:root {
    --bg-color: #000000; --text-color: #e0e0e0; --primary-accent: #a855f7; --secondary-accent: #4f46e5;
    --container-bg: rgba(22, 22, 22, 0.7); --container-border: rgba(255, 255, 255, 0.1);
    --bot-message-bg: #2c2c2e; --user-message-bg: var(--secondary-accent); --input-bg: #161616;
    --btn-bg: #ffffff; --btn-text: #000000; --menu-bg: #111111; --menu-hover-bg: #2c2c2e;
}
body.light-theme {
    --bg-color: #f0f2f5; --text-color: #1c1e21; --primary-accent: #8e44ad; --secondary-accent: #3498db;
    --container-bg: rgba(255, 255, 255, 0.8); --container-border: rgba(0, 0, 0, 0.1);
    --bot-message-bg: #e4e6eb; --input-bg: #ffffff; --btn-bg: #000000; --btn-text: #ffffff;
    --menu-bg: #f8f8f8; --menu-hover-bg: #e0e0e0;
}
* { margin: 0; padding: 0; box-sizing: border-box; }
body {
    font-family: 'Inter', sans-serif; background-color: var(--bg-color); color: var(--text-color);
    display: flex; justify-content: center; align-items: center; min-height: 100vh; padding: 20px;
    overflow: hidden; transition: background-color 0.3s ease, color 0.3s ease;
}
#intro-screen {
    position: fixed; top: 0; left: 0; width: 100%; height: 100%; background-color: var(--bg-color);
    display: flex; justify-content: center; align-items: center; text-align: center;
    z-index: 100; transition: opacity 0.5s ease-out, visibility 0.5s ease-out, background-color 0.3s ease;
}
.intro-content h1 {
    font-size: clamp(4rem, 12vw, 8rem); font-weight: 700; letter-spacing: -2px;
    background: linear-gradient(90deg, var(--primary-accent), var(--secondary-accent));
    -webkit-background-clip: text; -webkit-text-fill-color: transparent; margin-bottom: 10px;
}
.intro-content p { font-size: clamp(1rem, 3vw, 1.5rem); color: #a0a0a0; margin-bottom: 40px; }
#start-btn {
    padding: 15px 30px; background-color: var(--btn-bg); color: var(--btn-text);
    font-weight: 500; border-radius: 8px; border: none; cursor: pointer; transition: all 0.2s ease;
}
#start-btn:hover { filter: brightness(0.9); transform: translateY(-2px); }
#main-container {
    display: flex; gap: 20px; width: 90vw; max-width: 1100px; height: 85vh; max-height: 750px;
    transition: opacity 0.5s ease-in 0.3s;
}
.hidden { opacity: 0; visibility: hidden; pointer-events: none; }
#hamburger-btn {
    position: fixed; top: 30px; right: 30px; background: none; border: none;
    cursor: pointer; padding: 10px; z-index: 1002;
}
#hamburger-btn span {
    display: block; width: 22px; height: 2px; background-color: var(--text-color);
    margin: 5px 0; transition: all 0.3s ease-in-out;
}
#hamburger-btn.active span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
#hamburger-btn.active span:nth-child(2) { opacity: 0; }
#hamburger-btn.active span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }
#side-menu {
    position: fixed; top: 0; left: -260px; width: 260px; height: 100%; background: var(--menu-bg);
    z-index: 1001; transition: left 0.3s ease-in-out, background-color 0.3s ease;
    padding: 20px; display: flex; flex-direction: column; gap: 10px;
}
#side-menu.active { left: 0; }
.menu-item {
    display: flex; align-items: center; gap: 15px; padding: 12px 15px; border-radius: 8px;
    color: var(--text-color); text-decoration: none; font-weight: 500;
    transition: background-color 0.2s ease; background: none; border: none; font-size: inherit; cursor: pointer;
}
.menu-item:hover { background-color: var(--menu-hover-bg); }
.theme-switcher-wrapper { margin-top: auto; padding-top: 10px; border-top: 1px solid var(--container-border); }
#theme-switcher-btn { width: 100%; }
#menu-overlay {
    position: fixed; top: 0; left: 0; width: 100%; height: 100%; background: rgba(0, 0, 0, 0.5);
    z-index: 1000; opacity: 0; visibility: hidden; transition: opacity 0.3s ease-in-out, visibility 0.3s ease-in-out;
}
#menu-overlay.active { opacity: 1; visibility: visible; }
#live2d-container, #chat-container {
    background: var(--container-bg); border: 1px solid var(--container-border);
