/* =================================
    CSS VARIABLES (Light & Dark Mode)
    ================================= */
:root {
    /* Light Mode */
    --body-background: #f0f2f5;
    --header-background: #f8f8f8;
    --container-background: #ffffff;
    --container-shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
    --heading-color: #333;
    --label-color: #555;
    --input-background: #fff;
    --input-border-color: #ccc;
    --input-focus-border-color: #007bff;
    --select-arrow-color: #000000;
    --checkbox-label-color: #666;
    --checkbox-link-color: #007bff;
    --submit-button-bg: #28a745;
    --submit-button-hover-bg: #218838;
    --error-bg: #ffebe8;
    --error-border: #ff4d4f;
    --error-color: #ff4d4f;
    --success-bg: #e6ffed;
    --success-border: #52c41a;
    --success-color: #52c41a;
    --login-link-text: #555;
    --login-link-link: #007bff;
}

/* Dark Mode - Activated by System Preference or Manual Toggle */
@media (prefers-color-scheme: dark) {
    :root {
        --body-background: #121212;
        --header-background: #1e1e1e;
        --container-background: #1e1e1e;
        --container-shadow: 0 4px 15px rgba(0, 0, 0, 0.3);
        --heading-color: #e0e0e0;
        --label-color: #b0b0b0;
        --input-background: #2a2a2a;
        --input-border-color: #444;
        --input-focus-border-color: #6a9ce0;
        --select-arrow-color: #ffffff; /* White arrow for dark mode */
        --checkbox-label-color: #a0a0a0;
        --checkbox-link-color: #6a9ce0;
        --submit-button-bg: #218838;
        --submit-button-hover-bg: #1e7a32;
        --error-bg: #442a2a;
        --error-border: #993f3f;
        --error-color: #e38a8a;
        --success-bg: #2a442a;
        --success-border: #5a995a;
        --success-color: #8ce08c;
        --login-link-text: #b0b0b0;
        --login-link-link: #6a9ce0;
    }
}

body[data-theme='dark'] {
    /* Manual Dark Mode Override */
    --body-background: #121212;
    --header-background: #1e1e1e;
    --container-background: #1e1e1e;
    --container-shadow: 0 4px 15px rgba(0, 0, 0, 0.3);
    --heading-color: #e0e0e0;
    --label-color: #b0b0b0;
    --input-background: #2a2a2a;
    --input-border-color: #444;
    --input-focus-border-color: #6a9ce0;
    --select-arrow-color: #ffffff;
    --checkbox-label-color: #a0a0a0;
    --checkbox-link-color: #6a9ce0;
    --submit-button-bg: #218838;
    --submit-button-hover-bg: #1e7a32;
    --error-bg: #442a2a;
    --error-border: #993f3f;
    --error-color: #e38a8a;
    --success-bg: #2a442a;
    --success-border: #5a995a;
    --success-color: #8ce08c;
    --login-link-text: #b0b0b0;
    --login-link-link: #6a9ce0;
}

/* --- Core Layout & Global Styles --- */
body {
    font-family: 'Arial', sans-serif;
    background-color: var(--body-background);
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    padding-top: 100px;
    transition: background-color 0.3s ease;
}

header {
    background-color: var(--header-background);
    transition: background-color 0.3s ease;
}

.main-content {
    display: flex;
    justify-content: center;
    align-items: center;
    padding: 20px;
    min-height: calc(100vh - 180px);
}

.register-container {
    background-color: var(--container-background);
    padding: 40px;
    border-radius: 8px;
    box-shadow: var(--container-shadow);
    width: 100%;
    max-width: 450px;
    text-align: center;
    box-sizing: border-box;
    transition: background-color 0.3s ease, box-shadow 0.3s ease;
}

.register-container h2 {
    margin-bottom: 30px;
    color: var(--heading-color);
    font-size: 2em;
    transition: color 0.3s ease;
}

/* --- Form Elements --- */
.form-group {
    margin-bottom: 20px;
    text-align: left;
}

.form-group label {
    display: block;
    margin-bottom: 8px;
    color: var(--label-color);
    font-weight: bold;
    transition: color 0.3s ease;
}

/* Styles for text, email, and password input fields */
.form-group input[type="text"],
.form-group input[type="email"],
.form-group input[type="password"] {
    width: calc(100% - 22px);
    padding: 12px;
    border: 1px solid var(--input-border-color);
    border-radius: 5px;
    font-size: 1em;
    transition: border-color 0.3s ease, background-color 0.3s ease, color 0.3s ease;
    background-color: var(--input-background);
    color: var(--label-color);
}

