:root {
    --primary-color: #4361ee;
    --secondary-color: #3f37c9;
    --accent-color: #4895ef;
    --light-color: #f8f9fa;
    --dark-color: #212529;
    --success-color: #4cc9f0;
}

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

body {
    font-family: 'Roboto', sans-serif;
    background: linear-gradient(135deg, #f5f7fa 0%, #c3cfe2 100%);
    min-height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    padding: 20px;
}

.container {
    background-color: white;
    border-radius: 16px;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.1);
    padding: 40px;
    width: 100%;
    max-width: 500px;
    text-align: center;
    transition: all 0.3s ease;
}

h1 {
    color: var(--dark-color);
    margin-bottom: 30px;
    font-weight: 700;
    font-size: 28px;
}

.mode-options {
    display: flex;
    flex-direction: column;
    gap: 20px;
    margin-bottom: 30px;
}

.mode-option {
    position: relative;
    border: 2px solid #e9ecef;
    border-radius: 12px;
    padding: 20px;
    cursor: pointer;
    transition: all 0.3s ease;
    overflow: hidden;
}

.mode-option:hover {
    transform: translateY(-5px);
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.1);
    border-color: var(--accent-color);
}

.mode-option.selected {
    border-color: var(--primary-color);
    background-color: rgba(67, 97, 238, 0.05);
}

.mode-title {
    font-size: 20px;
    font-weight: 500;
    margin-bottom: 10px;
    color: var(--dark-color);
}

.mode-description {
    color: #6c757d;
    font-size: 14px;
    margin-bottom: 15px;
}

.remember-option {
    display: flex;
    align-items: center;
    justify-content: center;
    margin-top: 10px;
}

.remember-option input {
    margin-right: 8px;
    accent-color: var(--primary-color);
}

.remember-option label {
    font-size: 14px;
    color: #6c757d;
    cursor: pointer;
}

.start-btn {
    background-color: var(--primary-color);
    color: white;
    border: none;
    border-radius: 8px;
    padding: 12px 30px;
    font-size: 16px;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.3s ease;
    width: 100%;
    box-shadow: 0 4px 6px rgba(67, 97, 238, 0.2);
}

.start-btn:hover {
    background-color: var(--secondary-color);
    transform: translateY(-2px);
    box-shadow: 0 6px 12px rgba(67, 97, 238, 0.3);
}

.start-btn:active {
    transform: translateY(0);
}

.highlight {
    position: absolute;
    top: 0;
    left: 0;
    width: 5px;
    height: 100%;
    background-color: var(--primary-color);
    transition: all 0.3s ease;
    opacity: 0;
}

.mode-option.selected .highlight {
    opacity: 1;
}