/* Modern Enhanced Chat UI with Dark/Light Mode */

/* Light Mode Variables (Default) */
:root {
    --bg-gradient-start: #667eea;
    --bg-gradient-end: #764ba2;
    --main-bg: #ffffff;
    --message-display-bg-start: #f8f9ff;
    --message-display-bg-end: #ffffff;
    --header-gradient-start: #667eea;
    --header-gradient-end: #764ba2;
    --header-text: #ffffff;
    --user-message-bg-start: #667eea;
    --user-message-bg-end: #764ba2;
    --user-message-text: #ffffff;
    --user-message-tail: #764ba2;
    --ai-message-bg: #ffffff;
    --ai-message-text: #2d3748;
    --ai-message-border: #e2e8f0;
    --ai-message-tail: #ffffff;
    --input-bg: #f7fafc;
    --input-border: #e2e8f0;
    --input-focus-border: #667eea;
    --input-text: #2d3748;
    --input-placeholder: #a0aec0;
    --button-bg-start: #667eea;
    --button-bg-end: #764ba2;
    --button-text: #ffffff;
    --scrollbar-track: #f1f1f1;
    --scrollbar-thumb-start: #667eea;
    --scrollbar-thumb-end: #764ba2;
    --scrollbar-thumb-hover-start: #5568d3;
    --scrollbar-thumb-hover-end: #6a3d8f;
    --typing-dot: #667eea;
    --form-border: #e2e8f0;
    --system-message-bg: rgba(102, 126, 234, 0.05);
    --system-message-border: rgba(102, 126, 234, 0.2);
    --system-message-text: #718096;
    --shadow-color: rgba(0, 0, 0, 0.1);
    --shadow-color-heavy: rgba(0, 0, 0, 0.3);
}

/* Dark Mode Variables */
[data-theme="dark"] {
    --bg-gradient-start: #1a1a2e;
    --bg-gradient-end: #16213e;
    --main-bg: #0f1419;
    --message-display-bg-start: #16181d;
    --message-display-bg-end: #1a1d23;
    --header-gradient-start: #1e2a45;
    --header-gradient-end: #2d3a5f;
    --header-text: #e2e8f0;
    --user-message-bg-start: #667eea;
    --user-message-bg-end: #764ba2;
    --user-message-text: #ffffff;
    --user-message-tail: #764ba2;
    --ai-message-bg: #1e2128;
    --ai-message-text: #e2e8f0;
    --ai-message-border: #2d3748;
    --ai-message-tail: #1e2128;
    --input-bg: #1e2128;
    --input-border: #2d3748;
    --input-focus-border: #667eea;
    --input-text: #e2e8f0;
    --input-placeholder: #718096;
    --button-bg-start: #667eea;
    --button-bg-end: #764ba2;
    --button-text: #ffffff;
    --scrollbar-track: #1e2128;
    --scrollbar-thumb-start: #4a5568;
    --scrollbar-thumb-end: #2d3748;
    --scrollbar-thumb-hover-start: #667eea;
    --scrollbar-thumb-hover-end: #764ba2;
    --typing-dot: #667eea;
    --form-border: #2d3748;
    --system-message-bg: rgba(102, 126, 234, 0.1);
    --system-message-border: rgba(102, 126, 234, 0.3);
    --system-message-text: #a0aec0;
    --shadow-color: rgba(0, 0, 0, 0.3);
    --shadow-color-heavy: rgba(0, 0, 0, 0.6);
}

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

body {
    font-family: 'Inter', 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: linear-gradient(135deg, var(--bg-gradient-start) 0%, var(--bg-gradient-end) 100%);
    min-height: 100vh;
    padding: 20px;
    transition: background 0.3s ease;
}

main {
    width: 100%;
    max-width: 900px;
    margin: 0 auto;
    height: calc(100vh - 40px);
    border-radius: 20px;
    overflow: hidden;
    animation: slideUp 0.5s ease-out;
    display: flex;
    flex-direction: column;
    position: relative;
    box-shadow: 0 20px 60px var(--shadow-color-heavy);
    background: var(--main-bg);
    transition: background 0.3s ease, box-shadow 0.3s ease;
}

@keyframes slideUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {        
        opacity: 1;
        transform: translateY(0);
    }
}

/* Header with gradient */
header {
    background: linear-gradient(135deg, var(--header-gradient-start) 0%, var(--header-gradient-end) 100%);
    color: var(--header-text);
    padding: 25px 30px;
    font-size: 1.5em;
    font-weight: 700;
    text-align: center;
    position: relative;
    box-shadow: 0 4px 12px var(--shadow-color);
    letter-spacing: 0.5px;
    transition: background 0.3s ease, color 0.3s ease;
}

header::before {
    content: '💬';
    margin-right: 10px;
    font-size: 1.2em;
}

/* Button Container */
.button-container {
    position: absolute;
    top: 50%;
    right: 25px;
    transform: translateY(-50%);
    display: flex;
    gap: 10px;
    z-index: 10;
}