    backdrop-filter: blur(10px); transition: background-color 0.3s ease, border-color 0.3s ease;
    border-radius: 16px;
}
#live2d-container { flex-basis: 450px; flex-shrink: 0; min-width: 300px; height: 100%; }
#chat-container {
    flex: 1; min-width: 320px; height: 100%; display: flex; flex-direction: column; overflow: hidden;
}
.chat-header {
    display: flex; justify-content: center; align-items: center; padding: 20px 15px;
    border-bottom: 1px solid var(--container-border);
}
.chat-header h3 { font-weight: 500; }
#chat-window {
    flex: 1; padding: 20px; overflow-y: auto; display: flex; flex-direction: column;
}
#chat-window::-webkit-scrollbar { width: 6px; }
#chat-window::-webkit-scrollbar-track { background: transparent; }
#chat-window::-webkit-scrollbar-thumb { background-color: rgba(0, 0, 0, 0.2); border-radius: 3px; }
#chat-form { display: flex; padding: 15px; border-top: 1px solid var(--container-border); }
#chat-input {
    flex: 1; background-color: var(--input-bg); color: var(--text-color);
    border: 1px solid var(--container-border); border-radius: 8px; padding: 10px 15px;
    font-size: 1rem; outline: none; transition: border-color 0.2s ease, box-shadow 0.2s ease;
}
#chat-input:focus { border-color: var(--primary-accent); box-shadow: 0 0 10px color-mix(in srgb, var(--primary-accent) 30%, transparent); }
#chat-form button {
    margin-left: 10px; padding: 0 20px; border: none; background-color: var(--btn-bg); color: var(--btn-text);
    font-size: 0.9rem; font-weight: 500; border-radius: 8px; cursor: pointer; transition: background-color 0.2s ease;
}
#chat-form button:hover { filter: brightness(0.9); }
.message-wrapper { display: flex; align-items: flex-end; gap: 10px; margin-bottom: 20px; max-width: 85%; }
.message-wrapper.bot { align-self: flex-start; }
.message-wrapper.user { align-self: flex-end; flex-direction: row-reverse; }
.avatar {
    width: 32px; height: 32px; border-radius: 50%; display: flex; justify-content: center; align-items: center;
    font-weight: bold; flex-shrink: 0;
}
.bot-avatar { background-color: var(--primary-accent); }
.user-avatar { background-color: var(--secondary-accent); }
.message { padding: 12px 18px; border-radius: 18px; line-height: 1.6; }
.bot-message { background-color: var(--bot-message-bg); color: var(--text-color); border-bottom-left-radius: 4px; }
.user-message { background-color: var(--user-message-bg); color: #ffffff; border-bottom-right-radius: 4px; }
.typing-indicator {
    display: flex; align-items: center; gap: 5px; padding: 12px 18px;
    background-color: var(--bot-message-bg); border-radius: 18px; border-bottom-left-radius: 4px;
}
.typing-indicator span {
    width: 8px; height: 8px; background-color: color-mix(in srgb, var(--text-color) 60%, transparent);
    border-radius: 50%; animation: bounce 1.3s infinite;
}
.typing-indicator span:nth-child(2) { animation-delay: 0.2s; }
.typing-indicator span:nth-child(3) { animation-delay: 0.4s; }
@keyframes bounce { 0%, 100% { transform: translateY(0); } 50% { transform: translateY(-6px); } }
body::before, body::after { content: ''; position: fixed; z-index: -1; }
body::before {
    top: -20%; left: -20%; width: 600px; height: 600px;
    background: radial-gradient(circle, color-mix(in srgb, var(--primary-accent) 30%, transparent), transparent, transparent);
    animation: pulse-purple 15s infinite;
}
body::after {
    bottom: -20%; right: -20%; width: 600px; height: 600px;
    background: radial-gradient(circle, color-mix(in srgb, var(--secondary-accent) 30%, transparent), transparent, transparent);
    animation: pulse-blue 15s infinite alternate;
}
@keyframes pulse-purple { 0% { transform: scale(1); opacity: 0.3; } 50% { transform: scale(1.2); opacity: 0.5; } 100% { transform: scale(1); opacity: 0.3; } }
@keyframes pulse-blue { 0% { transform: scale(1); opacity: 0.3; } 50% { transform: scale(1.2); opacity: 0.5; } 100% { transform: scale(1); opacity: 0.3; } }