/* === RESET & BASE === */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

input,
button,
textarea,
select {
    font-family: inherit;
    font-weight: inherit;
    font-size: inherit;
}

body {
    font-family: var(--font-primary);
    font-weight: 400;
    background: var(--color-primary-gradient);
    min-height: 100vh;
    color: var(--color-text);
    /* overflow per-page: chat=hidden (fixed layout), others=auto */
}

/* Chat cần fixed height layout — không scroll body */
body.chat-page {
    overflow: hidden;
    background: var(--color-surface, #ffffff);
}

/* === CONTAINER === */
.container {
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    padding: var(--space-xl);
}

.welcome-card {
    background: var(--color-surface);
    padding: var(--space-4xl);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-xl);
    text-align: center;
    max-width: 500px;
}

.welcome-card h1 {
    color: var(--color-primary);
    margin-bottom: 10px;
    font-size: 2.5em;
}

.welcome-card p {
    color: var(--color-text-muted);
    margin-bottom: 30px;
    font-size: 1.1em;
}

/* === BUTTONS === */
.btn {
    display: inline-block;
    padding: var(--space-md) var(--space-2xl);
    border: none;
    border-radius: var(--radius-md);
    font-size: var(--font-size-lg);
    font-weight: 600;
    cursor: pointer;
    text-decoration: none;
    transition: var(--transition-normal);
    text-align: center;
}

.btn-primary {
    background: var(--color-primary-gradient);
    color: var(--color-surface);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(102, 126, 234, 0.4);
}

.btn-block {
    width: 100%;
}

.btn-small {
    padding: var(--space-xs) var(--space-md);
    font-size: var(--font-size-base);
    background: var(--color-border);
    color: var(--color-text);
}

.btn-small:hover {
    background: var(--color-surface-hover);
}

.btn-secondary {
    background: var(--color-gray);
    color: var(--color-surface);
}

.btn-secondary:hover {
    background: var(--color-gray-hover);
}

.btn-danger {
    background: var(--color-danger);
    color: var(--color-surface);
}

.btn-danger:hover {
    background: var(--color-danger-dark);
}

.btn-link {
    color: var(--color-primary);
    text-decoration: none;
    font-size: var(--font-size-base);
}

.btn-link:hover {
    text-decoration: underline;
}

/* === ANIMATIONS === */
@keyframes slideIn {
    from {
        opacity: 0;
        transform: translateY(10px);
    }

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

@keyframes messagePulse {
    0% {
        transform: scale(0.98);
        box-shadow: 0 2px 5px rgba(0, 0, 0, 0.05);
    }

    50% {
        transform: scale(1.01);
        box-shadow: 0 4px 15px rgba(102, 126, 234, 0.3);
    }

    100% {
        transform: scale(1);
        box-shadow: 0 2px 5px rgba(0, 0, 0, 0.05);
    }
}

@keyframes pulse {

    0%,
    100% {
        transform: scale(1);
    }

    50% {
        transform: scale(1.1);
    }
}

@keyframes slideInRight {
    from {
        opacity: 0;
        transform: translateX(20px);
    }

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

/* === SCROLLBAR === */
.chat-messages::-webkit-scrollbar,
.conversation-list::-webkit-scrollbar,
.notifications-list::-webkit-scrollbar,
.users-list-container::-webkit-scrollbar {
    width: 8px;
}

.chat-messages::-webkit-scrollbar-track,
.conversation-list::-webkit-scrollbar-track,
.notifications-list::-webkit-scrollbar-track,
.users-list-container::-webkit-scrollbar-track {
    background: var(--color-scrollbar-track);
}

.chat-messages::-webkit-scrollbar-thumb,
.conversation-list::-webkit-scrollbar-thumb,
.notifications-list::-webkit-scrollbar-thumb,
.users-list-container::-webkit-scrollbar-thumb {
    background: var(--color-scrollbar-thumb);
    border-radius: var(--radius-sm);
}

.chat-messages::-webkit-scrollbar-thumb:hover,
.conversation-list::-webkit-scrollbar-thumb:hover,
.notifications-list::-webkit-scrollbar-thumb:hover,
.users-list-container::-webkit-scrollbar-thumb:hover {
    background: var(--color-scrollbar-thumb-hover);
}

/* === LOADING & ERROR INDICATORS === */
.loading-indicator {
    text-align: center;
    padding: var(--space-4xl) var(--space-xl);
    color: var(--color-text-muted);
    font-size: var(--font-size-lg);
}

.error-message {
    text-align: center;
    padding: var(--space-4xl) var(--space-xl);
    color: var(--color-danger);
    font-size: var(--font-size-lg);
    background: var(--color-danger-bg);
    border-radius: var(--radius-lg);
    margin: var(--space-xl);
}

.no-messages,
.no-notifications {
    text-align: center;
    padding: var(--space-4xl) var(--space-xl);
    color: var(--color-text-light);
    font-size: var(--font-size-lg);
}

.no-notifications {
    font-size: var(--font-size-base);
}

/* === ALERT === */
.alert {
    padding: var(--space-md) var(--space-xl);
    border-radius: var(--radius-md);
    margin-bottom: var(--space-xl);
}

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

/* Hidden elements */
.hidden-input,
.hidden-element {
    display: none;
}

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