:root {
    /* Apple + Stripe Color Palette (Light) */
    --auth-bg-gradient-1: #fdfbfb;
    --auth-bg-gradient-2: #ebedee;
    --auth-bg-gradient-3: #e0c3fc;
    --auth-bg-gradient-4: #8ec5fc;
    
    --auth-glass-bg: rgba(255, 255, 255, 0.7);
    --auth-glass-border: rgba(255, 255, 255, 0.5);
    --auth-glass-shadow: rgba(0, 0, 0, 0.05);
    
    --auth-text-main: #1d1d1f;
    --auth-text-muted: #86868b;
    
    --auth-input-bg: rgba(255, 255, 255, 0.8);
    --auth-input-border: #d2d2d7;
    --auth-input-focus: #0066cc;
    --auth-input-focus-shadow: rgba(0, 102, 204, 0.2);
    
    --auth-btn-bg: #0066cc;
    --auth-btn-text: #ffffff;
    --auth-btn-hover: #0077ed;
    
    --auth-shape-1: rgba(142, 197, 252, 0.6);
    --auth-shape-2: rgba(224, 195, 252, 0.6);
    --auth-shape-3: rgba(255, 209, 255, 0.6);
}

[data-bs-theme="dark"] {
    /* Apple + Stripe Color Palette (Dark) */
    --auth-bg-gradient-1: #000000;
    --auth-bg-gradient-2: #1c1c1e;
    --auth-bg-gradient-3: #2c1b4d;
    --auth-bg-gradient-4: #1a2a42;
    
    --auth-glass-bg: rgba(28, 28, 30, 0.65);
    --auth-glass-border: rgba(255, 255, 255, 0.1);
    --auth-glass-shadow: rgba(0, 0, 0, 0.3);
    
    --auth-text-main: #f5f5f7;
    --auth-text-muted: #86868b;
    
    --auth-input-bg: rgba(44, 44, 46, 0.8);
    --auth-input-border: #3a3a3c;
    --auth-input-focus: #2997ff;
    --auth-input-focus-shadow: rgba(41, 151, 255, 0.25);
    
    --auth-btn-bg: #2997ff;
    --auth-btn-text: #ffffff;
    --auth-btn-hover: #0071e3;
    
    --auth-shape-1: rgba(26, 42, 66, 0.8);
    --auth-shape-2: rgba(44, 27, 77, 0.8);
    --auth-shape-3: rgba(66, 42, 66, 0.8);
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    margin: 0;
    padding: 0;
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    background: linear-gradient(-45deg, var(--auth-bg-gradient-1), var(--auth-bg-gradient-2), var(--auth-bg-gradient-3), var(--auth-bg-gradient-4));
    background-size: 400% 400%;
    animation: gradientBG 15s ease infinite;
    color: var(--auth-text-main);
    overflow: hidden;
    position: relative;
    transition: background-color 0.4s ease, color 0.4s ease;
}

/* Animated Gradient Background */
@keyframes gradientBG {
    0% { background-position: 0% 50%; }
    50% { background-position: 100% 50%; }
    100% { background-position: 0% 50%; }
}

/* Canvas Particle Layer */
#particleCanvas {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: 0;
    pointer-events: none;
}

/* Floating Shapes */
.bg-shape {
    position: absolute;
    filter: blur(60px);
    border-radius: 50%;
    z-index: 1;
    animation: float 20s infinite alternate;
}

.shape-1 {
    width: 400px;
    height: 400px;
    background: var(--auth-shape-1);
    top: -100px;
    left: -100px;
    animation-delay: 0s;
}

.shape-2 {
    width: 500px;
    height: 500px;
    background: var(--auth-shape-2);
    bottom: -150px;
    right: -100px;
    animation-delay: -5s;
}

.shape-3 {
    width: 300px;
    height: 300px;
    background: var(--auth-shape-3);
    top: 40%;
    left: 50%;
    animation-delay: -10s;
}

@keyframes float {
    0% { transform: translate(0, 0) rotate(0deg) scale(1); }
    33% { transform: translate(30px, -50px) rotate(10deg) scale(1.1); }
    66% { transform: translate(-20px, 20px) rotate(-5deg) scale(0.9); }
    100% { transform: translate(0, 0) rotate(0deg) scale(1); }
}

/* Wrapper */
.auth-wrapper {
    position: relative;
    z-index: 10;
    width: 100%;
    max-width: 1000px;
    padding-inline: 20px;
}

