/* 首页样式 - 小石头纠错官网 */

/* 首屏主视觉 */
.hero {
    text-align: center;
    padding: 60px 0 80px;
    color: #fff;
}

.hero h2 {
    font-size: clamp(28px, 5vw, 48px);
    margin-bottom: 20px;
    font-weight: 800;
    line-height: 1.2;
    color: #fff;
}

.hero p {
    font-size: clamp(16px, 2.5vw, 20px);
    margin-bottom: 40px;
    color: rgba(255, 255, 255, 0.95);
}

.download-buttons {
    display: flex;
    gap: 20px;
    justify-content: center;
    flex-wrap: wrap;
    margin-bottom: 60px;
}

.download-btn {
    display: inline-flex;
    align-items: center;
    gap: 12px;
    padding: 16px 32px;
    background: #fff;
    color: #336799;
    text-decoration: none;
    border-radius: 50px;
    font-size: 18px;
    font-weight: 600;
    border: 2px solid #fff;
    transition: transform 0.2s ease, background 0.2s ease, color 0.2s ease, border-color 0.2s ease;
}

.download-btn:hover {
    transform: translateY(-2px);
    background: rgba(255, 255, 255, 0.95);
    color: #2a5280;
}

.download-btn:focus {
    outline: 2px solid #fff;
    outline-offset: 2px;
}

.download-btn .store-logo {
    width: 28px;
    height: 28px;
    object-fit: contain;
    flex-shrink: 0;
}

/* 应用预览 - 手机 mockup */
.app-preview {
    text-align: center;
    margin-bottom: 80px;
}

.phone-mockup {
    position: relative;
    max-width: 280px;
    margin: 0 auto;
    background: linear-gradient(145deg, #e8e8e8 0%, #fff 50%);
    border-radius: 36px;
    padding: 14px;
    box-shadow:
        0 25px 50px rgba(0, 0, 0, 0.25),
        0 0 0 2px rgba(255, 255, 255, 0.1) inset;
    animation: previewFadeIn 0.6s ease-out;
}

@keyframes previewFadeIn {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.screen {
    background: linear-gradient(180deg, #e8ecf1 0%, #d1d9e6 100%);
    border-radius: 24px;
    padding: 24px 16px 36px;
    min-height: 420px;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
}

.screen-content {
    background: #fff;
    padding: 20px 18px;
    border-radius: 14px;
    box-shadow: 0 2px 12px rgba(0, 0, 0, 0.08);
    width: 100%;
    max-width: 220px;
}

.screen-label {
    font-size: 14px;
    font-weight: 600;
    color: #336799;
    margin-bottom: 14px;
    text-align: center;
}

.math-row {
    display: flex;
    align-items: center;
    gap: 10px;
    margin-bottom: 12px;
    padding: 8px 10px;
    border-radius: 10px;
}

.math-row.math-correct {
    background: rgba(72, 187, 120, 0.12);
}

.math-row.math-wrong {
    background: rgba(245, 101, 101, 0.1);
}

.math-check {
    flex-shrink: 0;
    width: 22px;
    height: 22px;
    border-radius: 50%;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    font-size: 14px;
    font-weight: 700;
}

.math-correct .math-check {
    background: #48bb78;
    color: #fff;
}

.math-wrong .math-check {
    background: #f56565;
    color: #fff;
}

.math-example {
    font-size: 18px;
    font-weight: 600;
    color: #2d3748;
    font-family: 'Courier New', Consolas, monospace;
    line-height: 1.4;
}

.math-vertical {
    font-size: 16px;
    letter-spacing: 0.02em;
}

.error-badge {
    margin-top: 12px;
    padding: 6px 12px;
    background: #c53030;
    color: #fff;
    font-size: 13px;
    font-weight: 600;
    border-radius: 20px;
    text-align: center;
}

.phone-home-bar {
    position: absolute;
    bottom: 8px;
    left: 50%;
    transform: translateX(-50%);
    width: 100px;
    height: 4px;
    background: rgba(0, 0, 0, 0.25);
    border-radius: 2px;
}

@media (max-width: 768px) {
    .phone-mockup {
        max-width: 260px;
    }

    .screen {
        min-height: 360px;
        padding: 20px 12px 32px;
    }

    .screen-content {
        padding: 16px 14px;
        max-width: 200px;
    }

    .math-example {
        font-size: 16px;
    }

    .math-vertical {
        font-size: 14px;
    }

    .error-badge {
        font-size: 12px;
        padding: 5px 10px;
    }
}

/* 特性介绍 */
.features {
    background: white;
    padding: 80px 0;
}

.features h2 {
    text-align: center;
    font-size: clamp(28px, 4vw, 42px);
    margin-bottom: 60px;
    color: #333;
}

.feature-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 40px;
}

.feature-card {
    text-align: center;
    padding: 30px;
    border-radius: 16px;
    background: #fff;
    border: 1px solid rgba(51, 103, 153, 0.2);
    box-shadow: 0 2px 8px rgba(0,0,0,0.06);
    transition: transform 0.2s ease, box-shadow 0.2s ease, border-color 0.2s ease;
}

.feature-card:hover {
    transform: translateY(-4px);
    box-shadow: 0 8px 20px rgba(51, 103, 153, 0.15);
    border-color: #66cdcc;
}

.feature-icon {
    width: 80px;
    height: 80px;
    margin: 0 auto 20px;
    background: linear-gradient(-45deg, #66cdcc 0%, #336799 100%);
    border-radius: 20px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 40px;
}

.feature-card h3 {
    font-size: 24px;
    margin-bottom: 12px;
    color: #333;
}

.feature-card p {
    color: #666;
    font-size: 16px;
    line-height: 1.6;
}

/* 年级覆盖 */
.grades {
    padding: 80px 0;
    background: linear-gradient(-45deg, #66cdcc 0%, #336799 100%);
    color: #fff;
}

.grades h2 {
    text-align: center;
    font-size: clamp(28px, 4vw, 42px);
    margin-bottom: 40px;
    color: #fff;
}

.grade-list {
    display: flex;
    justify-content: center;
    gap: 20px;
    flex-wrap: wrap;
    margin-bottom: 30px;
}

.grade-badge {
    padding: 16px 32px;
    background: rgba(255, 255, 255, 0.2);
    border-radius: 50px;
    font-size: 20px;
    font-weight: 600;
    border: 2px solid rgba(255, 255, 255, 0.5);
    color: #fff;
}

.grade-info {
    text-align: center;
    font-size: 18px;
    color: rgba(255, 255, 255, 0.95);
}

/* 响应式 */
@media (max-width: 768px) {
    .hero h2 {
        font-size: 36px;
    }

    .hero p {
        font-size: 18px;
    }

    .download-buttons {
        flex-direction: column;
        align-items: center;
    }

    .download-btn {
        width: 100%;
        max-width: 300px;
    }

    .features h2,
    .grades h2 {
        font-size: 32px;
    }

    .feature-grid {
        grid-template-columns: 1fr;
    }

    .grade-list {
        flex-direction: column;
        align-items: center;
    }

    .grade-badge {
        width: 100%;
        max-width: 200px;
    }
}