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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    background-color: #f8f9fa;
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 20px;
}

.signin-container {
    background: white;
    border-radius: 12px;
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.08);
    padding: 40px;
    width: 100%;
    max-width: 440px;
    position: relative;
}

.logo {
    display: flex;
    align-items: center;
    justify-content: flex-start;
    margin-bottom: 30px;
}

.logo-icon {
    width: 40px;
    height: 40px;
    border-radius: 8px;
    background: linear-gradient(135deg, #ffd700, #ffed4e);
    margin-right: 15px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 900;
    font-size: 20px;
    color: #2c3e50;
    text-shadow: 0 1px 2px rgba(0,0,0,0.2);
}

.back-button {
    position: absolute;
    top: 40px;
    right: 40px;
    background: none;
    border: none;
    color: #6b7280;
    font-size: 14px;
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 5px;
    transition: color 0.3s ease;
}

.back-button:hover {
    color: #374151;
}

.back-button::before {
    content: '←';
    font-size: 16px;
}

.title {
    font-size: 24px;
    font-weight: 600;
    color: #111827;
    margin-bottom: 10px;
}

.subtitle {
    font-size: 14px;
    color: #6b7280;
    margin-bottom: 40px;
}

.form-group {
    margin-bottom: 24px;
}

.form-group label {
    display: block;
    font-size: 14px;
    font-weight: 500;
    color: #374151;
    margin-bottom: 8px;
}

.form-group input {
    width: 100%;
    padding: 12px 16px;
    border: 1px solid #d1d5db;
    border-radius: 8px;
    font-size: 16px;
    transition: all 0.3s ease;
    background-color: #fff;
}

.form-group input:focus {
    outline: none;
    border-color: #3b82f6;
    box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.1);
}

.form-group input::placeholder {
    color: #9ca3af;
}

.password-container {
    position: relative;
}

.password-toggle {
    position: absolute;
    right: 12px;
    top: 50%;
    transform: translateY(-50%);
    background: none;
    border: none;
    color: #6b7280;
    cursor: pointer;
    font-size: 18px;
    padding: 4px;
    transition: color 0.3s ease;
}

.password-toggle:hover {
    color: #374151;
}

.password-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 8px;
}

.forgot-password {
    color: #3b82f6;
    text-decoration: none;
    font-size: 14px;
    font-weight: 500;
}

.forgot-password:hover {
    text-decoration: underline;
}

.checkbox-group {
    display: flex;
    align-items: center;
    gap: 12px;
    margin-bottom: 24px;
}

.checkbox-group input[type="checkbox"] {
    width: 18px;
    height: 18px;
    margin: 0;
    cursor: pointer;
    accent-color: #3b82f6;
}

.checkbox-group label {
    font-size: 14px;
    color: #374151;
    cursor: pointer;
    margin: 0;
}

.signup-link {
    text-align: center;
    margin-bottom: 24px;
    font-size: 14px;
    color: #6b7280;
}

.signup-link a {
    color: #3b82f6;
    text-decoration: none;
    font-weight: 500;
}

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

.login-button {
    width: 100%;
    background: #3b82f6;
    color: white;
    border: none;
    padding: 14px 24px;
    border-radius: 8px;
    font-size: 16px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
}

.login-button:hover {
    background: #2563eb;
    transform: translateY(-1px);
    box-shadow: 0 4px 12px rgba(59, 130, 246, 0.3);
}

.login-button:active {
    transform: translateY(0);
}

.login-button:disabled {
    background: #9ca3af;
    cursor: not-allowed;
    transform: none;
    box-shadow: none;
}

@media (max-width: 640px) {
    .signin-container {
        padding: 30px 24px;
        margin: 10px;
    }

    .back-button {
        top: 30px;
        right: 24px;
    }

    .title {
        font-size: 20px;
        margin-bottom: 8px;
    }

    .subtitle {
        margin-bottom: 30px;
    }
}

@media (max-width: 480px) {
    .signin-container {
        padding: 24px 20px;
    }

    .logo-icon {
        width: 35px;
        height: 35px;
        margin-right: 12px;
    }

    .logo-icon::before {
        width: 18px;
        height: 18px;
    }
}

.error-message {
    color: #ef4444;
    font-size: 14px;
    margin-top: 6px;
    display: none;
}

.success-message {
    color: #10b981;
    font-size: 14px;
    margin-top: 6px;
    display: none;
}