:root {
    --bg-color: #0d0f12;
    --card-bg: rgba(26, 30, 35, 0.6);
    --card-border: rgba(255, 255, 255, 0.08);
    --text-primary: #ffffff;
    --text-secondary: #94a3b8;
    --accent-color: #3b82f6;
    --accent-hover: #2563eb;
    --warning-color: #f59e0b;
    --success-color: #10b981;
    --shadow: 0 4px 30px rgba(0, 0, 0, 0.3);
    --backdrop-blur: blur(12px);
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

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

body {
    background-color: var(--bg-color);
    color: var(--text-primary);
    font-family: 'Inter', 'Noto Sans JP', sans-serif;
    line-height: 1.6;
    min-height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    background-image: 
        radial-gradient(circle at 15% 50%, rgba(59, 130, 246, 0.15), transparent 25%),
        radial-gradient(circle at 85% 30%, rgba(16, 185, 129, 0.1), transparent 25%);
    background-attachment: fixed;
}

.app-container {
    width: 100%;
    max-width: 600px;
    padding: 20px;
    position: relative;
    z-index: 1;
}

/* Progress Bar */
.progress-bar-container {
    height: 4px;
    background: rgba(255, 255, 255, 0.1);
    border-radius: 4px;
    margin-bottom: 40px;
    overflow: hidden;
}

.progress-bar {
    height: 100%;
    background: linear-gradient(90deg, #3b82f6, #10b981);
    width: 0%;
    transition: width 0.4s ease;
}

/* Steps */
.step-container {
    position: relative;
    min-height: 400px;
}

.step {
    display: none;
    animation: fadeIn 0.5s ease forwards;
}

.step.active {
    display: block;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}

/* Typography */
h1 {
    font-size: 2.5rem;
    font-weight: 900;
    line-height: 1.1;
    margin-bottom: 1rem;
    letter-spacing: -0.02em;
}

h1 span {
    background: linear-gradient(to right, #3b82f6, #60a5fa);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

h2 {
    font-size: 1.4rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
    text-align: center;
    letter-spacing: -0.01em;
}

.subtitle {
    color: var(--text-secondary);
    font-size: 1.1rem;
    margin-bottom: 2.5rem;
    text-align: center;
}

.step-note {
    text-align: center;
    color: var(--text-secondary);
    font-size: 0.9rem;
    margin-bottom: 2rem;
}

.note {
    font-size: 0.8rem;
    color: var(--text-secondary);
    margin-top: 1rem;
    opacity: 0.7;
}

/* Welcome Screen */
.welcome-content {
    text-align: center;
    background: var(--card-bg);
    backdrop-filter: var(--backdrop-blur);
    -webkit-backdrop-filter: var(--backdrop-blur);
    border: 1px solid var(--card-border);
    border-radius: 24px;
    padding: 3rem 2rem;
    box-shadow: var(--shadow);
}

/* Sub sections */
.sub-section {
    margin-bottom: 2rem;
}

.section-title {
    font-weight: 600;
    margin-bottom: 1rem;
    font-size: 1.1rem;
}

.text-warning {
    color: var(--warning-color);
}

.alert-box {
    background: rgba(245, 158, 11, 0.1);
    border: 1px solid rgba(245, 158, 11, 0.3);
    border-radius: 12px;
    padding: 1.5rem;
}

.alert-text {
    font-size: 0.85rem;
    color: rgba(255, 255, 255, 0.8);
    margin-bottom: 1rem;
    line-height: 1.5;
}

/* Options Grid */
.options-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 16px;
    margin-bottom: 2rem;
}

.options-grid.two-cols {
    grid-template-columns: 1fr;
}

@media (min-width: 480px) {
    .options-grid.two-cols {
        grid-template-columns: repeat(2, 1fr);
    }
}

.option-card {
    background: var(--card-bg);
    backdrop-filter: var(--backdrop-blur);
    -webkit-backdrop-filter: var(--backdrop-blur);
    border: 1px solid var(--card-border);
    border-radius: 16px;
    padding: 1.5rem 1rem;
    text-align: center;
    cursor: pointer;
    transition: var(--transition);
}

.option-card:hover {
    transform: translateY(-4px);
    border-color: rgba(255, 255, 255, 0.3);
    background: rgba(255, 255, 255, 0.05);
    box-shadow: 0 10px 40px rgba(0, 0, 0, 0.4);
}

.option-card:active {
    transform: translateY(0);
}

.option-card.selected {
    border-color: var(--accent-color);
    background: rgba(59, 130, 246, 0.1);
}

.option-card .icon {
    font-size: 2.5rem;
    margin-bottom: 0.8rem;
}

.option-card h3 {
    font-size: 1.1rem;
    margin-bottom: 0.4rem;
    font-weight: 600;
}

.option-card p {
    font-size: 0.8rem;
    color: var(--text-secondary);
    line-height: 1.4;
}

