:root {
    --bg-color: #0b0f19; /* Xanh đen mềm mại hơn */
    --card-bg: rgba(15, 20, 35, 0.7);
    --text-primary: #f8fafc;
    --text-secondary: #94a3b8;
    --primary-color: #fb7185; /* Đỏ hồng pastel nhẹ nhàng (Rose 400) */
    --primary-hover: #e11d48;
    --gradient-1: #fb7185; /* Soft Rose */
    --gradient-2: #9f1239; /* Deep Burgundy */
    --input-bg: rgba(10, 15, 25, 0.6);
    --border-color: rgba(255, 255, 255, 0.08);
    --transition: all 0.3s ease-in-out;
}

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

body {
    font-family: 'Inter', sans-serif;
    background-color: var(--bg-color);
    color: var(--text-primary);
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    overflow: hidden;
    position: relative;
}

/* Language Switcher */
.lang-switcher {
    position: absolute;
    top: 20px;
    right: 30px;
    display: flex;
    gap: 10px;
    z-index: 1000;
}

.lang-btn {
    background: transparent;
    border: 1px solid var(--border-color);
    color: var(--text-secondary);
    padding: 6px 12px;
    border-radius: 8px;
    font-size: 12px;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
}

.lang-btn:hover {
    color: var(--text-primary);
    border-color: var(--text-secondary);
    background-color: rgba(255, 255, 255, 0.05);
}

.lang-btn.active {
    color: #ffffff;
    background: linear-gradient(135deg, var(--gradient-1), var(--gradient-2));
    border-color: transparent;
}

/* Background Animated Blobs */
.background-elements {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    overflow: hidden;
    z-index: -1;
}

.blob {
    position: absolute;
    filter: blur(100px);
    opacity: 0.35;
    border-radius: 50%;
    animation: float 10s infinite ease-in-out alternate;
}

.blob-1 {
    top: -10%;
    left: -10%;
    width: 500px;
    height: 500px;
    background: radial-gradient(circle, var(--gradient-1), transparent 70%);
}

.blob-2 {
    bottom: -10%;
    right: -10%;
    width: 600px;
    height: 600px;
    background: radial-gradient(circle, var(--gradient-2), transparent 70%);
    animation-delay: -5s;
}

@keyframes float {
    0% { transform: translate(0, 0) scale(1); }
    100% { transform: translate(30px, 50px) scale(1.1); }
}

/* Container */
h2 {
    font-weight: 600;
    margin-bottom: 20px;
    font-size: 28px;
}

p {
    font-size: 14px;
    font-weight: 300;
    line-height: 20px;
    letter-spacing: 0.5px;
    margin: 20px 0 30px;
    color: var(--text-secondary);
}

span.divider {
    font-size: 12px;
    color: var(--text-secondary);
    margin: 15px 0;
    display: block;
}

a {
    color: var(--text-secondary);
    font-size: 14px;
    text-decoration: none;
    margin: 15px 0;
    transition: var(--transition);
}

a:hover {
    color: var(--text-primary);
}

.container {
    background: var(--card-bg);
    border-radius: 24px;
    box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.5);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border: 1px solid var(--border-color);
    position: relative;
    overflow: hidden;
    width: 850px;
    max-width: 100%;
    min-height: 550px;
}

.form-container {
    position: absolute;
    top: 0;
    height: 100%;
    transition: var(--transition);
}

.sign-in-container {
    left: 0;
    width: 50%;
    z-index: 2;
}

.sign-up-container {
    left: 0;
    width: 50%;
    opacity: 0;
    z-index: 1;
}

form {
    display: flex;
    align-items: center;
    justify-content: center;
    flex-direction: column;
    padding: 0 50px;
    height: 100%;
    text-align: center;
}

/* Inputs */
.input-group {
    width: 100%;
    margin-bottom: 15px;
}

input {
    background-color: var(--input-bg);
    border: 1px solid var(--border-color);
    padding: 14px 15px;
    margin: 5px 0;
    width: 100%;
    border-radius: 12px;
    color: var(--text-primary);
    font-family: inherit;
    font-size: 14px;
    outline: none;
    transition: var(--transition);
}

input::placeholder {
    color: var(--text-secondary);
}

input:focus {
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.2);
}

/* Buttons */
button {
    border-radius: 12px;
    border: none;
    color: #ffffff;
    font-size: 14px;
    font-weight: 600;
    padding: 14px 40px;
    letter-spacing: 1px;
    text-transform: uppercase;
    transition: transform 0.1s ease-in, background-color 0.3s ease;
    cursor: pointer;
    font-family: inherit;
}

button:active {
    transform: scale(0.95);
}

button:focus {
    outline: none;
}

.primary-btn {
    background: linear-gradient(135deg, var(--gradient-1), var(--gradient-2));
    width: 100%;
    margin-top: 10px;
    box-shadow: 0 4px 15px rgba(99, 102, 241, 0.4);
}

