:root {
    /* Light Theme (Default) */
    --md-primary: #4285F4; /* Google Blue */
    --md-primary-hover: #3a7ae0;
    --md-surface: #ffffff;
    --md-background: #f1f3f4;
    --md-on-surface: #202124;
    --md-on-surface-variant: #5f6368;
    --md-outline: #dadce0;
    --md-error: #d93025;
    --md-error-bg: #fce8e6;
    --md-ripple-color: rgba(255, 255, 255, 0.6);
    --md-icon-button-hover: rgba(60, 64, 67, 0.08);

    /* Animation & Layout */
    --md-radius: 12px;
    --md-transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    --md-elevation-1: 0 1px 2px 0 rgba(60,64,67,0.3), 0 1px 3px 1px rgba(60,64,67,0.15);
    --md-elevation-2: 0 2px 6px 2px rgba(60,64,67,0.15), 0 1px 2px 0 rgba(60,64,67,0.3);
}

body[data-theme='dark'] {
    /* Dark Theme */
    --md-primary: #8ab4f8; /* A lighter blue for better contrast on dark */
    --md-primary-hover: #9ac1ff;
    --md-surface: #202124;
    --md-background: #121212;
    --md-on-surface: #e8eaed;
    --md-on-surface-variant: #9aa0a6;
    --md-outline: #5f6368;
    --md-error: #f28b82;
    --md-error-bg: rgba(242, 139, 130, 0.15);
    --md-ripple-color: rgba(0, 0, 0, 0.4);
    --md-icon-button-hover: rgba(232, 234, 237, 0.08);

    /* Dark shadows are more subtle */
    --md-elevation-1: 0 1px 2px 0 rgba(0,0,0,0.3), 0 1px 3px 1px rgba(0,0,0,0.15);
    --md-elevation-2: 0 2px 6px 2px rgba(0,0,0,0.15), 0 1px 2px 0 rgba(0,0,0,0.3);
}

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

body {
    min-height: 100vh;
    font-family: 'Roboto', 'Segoe UI', Helvetica, Arial, sans-serif;
    color: var(--md-on-surface);
    background-color: var(--md-background);
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
    transition: background-color 0.3s, color 0.3s;
}

#matrix-background {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: -1;
}

.theme-toggle {
    position: fixed;
    top: 16px;
    right: 16px;
    width: 48px;
    height: 48px;
    border-radius: 50%;
    background: transparent;
    border: none;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 1000;
    transition: background-color 0.2s;
}
.theme-toggle:hover {
    background-color: var(--md-icon-button-hover);
}
.theme-toggle svg {
    width: 24px;
    height: 24px;
    fill: var(--md-on-surface-variant);
}
#icon-sun { display: none; }
body[data-theme='dark'] #icon-moon { display: none; }
body[data-theme='dark'] #icon-sun { display: block; }

.login-container {
    background: var(--md-surface);
    border-radius: var(--md-radius);
    box-shadow: var(--md-elevation-2);
    padding: 40px 32px;
    width: 400px;
    max-width: 90vw;
    display: flex;
    flex-direction: column;
    align-items: center;
    z-index: 2;
    opacity: 0;
    transform: translateY(20px);
    animation: fadeIn 0.5s 0.2s cubic-bezier(0.0, 0.0, 0.2, 1) forwards;
    transition: background-color 0.3s;
}

@media (max-width: 480px) {
    .login-container {
        padding: 32px 24px;
    }
}

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

.login-container h2 {
    font-size: 28px;
    font-weight: 700;
    margin-bottom: 24px;
    color: var(--md-on-surface);
}

.input-group {
    position: relative;
    width: 100%;
    margin-bottom: 24px;
}

.input-group label {
    position: absolute;
    top: 16px;
    left: 16px;
    color: var(--md-on-surface-variant);
    pointer-events: none;
    transition: all 0.2s ease;
    background-color: var(--md-surface);
    padding: 0 4px;
}

.input-group input {
    width: 100%;
    padding: 16px;
    border: 1px solid var(--md-outline);
    border-radius: 8px;
    background: transparent;
    font-size: 16px;
    color: var(--md-on-surface);
    transition: var(--md-transition);
}

.input-group input:focus {
    outline: none;
    border-color: var(--md-primary);
    box-shadow: 0 0 0 1px var(--md-primary);
}

.input-group input:focus + label,
.input-group input:not(:placeholder-shown) + label {
    top: -10px;
    left: 12px;
    font-size: 12px;
    color: var(--md-primary);
}

.login-button {
    width: 100%;
    padding: 14px 0;
    background: var(--md-primary);
    color: var(--md-surface);
    border: none;
    border-radius: 8px;
    font-size: 16px;
    font-weight: 500;
    cursor: pointer;
    transition: var(--md-transition);
    box-shadow: var(--md-elevation-1);
    position: relative;
    overflow: hidden; 
}

.login-button:hover {
    background: var(--md-primary-hover);
    box-shadow: var(--md-elevation-2);
}

.ripple {
    position: absolute;
    border-radius: 50%;
    background: var(--md-ripple-color);
    transform: scale(0);
    animation: ripple 0.6s linear;
    pointer-events: none;
}

@keyframes ripple {
    to {
        transform: scale(4);
        opacity: 0;
    }
}

.login-button.loading span {
    opacity: 0;
}

.login-button.loading::after {
    content: '';
    position: absolute;
    width: 20px;
    height: 20px;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    margin: auto;
    border: 3px solid transparent;
    border-top-color: var(--md-surface);
    border-radius: 50%;
    animation: spin 1s ease-in-out infinite;
}

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

.login-links {
    margin-top: 16px;
    width: 100%;
    display: flex;
    justify-content: space-between;
    font-size: 14px;
}

.login-links a {
    color: var(--md-primary);
    text-decoration: none;
    font-weight: 500;
    padding: 4px;
    border-radius: 4px;
    transition: background-color 0.2s;
}

.login-links a:hover {
    background-color: rgba(var(--md-primary), 0.1);
}