/* Reset and Base */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'PingFang SC', 'Helvetica Neue', Arial, sans-serif;
}

html, body {
    width: 100%;
    height: 100%;
    background-color: #f7f9fb;
    color: #333;
    line-height: 1.75;
}

.container {
    display: flex;
    justify-content: center;
    align-items: center;
    padding: 40px 20px;
    min-height: 100vh;
}

/* Card */
.card {
    background-color: #fff;
    border-radius: 12px;
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.05);
    width: 100%;
    max-width: 460px;
    overflow: hidden;
    display: flex;
    flex-direction: column;
}

/* Header */
.card-header {
    background-color: #4a90e2;
    color: #fff;
    padding: 30px 20px;
    text-align: center;
}

.card-header h1 {
    font-size: 22px;
    font-weight: 600;
    margin-bottom: 8px;
}

.card-header p {
    font-size: 14px;
    opacity: 0.9;
}

/* Body */
.card-body {
    padding: 30px 25px;
    flex: 1;
}

/* Form */
.form-group {
    margin-bottom: 20px;
}

.form-group label {
    display: block;
    margin-bottom: 8px;
    font-size: 15px;
    font-weight: 500;
    color: #666;
}

.form-group input {
    width: 100%;
    padding: 12px 14px;
    font-size: 15px;
    border: 1px solid #e0e0e0;
    border-radius: 6px;
    transition: all 0.3s ease;
}

.form-group input:focus {
    border-color: #4a90e2;
    background-color: #f0f7ff;
    outline: none;
}

/* Button */
.form-group button {
    width: 100%;
    padding: 12px 0;
    background-color: #4a90e2;
    color: #fff;
    border: none;
    border-radius: 6px;
    font-size: 16px;
    font-weight: 600;
    cursor: pointer;
    transition: background-color 0.3s;
}

.form-group button:hover {
    background-color: #357abd;
}

/* Result Message */
.result-message {
    margin-top: 20px;
    padding: 14px;
    border-radius: 6px;
    font-size: 14px;
    text-align: center;
    display: none;
}

.result-message.success {
    background-color: #e6ffed;
    border: 1px solid #b7eb8f;
    color: #389e0d;
}

.result-message.error {
    background-color: #fff1f0;
    border: 1px solid #ffa39e;
    color: #cf1322;
}

/* Loading Spinner */
.loading-spinner {
    display: none;
    text-align: center;
    margin-top: 20px;
}

.spinner {
    width: 32px;
    height: 32px;
    border: 3px solid rgba(74, 144, 226, 0.3);
    border-top-color: #4a90e2;
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

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

/* Responsive */
@media (max-width: 576px) {
    .card {
        border-radius: 0;
        box-shadow: none;
        height: 100vh;
    }

    .card-header {
        padding: 24px 16px;
    }

    .card-body {
        padding: 24px 16px;
        justify-content: center;
    }

    .form-group label,
    .form-group input,
    .form-group button {
        font-size: 14px;
    }
}