.primary-btn:hover {
    background: linear-gradient(135deg, var(--gradient-2), var(--gradient-1));
    box-shadow: 0 6px 20px rgba(99, 102, 241, 0.6);
}

.ghost-btn {
    background-color: transparent;
    border: 1px solid #ffffff;
}

.ghost-btn:hover {
    background-color: rgba(255, 255, 255, 0.1);
}

/* Social Buttons */
.social-container {
    margin: 15px 0;
    width: 100%;
}

.social-btn {
    background-color: var(--input-bg);
    border: 1px solid var(--border-color);
    display: flex;
    align-items: center;
    justify-content: center;
    width: 100%;
    padding: 12px;
    border-radius: 12px;
    transition: var(--transition);
    color: var(--text-primary);
    text-transform: none;
    font-weight: 500;
}

.social-btn svg {
    margin-right: 10px;
}

.social-btn:hover {
    background-color: rgba(255, 255, 255, 0.05);
    border-color: var(--text-secondary);
}

/* Overlay */
.overlay-container {
    position: absolute;
    top: 0;
    left: 50%;
    width: 50%;
    height: 100%;
    overflow: hidden;
    transition: transform 0.6s ease-in-out;
    z-index: 100;
    border-radius: 24px;
}

.overlay {
    background: linear-gradient(135deg, var(--gradient-1), var(--gradient-2));
    background-repeat: no-repeat;
    background-size: cover;
    background-position: 0 0;
    color: #ffffff;
    position: relative;
    left: -100%;
    height: 100%;
    width: 200%;
    transform: translateX(0);
    transition: transform 0.6s ease-in-out;
}

.overlay-panel {
    position: absolute;
    display: flex;
    align-items: center;
    justify-content: center;
    flex-direction: column;
    padding: 0 40px;
    text-align: center;
    top: 0;
    height: 100%;
    width: 50%;
    transform: translateX(0);
    transition: transform 0.6s ease-in-out;
}

.overlay-panel p {
    color: #f8fafc;
}

.overlay-left {
    transform: translateX(-20%);
}

.overlay-right {
    right: 0;
    transform: translateX(0);
}

/* Animation Classes */
.container.right-panel-active .sign-in-container {
    transform: translateX(100%);
    opacity: 0;
    z-index: 1;
}

.container.right-panel-active .sign-up-container {
    transform: translateX(100%);
    opacity: 1;
    z-index: 5;
    animation: show 0.6s;
}

.container.right-panel-active .overlay-container {
    transform: translateX(-100%);
}

.container.right-panel-active .overlay {
    transform: translateX(50%);
}

.container.right-panel-active .overlay-left {
    transform: translateX(0);
}

.container.right-panel-active .overlay-right {
    transform: translateX(20%);
}

@keyframes show {
    0%, 49.99% {
        opacity: 0;
        z-index: 1;
    }
    50%, 100% {
        opacity: 1;
        z-index: 5;
    }
}

/* Responsive */
@media (max-width: 768px) {
    .container {
        width: 100%;
        height: 100vh;
        border-radius: 0;
        min-height: auto;
        display: flex;
        flex-direction: column;
    }

    .form-container {
        width: 100%;
        height: 70%;
        position: absolute;
        top: 30%;
        transition: transform 0.6s ease-in-out;
    }

    .sign-in-container,
    .sign-up-container {
        left: 0;
    }

    .overlay-container {
        width: 100%;
        height: 30%;
        left: 0;
        top: 0;
        border-radius: 0 0 24px 24px;
        transition: transform 0.6s ease-in-out;
    }

    .overlay {
        width: 100%;
        height: 200%;
        left: 0;
        top: -100%;
        transform: translateY(50%);
    }

    .overlay-panel {
        width: 100%;
        height: 50%;
        padding: 0 20px;
    }

    .overlay-left {
        top: 0;
        transform: translateY(0);
    }

    .overlay-right {
        bottom: 0;
        top: auto;
        transform: translateY(0);
    }

    /* Mobile Animation Classes */
    .container.right-panel-active .sign-in-container {
        transform: translateY(-100%);
    }

    .container.right-panel-active .sign-up-container {
        transform: translateY(0);
        opacity: 1;
        z-index: 5;
    }

    .container.right-panel-active .overlay-container {
        transform: translateY(0); /* Stay at top */
    }

    .container.right-panel-active .overlay {
        transform: translateY(0); /* Move overlay background */
    }
    
    form {
        padding: 0 30px;
    }
    
    h2 {
        font-size: 24px;
        margin-bottom: 10px;
    }
    
    .blob-1, .blob-2 {
        width: 300px;
        height: 300px;
    }
}