#logout-button,
#clear-memory-button {
    background: rgba(255, 255, 255, 0.2);
    backdrop-filter: blur(10px);
    color: white;
    border: 1px solid rgba(255, 255, 255, 0.3);
    padding: 10px 20px;
    font-size: 14px;
    border-radius: 25px;
    cursor: pointer;
    transition: all 0.3s ease;
    font-weight: 500;
}

#logout-button:hover,
#clear-memory-button:hover {
    background: rgba(255, 255, 255, 0.3);
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
}

/* Message Display Area */
#message-display {
    flex: 1;
    overflow-y: auto;
    padding: 30px;
    display: flex;
    flex-direction: column;
    gap: 16px;
    background: linear-gradient(to bottom, var(--message-display-bg-start) 0%, var(--message-display-bg-end) 100%);
    scroll-behavior: smooth;
    transition: background 0.3s ease;
}

/* Custom Scrollbar */
#message-display::-webkit-scrollbar {
    width: 8px;
}

#message-display::-webkit-scrollbar-track {
    background: var(--scrollbar-track);
}

#message-display::-webkit-scrollbar-thumb {
    background: linear-gradient(135deg, var(--scrollbar-thumb-start) 0%, var(--scrollbar-thumb-end) 100%);
    border-radius: 10px;
    transition: background 0.3s ease;
}

#message-display::-webkit-scrollbar-thumb:hover {
    background: linear-gradient(135deg, var(--scrollbar-thumb-hover-start) 0%, var(--scrollbar-thumb-hover-end) 100%);
}

/* Message Bubbles */
.message {
    margin-bottom: 8px;
    padding: 16px 20px;
    border-radius: 18px;
    max-width: 70%;
    box-shadow: 0 2px 8px var(--shadow-color);
    animation: messageSlide 0.3s ease-out;
    position: relative;
    transition: background 0.3s ease, color 0.3s ease, border-color 0.3s ease;
}

@keyframes messageSlide {
    from {
        opacity: 0;
        transform: translateY(10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.user-message {
    align-self: flex-end;
    background: linear-gradient(135deg, var(--user-message-bg-start) 0%, var(--user-message-bg-end) 100%);
    color: var(--user-message-text);
    border-bottom-right-radius: 4px;
}

.user-message::after {
    content: '';
    position: absolute;
    bottom: 0;
    right: -8px;
    width: 0;
    height: 0;
    border-left: 8px solid var(--user-message-tail);
    border-bottom: 8px solid transparent;
}

.ai-message {
    align-self: flex-start;
    background: var(--ai-message-bg);
    color: var(--ai-message-text);
    border: 1px solid var(--ai-message-border);
    border-bottom-left-radius: 4px;
    box-shadow: 0 2px 8px var(--shadow-color);
}

.ai-message::before {
    content: '';
    position: absolute;
    bottom: 0;
    left: -8px;
    width: 0;
    height: 0;
    border-right: 8px solid var(--ai-message-tail);
    border-bottom: 8px solid transparent;
}

.message-text {
    white-space: pre-wrap;
    word-wrap: break-word;
    font-size: 15px;
    line-height: 1.6;
    letter-spacing: 0.3px;
}

.user-message .message-text {
    color: var(--user-message-text);
}

.ai-message .message-text {
    color: var(--ai-message-text);
}

/* Typing Indicator */
.typing-indicator {
    display: flex;
    align-items: center;
    padding: 16px 20px;
    background: var(--ai-message-bg);
    border-radius: 18px;
    border-bottom-left-radius: 4px;
    max-width: 100px;
    box-shadow: 0 2px 8px var(--shadow-color);
    border: 1px solid var(--ai-message-border);
    transition: background 0.3s ease, border-color 0.3s ease;
}

.typing-indicator span {
    display: inline-block;
    width: 8px;
    height: 8px;
    background: var(--typing-dot);
    border-radius: 50%;
    margin: 0 3px;
    animation: bounce 1.4s infinite;
}

.typing-indicator span:nth-child(1) {
    animation-delay: 0s;
}

.typing-indicator span:nth-child(2) {
    animation-delay: 0.2s;
}

.typing-indicator span:nth-child(3) {
    animation-delay: 0.4s;
}

@keyframes bounce {
    0%, 60%, 100% {
        transform: translateY(0);
    }
    30% {
        transform: translateY(-10px);
    }
}

/* Input Form */
form {
    padding: 20px 25px;
    background: var(--main-bg);
    border-top: 1px solid var(--form-border);
    box-shadow: 0 -4px 12px var(--shadow-color);
    transition: background 0.3s ease, border-color 0.3s ease;
}

