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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    background: linear-gradient(135deg, #e8f4f8 0%, #b8d4e0 100%);
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 20px;
}

.container {
    max-width: 450px;
    width: 100%;
}

.login-card {
    background: white;
    border-radius: 20px;
    padding: 40px;
    box-shadow: 0 20px 60px rgba(0, 0, 0, 0.3);
    animation: slideUp 0.4s ease-out;
}

@keyframes slideUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.logo {
    text-align: center;
    margin-bottom: 30px;
}

.logo h1 {
    font-size: 2.5em;
    color: #2c3e50;
    margin-bottom: 5px;
}

.subtitle {
    color: #666;
    font-size: 0.95em;
}

.login-form {
    margin-bottom: 25px;
}

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

.form-group label {
    display: block;
    margin-bottom: 8px;
    color: #333;
    font-weight: 500;
    font-size: 0.95em;
}

.form-group input {
    width: 100%;
    padding: 14px 16px;
    border: 2px solid #e1e8ed;
    border-radius: 10px;
    font-size: 1em;
    transition: all 0.3s ease;
}

.form-group input:focus {
    outline: none;
    border-color: #5dade2;
    box-shadow: 0 0 0 3px rgba(93, 173, 226, 0.1);
}

.submit-button {
    width: 100%;
    padding: 16px;
    background: linear-gradient(135deg, #5dade2 0%, #3498db 100%);
    color: white;
    border: none;
    border-radius: 10px;
    font-size: 1.1em;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    position: relative;
}

.submit-button:hover:not(:disabled) {
    transform: translateY(-2px);
    box-shadow: 0 10px 25px rgba(93, 173, 226, 0.4);
}

.submit-button:active:not(:disabled) {
    transform: translateY(0);
}

.submit-button:disabled {
    opacity: 0.7;
    cursor: not-allowed;
}

.spinner {
    display: inline-block;
    width: 20px;
    height: 20px;
    border: 3px solid rgba(255, 255, 255, 0.3);
    border-radius: 50%;
    border-top-color: white;
    animation: spin 0.8s linear infinite;
}

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

.hidden {
    display: none !important;
}

.error-message {
    background: #fee;
    color: #c33;
    padding: 15px;
    border-radius: 10px;
    margin-bottom: 20px;
    border-left: 4px solid #c33;
    font-size: 0.95em;
}

.success-message {
    background: #efe;
    color: #3c3;
    padding: 15px;
    border-radius: 10px;
    margin-bottom: 20px;
    border-left: 4px solid #3c3;
    font-size: 0.95em;
    white-space: pre-line;
}

.info-box {
    background: #f7f9fc;
    padding: 20px;
    border-radius: 10px;
    border-left: 4px solid #5dade2;
}

.info-box strong {
    color: #2c3e50;
    display: block;
    margin-bottom: 8px;
}

.info-text {
    color: #666;
    font-size: 0.9em;
    line-height: 1.5;
}

.platform-info {
    margin-top: 20px;
    padding: 15px;
    background: #f0f4ff;
    border-radius: 10px;
    text-align: center;
}

.platform-text {
    color: #5dade2;
    font-weight: 500;
}

.footer {
    text-align: center;
    margin-top: 20px;
    color: rgba(255, 255, 255, 0.9);
    font-size: 0.85em;
}

/* Course Selection Styles */
.course-selection {
    animation: slideUp 0.4s ease-out;
}

.course-selection-title {
    font-size: 1.5em;
    color: #2c3e50;
    text-align: center;
    margin-bottom: 10px;
}

.course-selection-subtitle {
    text-align: center;
    color: #666;
    margin-bottom: 25px;
    font-size: 0.95em;
}

.course-list {
    display: flex;
    flex-direction: column;
    gap: 12px;
    margin-bottom: 20px;
}

.course-button {
    width: 100%;
    padding: 18px 20px;
    background: linear-gradient(135deg, #f7f9fc 0%, #e8ecf3 100%);
    border: 2px solid #e1e8ed;
    border-radius: 12px;
    cursor: pointer;
    transition: all 0.3s ease;
    text-align: left;
}

.course-button:hover:not(:disabled) {
    transform: translateY(-2px);
    box-shadow: 0 8px 20px rgba(93, 173, 226, 0.2);
    border-color: #5dade2;
    background: linear-gradient(135deg, #ffffff 0%, #e8f4f8 100%);
}

.course-button:active:not(:disabled) {
    transform: translateY(0);
}

.course-button:disabled {
    opacity: 0.6;
    cursor: not-allowed;
}

.course-title {
    font-size: 1.05em;
    font-weight: 600;
    color: #333;
    margin-bottom: 4px;
}

.course-subtitle {
    font-size: 0.85em;
    color: #666;
}

.back-button {
    width: 100%;
    padding: 14px;
    background: #f7f9fc;
    color: #5dade2;
    border: 2px solid #e1e8ed;
    border-radius: 10px;
    font-size: 1em;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
}

.back-button:hover:not(:disabled) {
    background: #e8ecf3;
    border-color: #5dade2;
}

.back-button:disabled {
    opacity: 0.6;
    cursor: not-allowed;
}

@media (max-width: 480px) {
    .login-card {
        padding: 30px 25px;
    }

    .logo h1 {
        font-size: 2em;
    }

    .course-selection-title {
        font-size: 1.3em;
    }
}