/* ============================================
   03 - Buttons
   ============================================ */

/* --- Base Button --- */
.btn {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 14px 28px;
    border-radius: var(--radius-md);
    font-weight: 600;
    font-size: 1rem;
    cursor: pointer;
    transition: all var(--transition-base);
    border: 2px solid transparent;
    position: relative;
    overflow: hidden;
    font-family: var(--font-body);
}

/* リップルエフェクト */
.btn::before {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    width: 0;
    height: 0;
    border-radius: 50%;
    background: rgba(255, 255, 255, 0.2);
    transform: translate(-50%, -50%);
    transition: width 0.6s, height 0.6s;
}

.btn:hover::before {
    width: 300px;
    height: 300px;
}

/* --- Arrow Icon --- */
.btn-arrow {
    transition: transform var(--transition-base);
}

.btn:hover .btn-arrow {
    transform: translateX(4px);
}

/* --- Size Variant --- */
.btn-large {
    padding: 18px 36px;
    font-size: 1.0625rem;
}

/* --- Color Variants --- */
.btn-primary {
    background: linear-gradient(135deg, var(--primary-blue) 0%, var(--accent-cyan) 100%);
    color: white;
    box-shadow: var(--shadow-lg);
}

.btn-primary:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-xl);
}

.btn-secondary {
    background: white;
    color: var(--primary-blue);
    border: 2px solid white;
}

.btn-secondary:hover {
    background: rgba(255, 255, 255, 0.9);
    transform: translateY(-3px);
}

.btn-black {
    background: var(--text-dark);
    color: white;
    box-shadow: var(--shadow-lg);
}

.btn-black:hover {
    background: #000;
    transform: translateY(-3px);
    box-shadow: var(--shadow-xl);
}

.btn-tiktok {
    background: var(--tiktok-pink);
    color: white;
    box-shadow: var(--shadow-lg);
}

.btn-tiktok:hover {
    background: #FE1C45;
    transform: translateY(-3px);
    box-shadow: 0 20px 25px rgba(254, 44, 85, 0.3);
}

.btn-line {
    background: var(--line-green);
    color: white;
    box-shadow: var(--shadow-lg);
}

.btn-line:hover {
    background: var(--line-green-dark);
    transform: translateY(-3px);
    box-shadow: 0 20px 25px rgba(0, 195, 0, 0.3);
}

.btn-plan {
    background: var(--primary-blue);
    color: white;
}

.btn-plan:hover {
    background: var(--primary-blue-dark);
    transform: translateY(-3px);
}

.btn-plan-popular {
    background: linear-gradient(135deg, var(--primary-blue) 0%, var(--accent-cyan) 100%);
    color: white;
    box-shadow: var(--shadow-xl);
}

.btn-plan-popular:hover {
    transform: translateY(-3px);
    box-shadow: 0 25px 30px rgba(0, 102, 255, 0.4);
}

/* --- Utility --- */
.btn-submit {
    width: 100%;
    justify-content: center;
}