.input-container {
    display: flex;
    align-items: center;
    gap: 12px;
}

input[type="text"] {
    flex: 1;
    padding: 14px 20px;
    border: 2px solid var(--input-border);
    border-radius: 25px;
    font-size: 15px;
    background: var(--input-bg);
    color: var(--input-text);
    transition: all 0.3s ease;
    font-family: inherit;
}

input[type="text"]:focus {
    outline: none;
    border-color: var(--input-focus-border);
    background: var(--main-bg);
    box-shadow: 0 0 0 4px rgba(102, 126, 234, 0.1);
}

input[type="text"]::placeholder {
    color: var(--input-placeholder);
}

.button-group {
    display: flex;
    gap: 8px;
}

input[type="submit"],
#upload-button {
    background: linear-gradient(135deg, var(--button-bg-start) 0%, var(--button-bg-end) 100%);
    color: var(--button-text);
    border: none;
    padding: 14px 24px;
    border-radius: 25px;
    font-size: 15px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    box-shadow: 0 4px 12px rgba(102, 126, 234, 0.3);
}

input[type="submit"]:hover,
#upload-button:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(102, 126, 234, 0.4);
}

input[type="submit"]:active,
#upload-button:active {
    transform: translateY(0);
}

input[type="submit"]:disabled {
    background: linear-gradient(135deg, #cbd5e0 0%, #a0aec0 100%);
    cursor: not-allowed;
    box-shadow: none;
    transform: none;
}

#upload-button {
    padding: 14px 20px;
}

#upload-button::before {
    content: '📎 ';
    margin-right: 4px;
}

/* Scroll to Bottom Button */
#scroll-to-bottom {
    position: fixed;
    bottom: 120px;
    right: 40px;
    background: linear-gradient(135deg, var(--button-bg-start) 0%, var(--button-bg-end) 100%);
    color: var(--button-text);
    border: none;
    border-radius: 50%;
    width: 56px;
    height: 56px;
    font-size: 24px;
    cursor: pointer;
    display: none;
    box-shadow: 0 8px 24px rgba(102, 126, 234, 0.4);
    transition: all 0.3s ease;
    z-index: 1000;
}

#scroll-to-bottom:hover {
    transform: translateY(-4px) scale(1.05);
    box-shadow: 0 12px 32px rgba(102, 126, 234, 0.5);
}

#scroll-to-bottom:active {
    transform: translateY(-2px) scale(1);
}

/* System Messages */
.system-message {
    color: var(--system-message-text);
    font-style: italic;
    text-align: center;
    margin: 20px 0;
    font-size: 14px;
    padding: 8px 16px;
    background: var(--system-message-bg);
    border-radius: 12px;
    border: 1px dashed var(--system-message-border);
    transition: background 0.3s ease, color 0.3s ease, border-color 0.3s ease;
}

/* Theme Toggle Button */
#theme-toggle {
    background: rgba(255, 255, 255, 0.2);
    backdrop-filter: blur(10px);
    color: white;
    border: 1px solid rgba(255, 255, 255, 0.3);
    padding: 10px 20px;
    font-size: 14px;
    border-radius: 25px;
    cursor: pointer;
    transition: all 0.3s ease;
    font-weight: 500;
    display: flex;
    align-items: center;
    gap: 8px;
}

#theme-toggle:hover {
    background: rgba(255, 255, 255, 0.3);
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
}

#theme-toggle .theme-icon {
    font-size: 16px;
    transition: transform 0.3s ease;
}

#theme-toggle:hover .theme-icon {
    transform: rotate(20deg);
}

/* Responsive Design */
@media (max-width: 768px) {
    body {
        padding: 10px;
    }

    main {
        height: calc(100vh - 20px);
        max-width: 100%;
        border-radius: 16px;
    }

    header {
        padding: 20px 20px;
        font-size: 1.3em;
    }

    .button-container {
        right: 15px;
        gap: 6px;
    }

    #logout-button,
    #clear-memory-button {
        padding: 8px 14px;
        font-size: 13px;
    }

    #message-display {
        padding: 20px 15px;
    }

    .message {
        max-width: 85%;
        padding: 14px 16px;
    }

    form {
        padding: 15px;
    }

    .input-container {
        gap: 8px;
    }

    input[type="text"] {
        padding: 12px 16px;
        font-size: 14px;
    }

    input[type="submit"],
    #upload-button {
        padding: 12px 18px;
        font-size: 14px;
    }

    #scroll-to-bottom {
        bottom: 100px;
        right: 20px;
        width: 48px;
        height: 48px;
        font-size: 20px;
    }
}

@media (max-width: 480px) {
    header {
        font-size: 1.1em;
        padding: 18px 15px;
    }

    header::before {
        font-size: 1em;
    }

    .button-container {
        position: static;
        transform: none;
        justify-content: center;
        margin-top: 10px;
        padding-top: 10px;
        border-top: 1px solid rgba(255, 255, 255, 0.2);
    }

    #message-display {
        padding: 15px 10px;
    }

    .message {
        max-width: 90%;
        font-size: 14px;
    }

    .input-container {
        flex-wrap: wrap;
    }

    input[type="text"] {
        flex-basis: 100%;
        order: 1;
    }

    .button-group {
        width: 100%;
        order: 2;
        margin-top: 8px;
        justify-content: flex-end;
    }

    input[type="submit"],
    #upload-button {
        flex: 0 1 auto;
    }
}

/* Loading Animation */
@keyframes pulse {
    0%, 100% {
        opacity: 1;
    }
    50% {
        opacity: 0.5;
    }
}