/* Glass Card */
.glass-card {
    background: var(--auth-glass-bg);
    backdrop-filter: blur(24px);
    -webkit-backdrop-filter: blur(24px);
    border: 1px solid var(--auth-glass-border);
    border-radius: 24px;
    box-shadow: 0 8px 32px var(--auth-glass-shadow), 0 1px 3px rgba(0,0,0,0.02);
    overflow: hidden;
    display: flex;
    flex-direction: row;
    min-height: 550px;
    transition: all 0.4s cubic-bezier(0.16, 1, 0.3, 1);
}

.glass-card:hover {
    box-shadow: 0 12px 48px rgba(0,0,0,0.08), 0 1px 3px rgba(0,0,0,0.02);
    transform: translateY(-2px);
}

/* Two-column layout */
.auth-illustration {
    flex: 1;
    background: rgba(255, 255, 255, 0.03);
    border-inline-end: 1px solid var(--auth-glass-border);
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    padding: 3rem;
    text-align: center;
}

.auth-form-container {
    flex: 1;
    padding: 3rem;
    display: flex;
    flex-direction: column;
    justify-content: center;
    position: relative;
}

/* Typography */
.auth-title {
    font-weight: 700;
    font-size: 1.75rem;
    margin-bottom: 0.5rem;
    letter-spacing: -0.02em;
    color: var(--auth-text-main);
}

.auth-subtitle {
    color: var(--auth-text-muted);
    font-size: 0.95rem;
    margin-bottom: 2rem;
}

/* Microsoft Fluent / Stripe Inputs */
.form-floating > .form-control,
.form-floating > .form-control:focus {
    background-color: var(--auth-input-bg);
    border: 1.5px solid var(--auth-input-border);
    color: var(--auth-text-main);
    border-radius: 12px;
    transition: all 0.2s cubic-bezier(0.16, 1, 0.3, 1);
}

.form-floating > .form-control:focus {
    border-color: var(--auth-input-focus);
    box-shadow: 0 0 0 4px var(--auth-input-focus-shadow);
}

.form-floating > label {
    color: var(--auth-text-muted);
}

.form-control:focus ~ label {
    color: var(--auth-input-focus);
}

/* Micro-interaction Button */
.btn-auth {
    background-color: var(--auth-btn-bg);
    color: var(--auth-btn-text);
    border: none;
    border-radius: 12px;
    padding: 14px 20px;
    font-weight: 600;
    font-size: 1rem;
    letter-spacing: 0.01em;
    transition: all 0.2s cubic-bezier(0.16, 1, 0.3, 1);
    position: relative;
    overflow: hidden;
}

.btn-auth:hover {
    background-color: var(--auth-btn-hover);
    transform: scale(1.02);
    box-shadow: 0 4px 12px var(--auth-input-focus-shadow);
}

.btn-auth:active {
    transform: scale(0.98);
}

/* Loading Overlay */
.auth-loading-overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: var(--auth-glass-bg);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border-radius: 24px;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    z-index: 100;
    opacity: 0;
    pointer-events: none;
    transition: opacity 0.3s ease;
}

.auth-loading-overlay.active {
    opacity: 1;
    pointer-events: all;
}

.spinner {
    width: 40px;
    height: 40px;
    border: 3px solid var(--auth-input-border);
    border-top-color: var(--auth-btn-bg);
    border-radius: 50%;
    animation: spin 1s linear infinite;
    margin-bottom: 1rem;
}

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

/* Theme Switcher & Lang Toggle */
.auth-controls {
    position: absolute;
    top: 1.5rem;
    inset-inline-end: 1.5rem;
    display: flex;
    gap: 0.5rem;
    z-index: 20;
}

.control-btn {
    background: var(--auth-glass-bg);
    border: 1px solid var(--auth-glass-border);
    color: var(--auth-text-muted);
    width: 36px;
    height: 36px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: all 0.2s ease;
}

.control-btn:hover {
    color: var(--auth-text-main);
    background: var(--auth-input-bg);
    transform: rotate(15deg) scale(1.1);
}

/* Responsive */
@media (max-width: 768px) {
    .glass-card {
        flex-direction: column;
    }
    .auth-illustration {
        border-inline-end: none;
        border-bottom: 1px solid var(--auth-glass-border);
        padding: 2rem;
        flex: none;
    }
    .auth-form-container {
        padding: 2rem;
    }
}