/* Checkbox */
.checkbox-container {
    display: block;
    position: relative;
    padding-left: 35px;
    cursor: pointer;
    font-size: 0.9rem;
    user-select: none;
}

.checkbox-container input {
    position: absolute;
    opacity: 0;
    cursor: pointer;
    height: 0;
    width: 0;
}

.checkmark {
    position: absolute;
    top: 0;
    left: 0;
    height: 22px;
    width: 22px;
    background-color: rgba(255, 255, 255, 0.1);
    border: 1px solid var(--card-border);
    border-radius: 4px;
    transition: var(--transition);
}

.checkbox-container:hover input ~ .checkmark {
    background-color: rgba(255, 255, 255, 0.2);
}

.checkbox-container input:checked ~ .checkmark {
    background-color: var(--accent-color);
    border-color: var(--accent-color);
}

.checkmark:after {
    content: "";
    position: absolute;
    display: none;
}

.checkbox-container input:checked ~ .checkmark:after {
    display: block;
}

.checkbox-container .checkmark:after {
    left: 8px;
    top: 4px;
    width: 5px;
    height: 10px;
    border: solid white;
    border-width: 0 2px 2px 0;
    transform: rotate(45deg);
}

/* Buttons */
button {
    font-family: inherit;
    cursor: pointer;
    border: none;
    outline: none;
}

button:disabled {
    opacity: 0.5;
    cursor: not-allowed;
    transform: none !important;
    box-shadow: none !important;
}

.btn-primary {
    background: var(--accent-color);
    color: white;
    font-weight: 600;
    font-size: 1.1rem;
    padding: 14px 32px;
    border-radius: 12px;
    transition: var(--transition);
    width: 100%;
    max-width: 300px;
}

.btn-primary:not(:disabled):hover {
    background: var(--accent-hover);
    transform: translateY(-2px);
    box-shadow: 0 4px 15px rgba(59, 130, 246, 0.4);
}

.btn-secondary {
    background: transparent;
    color: var(--text-secondary);
    border: 1px solid var(--card-border);
    padding: 12px 24px;
    border-radius: 12px;
    font-weight: 600;
    transition: var(--transition);
}

.btn-secondary:hover {
    background: rgba(255, 255, 255, 0.05);
    color: white;
}

.btn-text {
    background: none;
    color: var(--text-secondary);
    text-decoration: underline;
    font-size: 0.9rem;
    transition: var(--transition);
}

.btn-text:hover {
    color: white;
}

.step-actions {
    display: flex;
    justify-content: center;
    gap: 1rem;
    margin-top: 1rem;
}

/* Results Screen */
.result-container {
    background: var(--card-bg);
    backdrop-filter: var(--backdrop-blur);
    border: 1px solid var(--card-border);
    border-radius: 24px;
    padding: 2.5rem 2rem;
    text-align: center;
    box-shadow: var(--shadow);
}

.result-subtitle {
    color: var(--text-secondary);
    margin-bottom: 2rem;
}

.price-box {
    background: rgba(0, 0, 0, 0.4);
    border-radius: 16px;
    padding: 2rem 1rem;
    margin-bottom: 1.5rem;
    border: 1px solid rgba(255, 255, 255, 0.05);
}

.price-box .label {
    display: block;
    font-size: 0.9rem;
    color: var(--text-secondary);
    margin-bottom: 0.5rem;
}

.price-box .price {
    font-size: 3rem;
    font-weight: 900;
    color: white;
    display: flex;
    align-items: baseline;
    justify-content: center;
    gap: 4px;
}

.price-box .currency {
    font-size: 1.2rem;
    font-weight: 600;
    color: var(--text-secondary);
}

.details-box {
    margin-bottom: 2.5rem;
    background: rgba(255, 255, 255, 0.02);
    border-radius: 12px;
    padding: 0 1rem;
}

.detail-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 0;
    border-bottom: 1px solid var(--card-border);
}

.detail-item:last-child {
    border-bottom: none;
}

.detail-label {
    color: var(--text-secondary);
    font-size: 0.9rem;
}

.detail-value {
    font-weight: 600;
    font-size: 0.95rem;
    text-align: right;
}

.cta-section p {
    font-size: 0.9rem;
    color: var(--text-secondary);
    margin-bottom: 1.5rem;
}

.line-btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    background: #06C755;
    text-decoration: none;
    width: 100%;
}

.line-btn:hover {
    background: #05b34c;
    box-shadow: 0 4px 15px rgba(6, 199, 85, 0.4);
}

.mt-3 {
    margin-top: 1rem;
    display: inline-block;
    width: 100%;
    text-align: center;
    text-decoration: none;
    box-sizing: border-box;
}

/* Responsive */
@media (max-width: 480px) {
    .options-grid {
        grid-template-columns: 1fr;
    }
    
    h1 {
        font-size: 2rem;
    }

    .price-box .price {
        font-size: 2.5rem;
    }
}