/* =========================================
   1. Theme Variables
   ========================================= */
:root {
    /* ------ Dark Mode (Default) ------ */
    /* Background & Overlay */
    --bg-overlay: rgba(0, 0, 0, 0.85);
    /* External image for demo */
    --bg-image: url('https://picsum.photos/1920/1080?grayscale');

    /* Card & Surface */
    --surface-color: #181818;

    /* Typography */
    --text-main: #ffffff;
    --text-sub: #b0b0b0;
    --text-brand: #ffffff;

    /* Brand Colors (Material 3 Purple) */
    --primary-color: #d0bcff;
    --primary-container: #4f378b;
    --on-primary-container: #ffffff;

    /* Input Fields */
    --input-bg: #2b2b2b;
    --input-border: #555555;
    --input-focus: #d0bcff;

    /* Components */
    --toggle-bg: #333333;
    --toggle-icon: #ffee00;
}

/* ------ Light Mode ------ */
[data-theme="light"] {
    --bg-overlay: rgba(255, 255, 255, 0.85);
    --bg-image: url('https://picsum.photos/1920/1080?blur=2');

    --surface-color: #ffffff;

    --text-main: #1c1b1f;
    --text-sub: #5f6368;
    --text-brand: #4f378b;

    --primary-color: #6750a4;
    --primary-container: #6750a4;
    --on-primary-container: #ffffff;

    --input-bg: #f3f4f6;
    --input-border: #79747e;
    --input-focus: #6750a4;

    --toggle-bg: #e7e0ec;
    --toggle-icon: #6750a4;
}

/* =========================================
   2. Global Reset
   ========================================= */
* {
    box-sizing: border-box;
}

body {
    margin: 0;
    font-family: 'Roboto', sans-serif;
    background: linear-gradient(var(--bg-overlay), var(--bg-overlay)), var(--bg-image);
    background-size: cover;
    background-position: center;
    background-attachment: fixed;
    height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    transition: background 0.3s ease;
}

/* =========================================
   3. Layout
   ========================================= */
.login-container {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 60px;
    padding: 20px;
    width: 100%;
    max-width: 1000px;
}

.brand-section {
    text-align: right;
    border-right: 3px solid var(--primary-color);
    padding-right: 40px;
}

.brand-title {
    font-size: 3.5rem;
    margin: 0;
    color: var(--text-brand);
    font-weight: 700;
    letter-spacing: 2px;
    transition: color 0.3s;
}

.brand-subtitle {
    font-size: 1rem;
    color: var(--text-sub);
    letter-spacing: 5px;
    margin-top: 5px;
    text-transform: uppercase;
}

/* =========================================
   4. Login Card
   ========================================= */
.login-card {
    background-color: var(--surface-color);
    width: 380px;
    padding: 40px 30px;
    border-radius: 20px;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.2);
    position: relative;
    transition: background-color 0.3s;
}

.theme-toggle-btn {
    position: absolute;
    top: 20px;
    right: 20px;
    width: 36px;
    height: 36px;
    border-radius: 50%;
    border: none;
    background: var(--toggle-bg);
    color: var(--toggle-icon);
    font-size: 18px;
    cursor: pointer;
    display: flex;
    justify-content: center;
    align-items: center;
    box-shadow: 0 2px 5px rgba(0, 0, 0, 0.2);
    transition: transform 0.2s;
}

.theme-toggle-btn:hover {
    transform: scale(1.1);
}

.form-title {
    margin-top: 10px;
    margin-bottom: 25px;
    font-size: 1.5rem;
    font-weight: 500;
    text-align: center;
    color: var(--text-main);
}

/* =========================================
   5. Module Selector
   ========================================= */
.module-selector {
    display: flex;
    background: var(--input-bg);
    padding: 4px;
    border-radius: 12px;
    margin-bottom: 24px;
    border: 1px solid var(--input-border);
}

.module-option {
    flex: 1;
}

.module-option input {
    display: none;
}

.module-option label {
    display: block;
    text-align: center;
    padding: 10px 0;
    font-size: 14px;
    cursor: pointer;
    border-radius: 8px;
    color: var(--text-sub);
    transition: 0.3s;
    font-weight: 500;
}

.module-option input:checked+label {
    background-color: var(--surface-color);
    color: var(--primary-color);
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
}

/* =========================================
   6. Input Fields
   ========================================= */
.input-group {
    position: relative;
    margin-bottom: 24px;
}

.input-group input {
    width: 100%;
    padding: 14px 16px;
    background: var(--input-bg);
    border: 1px solid var(--input-border);
    border-radius: 8px;
    font-size: 16px;
    color: var(--text-main);
    outline: none;
    transition: 0.2s;
}

.input-group input:focus {
    border: 2px solid var(--primary-color);
    padding: 13px 15px;
}

.input-group label {
    position: absolute;
    left: 14px;
    top: 16px;
    color: var(--text-sub);
    font-size: 16px;
    pointer-events: none;
    transition: 0.2s ease all;
    background: transparent;
    padding: 0 4px;
    z-index: 10;
}

/* Floating Label Logic */
.input-group input:focus~label,
.input-group input:not(:placeholder-shown)~label {
    top: -10px;
    left: 10px;
    font-size: 12px;
    background-color: var(--surface-color);
    color: var(--primary-color);
    font-weight: 600;
    border-radius: 4px;
}

/* =========================================
   7. Buttons
   ========================================= */
.btn-login {
    width: 100%;
    padding: 14px;
    background-color: var(--primary-container);
    color: var(--on-primary-container);
    border: none;
    border-radius: 25px;
    font-size: 16px;
    font-weight: 600;
    cursor: pointer;
    transition: opacity 0.2s;
    letter-spacing: 1px;
}

.btn-login:hover {
    opacity: 0.9;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.2);
}

/* =========================================
   8. Responsive
   ========================================= */
@media (max-width: 768px) {
    .login-container {
        flex-direction: column;
        gap: 30px;
        padding: 10px;
    }

    .brand-section {
        border-right: none;
        border-bottom: 2px solid var(--primary-color);
        padding-right: 0;
        padding-bottom: 20px;
        text-align: center;
    }

    .brand-title {
        font-size: 2.5rem;
    }

    .login-card {
        width: 100%;
        max-width: 360px;
    }
}