.form-group select {
    width: calc(100% - 22px);
    padding: 12px;
    border: 1px solid var(--input-border-color);
    border-radius: 5px;
    font-size: 1em;
    transition: border-color 0.3s ease, background-color 0.3s ease, color 0.3s ease;
    -webkit-appearance: none;
    -moz-appearance: none;
    appearance: none;
    background-color: var(--input-background);
    color: var(--label-color);
    background-repeat: no-repeat;
    background-position: right 10px top 50%;
    background-size: 12px auto;
}

.form-group input[type="text"]:focus,
.form-group input[type="email"]:focus,
.form-group input[type="password"]:focus {
    border-color: var(--input-focus-border-color);
    outline: none;
}

.form-group select:focus {
    border-color: var(--input-focus-border-color);
    outline: none;
}

/* Update the background-image for the select dropdown */
.form-group select {
    /* This SVG is for a black arrow */
    background-image: url('data:image/svg+xml;charset=US-ASCII,%3Csvg%20xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%22%20width%3D%22292.4%22%20height%3D%22292.4%22%3E%3Cpath%20fill%3D%22%23000000%22%20d%3D%22M287%2C114.7L153.2%2C248.5c-4.7%2C4.7-12.3%2C4.7-17%2C0L5.4%2C114.7c-4.7-4.7-4.7-12.3%2C0-17l14.1-14.1c4.7-4.7%2C12.3-4.7%2C17%2C0l110.5%2C110.5l110.5-110.5c4.7-4.7%2C12.3-4.7%2C17%2C0l14.1%2C14.1C291.7%2C102.4%2C291.7%2C110%2C287%2C114.7z%22%2F%3E%3C%2Fsvg%3E');
}
body[data-theme='dark'] .form-group select {
    /* This SVG is for a white arrow */
    background-image: url('data:image/svg+xml;charset=US-ASCII,%3Csvg%20xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%22%20width%3D%22292.4%22%20height%3D%22292.4%22%3E%3Cpath%20fill%3D%22%23ffffff%22%20d%3D%22M287%2C114.7L153.2%2C248.5c-4.7%2C4.7-12.3%2C4.7-17%2C0L5.4%2C114.7c-4.7-4.7-4.7-12.3%2C0-17l14.1-14.1c4.7-4.7%2C12.3-4.7%2C17%2C0l110.5%2C110.5l110.5-110.5c4.7-4.7%2C12.3-4.7%2C17%2C0l14.1%2C14.1C291.7%2C102.4%2C291.7%2C110%2C287%2C114.7z%22%2F%3E%3C%2Fsvg%3E');
}

.checkbox-group {
    display: flex;
    align-items: center;
    margin-top: 25px;
    margin-bottom: 25px;
}

.checkbox-group input[type="checkbox"] {
    margin-right: 10px;
}

.checkbox-group label {
    margin-bottom: 0;
    font-weight: normal;
    font-size: 0.95em;
    color: var(--checkbox-label-color);
    transition: color 0.3s ease;
}

.checkbox-group a {
    color: var(--checkbox-link-color);
    text-decoration: none;
    transition: color 0.3s ease;
}

.checkbox-group a:hover {
    text-decoration: underline;
}

button[type="submit"] {
    background-color: var(--submit-button-bg);
    color: white;
    padding: 15px 25px;
    border: none;
    border-radius: 5px;
    cursor: pointer;
    font-size: 1.1em;
    font-weight: bold;
    transition: background-color 0.3s ease;
    width: 100%;
}

button[type="submit"]:hover {
    background-color: var(--submit-button-hover-bg);
}

.error-messages {
    background-color: var(--error-bg);
    border: 1px solid var(--error-border);
    color: var(--error-color);
    padding: 10px 15px;
    border-radius: 5px;
    margin-bottom: 20px;
    text-align: left;
    transition: background-color 0.3s ease, border-color 0.3s ease, color 0.3s ease;
}

.error-messages ul {
    margin: 0;
    padding-left: 20px;
    list-style-type: disc;
}

.error-messages li {
    margin-bottom: 5px;
}

.success-message {
    background-color: var(--success-bg);
    border: 1px solid var(--success-border);
    color: var(--success-color);
    padding: 10px 15px;
    border-radius: 5px;
    margin-bottom: 20px;
    text-align: center;
    transition: background-color 0.3s ease, border-color 0.3s ease, color 0.3s ease;
}

.login-link {
    margin-top: 25px;
    color: var(--login-link-text);
    font-size: 0.95em;
    transition: color 0.3s ease;
}

.login-link a {
    color: var(--login-link-link);
    text-decoration: none;
    font-weight: bold;
    transition: color 0.3s ease;
}

.login-link a:hover {
    text-decoration: underline;
}